Effects of sn-2 Palmitic Triacylglycerols and the Ratio of OPL to OPO in Human Milk Fat Substitute on Metabolic Regulation in Sprague-Dawley Rats

In this study, the influence of total sn-2 palmitic triacylglycerols (TAGs) and ratio of 1-oleoyl-2-palmitoyl-3-linoleoylglycerol (OPL) to 1,3-dioleoyl-2-palmitoylglycerol (OPO) in human milk fat substitute (HMFS) on the metabolic changes were investigated in Sprague-Dawley rats. Metabolomics and lipidomics profiling analysis indicated that increasing the total sn-2 palmitic TAGs and OPL to OPO ratio in HMFS could significantly influence glycine, serine and threonine metabolism, glycerophospholipid metabolism, glycerolipid metabolism, sphingolipid metabolism, bile acid biosynthesis, and taurine and hypotaurine metabolism pathways in rats after 4 weeks of feeding, which were mainly related to lipid, bile acid and energy metabolism. Meanwhile, the up-regulation of taurine, L-tryptophan, and L-cysteine, and down-regulations of lysoPC (18:0) and hypoxanthine would contribute to the reduction in inflammatory response and oxidative stress, and improvement of immunity function in rats. In addition, analysis of targeted biochemical factors also revealed that HMFS-fed rats had significantly increased levels of anti-inflammatory factor (IL-4), immunoglobulin A (IgA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-px), and decreased levels of pro-inflammatory factors (IL-6 and TNF-α) and malondialdehyde (MDA), compared with those of the control fat-fed rats. Collectively, these observations present new in vivo nutritional evidence for the metabolic regulatory effects of the TAG structure and composition of human milk fat substitutes on the host.

Total Sn-2 Palmitic Triacylglycerols and the Ratio of OPL to OPO in Human Milk Fat Substitute Modulated Bile Acid Metabolism and Intestinal Microbiota Composition in Rats

In this study, the impact of sn-2 palmitic triacyclglycerols (TAGs) in combination with their ratio of two major TAGs (1-oleoyl-2-palmitoyl-3-linoleoylglycerol (OPL) to 1,3-dioleoyl-2-palmitoylglycerol (OPO)) in human milk fat substitute (HMFS) on bile acid (BA) metabolism and intestinal microbiota composition was investigated in newly-weaned Sprague-Dawley rats after four weeks of high-fat feeding. Compared to those of control group rats, HMFS-fed rats had significantly increased contents of six hepatic primary BAs (CDCA, αMCA, βMCA, TCDCA, TαMCA and TβMCA), four ileal primary BAs (UDCA, TCA, TCDCA and TUDCA) and three secondary BAs (DCA, LCA and ωMCA), especially for the HMFS with the highest sn-2 palmitic acid TAGs of 57.9% and OPL to OPO ratio of 1.4. Meanwhile, the inhibition of ileal FXR-FGF15 and activation of TGR5-GLP-1 signaling pathways in HMFS-fed rats were accompanied by the increased levels of enzymes involved in BA synthesis (CYP7A1, CYP27A1 and CYP7B1) in the liver and two key thermogenic proteins (PGC1α and UCP1) in perirenal adipose tissue, respectively. Moreover, increasing sn-2 palmitic TAGs and OPL to OPO ratio in HMFS also altered the microbiota composition both on the phylum and genus level in rats, predominantly microbes associated with bile-salt hydrolase activity, short-chain fatty acid production and reduced obesity risk, which suggested a beneficial effect on host microbial ecosystem. These observations provided important nutritional evidence for developing new HMFS products for infants.

Carbohydrate-Based Fat Mimetics Can Affect the Levels of 3-Monochloropropane-1,2-Diol Esters and Glycidyl Esters in Shortbread Biscuits

Shortbread biscuits have become one of the most desirable snacks in all population groups but due to its high fat content it is searching for new solutions of fat reduction such as the use of carbohydrate-based fat mimetics. However, the thermal processing of food containing lipids in the presence of certain carbohydrates can contribute to the formation of toxic compounds or alter its levels. Therefore, the aim of the study was to evaluate the use of inulin and pectin gels as partial fat replacers (10-40%) in classical shortbread biscuits in a view of the changes of 3-monochloropropane-1,2-diol ester (3-MCPDE) and glycidyl ester (GE) levels after baking, and also after a two-months storage. The experiment showed that the amount of inulin gel higher than 10% promoted the endogenous formation of 3-MCPDE probably due to the higher amount of Maillard products formed in the biscuits, but after two months the levels decreased and were comparable with those transferred from shortening. Pectin did not demonstrate such phenomenon, owing to the presence of bound water in gel. Glycidyl esters were partially decomposed during baking and also during storage, particularly in the samples with the addition of pectin gel, which presumably caused by low stability of GE under acidic conditions resulting from the occurrence of galacturonic acid in pectin.

Review of the effects of dilution of dietary energy with olestra on energy intake

The non-absorbable substitute for dietary triacylglycerol, olestra, has been marketed in the United States for fifteen years. Olestra is comprised of sucrose with six to eight of its hydroxyl groups forming ester links with long-chain fatty acids. Because olestra is not hydrolyzed by fat-splitting enzymes in the small intestine, it is not absorbed from the small intestine into blood and tissues, and therefore provides no energy that can be utilized by the body. The hedonic properties of olestra with a specific fatty acid composition are similar to those of a triacylglycerol with the same fatty acid composition. Its use by consumers has been restricted by federal regulation to the commercial preparation of savory snack food items, principally as a frying medium for potato chips. An important question about the substitution of olestra for absorbable fat in the diet is whether the consumer will sense that a smaller amount of energy has been ingested. If it is sensed, thereby providing no satiation, then consuming additional energy in later meals will compensate for the removal of absorbable energy from the diet. If it is not sensed at all, then there is no compensation, and the person reduces caloric intake. This review first summarizes studies with olestra that have focused on its effect on the physiology of appetite. In general these studies have demonstrated that olestra does not influence signals of satiation including cholecystokinin and stomach emptying. The review then discusses studies of food consumption in experimental animals in which olestra was substituted for fat in the diet. Rodents have been repeatedly observed to compensate completely for the substitution of olestra for normal fat by eating more total diet. Most studies of the effect of olestra on human satiation have found incomplete or no compensation through additional energy consumption when olestra was substituted for dietary fat. In two clinical studies, however, complete compensation was observed, suggesting that experimental conditions and individual variability influence the ability to sense the substitution of olestra for absorbable fat. There is no evidence that dietary olestra causes consumption of more energy than would have been consumed without olestra in the diet. The data from animals and humans strongly suggest that the rodent is not a satisfactory model for the human in the determination of the extent of compensation by substitution of olestra for dietary fat.

Fat substitutes promote weight gain in rats consuming high-fat diets

The use of food products designed to mimic the sensory properties of sweet and fat while providing fewer calories has been promoted as a method for reducing food intake and body weight. However, such products may interfere with a learned relationship between the sensory properties of food and the caloric consequences of consuming those foods. In the present experiment, we examined whether use of the fat substitute, olestra, affect energy balance by comparing the effects of consuming high-fat, high-calorie potato chips to the effects of consuming potato chips that sometimes signaled high calories (using high-fat potato chips) and that sometimes signaled lower calories (using nonfat potato chips manufactured with the fat substitute olestra). Food intake, body weight gain and adiposity were greater for rats that consumed both the high-calorie chips and the low-calorie chips with olestra compared to rats that consumed consuming only the high-calorie chips, but only if animals were also consuming a chow diet that was high in fat and calories. However, rats previously exposed to both the high- and low-calorie chips exhibited increased body weight gain, food intake and adiposity when they were subsequently provided with a high fat, high calorie chow diet suggesting that experience with the chips containing olestra affected the ability to predict high calories based on the sensory properties of fat. These results extend the generality of previous findings that interfering with a predictive relationship between sensory properties of foods and calories may contribute to dysregulation of energy balance, overweight and obesity.

Stimulation of fecal fat excretion and the disposal of protoporphyrin in a murine model for erythropoietic protoporphyria

Erythropoietic protoporphyria (EPP) is characterized by toxic accumulation of the hydrophobic compound protoporphyrin (PP). Ferrochelatase-deficient (fch/fch) mice are an animal model for human EPP. Recently, we have demonstrated that the accumulation of another hydrophobic compound, unconjugated bilirubin, could effectively be treated by stimulation of fecal fat excretion. We investigated whether stimulation of fecal fat excretion enhanced the disposal of PP in fch/fch mice. Fch/fch mice were fed for 8 wk with a high-fat diet (16 wt% fat; control) or with the high-fat diet mixed with either a nonabsorbable fat (sucrose polyester) or the intestinal lipase inhibitor orlistat. The effects of the treatments on fecal excretion of fat and PP and on hepatic PP concentrations were compared with control diets. Fecal fat excretion in fch/fch mice on a high-fat diet was higher than in mice on a low-fat diet (+149%, P < 0.05). Sucrose polyesters and orlistat increased fecal fat excretion even more, up to sixfold of control values. However, none of the different treatments affected fecal PP excretion or hepatic PP concentration. Treatment of fch/fch mice with a high-fat diet, a nonabsorbable fat diet, or with orlistat increased the fecal excretion of fat but did not increase fecal PP excretion or decrease hepatic PP concentration. The present data indicate that accumulation of PP is not amenable to stimulation of fecal fat excretion.

Effect of fat replacement by inulin or lupin-kernel fibre on sausage patty acceptability, post-meal perceptions of satiety and food intake in men

The present study examined whether replacing fat with inulin or lupin-kernel fibre influenced palatability, perceptions of satiety, and food intake in thirty-three healthy men (mean age 52 years, BMI 27·4kg/m2), using a within-subject design. On separate occasions, after fasting overnight, the participants consumed a breakfast consisting primarily of either a full-fat sausage patty (FFP) or a reduced-fat patty containing inulin (INP) or lupin-kernel fibre (LKP). Breakfast variants were alike in mass, protein and carbohydrate content; however the INP and LKP breakfasts were 36 and 37% lower in fat and 15 and 17% lower in energy density respectively compared with the FFP breakfast. The participants rated their satiety before breakfast then evaluated patty acceptability. Satiety was rated immediately after consuming the breakfast, then over the subsequent 4·5h whilst fasting. Food consumed until the end of the following day was recorded. All patties were rated above ‘neither acceptable or unacceptable’, however the INP rated lower for general acceptability (P=0·039) and the LKP lower for flavour (P=0·023) than the FFP. The LKP breakfast rated more satiating than the INP (P=0·010) and FFP (P=0·016) breakfasts. Total fat intake was 18g lower on the day of the INP (P=0·035) and 26g lower on the day of the LKP breakfast (P=0·013) than the FFP breakfast day. Energy intake was lower (1521kJ) only on the day of the INP breakfast (P=0·039). Both inulin and lupin-kernel fibre appear to have potential as fat replacers in meat products and for reducing fat and energy intake in men.

Treatment with a dietary fat substitute decreased Arochlor 1254 contamination in an obese diabetic male

A case manifesting symptoms due to organochlorine toxicity was treated with the fat substitute olestra in his diet. Before treatment, the patient was obese, with severe type 2 diabetes mellitus and mixed hyperlipidemia, chloracne, frequent headaches, and numbness and paraesthesias of his trunk and lower limbs. Earlier attempts at weight loss had been unsuccessful due to worsening of his symptoms. After inclusion of olestra in his diet for 2 years, weight loss was successful without aggravation of his symptoms, and the patient reverted to normoglycemia and normolipidemia. Olestra may have assisted weight loss and amelioration of his diabetes by increasing fecal elimination of organochlorines, rather than by preventing the partitioning of these pollutants into tissues, where they have been reported to exert antimetabolic effects on substrate oxidation.

Daily intake of multivitamins during long-term intake of olestra in men prevents declines in serum vitamins A and E but not carotenoids

The objective of this study was to determine whether vitamin supplementation during long-term (36 wk) ingestion of olestra supplemented with vitamin E could prevent decreases in vitamin E, vitamin A, and carotenoids. This was a 36-wk study of 37 healthy males randomly assigned to consume a control diet composed of 33% energy from fat, a similar diet in which one third of the energy from fat had been replaced with olestra, or a fat-reduced (25% of energy from fat) diet. Subjects also ingested a daily multivitamin (Centrum). Serum concentrations of alpha-tocopherol, retinol, beta-carotene, lycopene, and lutein + zeaxanthin were analyzed by HPLC. Subjects eating the olestra-containing diet had substantial decreases in serum beta-carotene, lycopene, and lutein + zeaxanthin, which occurred by 12 wk; these changes were found despite correcting for serum total cholesterol or BMI. Serum beta-carotene and lycopene concentrations were below the lower limit of the reference range (<0.186 and <0.298 mumol/L, respectively) at one or more time points. The slight decline in serum alpha-tocopherol concentration, significant at 24 wk, was caused by the decline in serum cholesterol. Retinol concentrations decreased with time in all 3 groups, but were not affected by olestra. We conclude that supplementation with a multivitamin containing vitamins A and E was adequate to prevent olestra-induced decrease in serum alpha-tocopherol and retinol. Olestra-induced decreases in serum beta-carotene, lycopene, and lutein + zeaxanthin were not prevented by the vitamin supplement used in this study.

Effects of yo-yo diet, caloric restriction, and olestra on tissue distribution of hexachlorobenzene

Chlorinated hydrocarbons are lipophilic, toxic, and persistent in the environment and animal tissues. They enter the body in food and are stored in adipose tissue. Loss of body fat through caloric restriction mobilizes stored lipophilic xenobiotics and results in distribution to other tissues. We have studied the reversibility of this process in mice that followed a regimen of body weight cycling. Weight gain was followed by weight loss, a second gain, and a second loss ("yo-yo diet regimen"). We measured the distribution of orally gavaged [14C]hexachlorobenzene, which is sparingly metabolized. We found that weight cycling has different effects in different organs. Continued weight loss resulted in a threefold increase of 14C amount and concentration in the brain. After weight regain, 14C in the brain decreased but then increased again after a second weight loss. Weight loss resulted in an increase in the concentration of 14C in adipose tissue without changing the total amount in that tissue. Weight loss and regain resulted in an increase of 14C in the liver, which reflected an increase of fat in the liver. The regimen of weight gain and loss was repeated in mice gavaged with [14C]hexachlorobenzene, with one group receiving the nonabsorbable fat olestra in the diet. Combined dietary olestra and caloric restriction caused a 30-fold increase in the rate of excretion of 14C relative to an ad libitum diet or a reduced caloric diet alone. Distribution of 14C into the brain resulting from the restricted diet was reduced by 50% by dietary olestra.

Intestinal alkaline phosphatase release is not associated with chylomicron formation

Intestinal alkaline phosphatase (IAP) is one of the major sources of alkaline phosphatase in circulation. It is secreted into the intestinal lumen, serum, and lymph. After the ingestion of lipid, lymphatic alkaline phosphatase secretion increases significantly. We have found that the nonabsorbable fat olestra is unable to stimulate lymphatic alkaline phosphatase secretion. We also found that the hydrophobic surfactant Pluronic L-81, which blocks chylomicron formation, fails to inhibit this increase in lymphatic alkaline phosphatase secretion. These results suggest that it is the lipid uptake into the mucosa and/or reesterification to form triacylglycerols, but not the formation of chylomicrons, that is necessary for the stimulation of the secretion of alkaline phosphatase into the lymph.

Modifications in cyclosporine (CsA) microemulsion blood concentrations by olestra

OBJECTIVE

Determine whether olestra alters the absorption of cyclosporine microemulsion in pediatric renal transplant recipients.

DESIGN

Prospective, open-label, crossover pharmacokinetic study.

SETTING

General clinical research center in a university medical setting providing tertiary care.

PARTICIPANTS

Seven pediatric-adolescent renal transplant recipients, ages 9 to 18, 5 to 24 months post-transplant with mean serum creatinine of 0.9 mg/dL (range, 0.7-1.6 mg/dL).

METHODOLOGY

Patients participated in 2 study periods: 1. Patients were given their usual dose of Neoral (Novartis Pharmaceuticals Corporation, East Hanover, NJ) without olestra, 2. patients were given their usual dose of Neoral combined with 0.35 g/kg (maximum of 16 g of olestra or approximately 2 ounces of Lays WOW [Frito Lay, Plano, TX] potato chips). The 2 study periods were separated by a minimum 7-day washout period. CsA blood concentrations were obtained at 1, 2, 3, 4, 6, 8, and 12 hours after drug administration.

RESULTS

Each patient in the study had a consistent decrease in area under the curve (AUC) when given olestra along with their usual dose of Neoral, compared with giving Neoral alone (5,018 ng*hr/mL versus 4,086 ng*hr/mL; P <.001). There also was a decrease in maximum concentration (Cmax) when Neoral was given with olestra compared with giving Neoral alone (1,202 ng/mL versus 876 ng/mL; P =.015). There was no statistical difference in the mean elimination rate or the trough values for both regimens (half-life 4.767 hours versus 4.771 hours and trough levels of 143 ng/mL versus 124 ng/mL).

CONCLUSION

Olestra decreases total CsA exposure in pediatric renal transplant recipients. The noted decrease in AUC was not adequately predicted by CsA trough values which could lead to rejection episodes in the clinical setting.

A role for olestra in body weight management

Olestra is a fat substitute made from fatty acids esterified to sucrose and can be used in the preparation of virtually any food made with fat. Foods made with olestra retain the mouthfeel, palatability and satiating effects of their full-fat counterparts without providing any digestible energy. Because olestra provides no energy, it has the potential to be a useful tool in weight loss and weight maintenance. Short-term studies of olestra replacement in foods demonstrate that fat replacement leads to a net reduction in fat intake. When excess total energy is available, fat replacement also reduces total energy intake in lean and obese men and women. In longer-term studies in which olestra is incorporated into the daily diet, there is an incomplete compensation for the fat energy replaced by olestra. When overweight men consumed olestra as part of a varied diet over nine months, weight loss continued for the duration of the study, whereas individuals receiving a typical low-fat diet regained most of the initial weight lost. Other studies are underway to examine the usefulness of olestra in long-term weight maintenance following weight loss. Post-marketing surveillance of olestra foods in the United States indicates that substitution of olestra for only 1-2 g of fat d-1 may be sufficient to prevent the average weight gain reported in adults of 0.5-1.0 kg year-1.

Substrate oxidation and control of food intake in men after a fat-substitute meal compared with meals supplemented with an isoenergetic load of carbohydrate, long-chain triacylglycerols, or medium-chain triacylglycerols

BACKGROUND

It has been suggested that hunger may be delayed and food intake reduced under metabolic conditions that spare carbohydrate oxidation.

OBJECTIVE

Our objective was to examine the role of glucose metabolism in the control of food intake in men by using medium-chain triacylglycerols (MCTs) to spare carbohydrate oxidation.

DESIGN

In 10 male volunteers, isolated and deprived of any time cues, we studied the effects of 4 lunches on hunger ratings, the duration of satiety, the amount of food ingested at dinner, energy expenditure, substrate oxidation, and plasma variables until the time of the dinner request. One lunch was a basic 2310-kJ meal containing 40 kJ fat substitute (Sub lunch). The 3 other lunches consisted of the same basic meal supplemented with either 1200 kJ long-chain triacylglycerols (LCT lunch), 1200 kJ MCTs (MCT lunch), or 900 kJ carbohydrate plus 300 kJ LCTs (Cho lunch).

RESULTS

Energy expenditure was not significantly different after the different lunches, but carbohydrate oxidation was lower after the MCT and LCT lunches than after the Cho lunch. Fat oxidation was greater after the MCT and LCT lunches. The time of the dinner request was significantly delayed after the Cho lunch. Food intake at dinner was significantly lower after the MCT lunch than after the Sub and Cho lunches, but the dinner meal request was not delayed.

CONCLUSION

Carbohydrate may have a greater role in the duration of satiety than does fat, but MCTs may play an active role in other aspects of the control of food intake, especially in satiation at the next meal.

The effect of ingesting olestra-based foods on feeding behavior and energy balance in humans

This article reviews currently published works on the effects of olestra on appetite and energy intake (EI) in humans. To date 24 studies have examined the impact of olestra-containing foods on aspects of feeding behavior, which are published in 20 reports. The general response of human subjects to olestra-based decreases in dietary energy density (ED) is either poor caloric compensation or partial (nonmacronutrient specific) increases in EI. Averaging the degree of energy compensation across 22 studies gives a value of 27% (nonweighted mean). In studies where compensation occurred, fat intake but not EI was reduced. These effects appear to occur in both lean and obese, men and women and under a variety of conditions ranging from the laboratory to real life. However, all but two of these studies were short term. One study suggests that in subjects to whom weight loss is desirable these deficits can persist for up to 3 months. Subjects with no wish to lose weight may compensate better over longer periods. In another 3-month study, ingestion of olestra-based foods did not induce energy deficits but limited the significant weight gain seen on a full-fat control. The longer term effects of olestra on body weight requires further investigation. There is evidence that restrained eaters tend to eat slightly more of olestra-based foods if they know that they are reduced in fat and energy. This is probably a general response to low-fat foods rather than to olestra per se. The fact that olestra-based foods have the potential to provide the sensory qualities of real fat suggests that these foods may be particularly effective in habitual high-fat consumers with a sensory preference for dietary fat.

Olestra consumption does not predict serum concentrations of carotenoids and fat-soluble vitamins in free-living humans: early results from the sentinel site of the olestra post-marketing surveillance study

In 1996, the U.S. Food and Drug Administration approved olestra, a fat substitute, for use in snack foods. Previous studies had shown that olestra consumption could reduce absorption of carotenoids and fat-soluble vitamins. To determine the association between consumption of olestra-containing snack foods and serum concentrations of carotenoids and fat-soluble vitamins in a free-living population, we interviewed independent population-based cross-sectional samples of 1043 adults before olestra was available and 933 adults 9 mo after olestra snacks were introduced into the marketplace in Marion County, IN, the first major test market for olestra. A cohort composed of 403 adults from the first survey, oversampling those most frequently reporting olestra consumption during follow-up telephone interviews, completed a second survey. We assessed diet, lifestyle factors and olestra consumption, and collected blood for assays for the serum concentrations of six carotenoids, four fat-soluble vitamins and lipids. Nine months after the introduction of olestra into the marketplace, 15.5% of Marion County residents reported consuming an olestra-containing snack in the previous month, with a median frequency among consumers of 3.0 times per month. There were no significant associations or consistent trends for decreased serum carotenoids or fat-soluble vitamins associated with olestra consumption, although cohort members consuming >/=2 g/d of olestra had adjusted total serum carotenoids 15% lower compared with baseline. There were increases in serum vitamin K concentrations associated with olestra consumption (P = 0.03 in the cross section and P = 0.06 in the cohort). In summary, there was no statistically significant evidence in this free-living population of associations between olestra consumption and decreased serum concentrations of carotenoids and fat-soluble vitamins.

Effects of wheat bran and Olestra on objective measures of stool and subjective reports of GI symptoms

OBJECTIVE

The aim of this study was to compare the effects of two nondigested, nonabsorbed dietary components on objective and subjective measures of gastrointestinal (GI) function.

METHODS

A placebo-controlled parallel study compared the effects of wheat bran (20 g/day or 40 g/day in cereal), a well-known dietary fiber, with those of olestra (20 g or 40 g/day in potato chips), a nonabsorbed fat, on stool output, stool apparent viscosity (log peak force for extrusion [PF]), stool water content, and GI symptoms. Sixty subjects resided on a metabolic ward for 9 days: 3 days baseline and 6 days treatment.

RESULTS

Compared with placebo, consumption of 20 g/day wheat bran for 6 days resulted in a rapid (within 38 h) increase in mean (+/-SE) stool output (placebo, 150 +/- 29 g/day; bran, 246 +/- 35 g/day, p < 0.05), a directional increase in mean stool water content (placebo, 81.2 +/- 0.8%; bran, 83.9 +/- 0.8%), stool water output (placebo, 159 +/- 54 g/day; bran, 238 +/- 30 g/day), and bowel movement frequency (BM/day) (placebo, 2.2 +/- 0.4; bran, 2.6 +/- 0.4), and no stool-softening effect (placebo log PF, 2.9 +/- 0.1 g; bran log PF, 2.9 +/- 0.1 g). Wheat bran 40 g/day results were not significantly different from wheat bran 20 g/day. Compared with placebo, consumption of olestra 20 g/day and 40 g/day for 6 days showed no significant difference in mean stool output (151 +/- 18 g/day and 204 +/- 28 g/day, respectively), mean BM frequency (1.8 +/- 0.2 BM/day and 2.1 +/- 0.3 BM/day, respectively), and stool water output (138 +/- 13 g/day and 184 +/- 31 g/day, respectively), a significant (p < 0.05) decrease in stool water content (75.5 +/- 1.7% and 72.6 +/- 2.2%, respectively), and either no effect on stool apparent viscosity (olestra 20 g/day, mean log PF, 3.0 +/- 0.1 g) or a gradual stool-softening effect beginning study day 6 (olestra 40 g/day, log PF, 2.7 +/- 0.1 g). None of the treatment groups showed a significant increase in GI symptoms compared with placebo.

CONCLUSIONS

Consumption of wheat bran in excess of levels in a typical Western diet significantly increased stool output, but did not soften normal-viscosity stool nor result in an increase in common GI symptoms. The observed plateau effect for wheat bran at 40 g/day suggests a maximal mechanical stimulatory effect. Consumption of olestra in excess of usual snacking conditions did not result in a significant increase in stool output or common GI symptoms. At the highest level tested, olestra resulted in a gradual stool-softening effect after several days of consumption.

Effects of dietary fibre and olestra on regional apparent viscosity and water content of digesta residue in porcine large intestine

BACKGROUND

Increased consumption of non-digested, non-absorbed substrates, such as dietary fibre, can lead to an increase in colonic transit rate and stool output. The effects of dietary fibre and olestra on the consistency and water content of digesta residue within the large bowel were not known.

AIM

The aim of this study was to determine the effects of dietary fibre and olestra on regional dehydration and apparent viscosity of digesta residue throughout the large bowel.

METHODS

Seventy-eight pigs were fed diet alone (control) or supplemented with 40 g/day or 80 g/day dietary fibre or olestra and sacrificed 24, 48, 96 or 192 h after initiation of dosing. The large bowel was removed, divided into 13 segments, and the digesta residue/stool was analysed for apparent viscosity (peak force for extrusion) and percentage water content.

RESULTS

In control animals, digesta residue occurred as a continuum, from liquid in the cecum (87.9% water) to solid in the rectum (71. 5% water). The relatively small decrease in percentage water content (16.4%) resulted in a marked increase in mean apparent viscosity (liquid = 87 g peak force; solid=3919 g peak force). Dietary fibre increased the percentage water content of digesta residue throughout the large bowel. In contrast, olestra decreased the percentage water content of digesta residue in the mid and distal large bowel. At 40 g/day, dietary fibre showed a significant (P < 0.05) digesta residue/stool softening effect for all time points, beginning at 24-h (single dose). Olestra 40 g/day did not significantly soften digesta residue/stool until 48 h (2 doses, P < 0.05), and was not different from control at 96 h. At 80 g/day, both dietary fibre and olestra significantly (P < 0.01) softened digesta residue/stool at all time points. There were no liquid or oily stools at any dose or time-point.

CONCLUSIONS

Relatively small changes in water content result in large changes in digesta residue/stool apparent viscosity. Dietary fibre increased digesta residue/stool water content throughout the bowel, resulting in softer digesta residue/stool. In contrast, olestra decreased stool water content, yet had a similar stool softening effect compared to dietary fibre.

Olestra consumption is not associated with macular pigment optical density in a cross-sectional volunteer sample in Indianapolis

The associations between the intake of the fat-substitute olestra and the concentrations of macular carotenoid pigments and serum lutein and zeaxanthin were investigated in a volunteer cross-sectional sample in Indianapolis. The study was conducted in January through March, 1998 after olestra-containing savory snacks had been sold in central Indiana for a year. Volunteers (n = 280) aged 18-50 y were recruited to make a single clinic visit during which macular pigment optical density (MPOD) was determined by psychophysical flicker photometry, serum was obtained for determination of lutein and zeaxanthin concentration, usual intake of olestra, carotenoids and nutrients were assessed by 1-y food frequency questionnaire, and health habits including smoking, physical characteristics such as eye color, demographics and medical history were determined by questionnaire. Intake of olestra at least one time per month for the past year was reported by 81:280 subjects and their mean, median and 90(th) percentile intakes were 1.09, 0.34 and 2.43 g olestra/d, respectively. Mean macular pigment optical density was not significantly different between olestra consumers and nonconsumers (0.213 +/- 0.014 vs. 0.211 +/- 0.010) nor was serum lutein and zeaxanthin concentration (0.361 +/- 0.017 vs. 0.375 +/- 0. 013 micromol/L) or intake (1242 +/- 103 mg/d vs. 1042 +/- 58 mg/d) in one-way or two-way ANOVA. Olestra intake was not associated with MPOD or serum lutein and zeaxanthin before or after correction for significant covariates of MPOD. Thus, olestra intake over the past year in a cross-sectional volunteer sample in Indianapolis was not associated with MPOD.

Positive results on tests for steatorrhea in persons consuming olestra potato chips

BACKGROUND

Olestra is a nonabsorbable fat substitute that consists of fatty acids esterified to a sucrose molecule.

OBJECTIVE

To determine the effect of olestra consumption on measurements of fecal fat excretion.

DESIGN

Controlled cross-over trial.

SETTING

Clinical research center and outpatient research laboratory.

PARTICIPANTS

10 healthy volunteers.

INTERVENTION

On days 1 to 6 of the study, participants consumed 5 oz of conventional potato chips per day; on days 7 to 12, they consumed 5 oz of potato chips containing 40 g of olestra per day.

MEASUREMENTS

Quantitative measurement of fecal fat by the van de Kamer titration, van de Kamer gravimetric, and Jeejeebhoy gravimetric methods and qualitative assessment of fecal fat by Sudan III staining.

RESULTS

Excellent correlation was seen among the three quantitative assays, but the van de Kamer titration method yielded lower measurements than the two gravimetric methods. When participants consumed 40 g of olestra per day, the excretion of fecal fat increased to levels observed in patients with steatorrhea caused by the malabsorption syndrome.

CONCLUSION

Consumption of olestra can cause false-positive results on tests for steatorrhea and may therefore lead to an erroneous diagnosis of the malabsorption syndrome.

Effect of the moderate consumption of olestra in patients receiving long-term warfarin therapy

We conducted a prospective, randomized, double-blind, placebo-controlled, parallel-group trial to evaluate the effect of the moderate consumption of snacks containing olestra on the international normalized ratio (INR) in 40 patients receiving long-term warfarin therapy. Patients continued their warfarin regimen and were assigned to receive 1.5 servings/day (42 g) for 2 weeks of Pringles Original Flavor Fat Free Potato Crisps with Olean (12 g olestra/1.5 servings) or Pringles Original Flavor Potato Crisps (placebo group). Patients' INRs were measured weekly for 2 weeks. Thirty-six patients completed the first week of the trial. After 1 week, the mean change in the INR from baseline increased by 0.02 +/- 0.5 in the olestra group and by 0.17 +/-0.4 in the placebo group (p= 0.327). Ten patients in the olestra group and 12 in the placebo group completed the second week of the study. Mean change in the INR from baseline was similar at week 2, -0.18 +/- 0.38 and 0.09 +/- 0.53 (p=0.193), respectively. Gastrointestinal side effects (diarrhea, gas, bloating) occurred in three patients in the olestra group and five in the placebo group (p=0.3). Moderate consumption of snacks containing olestra did not significantly affect the INR (> 0.3 U) at 1 week in patients receiving long-term anticoagulation with warfarin. It does not appear that moderate consumption of these snacks would affect the INR after 2 weeks, but this must be confirmed in a larger sample with adequate power at 2 weeks.

Olestra formulation and the gastrointestinal tract

Olestra is a mixture of compounds comprising sucrose esterified with 6-8 long-chain fatty acids. It is not hydrolyzed by pancreatic lipase and as a result is not absorbed from the small intestine. Olestra in general has physical properties similar to those of a triacylglycerol with the same fatty acid composition. Foods made with olestra are virtually identical in taste and texture to those made with typical triacylglycerols. Olestra consumption does not generate hydrolytic products in the small intestine and, therefore, does not generate some of the signals that alter motility in the gastrointestinal tract. A reduction in gastroesophageal reflux with olestra, in contrast to triacylglycerols, is consistent with a lack of effect on stomach emptying. Unlike triacylglycerols that are absorbed in the proximal small intestine, olestra is distributed throughout the small intestine during transit and passes into the colon. In the colon, olestra's effects depend on its physical properties. Liquid nondigestible lipids result in separation of oil from the fecal matrix. Olestra formulations made with specific fatty acid compositions, particularly those containing a solid sucrose polyester component including behenic acid, possess appropriate rheology to hinder separation of oil from the rest of the fecal matrix, thereby reducing gastrointestinal symptoms.

Comparison of effects on colonic motility and stool characteristics associated with feeding olestra and wheat bran to ambulatory mini-pigs

The goal of this study was to compare the stool-softening effects of olestra and wheat bran and to determine if changes in patterns of propagating colonic motility were associated with the observed stool softening. Mini-pigs were fed chow (control) or chow supplemented with olestra (80 g/day) or wheat bran (80 g/day) for four days. Proximal colonic motility was monitored continuously, stool viscosity and fecal output measured daily, and cecal-to-anal transit time determined. Compared to controls, olestra and wheat bran significantly softened stool but had no effect on fecal wet weight or colonic transit time. Neither olestra nor wheat bran changed the number of propagating contractions per day, amplitude, motility index, propagation velocity, or the relative distribution of fast and slow propagating contractions. Our data suggest that the stool-softening effects of olestra and wheat bran are not due to direct stimulation of propagating contractions in the colon of the mini-pig.

Demographic, dietary and lifestyle factors differentially explain variability in serum carotenoids and fat-soluble vitamins: baseline results from the sentinel site of the Olestra Post-Marketing Surveillance Study

Biochemical measures of nutrients or other dietary constituents can be an important component of nutritional assessment and monitoring. However, accurate interpretation of the nutrient concentration is dependent on knowledge of the determinants of the body pool measured. The purpose of this study was to identify the determinants of serum carotenoid and fat-soluble vitamin concentrations in a large, community-based sample (n = 1042). Multiple linear regression analysis was used to examine effects of demographic characteristics (age, sex, race/ethnicity, education), health-related behavior (exercise, sun exposure, smoking, alcohol consumption), and intake (diet, supplements) on serum retinol, 25-hydroxyvitamin D, alpha-tocopherol, phylloquinone, and carotenoid concentrations. Age, sex, race/ethnicity, vitamin A intake, and alcohol consumption were found to be determinants of serum retinol concentration. Race/ethnicity, vitamin D intake, body mass index, smoking status, and sun exposure were determinants of serum 25-hydroxyvitamin D concentration. Determinants of serum alpha-tocopherol were age, sex, race/ethnicity, alpha-tocopherol intake, serum cholesterol, percentage of energy from fat (inversely related), supplement use, and body mass index. Age, sex, phylloquinone intake, serum triglycerides, and supplement use were determinants of serum phylloquinone concentration. Primary determinants of serum carotenoids were age, sex, race/ethnicity, carotenoid intake, serum cholesterol, alcohol consumption, body mass index, and smoking status. Overall, the demographic, dietary, and other lifestyle factors explained little of the variability in serum concentrations of retinol (R2 = 0.20), 25-hydroxyvitamin D (R2 = 0.24), and the carotenoids (R2 = 0.15-0.26); only modest amounts of the variability in serum phylloquinone concentration (R2 = 0.40); and more substantial amounts of the variability in serum alpha-tocopherol concentration (R2 = 0.62).

Transient overconsumption of novel foods by deafferentated rats: effects of novel diet composition

We recently demonstrated that capsaicin-treated rats consume more of an unfamiliar high-fat diet than vehicle-treated controls, but only on initial exposure (Chavez et al, 1997). We hypothesized that negative feedback signals carried by capsaicin-sensitive visceral afferents are critical for the regulation of intake of novel foods, but redundant pathways take over during subsequent exposures. To examine the role of nutrient content of the novel diet, rats were systemically treated with capsaicin (n = 15) or vehicle (n = 10), and exposed to 1) a fat/olestra diet that was isocaloric with chow; 2) a readily accepted fat-free cake; and 3) pure corn oil. Each 3-h feeding trial was preceded by 24-h food deprivation. Treated rats did not overconsume familiar chow, but did consume 50% more than controls of both the fat/olestra diet and the corn oil on first exposure; this suggests that capsaicin eliminated visceral afferents that normally carry satiety signals. However, the effect with the fat/olestra mixture was due primarily to depressed intake by controls, unlike the pure fat diets; this apparent neophobic response was blunted in treated rats. Because treated rats failed to overconsume the fat-free cakes, the neural system damaged by capsaicin appears to be linked to energy or fat sensory mechanisms, and possibly to hedonic responsiveness.

A 3-month, double-blind, controlled trial of feeding with sucrose polyester in human volunteers

Sucrose polyester (SPE) is a tasteless, odourless substance which reduces plasma cholesterol concentrations and may therefore be valuable as a fat substitute in human foodstuffs. It has recently been approved for use in snack foods by the United States Federal Drug Administration. The current study was designed to investigate its effects on gastrointestinal physiology and nutrient absorption in human subjects. A 6-month (2 x 3-month periods) double-blind, placebo-controlled, randomized, cross-over trial of SPE and control fat was performed in healthy free-living volunteers. Subjects consumed 20-40 g of SPE daily (mean 26.8 (SE 6.8) g) which reduced the intake of total and saturated fat but had no effect on energy intake or body weight. Plasma cholesterol and triacylglycerols were reduced. The frequency of bowel movements and their urgency were increased and anal leakage occurred in 7.2% of subjects. Abdominal pain was more frequent in subjects receiving SPE and was significantly greater than in the control group after 8 weeks feeding. The plasma concentrations of vitamin E and six carotenoids were significantly reduced. Routine haematology and biochemistry, other vitamins, intestinal biopsies, bile-salt retention, rectal prostaglandins, fractional Ca absorption and aminopyrine metabolism were unaffected. The ingestion of foods containing 20-40 g SPE daily provoked significant gastrointestinal problems. This intake is greater than that to be expected from the use of SPE in savoury snack foods, for which it has been approved by the United States Federal Drug Administration. However, the favourable effects on lipid profiles must be balanced against the reduction in the concentrations of vitamins and carotenoids, as these compounds may have beneficial effects on health through protection from free-radical oxidative stress.

Effects of 14 d of covert substitution of olestra for conventional fat on spontaneous food intake

We conducted a double-blind, placebo-controlled, within-subject crossover study to investigate the effects of covert substitution of olestra, a non-energy-containing fat replacer, for conventional fat on food selection and energy intake in lean and obese men and women. Fifty-one subjects [BMI (kg/m2): 19-36; age: 25-63 y] were studied during two 14-d treatment periods (olestra and placebo), with a 7-d washout between feeding periods. During the intervention periods all foods were provided to the subjects. The aim was to produce a 10% dilution of total energy intake by replacing conventional triacylglycerol with olestra. To accomplish this, subjects were required to consume core foods providing 20-35 g olestra (depending on estimated energy needs) or the same foods containing placebo triacylglycerol. Additional items could be selected from foods that varied in macronutrient composition. When the two treatment periods were compared, total energy intake was 8% lower and fat intake 11% lower during the olestra period than during the placebo treatment period (P < 0.0001). Overall, subjects compensated for 15% of the fat and 20% of the total energy replaced by olestra. In absolute terms, subjects consumed 32% of total energy from fat during the placebo period and 27% of total energy from fat during the olestra period. Neither carbohydrate nor protein intake (g/d) differed between periods. The results did not differ as a function of BMI (lean compared with obese) or sex. Over a 2-wk period, covert substitution of olestra for conventional fat led to reductions in dietary fat intake and total energy intake in all subjects.

Update on the pharmacotherapy of obesity

OBJECTIVE

To review recent developments in the pharmacotherapy of obesity, including the agents currently approved for use in the management of obesity and those under development.

DATA SOURCES

A MEDLINE search from January 1990 to July 1997 was conducted to identify English literature available on the pharmacotherapy of obesity. The search was supplemented by a review of the bibliographies of identified literature.

STUDY SELECTION

All controlled and uncontrolled trials were reviewed. When available, double-blind, placebo-controlled trials were used preferentially.

DATA EXTRACTION

Agents were reviewed with regard to mechanism of action, clinical trial data regarding efficacy, adverse effects, pharmacokinetics, drug interactions, and contraindications where information was available. Study design, selected population, results, and adverse effect information were included.

DATA SYNTHESIS

The anorexiants currently available or under development for the management of obesity regulate food intake and satiety via the adrenergic and/or serotonergic pathways. Clinical trials have shown a 10-15% weight loss can typically be anticipated; however, little long-term safety and efficacy data are available. Adverse events tend to be mild and self-limiting, but serious adverse events can occur. Treatment options under development include thermogenic agents, digestive inhibitors, and analogs and antagonists of hormones that regulate food intake and satiety.

CONCLUSIONS

Several mechanisms to control weight are currently under investigation for the management of obesity. Since obesity is a chronic condition, further studies should be conducted to evaluate the long-term safety and efficacy of these agents and the role of combination therapy using different modalities.

A randomized, double-blind study of the effect of olestra on disease activity in patients with quiescent inflammatory bowel disease. Olestra in IBD Study Group

PURPOSE

To determine the effects of olestra, a zero-calorie fat substitute that is neither digested nor absorbed, on the well-being and disease state of persons with chronic inflammatory bowel disease (IBD) in remission.

PATIENTS AND METHODS

Eighty-nine patients with mild to moderate ulcerative colitis (n = 43) or Crohn's disease (n = 46) in remission, with a history of disease of 2 years or longer, were enrolled in this prospective study from nine private practices, three university-based medical centers, and one Veterans Administration medical center in the United States. Forty-four patients were randomly assigned to receive olestra and 45 to receive triglycerides in chips or cookies daily for 4 weeks. At Week 4, patients were classified as in remission, worsened, or relapsed according to an investigator's global assessment based on sigmoidoscopy (for ulcerative colitis) or the Crohn's disease activity index, laboratory findings, and clinical course.

RESULTS

At Week 4, the olestra and triglyceride groups did not differ significantly with respect to the percentages of patients who relapsed (P = 0.494; difference = 2.4%; upper 95% CL = 8.8%) or with respect to the percentages of patients who experienced any worsening of their symptoms (P = 0.630; difference = 0.2%; upper 95% CL = 13.3%). Of evaluable patients, 90% (37 of 41) given olestra remained in remission with no worsening, compared with 90% (38 of 42) given triglycerides. Gastrointestinal symptoms were comparable between the treatment groups, and there were no treatment-related laboratory abnormalities. Six patients were excluded from analysis for reasons unrelated to treatment.

CONCLUSION

Olestra did not affect the activity of quiescent mild to moderate IBD.

Olestra affects serum concentrations of alpha-tocopherol and carotenoids but not vitamin D or vitamin K status in free-living subjects

Normal, healthy, free-living adults ingested either 18 g/d olestra, with or without 1.1 mg tocopheryl acetate/g olestra, or 18 g/d triglyceride placebo, for 16 wk in a double-blind, placebo-controlled study. Serum concentrations of alpha-tocopherol, alpha-carotene, beta-carotene, lycopene, lutein/zeaxanthin, retinol and cholesterol were measured biweekly. Serum 25-hydroxyvitamin D concentration, prothrombin time, partial thromboplastin time and plasma concentration of functional prothrombin (Simplastin-Ecarin assay) were measured at wk 0, 8 and 16. Relative to the placebo group, serum alpha-tocopherol concentration was reduced 6% for the group given 18 g/d olestra. Addition of tocopheryl acetate to olestra partially offset the effect of olestra. For the group given 18 g/d olestra plus 1.1 mg tocopheryl acetate/g olestra, serum alpha-tocopherol concentration was 4% less than the placebo value. Olestra reduced serum concentration of beta-carotene by 27%; the other carotenoids were similarly affected. Serum cholesterol concentration was reduced approximately 4.5% in the olestra groups, relative to placebo, but the differences were not significant. Serum triglycerides, serum 25-hydroxyvitamin D, prothrombin time, partial thromboplastin time or the plasma concentration of under-gamma-carboxylated prothrombin were unaffected by olestra. Clinical observations and laboratory measures indicated no health-related effects of olestra; mild-to-moderate transient gastrointestinal symptoms such as bloating, cramping, loose stools and diarrhea were reported by all groups.

An indirect means of assessing potential nutritional effects of dietary olestra in healthy subgroups of the general population

The potential for olestra to affect the absorption of dietary components was measured in 18- to 44-y-old humans and the weanling pig. Results from the studies were assessed to determine if they were relevant to subgroups of the population not included in the studies. Hypothetrically, two factors that might cause the study results not to be relevant to certain subgroups are dietary pattern and metabolic need. A dietary pattern resulting in olestra-to-nutrient intake ratios greater than those tested in the studies might produce effects greater than those measured. Metabolic needs (i.e., nutrient requirements) among subgroups greater than those of the study population might mean that any effects on nutrient absorption seen in the studies would be larger among subgroups. If olestra-to-nutrient ratios and nutrient requirements of a subgroup were less than those covered in the studies, then the effects of olestra on the nutritional status of the subgroup should be no different than the effects measured in the studies. Subgroups with high olestra-to-nutrient intake ratios were identified by calculating the ratios for those nutrients assessed in the studies [i.e., macronutrients, vitamins A (including beta-carotene), D, E and K, folate, vitamin B12, calcium, iron and zinc]. Subgroups with the greatest olestra-to-nutrient intake ratios for one or more nutrients included children, teenagers and young adults, women from low income families and vegetarians. Subgroups with the greatest metabolic need for one or more nutrients included children, teenagers, and pregnant and lactating women. The olestra-to-nutrient ratios and nutrient requirements of the subgroups having the greatest ratios and requirements were compared with those of the test population. The olestra-to-nutrient intake ratios fed in the studies were greater than those for any subgroup for all nutrients except calcium, which is not affected by olestra. Metabolic needs of the test population were greater than those of all population subgroups for all nutrients. The effects of olestra on nutritional status should not be different or greater than those measured in the controlled clinical tests for subgroups not directly tested.

Olestra's effect on the status of vitamins A, D and E in the pig can be offset by increasing dietary levels of these vitamins

Groups of weanling pigs (5 castrated males, 5 females per group) were fed purified diets containing the NRC's requirements for nutrients and 0, 1.1, 4.4 or 7.7% olestra for 12 wk. Graded concentrations of vitamins A, D2 and E were added at each olestra concentration. The primary purpose of the study was to establish relationships between dietary concentration of olestra and the amounts of vitamins A, D2 and E needed to restore tissue concentrations of these vitamins to control concentrations. A secondary purpose was to confirm that olestra does not affect the status of vitamin K or water-soluble nutrients. Liver concentrations of vitamins A, E and B12, iron and zinc and bone concentrations of ash, zinc, calcium and phosphorus, were measured in a group of pigs killed at the start of the study and in all pigs killed at wk 12. Growth, feed efficiency, hematology, clinical chemistry, blood concentrations of retinol, alpha-tocopherol, 25-hydroxyergocalciferol, 25-hydroxycholecalciferol, 1,25-dihydroxyvitamin D, folate, iron, total iron-binding capacity, zinc and calcium and adipose concentration of vitamin E were measured at 4-wk intervals. Prothrombin time was measured weekly for the control and 7.7% olestra groups, monthly for others. Relationships derived from measured tissue concentrations of vitamins A and E showed that constant amounts of the vitamins were required per unit mass of olestra in the diet to restore tissue concentrations to control values. Such a relationship could not be determined for vitamin D because exposure of the pigs to UV light resulted in an apparent interaction between vitamin D2 and vitamin D3. Olestra did not affect growth, digestible feed efficiency, vitamin K status or the status of the water-soluble micronutrients, in agreement with other studies in the pig.

Olestra's effect on vitamins D and E in humans can be offset by increasing dietary levels of these vitamins

One hundred two normal healthy males and females were given 0, 8, 20 or 32 g/d olestra to which had been added graded amounts of vitamins A, D and E for 8 wk in a parallel, double-blind study. The primary purpose of the study was to determine the amounts of vitamins D and E needed to offset the effect of olestra on the availability of these vitamins. Serum concentrations of retinol, carotenoids, 25-hydroxyvitamin D metabolites, alpha-tocopherol, phylloquinone, lipids, ferritin and total iron, iron-binding capacity and hematology parameters, plasma concentrations of des-gamma-carboxyprothrombin and prothrombin, and urinary gamma-carboxyglutamic acid (Gla) excretion were measured biweekly. Clinical chemistry and urinalysis parameters, vitamin B12 absorption, and serum 1,25-dihydroxyvitamin D concentration were measured at wk 0 and 8. Serum concentrations of alpha-tocopherol and 25-hydroxyergocalciferol were restored to control concentration by adding 2.1 mg d-alpha-tocopheryl acetate and 0.06 microg ergocalciferol per gram of olestra, respectively, to the diet. Olestra reduced serum concentrations of 25-hydroxyergocalciferol, carotenoids and phylloquinone in a dose-responsive manner but did not affect Gla excretion, plasma des-gamma-carboxyprothrombin and prothrombin concentrations, overall vitamin D status, vitamin B12 absorption or iron status. Laboratory evaluations showed no olestra-related effects. Subjects in all groups reported mild to moderately severe transient gastrointestinal symptoms. These symptoms did not affect study compliance or the integrity of the data.

Assessment of the nutritional effects of olestra, a nonabsorbed fat replacement: summary

Olestra is a zero-calorie fat replacement intended to replace 100% of the fat used in the preparation of savory snacks. Olestra can affect the absorption of other dietary components, especially highly lipophilic ones, when ingested at the same time. The potential effects of olestra on the absorption of essential fat-soluble and water-soluble dietary components have been investigated in pigs and in humans. In these studies, subjects were fed daily amounts of olestra up to 10 times the estimated mean intake from savory snacks and the olestra was eaten each day of the studies. In real life, snacks are eaten on average five times in a 14-d period. Olestra did not affect the availability of water-soluble micronutrients or the absorption and utilization of macronutrients. Olestra reduced the absorption of fat-soluble vitamins A, D, E and K; however, the effects can be offset by adding specified amounts of the vitamins to olestra foods. Olestra also reduced the absorption of carotenoids; analysis of dietary patterns showed that in real life the reduction will likely be <10%. Any effect on vitamin A stores caused by a reduction in carotenoid uptake is offset by the addition of vitamin A to olestra foods. Because of the olestra-to-nutrient ratios fed and the nutritional requirements of the test subjects, the effects of olestra on nutritional status of subgroups of the population are unlikely to be different than those measured in the studies. An analysis of lipophilicity showed that olestra is unlikely to significantly affect the uptake of potentially beneficial phytochemicals from fruits and vegetables. Some people eating large amounts of olestra snacks may experience common GI symptoms such as stomach discomfort or changes in stool consistency, similar to symptoms accompanying other dietary changes. These symptoms present no health risks.

Physical or temporal separation of olestra and vitamins A, E and D intake decreases the effect of olestra on the status of the vitamins in the pig

A study was conducted in the domestic pig to determine 1 ) whether feeding olestra mixed in the diet exaggerated olestra effects on fat-soluble vitamin status compared with the effects of feeding it in a typical snack food, and 2) whether separating olestra consumption temporally from vitamin consumption affected the influence of olestra on vitamin status. Groups of 10 pigs each, five castrated males and five females, were fed 2.2% (wt/wt) olestra for 4 wk in purified diet that provided 1 time the National Research Council's requirements for swine of all micronutrients. The olestra was either mixed in the purified diet or fed in potato chips. The potato chips were given to the pigs at all three feedings, at the noon feeding only, or between the noon and the evening feedings. A control group was fed the purified diet with no olestra. The effects of olestra on indices of vitamin A, D and E status were from 1.7 to 4.5 times greater when olestra was fed three times daily mixed in the diet than when it was fed three times daily in potato chips. Because the effect of olestra on the status of the fat-soluble vitamins was diminished substantially by feeding the olestra in potato chips, it was not possible to conclude definitively how the temporal separation of olestra and vitamin consumption affected the olestra effect on vitamin status.

Evaluation of the potential for olestra to affect the availability of dietary phytochemicals

It has been hypothesized that phytochemicals found in fruits and vegetables are responsible for the inverse association observed between diets high in fruits and vegetables and risk of certain chronic diseases and cancer. This paper assesses the potential for olestra to affect the absorption of dietary phytochemicals and estimates the effect of olestra on the availability of carotenoids when olestra-containing snacks and foods containing carotenoids are eaten in free-living diets. Experimental data compiled on the effects of olestra on the availability of 29 compounds, mainly nutrients and oral medications, showed that olestra affects the availability of only molecules having octanol-water partition coefficients greater than approximately 7.5. Partition coefficients compiled for 382 dietary phytochemicals showed that only two classes of phytochemicals, phytosterols and carotenoids, contain molecules with octanol-water partition coefficients in the range in which olestra could potentially affect bioavailability. The potential effect on the bioavailability of phytosterols would be <10% and would not be expected to be of concern inasmuch as the hypothesized benefit of consuming pharmacological amounts of phytosterols is to reduce cholesterol availability, a function also of olestra. A 5.9% reduction in the average effective beta-carotene intake was calculated for individuals eating olestra-containing snack foods in free-living diets. The calculation was made by assuming that carotenoid bioavailability would be reduced to the extent measured in human clinical studies each time olestra-containing snacks and carotenoid-containing foods are eaten together and that all snacks eaten are made with olestra. Among individuals with low carotenoid intakes (the lowest 10%) the calculated reduction was 6.0%; for heavy snack eaters (the top 10%) it was 9.5%. These effects on carotenoid bioavailability are similar to those that can occur with other dietary factors.

The domestic pig as a model for evaluating olestra's nutritional effects

Experimental conditions for measuring the effect of the noncaloric fat substitute olestra on the availability of dietary nutrients were established in the weanling domestic pig. To evaluate the tolerance of the pig for dietary fat levels similar to those in the human diet, groups were fed a standard corn-soy-based swine feed with and without 14% (30% of energy) added fat for 4 wk. To evaluate the adequacy of a purified diet to produce good growth, groups of pigs were fed purified diets providing 30% of energy from fat and micronutrients at 1, 1.3 or 1.6 times the NRC's requirements for 5- to 10-kg swine. Cumulative body weight gain, digestible feed efficiency and a lack of adverse effects showed that the pig can tolerate diets providing 30% of energy from fat and that a purified diet providing the NRC's requirements for micronutrients produces growth comparable to a nutritionally complete swine feed. To determine whether tissue concentrations of vitamins A, D, E and K in the pig respond to olestra and dietary concentrations of the vitamins, two groups were fed purified diet providing 1 or 1.6 times the NRC's requirements for micronutrients and 4.8% olestra. Significant increases occurred in the serum concentration of 25-hydroxyergocalciferol and liver concentrations of retinol and alpha-tocopherol with increasing dietary concentrations of the vitamins. Olestra reduced the tissue concentrations of vitamins A, D and E. Prothrombin time was not affected by dietary concentration of either phylloquinone or olestra. To determine the amount of UV light exposure required to produce 50-80% of vitamin D status from vitamin D3, a range typical of humans, two groups of pigs were fed the NRC requirement for vitamin D and exposed to 15 or 45 min/d of UV light. Serum concentration of 25-hydroxycholecalciferol increased with increased exposure time. UV exposure of 1-2 min/d was calculated to be sufficient to produce 50-80% of total vitamin D status from vitamin D3. No antemortem observations indicated an adverse olestra effect.

Olestra dose response on fat-soluble and water-soluble nutrients in the pig

Groups of weanling pigs were fed a purified diet containing graded concentrations of olestra ranging from 1.1 to 7.7% (wt/wt) and the NRC's requirements for micronutrients for 12 wk. Each group consisted of 12 pigs, with the exception of the control group, which had 20, with equal numbers of females and castrated males. The purpose of the study was to determine the dose-response effects of olestra on fat-soluble vitamins and selected water-soluble micronutrients. At wk 0, 4, 8 and 12, hematology, clinical chemistry and blood concentrations of vitamins A, E, K and B12, and 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, folate, calcium, iron, zinc and adipose concentration of vitamin E were measured. Cumulative weight gain and feed efficiency were determined weekly. Prothrombin time was measured weekly for the control group and the groups fed 5.5 or 7.7% olestra, and monthly for other groups. Liver concentrations of vitamins A, E, and B12 and iron and bone concentrations of calcium, phosphorus, zinc and ash were measured for 12 pigs killed at wk 0 and for all animals at wk 12. By wk 12, the pigs were eating from 20 to 155 g/d of olestra. Olestra did not affect the pigs' growth or feed efficiency, indicating that the digestion and absorption of macronutrients were unaffected. Olestra reduced tissue concentrations of vitamin A, vitamin E and 25-hydroxyergocalciferol in a dose-responsive manner but did not affect prothrombin time. Olestra had no effect on the status of folate, vitamin B12, zinc or iron. Statistically reduced liver concentrations of vitamin B12 and iron in groups fed 5.5 or 7.7% olestra and a significant trend in bone ash content with olestra intake were possibly due to the poor vitamin A and/or vitamin E status of the pigs.

Assessment of the nutritional effects of olestra

Olestra is a mixture of polyesters formed from sucrose and fatty acids derived from edible fats and oils. It is not absorbed or digested and can serve as a zero-calorie replacement for dietary fat. Because olestra is lipophilic and not absorbed, it has the potential to interfere with the absorption of other dietary components, especially lipophilic ones, when it is in the digestive tract with those components. A series of studies were conducted in the domestic pig and in healthy adult humans to define the nature and extent of olestra's effect on fat-soluble vitamins, selected water-soluble micronutrients, and macronutrients, and to demonstrate that the effects of olestra on the absorption of fat-soluble vitamins can be offset by adding extra amounts of the affected vitamins to olestra foods. Before conducting the human and pig studies, the intake of olestra from the consumption of snack foods made with olestra was estimated for various subgroups. The potential for olestra to affect the absorption of nonessential but potentially beneficial dietary phytochemicals was also assessed. In addition, an assessment of how consumption patterns influence the effect of olestra on the absorption of the highly lipophilic carotenoids was made. Finally, the results from the pig and human studies were used to assess the potential for olestra to affect the nutritional status of subgroups of the population who have particularly high nutrient needs or unique dietary patterns that may lead to large olestra-to-nutrient intake ratios.

Nutritional status of pigs fed olestra with and without increased dietary levels of vitamins A and E in long-term studies

In a 26-wk study, five groups (n = 10) of domestic pigs were fed 0.25, 0.5, 1.1, 3.3 or 5.5% olestra; three groups were fed 0.25% with graded levels of vitamins A and E; and one group was fed 5.5% with added vitamins A and E and exposed to UV light. In a 39-wk study, two groups (n = 10) were fed 0.25% olestra with or without added vitamins A and E. In each study, a control group was fed basal diet with no olestra, and a group was killed at d 0 for base-line nutrient measurements. The diets provided the NRC's requirements of micronutrients for 5- to 10-kg pigs, with the following two exceptions: vitamin D was provided at twice the requirement in the 26-wk study and vitamin K was provided at 20% of the requirement in the 39-wk study. One purpose of the studies was to determine the amounts of vitamins A and E required to restore tissue concentrations of those vitamins to control concentrations. A second purpose was to determine the effects of olestra on the status of vitamins A, D, E, K and B12, and folate, iron, calcium and zinc when pigs eat olestra at intakes similar to estimated human intake for a period covering major growth and developmental phases, including sexual maturation. Olestra reduced tissue concentrations of vitamins A, D and E but did not affect prothrombin time or the status of the water-soluble nutrients. The amount of vitamin A required to restore liver concentration to control concentration was 93 microg retinyl palmitate/g olestra. Restoration levels for serum and liver concentrations of vitamin E were 2.2 and 2.1 mg d-alpha-tocopheryl acetate/g olestra. Olestra did not affect growth or digestible feed efficiency in either study, indicating that the absorption and utilization of macronutrients were unaffected. There were no antemortem observations or changes in clinical chemistry or hematology that would indicate an adverse effect of olestra.

Olestra dose response on fat-soluble and water-soluble nutrients in humans

Ninety normal healthy adults were given 0, 8, 20 or 32 g/d olestra for 8 wk as part of a diet that provided 1 +/- 0.2 of the recommended dietary allowance (RDA) of vitamins A, D, E and K, folate zinc, calcium and iron. In addition, a 20 microg/d supplement of vitamin D was supplied. The diet provided 15% of energy from protein, 35% from fat and 55% from carbohydrate. The purpose of the study was to determine the dose response of olestra on vitamins D, E and K, carotenoids, vitamin B12, folate and zinc. Circulating concentrations of retinol, carotenoids, tocopherols, 25-hydroxy- and 1,25-dihydroxyvitamin D metabolites, phylloquinone, des-gamma-carboxyprothrombin, prothrombin, folate and hematological parameters were measured biweekly, as were urine concentrations of zinc and gamma-carboxyglutamic acid (Gla). Clinical chemistry, urinalysis and vitamin B12 absorption were measured at wk 0 and 8. Olestra reduced serum concentrations of carotenoids, alpha-tocopherol, 25-hydroxyergocalciferol and phylloquinone in a dose-responsive manner. Olestra did not affect Gla excretion, plasma des-gamma-carboxyprothrombin or prothrombin concentrations, prothrombin time, vitamin B12 absorption, overall vitamin D status or the status of folate or zinc. Laboratory evaluations showed no health-related effects of olestra. Subjects in all groups reported common gastrointestinal symptoms such as loose stools, fecal urgency and flatulence, which were transient and generally mild to moderate in severity. These symptoms did not affect protocol compliance or the ability to measure the potential for olestra to affect nutrient availability.

Olestra ingestion and dietary fat absorption in humans

The effect of olestra, a zero-calorie fat replacement, on the absorption of dietary fat was determined with a dual-isotope technique in 67 healthy male subjects. After a 30-d adaptation period in which they consumed potato chips which delivered either 10 g/d olestra or 10 g/d triglyceride under free-living conditions, the subjects were housed in a metabolic ward and given 0, 8, 20 or 32 g olestra in potato chips. The chips were eaten as part of a breakfast containing about 38 g of fat, about 0.16 mg of 14C-triolein, and a nonabsorbable marker, 51CrCl3. Feces were collected for 7 d, and aliquots of the two daily collections containing the highest levels of 51Cr were oxidized. The CO2 was collected, and 14C content was determined by liquid scintillation spectrometry. The fractional absorption of 14C-triolein was calculated from the average ratios of 14C/51Cr dosed and measured in the feces. Olestra had a slight but significant dose-response effect on triglyceride absorption: the highest olestra dose (32 g) reduced absorption by 1.2%. This effect is not nutritionally significant with respect to either availability of essential fatty acids or energy intake.

Olestra ingestion and retinyl palmitate absorption in humans

This study examined the effect of olestra, a zero-calorie fat replacement, on the absorption of retinyl palmitate in humans. After a 30-d adaptation period during which they consumed 10 g olestra/d in potato chips under free-living conditions, 68 healthy male subjects were housed in a metabolic ward and given a single dose of retinyl palmitate (0.33 RDA) containing a trace amount of 3H-retinyl palmitate with a breakfast that contained 0, 8, 20 or 32 g of olestra and about 38 g of triglyceride. Blood was collected at defined intervals for 48 h and plasma analyzed for 3H-retinyl esters by HPLC and liquid scintillation spectrometry. There was no significant effect on retinyl palmitate absorption as determined from the area under the plasma 3H-retinyl esters concentration-time curve. However, an area under the plasma concentration-time curve in the 32-g olestra group that was 81% (mean value) or 70% (median value) of the area under the curve for the placebo group suggested that olestra may have affected retinyl palmitate absorption. Inclusion or exclusion of 13 high responders did not change the results.

Fat as a risk factor for overconsumption: satiation, satiety, and patterns of eating

Many people experience great difficulty in preventing energy intake from outstripping energy expenditure. Eating high-fat foods can facilitate the development of short-term positive energy balances by influencing satiation and satiety, the processes that control the size of eating episodes and the strength of postingestive appetite inhibition, respectively. An important feature of these processes is the relative potency of orosensory, postingestive (preabsorptive), and postabsorptive signals. Foods high in dietary fat have a weak effect on satiation, which leads to a form of passive overconsumption, and a disproportionately weak effect on satiety (joule-for-joule compared with protein and carbohydrate). This overconsumption (high-fat hyperphagia) is dependent upon both the high energy density and the potent sensory qualities (high palatability) of high-fat foods. A positive fat balance does not appear to generate a tendency for behavioral compensation, and there appears to be almost no autoregulatory link between fat oxidation and fat intake. The Leeds High Fat Study has found a higher frequency of obesity among high-fat than low-fat consumers, but the relationship between fat consumption and obesity is not a biologic imperative: analysis of the pathways between daily fat intakes and patterns of eating has revealed high-risk eating episodes. The physiologic responses to fat ingestion appear to be weak compared with the potent orosensory properties of high-fat foods, and such responses cannot prevent overconsumption. A first stage in a health program should be to prevent passive overconsumption.