Effects of 3 diets with various calcium contents on 24-h energy expenditure, fat oxidation, and adipose tissue message RNA expression of lipid metabolism-related proteins

Resveratrol sensitizes A549 cells to irradiation damage via suppression of store-operated calcium entry with Orai1 and STIM1 downregulation

Resveratrol is a natural polyphenol with multiple positive biofunctions and was found to have potential as a radiosensitizer with an intricate molecular mechanism. Store-operated calcium entry (SOCE) is a novel intracellular calcium regulatory pattern that is mainly mediated by iron channels, such as by the stromal interaction molecule (STIM) and calcium release-activated calcium channel protein (Orai) families. SOCE was recently reported to be suppressed via the downregulation of STIM or Orai families for the promotion of tumor cell death induced by resveratrol. In the present study, resveratrol combined with irradiation treatment were found to induce more evident cell damage compared with irradiation treatment alone, as shown with Cell Counting Kit-8 assay and mitochondrial membrane potential detection with rhodamine 123. Additionally, resveratrol combined with irradiation treatment decreased the expression of STIM1 and Orai1, while it had no effects on STIM2, Orai2 and Orai3. Moreover, resveratrol combined with irradiation treatment lead to alleviated thapsigargin-induced SOCE. In addition, overexpression of STIM1 and Orai1 reversed resveratrol-induced SOCE inhibition and reduced death in A549 cells under irradiation. In summary, the present results revealed that resveratrol can significantly enhance the effect of irradiation damage on lung adenocarcinoma A549 cells, and this effect may be mediated by suppression of SOCE with reduced expression of both STIM1 and Orai1.

High intake of dairy during energy restriction does not affect energy balance or the intestinal microflora compared with low dairy intake in overweight individuals in a randomized controlled trial

During weight loss, dairy calcium is proposed to accelerate weight and fat-mass loss through increased fecal fat excretion. The primary objective was to investigate if a high-dairy energy-restricted diet is superior to low dairy in terms of changes in body weight, body composition, and fecal fat excretion over 24 weeks. Secondary objectives included fecal energy and calcium excretion, resting energy expenditure, blood pressure, lipid metabolism, and gut microbiota. In a randomized, parallel-arm intervention study, 11 men and 69 women (body mass index, 30.6 ± 0.3 kg/m2; age, 44 ± 1 years) were allocated to a 500-kcal (2100 kJ) –deficit diet that was either high (HD: 1500 mg calcium/day) or low (LD: 600 mg calcium/day) in dairy products for 24 weeks. Habitual calcium intake was ∼1000 mg/day. Body weight loss (HD: –6.6 ± 1.3 kg, LD: –7.9 ± 1.5 kg, P = 0.73), fat-mass loss (HD: –7.8% ± 1.3%, LD: –8.5% ± 1.1%, P = 0.76), changes in fecal fat excretion (HD: –0.57 ± 0.76 g, LD: 0.46 ± 0.70 g, P = 0.12), and microbiota composition were similar for the groups over 24 weeks. However, total fat-mass loss was positively associated with relative abundance of Papillibacter (P = 0.017) independent of diet group. Consumption of a high-dairy diet did not increase fecal fat or accelerate weight and fat-mass loss beyond energy restriction over 24 weeks in overweight and obese adults with a habitual calcium intake of ∼1000 mg/day. However, this study indicates that Papillibacter is involved in body compositional changes.

Effect of calcium intake on fat oxidation in adults: a meta-analysis of randomized, controlled trials

Calcium intake is likely to increase body fat loss during energy restriction. Part of this effect may be explained by increased fat oxidation in the presence of a similar energy balance, yet studies have not provided a conclusive answer. Therefore a meta-analysis was performed to determine whether chronic or acute high calcium intake increases fat oxidation. Randomized controlled trials of high calcium intake in human adults where measures of fat oxidation were taken were included. A random-effects meta-analysis was performed on outcomes expressed as standardized mean differences. Chronic high calcium intake increased fat oxidation by a standardized mean difference of 0.42 (95% confidence intervals: 0.14, 0.69; P= 0.003; estimated to correspond to an 11% increase), displaying low heterogeneity (I(2) = 18%), which was more prominent when habitual calcium intake was low (<700 mg d(-1) ). Acute high calcium intake increased fat oxidation by a standardized mean difference of 0.41 (0.04, 0.77; P = 0.03), with low heterogeneity (I(2) = 19%), yet sensitivity analysis revealed that this effect was relatively weak. In conclusion, chronic high calcium intake is likely to increase rates of fat oxidation. The effects of acute high calcium intake appear to point in the same direction, but further work is needed to permit a greater degree of certainty.

Mechanistic roles for calcium and vitamin D in the regulation of body weight

Low intakes of calcium and inadequate vitamin D status often cluster with higher prevalence rates of obesity. Consequently, there has been much interest in the mechanisms by which calcium and vitamin D could regulate body weight and adiposity. This review has focused on randomized controlled trials (RCTs) that have manipulated these nutrients and studied pathways of energy balance. Overall, there is consistent evidence that calcium and vitamin D increase whole body fat oxidation after single and multiple meals, and that calcium promotes a modest energy loss through increased faecal fat excretion. The evidence is equivocal for a greater diet-induced thermogenesis, increased lipolysis, suppression of key lipogenic enzymes, decreased hunger ratings or reduced energy/macronutrient intake. Emerging evidence suggests a potential improvement in insulin sensitivity following vitamin D that would impinge on food intake and substrate oxidation. However, the very few RCTs on supplemental vitamin D and energy balance have not explored postprandial avenues of the hormone's actions. Future efforts in this area need to define the threshold intake of these nutrients that would maximize metabolic and gastrointestinal outcomes. Such studies would provide a platform for endorsing the non-skeletal role of calcium and vitamin D in human pathophysiology.

Calcium, dairy products, and energy balance in overweight adolescents: a controlled trial

BACKGROUND

Dairy product and calcium consumption have been associated with modifying body fat and body weight in children and adults.

OBJECTIVE

In overweight adolescent boys and girls, we aimed to determine the effect of the doubling of habitual calcium intake to the recommended intake from dairy or calcium carbonate on energy balance and purported mechanisms including fecal fat excretion, macronutrient use, and parathyroid hormone suppression.

DESIGN

Twenty-five girls with a mean (±SD) BMI (in kg/m(2)) of 33 ± 5 and 17 boys with a BMI of 28 ± 5, aged 12-15 y, participated in two 3-wk controlled feeding sessions that used a crossover design in random order as a summer research camp. In one session, 756 mg Ca/d was consumed; in the other session, an additional 650 mg Ca/d was provided as dairy or calcium carbonate supplements that were matched to the control in macronutrient content. Total energy and macronutrient intakes were controlled and were the same for the 2 sessions for each subject. Primary outcome measures were energy balance, fecal fat excretion, lipid oxidation, and postprandial energy expenditure.

RESULTS

There were no effects of quantity or source of calcium on energy or fat balance, despite calcium-induced increases (P <0.01) in postprandial serum parathyroid hormone suppression.

CONCLUSION

These data lend little evidence to support the proposed mechanisms for the relation between an increase in calcium intake from calcium carbonate or dairy and weight loss or weight maintenance in children. This trial was registered at clinicaltrials.gov as NCT00592137.

Calcium ameliorates obesity induced by high-fat diet and its potential correlation with p38 MAPK pathway

To investigate whether and on which pathway dietary calcium influence the obesity induced by high-fat diet, thirty male Kunming mice were fed in six groups for 4 weeks and mouse preadipocytes were divided into eight groups for different treatment. Body weight gain was measured each week. Calcium in serum and tissues, intracellular free Ca(2+) concentration ([Ca(2+)]i), blood fat and intracellular lipid content were also measured. The expression of Lipid metabolism-related genes were measured by q RT-PCR. Compared with control group, body weight gain (P < 0.05) and fat pad weight (P < 0.01) in Low calcium group decreased. Triglycerides (TG) and total Cholesterol (TC) level decreased (P < 0.01), while HDL-Cholesterol (HDL) level increased (P < 0.01). And calcium supply increased calcium content in blood serum and tissues. In tissues, adipogenesis and vitamin D receptor (VDR) genes expression decreased but lipoclasis genes expression increased. These anti-obesity effects were more obvious when supplying with 2.8% calcium, but the effects were reduced while supplying Nifedipine at the same time. The results in preadipocytes indicated that calcium-treated can reduce intracellular lipid content, along with adipogenesis and lipoclasis genes expression decrease, promoted the expression levels of p38 MAPK pathway upstream gene MKK6 (P < 0.01) and downstream gene MAPKAPK2 (P < 0.01). Treated with SB203580 could increase adipogenesis genes expression, decrease lipoclasis genes expression and ([Ca(2+)]i) (P < 0.01). These results implied that dietary calcium had remarkable effect on anti-obesity effect and p38 MAPK pathway potentially participated in calcium-mediated lipid accumulation and lipolysis in mouse preadipocytes.

Associations between dairy consumption and body weight: a review of the evidence and underlying mechanisms

As the incidence of obesity is reaching 'epidemic' proportions, there is currently widespread interest in the impact of dietary components on body-weight and food intake regulation. The majority of data available from both epidemiological and intervention studies provide evidence of a negative but modest association between milk and dairy product consumption and BMI and other measures of adiposity, with indications that higher intakes result in increased weight loss and lean tissue maintenance during energy restriction. The purported physiological and molecular mechanisms underlying the impact of dairy constituents on adiposity are incompletely understood but may include effects on lipolysis, lipogeneis and fatty acid absorption. Furthermore, accumulating evidence indicates an impact of dairy constituents, in particular whey protein derivatives, on appetite regulation and food intake. The present review summarises available data and provides an insight into the likely contribution of dairy foods to strategies aimed at appetite regulation, weight loss or the prevention of weight gain.

Supplementary dietary calcium stimulates faecal fat and bile acid excretion, but does not protect against obesity and insulin resistance in C57BL/6J mice

There is increased interest in the potential protective role of dietary Ca in the development of metabolic disorders related to the metabolic syndrome. Ca-induced intestinal precipitation of fatty acids and bile acids as well as systemic metabolic effects of Ca on adipose tissue is proposed to play a causal role. In this experiment, we have studied all these aspects to validate the suggested protective effect of Ca supplementation, independent of other dietary changes, on the development of diet-induced obesity and insulin resistance. In our diet intervention study, C57BL/6J mice were fed high-fat diets differing in Ca concentrations (50 v. 150 mmol/kg). Faecal excretion analyses showed an elevated precipitation of intestinal fatty acids (2·3-fold; P < 0·01) and bile acids (2-fold; P < 0·01) on the high-Ca diet. However, this only led to a slight reduction in fat absorption (from 98 to 95 %; P < 0·01), mainly in the distal small intestine as indicated by gene expression changes. We found no effect on body-weight gain. Lipolysis and lipogenesis-related parameters in adipose tissue also showed no significant changes on the high-Ca diet, indicating no systemic effects of dietary Ca on adiposity. Furthermore, early gene expression changes of intestinal signalling molecules predicted no protective effect of dietary Ca on the development of insulin resistance, which was confirmed by equal values for insulin sensitivity on both diets. Taken together, our data do not support the proposed protective effect of dietary Ca on the development of obesity and/or insulin resistance, despite a significant increase in faecal excretion of fatty acids and bile acids.

Dairy food consumption and obesity-related chronic disease

Dairy food comprises a range of different products with varying nutritional components. In the context of a healthy diet, dairy food may provide protection against and amelioration of chronic diseases related to obesity. These include overweight, insulin resistance/metabolic syndrome/type 2 diabetes, hypertension/stroke, and cardiovascular disease. Eliciting how dairy food may have this impact represents a challenge for modern nutritional science and requires an integration of knowledge from observational studies of population dietary patterns and disease prevalence, and experimental studies testing the effect of dairy food consumption. It also benefits from the recent identification of biomarkers of dairy fat intake and from mechanistic studies that support the plausibility of the observed effects. Future research might discriminate between types of dairy foods and focus on the synergy provided by the food matrix, rather than simply the component parts of the food.

Postprandial energy metabolism in the regulation of body weight: is there a mechanistic role for dietary calcium?

There has been much interest in the mechanisms by which calcium may attenuate weight gain or accelerate body fat loss. This review focuses on postprandial energy metabolism and indicates that dietary calcium increases whole body fat oxidation after single and multiple meals. There is, as yet, no conclusive evidence for a greater diet induced thermogenesis, an increased lipolysis or suppression of key lipogenic enzyme systems. There is however convincing evidence that higher calcium intakes promote a modest energy loss through increased fecal fat excretion. Overall, there is a role for dietary calcium in human energy metabolism. Future studies need to define threshold intakes for metabolic and gastrointestinal outcomes.

Investigation of the effect of high dairy diet on body mass index and body fat in overweight and obese children

OBJECTIVE

To investigate whether an increase in dairy food consumption improves the changes in BMI and adiposity in children on an energy restricted diet.

METHODS

Overweight and obese children (n = 120, age: 12-18 y, BMI: 27-40 kg/m2) were randomized to receive a calorie restricted diet providing a 500 kcal/d deficit from total energy expenditure and two (n = 40), three (n = 40) or four (n = 40) servings of dairy products/day. Anthropometric measurements in addition to serum hs-CRP and lipid profile were measured at baseline and after 12 weeks.

RESULTS

Among the 96 children who completed the study, significant reductions in overall BMI, BMI z-score, weight, total body fat percentage and total body fat mass were observed (p < 0.001) but these reductions were not significantly affected by increasing dairy intake (p > 0.05). Overall waist/hip ratio, Serum vitamin D and lipid profile did not change significantly (p > 0.05) apart from a significant increase in HDL-cholesterol (p < 0.001) which was independent of dairy intake (p > 0.05).

CONCLUSION

Increased intake of dairy products does not lead to an augmented change in BMI, weight and body fat in overweight and obese children beyond what is achieved by calorie restriction.

The role of dairy foods and dietary calcium in weight management

Overweight and obesity are the foremost public health problems in the U.S., other industrialized countries, and is rapidly increasing in developing countries. Obesity is a multifaceted disease which requires multiple approaches to successfully combat its increase. Nutritional factors play a key role and include modification of energy balance, intake and expenditure, as well as other factors. Emerging scientific evidence over the past decade suggests that dairy foods may be beneficial when included in a moderate energy restricted diet and possibly for weight maintenance as well. This paper provides a review of some of the scientific evidence that has examined the effect of dairy foods and dietary calcium on weight management. Topic areas presented are observational or retrospective studies with adults as well as children and adolescents; randomized clinical trials on body weight and composition, energy expenditure, substrate oxidation and fecal fat loss; research from animal and in vitro studies provide possible mechanisms of action.

Effect of calcium from dairy and dietary supplements on faecal fat excretion: a meta-analysis of randomized controlled trials

Observational studies have found that dietary calcium intake is inversely related to body weight and body fat mass. One explanatory mechanism is that dietary calcium increases faecal fat excretion. To examine the effect of calcium from dietary supplements or dairy products on quantitative faecal fat excretion, we performed a systematic review with meta-analysis. We included randomized, controlled trials of calcium (supplements or dairy) in healthy subjects, where faecal fat excretion was measured. Meta-analyses used random-effects models with changes in faecal fat excreted expressed as standardized mean differences, as the studies assessed the same outcome but measured in different ways. An increased calcium intake resulted in increased excretion of faecal fat by a standardized mean difference of 0.99 (95% confidence intervals: 0.63-1.34; P < 0.0001; expected to correspond to approximately 2g day(-1)) with moderate heterogeneity (I(2) = 49.5%) indicating some inconsistency in trial outcomes. However, the dairy trials showed homogeneous outcomes (I(2)=0%) indicating consistency among these trials. We estimated that increasing the dairy calcium intake by 1241 mg day(-1) resulted in an increase in faecal fat of 5.2 (1.6-8.8) g day(-1). In conclusion, dietary calcium has the potential to increase faecal fat excretion to an extent that could be relevant for prevention of weight (re-)gain. Long-term studies are required to establish its potential contribution.

Preponderance of the evidence: an example from the issue of calcium intake and body composition

Meta-analysis is typically applied to studies developed in fairly mature fields, but may be ill-suited for younger fields in which most of the evidence comes from studies that were designed for other endpoints entirely and that are often significantly underpowered for the effect in question. Here, there are no generally accepted methods for getting a grasp on the preponderance of the evidence. In this review, one way of doing so is proposed and the recently emergent literature concerning calcium intake and body composition is used as an illustration of how such an approach might be used.

Dairy product consumption and the metabolic syndrome

The metabolic syndrome is an important risk factor for type 2 diabetes mellitus and CVD. Epidemiological studies have now suggested protective effects of dairy product consumption on the development of this syndrome. Here we review the physiological effects and possible mechanisms involved of three main dairy constituents (Ca, protein, fat) on important components of the metabolic syndrome. Ca supplements improve the serum lipoprotein profile, particularly by decreasing serum total and LDL-cholesterol concentrations. They also lower systolic and diastolic blood pressure. Insufficient evidence exists for a significant role of Ca supplements or dairy in body-weight management. Effects of Ca may be related to intestinal binding to fatty acids or bile acids, or to changes in intracellular Ca metabolism by suppressing calciotropic hormones. Dietary proteins may increase satiety in both the short and longer term, which may result in a reduced energy intake. They have also been reported to improve the serum lipoprotein profile as compared with carbohydrates. Dairy proteins are precursors of angiotensin-I-converting enzyme-inhibitory peptides, which may lower blood pressure. Such effects, however, have inconsistently been reported in human studies. Finally, conjugated linoleic acid, which effectively lowers body weight in animals, has no such effect in humans in the quantities provided by dairy products. To reduce the intake of SFA, the consumption of low-fat instead of high-fat dairy products is recommended. In conclusion, more research is warranted to better understand the physiological effects and the mechanisms involved of dairy products in the prevention and treatment of the metabolic syndrome.

Influence of calcium and vitamin D supplementation on weight and fat loss in obese women

BACKGROUND

Dairy products not only reduce the risk of hypertension and cardiovascular diseases but may play a role in the treatment of obesity. As there is some evidence that calcium (Ca) and vitamin D may play a role in effective weight management, we decided to evaluate the influence of Ca and vitamin D supplementation on weight and fat loss in obese women.

MATERIAL AND METHODS

Forty obese women were enrolled in this study. Subjects were divided into 2 groups comparable with body mass index (BMI) and age. Group 1 was provided with calcium carbonate and 1-(OH)-vitamin D supplementation. Group 2 was provided with only a diet. Subjects participated in a 3-month weight reduction therapy (balanced diet, modification of life style, and regular physical exercise). Blood samples (serum concentration of Ca, phosphorus (P), parathormone (PTH), 25-(OH)-D3) and clinical characteristics (weight, height, BMI, body composition) were taken at baseline and after the 3-month program.

RESULTS

No significant differences of body weight, body fat content, serum parathormone, 25-(OH)-D3 concentration, and plasma total Ca and P concentration were observed between analyzed groups both before and after the treatment. Additionally, we did not observe any significant influence of Ca and vitamin D supplementation on weight and fat loss.

CONCLUSION

Ca plus vitamin D supplementation during a 3-month low caloric diet has no additional effect on weight and fat loss in obese women.

Recent developments in calcium-related obesity research

The influence of calcium and dairy food intake on energy balance is the object of a growing scientific literature. This manuscript presents the information discussed by subject experts during a symposium on calcium and obesity, initially planned to document in a comprehensive manner the role of calcium and dairy food on energy balance and body composition. This manuscript is organized into 13 propositions statements which either resume the presentation of an invited speaker or integrate recent developments in calcium-related obesity research. More specifically, the effects of calcium and dairy consumption on body weight and adiposity level, appetite, weight loss intervention outcome, lipid-lipoprotein profile and the risk to develop metabolic syndrome are discussed together with the metabolic mechanisms proposed to explain these effects. Taken together, the observations presented in this manuscript suggest that calcium and dairy food intake can influence many components of energy and fat balance, indicating that inadequate calcium/dairy intake may increase the risk of positive energy balance and of other health problems.

Greater resting energy expenditure and lower respiratory quotient after 1 week of supplementation with milk relative to supplementation with a sugar-only beverage in children

Previous studies have linked overweight to lower milk and calcium consumption and have proposed a role of milk consumption on energy expenditure (EE). The goal of this study was to compare EE and food intake after a meal of either mixed-nutrient or single-nutrient beverage and examine whether supplementation with that beverage for 1 week will impact EE. This was a randomized, controlled crossover study testing the effect of 2 beverages, milk or fruit-flavored beverage, before and after a supplementation period of 1 week on EE. Food intake at a meal after a snack intake of each beverage was assessed at the end of each measurement period. Ten children, aged 9 to 10 years, participated in all of the testing sessions in the study. There was a significant beverage by testing day interaction on daily EE and thermic effect of food (TEF), whereby EE was greater with milk consumption relative to the fruit-flavored beverage on day 8 (P = .0014) and with fruit-flavored beverage consumption on day 1 vs day 8 (P = .01). Similarly, the TEF was greater with milk compared with fruit-flavored beverage consumption on day 8 (P = .0007) and with fruit-flavored beverage consumption on day 1 relative to day 8 (P = .0097). The TEF declined more rapidly during 6 hours after a fruit-flavored beverage than a milk meal (P = .0018). Food intake did not differ after snack consumption of each beverage before and after milk and fruit-flavored beverage supplementation periods. Over the longer term, consumption of milk beverages may have more favorable effects on energy balance in children than consumption of fruit-flavored beverages.

The effects of hydralazine on lipolysis in subcutaneous adipose tissue in humans

Recent evidence from animal research and in vitro experiments indicates that changes in dietary calcium intake could cause changes in lipolysis through alterations of the intracellular calcium concentration in adipocytes. The objective of the study was to examine whether the calcium antagonist hydralazine affects blood flow and lipolysis in subcutaneous abdominal adipose tissue in vivo in humans. Three different concentrations of hydralazine (12.2, 24.4, and 48.8 micromol/L) were locally administered in adipose tissue using the microdialysis technique to assess effects on lipolysis and blood flow in subcutaneous adipose tissue in the abdominal region. Subjects from the general community were studied ambulatorily at a university hospital. Eight healthy men (age, 33.1 +/- 3.3 years; body mass index, 24.2 +/- 0.2 kg/m(2)) were recruited by local announcement. Subcutaneous adipose tissue in the abdominal region was perfused with increasing concentrations of hydralazine. The main outcome measures were adipose tissue lipolysis and blood flow. Hydralazine had no effect on ethanol outflow-inflow ratios, but significantly increased interstitial glycerol concentration at the highest concentration (P < .05). The present results indicate that hydralazine increases lipolysis in abdominal subcutaneous adipose tissue in healthy lean subjects, but hydralazine had no significant effects on local blood flow in adipose tissue.

An intervention study of the effects of calcium intake on faecal fat excretion, energy metabolism and adipose tissue mRNA expression of lipid-metabolism related proteins

CONTEXT

In various observational studies, an inverse relation between calcium intake and body weight has been observed. A possible explanation could be an increased calcium excretion through the faeces caused by an increased dietary calcium intake.

OBJECTIVE

To examine whether an increased calcium intake could lead to changes in faecal fat and energy excretion.

DESIGN

Four different isocaloric diets with various calcium contents (400, 1200 and 2500 mg from dairy and 1200 mg from calcium carbonate (1200S)) were administered in a crossover design for 7 days each.

SUBJECTS

Five healthy men and five healthy women (age=28+/-2, body mass index=24.1+/-0.4, body fat%=25.6+/-2.4) were recruited by local announcement.

MEASUREMENTS

At the end of every intervention period, faecal samples were collected for determination of fat, energy and calcium content, blood samples were obtained for determination of relevant blood parameters; and fat samples were obtained for measurement of the mRNA expression. Furthermore, resting energy expenditure and fat oxidation were measured with the ventilated-hood technique.

RESULTS

We observed a non-significant 56% increase in fat excretion (P=0.159) on the 2500 mg diet, compared to the 400 mg diet. The 2500 mg diet significantly reduced the expression of fatty acid synthase (FAS) mRNA (P<0.05) and the calcium content of the diets significantly affected calcium excretion. Furthermore, we saw a significant decrease of serum triglycerides on the 1200S diet (P<0.05).

CONCLUSION

In this study, we observed a trend towards a higher fat excretion on the high-calcium diet, but this difference failed to reach statistical significance. It is possible that the relatively high protein content of the experimental diets increased calcium absorption from the intestine, thus decreasing the amount of calcium available for binding to fat and eliminating possible effects of dietary calcium on fat excretion. Furthermore, we observed decreases in FAS mRNA expression and serum triglycerides as a result of a high calcium intake.

Effect of increased dairy consumption on appetitive ratings and food intake

OBJECTIVE

The influence of dairy product consumption on food intake and appetitive sensations was explored in a cross-over design study with individuals who were habitually low (<1 serving/d) or high (>3 servings/d) dairy consumers.

RESEARCH METHODS AND PROCEDURES

Fifty-eight participants were required to eat one portion of dairy each day (low dairy) or three portions of dairy each day (high dairy) for 7 days. After a 7-day washout period, the opposite treatment condition was completed. Food intake and appetitive ratings were measured on each day of the treatment periods.

RESULTS

During the high-dairy period, participants consumed 209 kcal/d more than during the low dairy period (p < 0.05). There were no significant differences in subjective appetite ratings. Habitual dairy use did not influence either the appetitive or dietary findings.

DISCUSSION

These data indicate that increasing dairy consumption may lead to increased energy intake, which could potentially cause weight gain.

Calcium and body fat in peripubertal girls: cross-sectional and longitudinal observations

OBJECTIVE

The objective was to investigate whether calcium intake is independently associated with body fat in peripubertal girls.

RESEARCH METHODS AND PROCEDURES

A total of 45 healthy premenarcheal girls (initially 10.5 +/- 0.6 years of age) completed a 2-year prospective observational study. Percent body fat and trunk fat (by DXA), height, weight, maturational stage, and eating attitudes (children's Eating Attitudes Test [EAT]) were measured at baseline and at 1 and 2 years. Physical activity (by questionnaire) and calcium intake (by calcium-specific food frequency questionnaire and 3-day food records) were assessed at 6-month intervals.

RESULTS

Girls with 2-year mean calcium intake below and above the median had similar age, height, lean mass, and maturational stage at baseline, but girls below the median had significantly higher baseline percentage body fat (29.3 +/- 10.3% vs. 22.0 +/- 6.8%, p < 0.01) and trunk fat (24.2 +/- 10.6% vs. 15.8 +/- 6.8%, p < 0.01). However, differences were no longer significant when covariates (most notably children's EAT dieting score) were considered. Regression analysis revealed that dieting score was a consistent positive predictor of percentage body and trunk fat at all cross-sectional time-points, accounting for >20% of the variance, but did not predict 2-year change in percentage fat. Calcium intake did not enter longitudinal regression equations for 2-year change in percentage fat.

DISCUSSION

In this group of girls, an inverse cross-sectional association between calcium intake and body fat appeared to result from avoidance of foods high in calcium by girls who were concerned about their body weight or shape. Calcium intake was not associated with change in fat over time.

Effect of dairy calcium or supplementary calcium intake on postprandial fat metabolism, appetite, and subsequent energy intake

BACKGROUND

High calcium intake has been shown to increase fecal fat excretion.

OBJECTIVE

Our aim was to examine whether a high calcium intake from dairy products or from supplements affects postprandial fat metabolism and appetite through fat malabsorption.

DESIGN

Four different isocaloric meals were tested in 18 subjects according to a randomized crossover design. The test meals contained high (HC meal: 172 mg/MJ), medium (MC meal: 84 mg/MJ), or low (LC meal: 15 mg/MJ) amounts of calcium from dairy products or a high amount of calcium given as a calcium carbonate supplement (Suppl meal: 183 mg/MJ). Concentrations of plasma total triacylglycerol, chylomicron triacylglycerol, serum total cholesterol, HDL cholesterol, cholecystokinin, glucagon-like peptide 1, ghrelin, peptide YY, glucose, and insulin and appetite sensation were measured before and at regular intervals until 420 min postprandially.

RESULTS

Dairy calcium significantly diminished the postprandial lipid response. The baseline adjusted area under the curve for chylomicron triacylglycerol was approximately 17% lower after the MC meal (P = 0.02) and approximately 19% lower after the HC meal (P = 0.007) than after the LC meal and approximately 15% lower after the MC meal (P = 0.0495) and approximately 17% lower after the HC meal (P = 0.02) than after the Suppl meal. No consistent effects of calcium on appetite sensation, or on energy intake at the subsequent meal, or on the postprandial responses of cholecystokinin, glucagon-like peptide 1, ghrelin, peptide YY, insulin, or glucose were observed.

CONCLUSIONS

Increased calcium intakes from dairy products attenuate postprandial lipidemia, most probably because of reduced fat absorption, whereas supplementary calcium carbonate does not exert such an effect. This may be due to differences in the chemical form of calcium or to cofactors in dairy products. Calcium did not affect appetite sensation, glucose metabolism, or gut hormone secretion.

Association between dairy food consumption and weight change over 9 y in 19,352 perimenopausal women

BACKGROUND

Dairy foods may play a role in the regulation of body weight.

OBJECTIVE

We examined the association between changes in dairy product consumption and weight change over 9 y.

DESIGN

The study was conducted in 19 352 Swedish women aged 40-55 y at baseline. Data on dietary intake, body weight, height, age, education, and parity were collected in 1987-1990 and 1997. The intake frequencies of whole milk and sour milk (3% fat), medium-fat milk (1.5% fat), low-fat milk and sour milk (<or=0.5% fat), cheese, and butter were calculated at baseline and follow-up. The women were categorized into 4 groups according to their intake: 1) constant, <1 serving/d; 2) increased from <1 serving/d to >or=1 serving/d; 3) constant, >or=1 serving/d; and 4) decreased from >or=1 serving/d to <1 serving/d. Odds ratios (ORs) with 95% CIs for an average weight gain of >or=1 kg/y were calculated by using multivariable logistic regression analyses, with group 1 as the reference.

RESULTS

Mean (+/-SD) body mass index (in kg/m2) at baseline was 23.7 +/- 3.5. The constant (>or=1 serving/d) intakes of whole milk and sour milk and of cheese were inversely associated with weight gain; ORs for group 3 were 0.85 (95% CI: 0.73, 0.99) and 0.70 (95% CI: 0.59, 0.84) respectively. No significant associations were seen for the other 3 intake groups. When stratified by BMI, the findings remained significant for cheese and, for normal-weight women only, for whole milk and sour milk.

CONCLUSION

The association between the intake of dairy products and weight change differed according to type of dairy product and body mass status. The mechanism behind these findings warrants further investigation.

The effects of increasing serum calcitriol on energy and fat metabolism and gene expression

OBJECTIVE

Evidence from a number of investigations indicates that calcium intake could be inversely related to body weight through alterations in the 1,25-OH(2)-D(3) metabolism. The objective of this study was to test whether energy and substrate metabolism and adipose tissue enzyme mRNA expression can be altered by changes in serum 1,25-OH(2)-D(3) through oral cholecalciferol supplementation in non-obese human subjects.

RESEARCH METHODS AND PROCEDURES

An intervention study was used with a treatment period of 7 days. During this intervention, energy expenditure (EE) and substrate metabolism were measured using indirect calorimetry at t = 0, 1, 3, and 7 days, and blood samples were obtained at t = -1, 0, 1, 2, 3, 5 and 7 days. Fat biopsies were obtained at t = 0 and 7 days for determination of expression of genes involved in lipolytic and lipogenic pathways. Subjects from the general community were studied in an ambulatory setting at a university hospital. Ten healthy young men (age, 28 +/- 3 years; BMI, 25.5 +/- 0.5 kg/m(2)) were recruited by local announcement, and all completed the study. All subjects received 2000 IU cholecalciferol/d for 7 days, and they were instructed to consume a low-cholecalciferol, low-calcium diet. EE, fat oxidation, and adipose tissue enzyme mRNA were the main outcome measures.

RESULTS

Despite a significant increase in serum 1,25-OH(2)-D(3) concentration at t = 5 and 7 days, no significant differences in substrate and energy metabolism nor mRNA concentrations of different lipid metabolism-related proteins were observed.

DISCUSSION

Seven-day supplementation with 2000 IU cholecalciferol/d together with a decrease in dietary calcium intake does not affect EE or substrate metabolism nor gene expression of proteins related to fat metabolism, despite a significant increase in serum 1,25-OH(2)-D(3) concentration.

Metabolically active functional food ingredients for weight control

The scale of the obesity epidemic creates a pressing consumer need as well as an enormous business opportunity for successful development and marketing of food products with added benefits for weight control. A number of proposed functional food ingredients have been shown to act post-absorptively to influence substrate utilization or thermogenesis. Characteristics and supporting data on conjugated linoleic acid, diglycerides, medium-chain triglycerides, green tea, ephedrine, caffeine, capsaicin and calcium, are reviewed here, giving examples of how these could act to alter energy expenditure or appetite control. Consideration is also given to other factors, in addition to efficacy, which must be satisfied to get such ingredients into foods. We conclude that, for each of the safe, putatively metabolically active agents, there remain gaps in clinical evidence or knowledge of mechanisms, which need to be addressed in order to specify the dietary conditions and food product compositions where these ingredients could be of most benefit for weight control.