Dairy augmentation of total and central fat loss in obese subjects

No relation between intakes of calcium and dairy products and body mass index in Japanese women aged 18 to 20 y

OBJECTIVE

This cross-sectional study examined possible associations of intakes of calcium and dairy products to body mass index (BMI; kilograms per square meter) in young Japanese women.

METHODS

Subjects were 1905 female Japanese dietetic students who were 18 to 20 y of age. Dietary intake was assessed over a 1-mo period with a validated, self-administered diet history questionnaire. BMI was computed by using self-reported weight and height. BMI among quartiles of energy-adjusted intakes (per 1000 kcal) of calcium and dairy products was compared while controlling for intakes of protein, fat, and dietary fiber, self-reported rate of eating, and other non-dietary variables.

RESULTS

Mean BMI +/- standard deviation was 20.8 +/- 2.6 kg/m2. Mean estimated intakes were 268 +/- 93 mg/1000 kcal for calcium and 80 +/- 63 g/1000 kcal for dairy products. Intakes of calcium and dairy products were not significantly associated with BMI (adjusted means in the lowest and highest quartiles were 20.7 and 20.8 for calcium, P for trend = 0.48, and 20.6 and 20.6 for dairy products, P for trend = 0.81). These results were also observed after excluding 481 energy under- and over-reporters for calcium (20.4 and 20.5, respectively, P for trend = 0.73) and dairy products (20.3 and 20.4, respectively, P for trend = 0.73).

CONCLUSIONS

Intakes of calcium and dairy products may not necessarily be associated with BMI among young Japanese women who not only are relatively lean but also have a relatively low intake of calcium and dairy products.

Calcium supplementation for the management of primary hypertension in adults

BACKGROUND

Metabolic studies suggest calcium may have a role in the regulation of blood pressure. Some epidemiological studies have reported that people with a higher intake of calcium tend to have lower blood pressure. Previous systematic reviews and meta-analyses have reached conflicting conclusions about whether oral calcium supplementation can reduce blood pressure.

OBJECTIVES

To evaluate the effects of oral calcium supplementation as a treatment for primary hypertension in adults.

SEARCH STRATEGY

We searched the Cochrane Library, MEDLINE, EMBASE, Science Citation Index, ISI Proceedings, ClinicalTrials.gov, Current Controlled Trials, CAB abstracts, and reference lists of systematic reviews, meta-analyses and randomised controlled trials (RCTs) included in the review.

SELECTION CRITERIA

Inclusion criteria were: 1) RCTs comparing oral calcium supplementation with placebo, no treatment, or usual care; 2) treatment and follow-up >/=8 weeks; 3) participants over 18 years old, with raised systolic blood pressure (SBP) >/=140 mmHg or diastolic blood pressure (DBP) >/=85 mmHg; 4) SBP and DBP reported at end of follow-up. We excluded trials where: participants were pregnant; received antihypertensive medication which changed during the study; or calcium supplementation was combined with other interventions.

DATA COLLECTION AND ANALYSIS

Two reviewers independently abstracted data and assessed trial quality. Disagreements were resolved by discussion or a third reviewer. Random effects meta-analyses and sensitivity analyses were conducted.

MAIN RESULTS

We included 13 RCTs (n=485), with between eight and 15 weeks follow-up. The results of the individual trials were heterogeneous. Combining all trials, participants receiving calcium supplementation as compared to control had a statistically significant reduction in SBP (mean difference: -2.5 mmHg, 95% CI: -4.5 to -0.6, I(2 )= 42%), but not DBP (mean difference: -0.8 mmHg, 95% CI: -2.1 to 0.4, I(2) = 48%). Sub-group analyses indicated that heterogeneity between trials could not be explained by dose of calcium or baseline blood pressure. Heterogeneity was reduced when poor quality trials were excluded. The one trial reporting adequate concealment of allocation and the one trial reporting adequate blinding yielded results consistent with the primary meta-analysis.

AUTHORS' CONCLUSIONS

In view of the poor quality of included trials and the heterogeneity between trials, the evidence in favour of causal association between calcium supplementation and blood pressure reduction is weak and is probably due to bias. This is because poor quality studies generally tend to over-estimate the effects of treatment. Larger, longer duration and better quality double-blind placebo controlled trials are needed to assess the effect of calcium supplementation on blood pressure and cardiovascular outcomes.

Major Scientific Advances with Dairy Foods in Nutrition and Health

A large body of scientific evidence collected in recent decades demonstrates that an adequate intake of calcium and other nutrients from dairy foods reduces the risk of osteoporosis by increasing bone acquisition during growth, slowing age-related bone loss, and reducing osteoporotic fractures. These results have culminated in the new (2005) Dietary Guidelines for Americans that now recommend 3 servings of milk products per day to reduce the risk of low bone mass and contribute important amounts of many nutrients that may have additional health attributes beyond bone health. A number of animal, observational, and clinical studies have shown that dairy food consumption can help reduce the risk of hypertension. Clinical trials indicate that the consumption of recommended levels of dairy products, as part of a healthy diet, can contribute to lower blood pressure in individuals with normal and elevated blood pressure. Emerging data also indicate that specific peptides associated with casein and whey proteins can significantly lower blood pressure. In addition, a growing body of evidence has provided support for a beneficial effect of dairy foods on body weight and fat loss. Clinical studies have demonstrated that during caloric restriction, body weight and body fat loss occurs when adequate calcium is provided by supplements and that this effect is further augmented by an equivalent amount of calcium supplied from dairy foods. Several studies support a role for calcium, vitamin D, and dairy foods against colon cancer. Additionally, conjugated linoleic acid, a fatty acid found naturally in dairy fat, confers a wide range of anticarcinogenic benefits in experimental animal models and is especially consistent for protection against breast cancer.

Low calcium intake among African Americans: effects on bones and body weight

This review was performed to summarize and integrate the evidence relating calcium intake to health status in African Americans, with special attention to bone and fat. Despite lower average calcium intakes, African Americans typically have skeletons more massive than those of whites. This is the result of a relative resistance of the bony resorptive apparatus to parathyroid hormone, which forces better urinary conservation of calcium and, at some life stages, more efficient intestinal calcium absorption as well. This adaptation, however, has other costs and appears to contribute to a greater risk in African Americans for several chronic diseases, including cardiovascular disease and stroke, obesity, and the insulin resistance syndrome. Higher calcium intakes not only support the skeleton in African Americans, just as they do in whites, but reduce the disease burden for other chronic diseases as well.

Dietary calcium regulates ROS production in aP2-agouti transgenic mice on high-fat/high-sucrose diets

OBJECTIVE

We have previously demonstrated that 1alpha, 25(OH)2D3 promotes adipocyte reactive oxygen species (ROS) production. We have now evaluated whether decreasing 1alpha, 25(OH)2D3 levels by increasing dietary calcium will decrease oxidative stress in vivo.

METHODS

We fed low-calcium (0.4% Ca) and high-calcium (1.2% Ca from CaCO3) obesity-promoting (high sucrose/high fat) diets to aP2-agouti transgenic mice and assessed regulation of ROS production in adipose tissue and skeletal muscle.

RESULTS

Mice on the high-calcium diet gained 50% of the body weight (P=0.04) and fat (P<0.001) as mice on the low-calcium diet (0.4% Ca). The high-calcium diet significantly reduced adipose intracellular ROS production by 64 and 18% (P<0.001) and inhibited adipose tissue nicotinamide adenine dinucleotide phosphate oxidase expression by 49% (P=0.012) and 63% (P=0.05) in visceral and subcutaneous adipose tissue, respectively. Adipocyte intracellular calcium ([Ca2+]i) levels were suppressed in mice on the high-calcium diet by 73-80% (P<0.001). The high-calcium diet also induced 367 and 191% increases in adipose mitochondrial uncoupling protein 2 (UCP2) expression (P<0.001) in visceral and subcutaneous adipose tissue, respectively. The pattern of UCP3 expression and indices of ROS production in skeletal muscle were consistent with those in adipose tissue. The high-calcium diet also suppressed 11beta-hydroxysteroid dehydrogenase (11beta-HSD) expression in visceral adipose tissue by 39% (P=0.034). 11beta-HSD expression was markedly higher in visceral vs subcutaneous adipose tissue in mice on the low-calcium diet (P=0.034), whereas no difference was observed between the fat depots in mice on the high-calcium diet.

CONCLUSION

These data support a potential role for dietary calcium in the regulation of obesity-induced oxidative stress.

Dairy products and cardiovascular disease

PURPOSE OF REVIEW

Although it has often been postulated that the consumption of dairy products is associated with a high risk of coronary heart disease, study results have been conflicting. This review summarizes recent observational and human intervention trial findings on dairy products and cardiovascular disease.

RECENT FINDINGS

Results from more recent observational studies on dairy products and milk disagree. This may be because of the very different methods used combined with several methodological problems. A somewhat surprising beneficial association between the intake of dairy products and the metabolic syndrome was observed in some studies, although not in a single study of elderly women. Milk may have the same cholesterol-raising properties as butter, whereas cheese does not seem to increase plasma cholesterol. Some milk products fermented by specific bacterial strains have been shown to have rather moderate cholesterol-reducing properties. There is also good evidence that certain fermented products (especially by Lactobacillus helveticus) have a mildly decreasing effect on hypertension, probably because of bioactive peptides.

SUMMARY

When guiding principles such as balance, variety and moderation are stressed, there is no strong evidence that dairy products increase the risk of coronary heart disease in healthy men of all ages or young and middle-aged healthy women. Human studies should investigate the role of dairy products with respect to sex and age by including classic and novel risk markers of coronary heart disease. Specific fermented milks may be beneficial in the future prevention of hypertension. The beneficially neutral effect of cheese on coronary heart disease risk factors should be elucidated further.

Effect of energy-reduced diets high in dairy products and fiber on weight loss in obese adults

OBJECTIVE

Studies suggest that high-dairy and high-fiber/low-glycemic index diets may facilitate weight loss, but data are conflicting. The effects on weight loss and body fat of a high-dairy diet and a diet high in dairy and fiber and low in glycemic index were compared with a standard diet.

RESEARCH METHODS AND PROCEDURES

Ninety obese subjects were recruited into a randomized trial of three diets designed to provide a calorie deficit of 500 calories/d over a 48-week period. The study compared a moderate (not low)-calcium diet with a high-calcium diet.

RESULTS

Seventy-two subjects completed the study. Significant weight and fat loss occurred with all three diets. A diet with 1400 mg of calcium did not result in greater weight (11.8 +/- 6.1 kg) or fat (9.0 +/- 6.0 kg) loss than a diet with 800 mg of calcium (10.0 +/- 6.8 and 7.5 +/- 6.6 kg, respectively). A diet with 1400 mg of calcium, increased fiber content, and fewer high-glycemic index foods did not result in greater weight (10.6 +/- 6.8 kg) or fat (8.5 +/- 7.8 kg) loss than the standard diet with 800 mg of calcium. Lipid profile, high-sensitivity C-reactive protein, leptin, fasting glucose, and insulin improved significantly, but there were no significant differences between the experimental diets and the control diet.

DISCUSSION

We found no evidence that diets higher than 800 mg of calcium in dairy products or higher in fiber and lower in glycemic index enhance weight reduction beyond what is seen with calorie restriction alone.

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

BACKGROUND

Evidence from molecular and animal research and epidemiologic investigations indicates that calcium intake may be inversely related to body weight, possibly through alterations in 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] metabolism.

OBJECTIVE

We tested whether energy and substrate metabolism and adipose tissue enzyme messenger RNA (mRNA) expression can be altered by dietary calcium intake in healthy, nonobese, human volunteers consuming an isocaloric diet.

DESIGN

Twelve healthy men [age: 28 +/- 2 y; body mass index (BMI; in kg/m(2)): 25.2 +/- 06] received 3 isocaloric diets [high calcium (1259 +/- 9 mg/d), high dairy (high/high); high calcium (1259 +/- 9 mg/d), low dairy (high/low); and low calcium (349 +/- 8 mg/d), low dairy (low/low)] in a randomized crossover design. At the end of the 7-d dietary periods, 24-h energy expenditure and substrate metabolism were measured, and fat biopsy specimens were obtained to determine mRNA expression in genes involved in the lipolytic and lipogenic pathways.

RESULTS

The 24-h energy expenditure was 11.8 +/- 0.3, 11.6 +/- 0.3, and 11.7 +/- 0.3 MJ/24 h in the high/high, high/low, and low/low conditions, respectively. Fat oxidation in these conditions was 108 +/- 7, 105 +/- 9, and 100 +/- 6 g/24 h. These differences were not statistically significant. mRNA concentrations of UCP2, FAS, GPDH2, HSL, and PPARG did not differ significantly. Serum 1,25(OH)(2)D(3) concentrations changed from 175 +/- 16 to 138 +/- 15, 181 +/- 23 to 159 +/- 19, and 164 +/- 13 to 198 +/- 19 pmol/L in the high/high, high/low, and low/low conditions, respectively, and was significantly different between the high/high and low/low conditions (P < 0.05).

CONCLUSION

Altering the dietary calcium content for 7 d does not influence substrate metabolism, energy metabolism, or gene expression in proteins related to fat metabolism, despite significant changes in 1,25(OH)(2)D(3) concentrations.

The influence of dairy product consumption on body composition

Recent epidemiologic research suggests that dairy product intake or its components (calcium, vitamin D, and amount or source of protein) are associated with lower body weight or body fat. Clinical intervention trials designed to test this association during weight loss are promising, but still controversial. Few data are available on the effect of calcium or dairy products on prevention of weight gain in long-term trials. The mechanisms proposed to mediate the putative effect of dietary calcium are primarily the formation of fecal fatty acid complexes to reduce fat absorption and the regulation of energy metabolism, including lipolysis from adipocytes and fatty acid oxidation, through the calciotropic hormones, parathyroid hormone, and 1,25-dihydroxyvitamin D. Increased energy expenditure, increased satiety, or a shift from fat to lean mass must accompany these changes in lipid metabolism to achieve changes in fat mass; however, measurable changes in these other parameters either have not been tested or have not been noted uniformly. If dairy products or their components have an effect on altering fat mass, it is likely to be a small change that may have a substantial effect on the incidence of obesity over time.

The Role of Dairy Foods in Weight Management

Dietary calcium appears to play a pivotal role in the regulation of energy metabolism and obesity risk. High calcium diets attenuate body fat accumulation and weight gain during periods of over-consumption of an energy-dense diet and to increase fat breakdown and preserve metabolism during caloric restriction, thereby markedly accelerating weight and fat loss. This effect is mediated primarily by circulating calcitriol, which regulates adipocyte intracellular Ca(2+). Studies of human adipocyte metabolism demonstrate a key role for intracellular Ca(2+) in regulating lipid metabolism and triglyceride storage, with increased intracellular Ca(2+) resulting in stimulation of lipogenic gene expression and lipogenesis and suppression of lipolysis, resulting in adipocyte lipid filling and increased adiposity. Moreover, the increased calcitriol produced in response to low calcium diets stimulates adipocyte Ca(2+) influx and, consequently, promotes adiposity, while higher calcium diets inhibit lipogenesis, promote lipolysis, lipid oxidation and thermogenesis and inhibit diet-induced obesity in mice. Notably, dairy sources of calcium exert markedly greater effects in attenuating weight and fat gain and accelerating fat loss. This augmented effect of dairy products versus supplemental calcium has been localized, in part, to the whey fraction of dairy and is likely due to additional bioactive compounds, such as angiotensin converting enzyme (ACE) inhibitors in dairy, as well as the rich concentration of branched chain amino acids, which act synergistically with calcium to attenuate adiposity; however, these compounds do not fully account for the observed effects, as whey has significantly greater bioactivity than found in these compounds. These concepts are confirmed by epidemiological data as well as recent clinical trials which demonstrate that diets which include at least three daily servings of dairy products result in significant reductions in body fat mass in obese humans in the absence of caloric restriction and markedly accelerates the weight and body fat loss secondary to caloric restriction compared to low dairy diets. These data indicate an important role for dairy products in both the ability to maintain a healthy weight and the management of overweight and obesity.

Growth: healthy status and active food model in pediatrics

OBJECTIVE

The brain integrates peripheral signals of nutrition in order to maintain a stable body weight. Nutritional status defined as the results of introduction, absorption, and utilization of the nutrients could be interpreted with the base of the relationship between nutritional status and healthy status. In this view, energy balance, body function, and body composition are three entities correlated to each other to the healthy status.

AIM

To discuss the nutritional status in relation with healthy status, and its relationship with growth and nutrients.

METHODS

A review of the available literature on food patterns and active food model was carried out.

RESULTS

In the reviewed studies, strategies that could offer promising results to prevent overweight and obesity were discussed, in particular in the light of functional foods that effect energy metabolism and fat partitioning.

CONCLUSION

At this moment it is necessary to proactively discuss and promote healthy eating behaviors among children at an early age and empower parents to promote children's ability to self-regulate energy intake while providing appropriate structure and boundaries around eating.

Functional foods: what are they? How are they regulated? What claims can be made?

Scientific studies continue to establish a strong relationship between constituents in foods and dietary supplements and certain diseases. The general population is inundated on a seemingly daily basis by media reports of new studies showing that a food or dietary supplement is useful in treating particular diseases or reducing the likelihood that a consumer will develop particular diseases. With increasing frequency, consumers are looking for foods and supplements to help manage and prevent the onset of disease.

Not surprisingly, the food and dietary supplement industries are responding by developing new products and repositioning old products efforts to help consumers manage their health. For example, yogurt used to be positioned only as a delicious component of a meal but now is also promoted for use in weight loss programs after a study showed that the calcium in dairy products is effective in weight loss.