No effect of dietary calcium on body weight of lean and obese mice and rats

Calcium Deficiency Decreases Bone Mass without Affecting Adiposity in Ovariectomized Rats Fed a High-Fat Diet

Obesity induced by a high-fat (HF) diet increases bone resorption and/or decreases bone formation, resulting in reduced bone mass and strength in various animal models. Studies showed that Ca intake is a modifiable factor for osteoporosis and obesity. This study investigated whether Ca deficiency affects bone structure and adiposity in ovariectomized (OVX) rats fed a HF diet. We hypothesized that Ca deficiency further decreases bone mass and increases fat mass in HF-fed OVX rats. Forty-seven OVX at 6-month-old were randomly assigned to four groups in a 2 × 2 factorial design: normal-fat (NF, 10% fat as energy) or HF (45% fat as energy) diet with either low Ca (LC, 1 g/4057 kcal) or normal Ca (NC, 6 g/4057 kcal). In addition, 12 sham-operated rats at 6 months old were fed a NFNC diet as a control for the OVX procedure. Rats were fed the respective diet for 4 months. Dietary Ca content did not affect body weight, fat mass, lean mass, food intake, energy intake, and serum cytokines. Compared to NC, LC resulted in lower tibial bone volume/total volume (BV/TV, p < 0.01), connectivity density (p < 0.01), trabecular number (Tb.N, p = 0.01), bone mineral density (BMD, p < 0.01), and femur weight (p < 0.01), femur content of Ca (p < 0.01), Cu (p = 0.03), Zn (p < 0.01), and greater trabecular separation (Tb.Sp, p < 0.01) at proximal tibia indicating bone structure deterioration. Compared to rats on the NF diet, animals fed the HF had lower BV/TV (p = 0.03) and Tb.N (p < 0.01) with greater body weight (p < 0.01), fat mass (p < 0.01), Tb.Sp (p = 0.01), the content of Ca, Cu, and Zn in the femur, and serum leptin (p < 0.01). There were no significant interactions between Ca and fat for body composition and bone structural parameters. Compared to Sham, OVX resulted in greater body weight and fat mass. The trabecular bone structure of the tibia, but not the cortical bone, was significantly impaired by the OVX procedure. These data indicate that inadequate Ca intake and a high-fat diet have independent negative effects on bone structure and that Ca deficiency does not affect adiposity in OVX rats.

Evaluation of an Ionic Calcium Fiber Supplement and Its Impact on Bone Health Preservation in a Dietary Calcium Deficiency Mice Model

Ionic calcium can help in the prevention of the process of osseous decalcification. This study aimed to evaluate the physicochemical properties and toxic effects of ionic calcium-fiber supplement (ICa+) and its impact on bone health preservation in mice C57/BL6 fed a calcium-deficient diet. Physicochemical properties include FTIR, apparent calcium solubility estimated by the calcium ratio obtained by ionization chromatography and atomic absorption. In vitro genotoxicity and cytotoxicity of the ICa+ were assessed. Twenty-five 7-week-old C57/BL6 mice were fed calcium-free diet (CFD) or CFD plus CaCO3 (1.33 mg Ca) or CFD plus ICa+ (1.33-6.66 mg Ca) for six weeks. After that, bone mass and microstructure parameters were assessed. Histological staining was performed to determine calcium deposits. ICa+ (100%) exhibited an apparent calcium solubility higher than CaCO3 (12.3%). ICa+ showed no cytotoxic and genotoxic in vitro activities. Histomorphometry analysis showed that the ICa+ treated group displayed a higher trabecular number than the trabecular space. Also, the ratio BV/TV was increased compared with all treatments. Ionic calcium-fiber supplementation prevents bone deterioration compared to mice fed a calcium-deficient diet.

Dietary calcium affects body composition and lipid metabolism in rats

Calcium (Ca) intakes may affect cardiovascular disease risk by altering body composition (body weight and fat) and serum lipid profile, but results have been inconsistent and the underlying mechanisms are not well understood. The effects of dietary Ca on body composition and lipid metabolism were examined in rats. Male Sprague-Dawley rats were fed high-fat, high-energy diets containing (g/kg) low (0.75Ca, 0.86 ± 0.05; 2Ca, 2.26 ± 0.02), normal (5Ca, 5.55 ± 0.08) or high (10Ca, 11.03 ± 0.17; 20Ca, 21.79 ± 0.15) Ca for 10 weeks. Rats fed the lowest Ca diet (0.75Ca) had lower (p < 0.05) body weight and fat mass compared to other groups. Rats fed the high Ca diets had lower serum total and LDL cholesterol compared to rats fed normal or low Ca. Liver total cholesterol was lower in rats fed high compared to low Ca. In general, liver mRNA expression of genes involved in cholesterol uptake from the circulation (Ldlr), cholesterol synthesis (Hmgcr and Hmgcs1), fatty acid oxidation (Cpt2) and cholesterol esterification (Acat2) were higher in rats fed higher Ca. Apparent digestibility of total trans, saturated, monounsaturated and polyunsaturated fatty acids was lower in rats fed the high compared to the low Ca diets, with the largest effects seen on trans and saturated fatty acids. Fecal excretion of cholesterol and total bile acids was highest in rats fed the highest Ca diet (20Ca). The results suggest little effect of dietary Ca on body composition unless Ca intakes are very low. Decreased bile acid reabsorption and reduced absorption of neutral sterols and saturated and trans fatty acids may contribute to the better serum lipid profile in rats fed higher Ca.

The effects of whole milk compared to skim milk and apple juice consumption in breakfast on appetite and energy intake in obese children: a three-way randomized crossover clinical trial

BACKGROUND

A limited number of studies have examined the effect of dairy on satiety and short-term energy intake among children; furthermore we are not aware of any study comparing high and low-fat dairy products regarding their effect on appetite and short-term energy intake. Our objective was to assess the effect skim milk (SM) compared to whole milk (WM) and apple juice (AJ) on satiety and energy intake at lunch among 10-12 y children with obesity.

METHODS

Fifty children with obesity who aged 10-12 y were randomized to consume a fixed content breakfast with 240 ml of SM, AJ, or WM for two consecutive days. The study was a three-way randomized crossover study; therefore each participant served as his/her own control. The total appetite, hunger, fullness, desire to eat and prospective consumption were measured using a visual analogue scale (VAS) before breakfast and every one hour after breakfast until a freely consumed lunch. VAS scores and energy intakes were compared using repeated measures procedure.

RESULTS

Forty-eight participants (24 girls and 24 boys) completed the study. The energy intake was not different between SM, AJ and WM periods (adjusted mean ± standard error (SE) of energy intake: SM = 831.27 ± 30.64 Kcal, AJ = 794.92 ± 28.72 Kcal, WM = 798.87 ± 24.09 Kcal; P = 0.56). The effect was the same for either gender. Children reported higher satiety score 4 h after drinking WM with breakfast compared with SM (P < 0.05). The same association was found only in girls. Furthermore, SM significantly reduced appetite compared to AJ, 2 h after preloads in girls (P < 0.05).

CONCLUSIONS

Full-fat milk may have favorable effects on satiety but not energy intake in subsequent meal compared to skim milk among the children with obesity. Future studies with longer follow-up periods are needed to confirm these results.

TRIAL REGISTRATION

The study protocol was registered with the Iranian registry of clinical trials on 9th October 2016 (registration ID: IRCT2016072012571N5).

Low-calcium diet prevents fructose-induced hyperinsulinemia and ameliorates the response to glucose load in rats

Background

Consuming a fructose-rich diet leads to hyperinsulinemia, impaired glucose tolerance, and insulin resistance. In humans, the consumption of high levels of refined sugars often coincides with a diet containing suboptimal levels of calcium. Calcium and carbohydrate metabolism interact, so there is potential for fructose to have different health outcomes depending on whether the diet is calcium-rich or calcium-poor.

Methods

We evaluated the metabolic effects of feeding fructose to rats that were maintained on either a calcium-replete diet or a low-calcium diet. Growing male Sprague Dawley rats were fed diets based on the AIN-93G formulation, with the main source of carbohydrate derived either from a mixture of cornstarch and sucrose or from fructose. Half the rats given each carbohydrate source were fed calcium at recommended levels (125 mmol/kg Ca²⁺); the others were fed a diet low in calcium (25 mmol/kg Ca²⁺). At various times, glucose and insulin tolerance tests were conducted to assess glucose metabolism.

Results

Rats fed low-calcium diet had lower fasting insulin levels irrespective of the carbohydrate source they ate. They had a normal glycemic response to a glucose load and did not develop hyperinsulinemia under conditions of fructose feeding. The drop in blood glucose levels in response to insulin injection was larger in rats fed low-calcium diet than in those fed calcium-replete diet.

Conclusions

Low-calcium diet prevented fructose-induced hyperinsulinemia and improved glucose handling under conditions of fructose feeding. Potential mechanisms underlying these effects of the low-calcium diet remain to be determined, but possibilities include impairment of insulin release from the pancreas and improved peripheral insulin sensitivity.

Evaluation of calcium supplementation with algae (Lithothamnion muelleri) on metabolic and inflammatory parameters in mice fed a high refined carbohydrate-containing diet

The aim of the present study was to evaluate the potential of calcium supplementation from Lithothamnium muelleri algae on metabolic and inflammatory parameters in mice with increased adiposity. Male mice were fed and divided during 8 weeks in: control (C), a high refined carbohydrate-containing diet (HC), HC diet supplemented with 1% of Lithothamnion muelleri algae (HC + A) and HC diet supplemented with 0.9% calcium carbonate (HC + C). Animals fed HC diet had increased body weight gain and adiposity, serum glucose and cholesterol, glucose intolerance and decreased insulin sensitivity, compared to control diet. However, the HC + A and HC + C groups did not prevent these aspects and were not able to change the CD14 + cells population in adipose tissue of animals fed HC diet. Calcium supplementation with Lithothamnium muelleri algae and calcium carbonate had no protective effect against the development of adiposity, metabolic and inflammatory alterations induced by HC diet.

High vitamin D and calcium intakes reduce diet-induced obesity in mice by increasing adipose tissue apoptosis

SCOPE

Modulation of apoptosis is emerging as a promising antiobesity strategy because removal of adipocytes through this process will result in reducing body fat. Effects of vitamin D on apoptosis are mediated via multiple signaling pathways that involve common regulators and effectors converging on cellular Ca(2+) . We have previously shown that 1,25-dihydroxyvitamin D3 induces the Ca(2+) signal associated with activation of Ca(2+) -dependent apoptotic proteases in mature adipocytes. In this study, a diet-induced obesity (DIO) mouse model was used to evaluate the role of vitamin D and calcium in adiposity.

METHODS AND RESULTS

DIO mice fed high vitamin D3 , high Ca, and high D3 plus high Ca diets demonstrated a decreased body and fat weight gain, improved markers of adiposity and vitamin D status (plasma concentrations of glucose, insulin, adiponectin, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, parathyroid hormone (PTH)), but an increased plasma Ca(2+) . High D3 and Ca intakes were associated with induction of apoptosis and activation of Ca(2+) -dependent apoptotic proteases, calpain and caspase-12, in adipose tissue of DIO mice. The combination of D3 plus Ca was more effective than D3 or Ca alone in decreasing adiposity.

CONCLUSION

The results imply that high vitamin D and Ca intakes activate the Ca(2+) -mediated apoptotic pathway in adipose tissue. Targeting this pathway with vitamin D and Ca supplementation could contribute to the prevention and treatment of obesity. However, this potentially effective and affordable approach needs to be evaluated from a safety point of view.

Effect of Low- and High-Calcium Dairy-Based Diets on Macronutrient Oxidation in Humans

OBJECTIVE

Higher calcium and dairy intakes may be associated with lower body weights, but a mechanism in humans has yet to be elucidated. We compared the effects of a dairy-based high-calcium diet and a low-calcium diet on macronutrient oxidation.

RESEARCH METHODS AND PROCEDURES

Subjects (10 men and nine women) consumed a low-dairy (LD, approximately one serving per day, approximately 500 mg Ca(2+)/d) or high-dairy (HD, approximately three to four servings per day, approximately 1400 mg Ca(2+)/d) energy balance diet for 1 week. Each diet condition was performed twice. On the 7th day, subjects were studied in a room calorimeter under one of four study conditions, applied in a randomized crossover design. Within each diet condition, subjects were studied under conditions of energy balance and acute energy deficit. The deficit (-600 kcal/d) was induced only for the 24 hours that subjects resided in the room and was achieved by a combination of caloric restriction and exercise.

RESULTS

Under energy balance conditions, there was no effect of diet treatment on respiratory quotient or 24-hour macronutrient oxidation. Under energy deficit conditions, 24-hour fat oxidation was significantly increased on the HD diet (HD with deficit = 136 +/- 13 g/d, LD with deficit = 106 +/- 7 g/d, p = 0.02).

DISCUSSION

Consumption of a dairy-based high-calcium diet increased 24-hour fat oxidation under conditions of acute energy deficit. We hypothesize that these effects are due to an increased fat oxidation during exercise.

Effect of calcium treatment on blood parameters, gonadal development and the structure of bone in immature female rats

Calcium is an essential nutrient required for critical biological functions. Calcium supplementation is to be evaluated using immature female rats. The present study focused on some blood parameters, gonadal development and bone structure. Forty immature female Sprague-Dawley rats were randomly divided into four equal-sized groups (80 g average body weight) to receive calcium chloride dihydrate (group I: control; groups II, III and IV: received 20 mg, 40 mg and 60 mg per kg body weight, respectively) for 5 weeks. Rats were decapitated, and their trunk blood was sampled for biochemical assays. Cholesterol, triglycerides, glucose and calcium were measured. Gonadal and bone structure were histologically evaluated. Results revealed that treatment of developing female rats with three calcium doses used have no marked effect on the serum calcium and cholesterol levels. However, serum triglyceride level and body weight gain are significantly decreased in rats treated with all of the three calcium doses. Serum glucose level showed a marked increase in animals treated with the higher calcium doses. Moreover, observable histological alterations are recognized in the ovaries. Bones of the experimental animals also showed morphological alterations. These results suggest that increasing calcium supplementation decreases triglycerides and percentage body weight gain and positively affects the bone and gonadal development.

Effect of dietary calcium (Ca) on body composition and Ca metabolism during growth in genetically obese (β) male rats

INTRODUCTION

Obese β rats may be a suitable model to evaluate the association between calcium intake (CaI) and obesity during growth.

OBJECTIVE

The present study comparatively evaluated Ca absorption and retention, and changes in body composition in spontaneously genetically obese (β) male rats fed three different dietary Ca levels: high 0.9% (HCa); normal: 0.5% (NCa); low: 0.2% (LCa).

METHODS

Pregnant rats were fed isocaloric diets which varied in Ca content only. Male pups continued feeding the same maternal diet until postnatal day 60. The percentage of Apparent Ca absorption (CaA %), Ca balance (CaB), body composition, glucose, triglycerides (TGL), and insulin levels were evaluated.

RESULTS

Food consumption and body weight (BW) were higher in Group LCa than in Groups NCa and HCa (p < 0.01); no differences were observed between the latter two groups. Group LCa presented the highest body fat, liver weight, perigonadal and retroperitoneal fat (p < 0.05); conversely, body ashes and total skeleton bone mineral content were significantly lower compared with animals in both the NCa (p < 0.01) and HCa groups (p < 0.01). CaB (mg/day) reached a plateau at the highest CaI (mg/day) value (r = 0.985, p < 0.001). CaA%, serum glucose, insulin, and TGL levels rose as CaI decreased (p < 0.01).

CONCLUSIONS

Although further studies are required, low Ca consumption in this strain of rats could modulate BW inducing changes in several lipid metabolism parameters, which in turn lead to an increase in body fat.

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.

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.

High-Calcium Milk Prevents Overweight and Obesity among Postmenopausal Women

Background

The Sixth National Nutrition Survey 2003 revealed that the highest prevalence of overweight and obesity among Filipino female adults (30.8%) was found in the age group from 40 to 59 years. Obesity is associated with a number of chronic diseases, including cardiovascular disease, hypertension, and diabetes. Low calcium intake has been identified as a potential contributing factor to overweight and obesity.

Objective

To assess the effect of a high-calcium, fortified, low-fat milk drink with added vitamin D versus a low-calcium placebo drink on anthropometric measurements of postmenopausal women.

Methods

Women who were at least 5 years postmenopausal were invited to participate in the study. Potential participants underwent three stages of screening: initial interview, dual-energy x-ray absorptiometry, and blood testing for biochemical screening. Anthropometric indices were measured at baseline and the end of the study. Sixty women were qualified to participate in the study. The women were randomly assigned to two groups, one of which received 400 ml of the high-calcium milk daily for 16 weeks while the other received the placebo drink.

Results

No significant increases were observed in the anthropometric indices of the subjects receiving the high-calcium fortified milk at the end of the study. However, there were significant increases in the weight ( p = .008), body mass index ( p = .007), and waist ( p = .018) and hip ( p = .003) circumferences of the subjects receiving the placebo drink.

Conclusions

A change in dietary calcium intake may be a useful measure as part of an overall approach to prevent the occurrence of overweight and obesity among postmenopausal women.

A high calcium, skim milk powder diet results in a lower fat mass in male, energy-restricted, obese rats more than a low calcium, casein, or soy protein diet

The combination of dairy protein and dietary calcium (Ca) may enhance weight loss more effectively than either compound alone. Our purpose in this study was to determine the effect of various protein sources [skim milk powder (SMP), whey, casein, and soy protein isolate (SPI)] and 2 levels of Ca [low, 0.67% Ca (LC) or high, 2.4% Ca (HC)] on weight loss. Sixty-four 12-wk-old Sprague-Dawley, diet-induced obese rats were assigned to 1 of 8 energy-restricted (ER) diets for 4 wk with 1 of the 4 protein sources and either LC or HC concentrations. Rats were ER to 70% of the ad libitum food and energy intake of a reference group (n = 8) fed the AIN-93M diet. The interaction between dietary protein and Ca affected final body weight and fat mass (FM) (P < 0.05). FM was less in rats fed SMP-HC than in those fed casein-LC or SPI-LC. Lean body mass was greater in rats fed SMP than in those fed whey. Rats fed HC diets had a lower plasma glucagon area under the curve (AUC) than those fed LC diets. The blood glucose AUC, homeostatic model of insulin resistance, and the expression of certain hepatic genes involved in energy metabolism were affected by protein and Ca. These data suggest that consuming a diet containing SMP and HC is associated with a lower FM in obese, male, ER rats than in diets containing casein or SPI and LC; however, the role of SMP and Ca in glucose homeostasis remains to be determined.

Dairy protein attenuates weight gain in obese rats better than whey or casein alone

Evidence suggests that dietary calcium (Ca) and particularly dairy foods may attenuate weight gain and improve symptoms of the metabolic syndrome. The purpose of this study was to determine the effect of different Ca-enriched dairy protein sources on the prevention of weight gain in Sprague-Dawley diet-induced obese (DIO) rats. Twelve week-old DIO rats were assigned to one of eight ad libitum diets that varied in protein source (casein, whey, or complete dairy), Ca content (0.67 or 2.4%) and energy level (high fat/high sucrose (HFHS); or normal calorie density (NC)). Body composition and response to a meal tolerance test (MTT) were measured. Average daily caloric intake did not differ within normal or high energy density groups. At the end of 8 weeks, the dairy/HFHS/0.67% and 2.4% groups had significantly lower body weight than all other HFHS groups. The dairy/HFHS/0.67% and 2.4% groups also had lower body fat and greater lean mass expressed as a percent (P < 0.05). Homeostatic model assessment of insulin resistance (HOMA(IR)) was lowest for dairy/HFHS/0.67% and significantly different from whey/HFHS/0.67% and 2.4%. Independent of protein source, high Ca decreased plasma insulin at 30 min in the MTT more so than low Ca (P < 0.05). Hepatic sterol regulatory element-binding protein (SREBP1c) and peroxisome proliferator-activated receptor-gamma (PPARgamma) mRNA was downregulated by dairy and whey compared to casein in the HFHS/0.67% diets. Overall, these data suggest that complete dairy improves body composition and insulin sensitivity to a greater extent than whey or casein alone.

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.

Skim milk compared with a fruit drink acutely reduces appetite and energy intake in overweight men and women

BACKGROUND

Several studies show that proteins, including whey and casein, are more satiating than carbohydrates. It follows that skim milk would be more satiating than sugar-rich beverages. However, this has yet to be shown.

OBJECTIVE

The objective was to investigate the effects of drinking skim milk in comparison with a fruit drink at breakfast on self-reported postmeal satiety and energy intake at lunch.

DESIGN

In a randomized crossover trial, 34 overweight women (n = 21) and men (n = 13) attended 2 sessions 1 wk apart. At each session, participants consumed a fixed-energy breakfast together with either 600 mL skim milk (25 g protein, 36 g lactose, <1 g fat; 1062 kJ) or 600 mL fruit drink (<1 g protein, 63 g sugar, <1 g fat; approximately 1062 kJ). Participants provided satiety ratings throughout the morning. Four hours after breakfast they consumed an ad libitum lunch, and energy intake was assessed.

RESULTS

Participants consumed significantly less energy at lunch after consuming skim milk (mean: 2432 kJ; 95% CI: 2160, 2704 kJ) than after consuming the fruit drink (mean: 2658 kJ; 95% CI: 2386, 2930 kJ), with a mean difference of approximately 8.5% (P < 0.05). In addition, self-reports of satiety were higher throughout the morning after consumption of skim milk than after consumption of the fruit drink (P < 0.05) with the differences becoming larger over the 4 h (P < 0.05).

CONCLUSION

Consumption of skim milk, in comparison with a fruit drink, leads to increased perceptions of satiety and to decreased energy intake at a subsequent meal. This trial was registered with the Australian New Zealand Clinical Trials Registry at (www.anzctr.org.au) as ACTRN12608000510347.

Calcium supplementation does not alter lipid oxidation or lipolysis in overweight/obese women

Based on cell culture and studies in mice, increased dietary calcium appears to stimulate lipolysis and could possibly reduce body adiposity through hormonal influences on adipocyte calcium uptake. In this study, we investigated the effects of 1,500 mg supplemental calcium daily for 3 months on hormones regulating calcium and energy metabolism and rates of lipid oxidation and lipolysis in overweight women. Fifteen overweight (BMI > 25 kg/m(2)) premenopausal women were supplemented with 1,500 mg of calcium, as CaCO(3), per day for 3 months while maintaining their usual diets and activity levels. Baseline and endpoint measurements were obtained after the subjects consumed a standardized 25% fat diet for 4 days. Lipid oxidation was measured by indirect calorimetry, lipolysis by infusion of deuterated glycerol, and body fat by dual-energy X-ray absorptiometry. Urinary calcium, circulating levels of hormones involved in energy and lipid metabolism (insulin, leptin, and adiponectin) or calcium metabolism (25(OH)D, 1,25(OH)(2)D), and parathyroid hormone (PTH)) were also measured. Urinary levels of calcium (P = 0.005) increased and 1,25(OH)(2)D declined (P = 0.03). However other parameters, including body weight, body fat, PTH, insulin, leptin, adiponectin, 25(OH)D, as well as rates of lipid oxidation and lipolysis were not altered by calcium supplementation. Calcium supplementation for 3 months increased urinary calcium excretion, decreased circulating levels of 1,25(OH)(2)-D, but had no effect on rates of lipid oxidation or lipolysis, in these overweight women.

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.

Can the controversial relationship between dietary calcium and body weight be mechanistically explained by alterations in appetite and food intake?

The prevalence of obesity has reached epidemic proportions worldwide and the incidence of overweight and obesity continues to rise. Diet plays a significant role in the modulation of body weight and there is some evidence to suggest that calcium or dairy intake may modulate body weight and body fat mass. Several mechanisms through which calcium or dairy products may affect body weight or fat have been suggested, including a possible effect on appetite and food intake. A recent study investigated to what extent people could compensate for increased energy intake from dairy products and found that a 7-day increase in dairy intake had no effect on appetite and no evidence of complete compensation for the raised energy intake. In another study, the effects of altered calcium content of a dairy-based test meal was evaluated in obese subjects; the findings indicated that although a higher calcium content of the meal reduced the extent of post-prandial chylomicron-associated triglyceridemia, there was no effect on appetite-related hormones (CCK, ghrelin, GLP-1, or PPY) or on energy intake from a subsequent ad libitum test meal. Thus, this new evidence does not support the hypothesis that high calcium or dairy intake reduces appetite or food intake.

Effect of dietary calcium and dairy proteins on the adipose tissue gene expression profile in diet-induced obesity

BACKGROUND/AIMS

Calcium and dairy proteins have been postulated to explain why the intake of dairy products correlates inversely with body mass index in several populations. We have shown that a high-calcium diet with whey protein attenuates weight gain and now we describe the effects of this diet on adipose tissue gene expression.

METHODS

Nine-week-old C57Bl/6J mice were divided into two groups (n = 10/group). The control diet was a standard high-fat diet (60% of energy) low in calcium (0.4%). The whey protein diet was a high-calcium (1.8%), high-fat diet with whey protein. After the 21-week treatment, adipose tissue transcript profiling (2 mice/group) was performed using Affymetrix Mouse Genome 430 2.0.

RESULTS

The high-calcium diet with whey protein altered the expression of 129 genes (+/- 1.2 fold). Quantitative RT-PCR analysis confirmed the significant up-regulation of Adrb3 (p = 0.002) and leptin (p = 0.0019) in the high-calcium whey group. Insulin and adipocytokine signaling pathways were enriched among the up-regulated genes and the fatty acid metabolism pathway among the down-regulated genes.

CONCLUSIONS

High-calcium diet with whey protein significantly modifies adipose tissue gene expression. These preliminary findings reveal that targets of a high-calcium diet with whey protein include genes for Adrb3 and leptin, and help to explain how the intake of dairy products might attenuate obesity.

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.

Forty mouse strain survey of body composition

We measured body weight and composition of approximately 10 male and approximately 10 female mice from 40 inbred strains. Body composition was assessed in approximately 16-wk old mice that had been individually housed and fed a high-carbohydrate, low-fat diet (AIN-76A) for the previous 8 wk. Carcass lean and fat weights were assessed using a PIXIMus II DEXA and confirmed by fat extraction assay. There was a nearly continuous range of body weights, from a strain mean+/-SE of 11.4+/-0.2 g (MSM/MsJ) to 39.3+/-1.8 g (NON/LtJ). The percentage of body weight that was fat (%Fat) ranged from 16+/-4% (C58/J) to 39+/-2% (NON/LtJ). In general, heavier strains had a higher %Fat (r=0.57) but several light strains were also quite fat (e.g., SPRET/EiJ, body weight=15.7+/-0.6 g, %Fat=26+/-1%). Males were significantly heavier than females in 26 strains and significantly fatter than females in 9 strains; only the KK/H1J strain had fatter females than males. Some of the fattest strains are infrequently used in obesity experiments, for example the JF1/Ms and CBA/J strains. These data illustrate the diversity of body weight and composition in inbred mice. They will serve as a reference standard and assist in the selection of strains for future work.

High-calcium diet with whey protein attenuates body-weight gain in high-fat-fed C57Bl/6J mice

An inverse relationship between Ca intake and BMI has been found in several studies. It has been suggested that Ca affects adipocyte metabolism via suppressing 1,25-dihydroxycholecalciferol (1,25(OH)2-D3) and decreases fat absorption. We studied the effect of Ca and milk proteins (whey and casein) on body weight in C57Bl/6J mice. Male mice, age 9 weeks, were divided into three groups (ten mice per group) receiving modified high-fat (60% of energy) diets. Two groups received a high-Ca diet (1.8% calcium carbonate (CaCO3)), with casein or whey protein (18% of energy), and one group received a low-Ca diet (0.4% CaCO3) with casein for 21 weeks. Food intake was measured daily and body weight twice per week. Body fat content (by dual-energy X-ray absorptiometry) of all mice and faecal Ca and fat excretion of seven mice/group were measured twice during the study. Final body weight (44.1 (SEM 1.1) g) and body fat content (41.6 (SEM 0.6) %) were significantly lower (P < 0.05) in the high-Ca whey group than in the low-Ca casein group (48.1 (SEM 0.8) g and 44.9 (SEM 0.8) %). Body weight and body fat content of the high-Ca casein group did not differ significantly from the low-Ca casein group even though serum 1,25(OH)2-D3 levels were significantly lower (P < 0.001) in both high-Ca groups than in the low-Ca casein group. Thus changes in serum 1,25(OH)2-D3 do not seem to affect body weight in this animal model. There was a significant difference in fat excretion between the high-Ca whey and low-Ca casein groups (3.9 (SEM 0.9) % in the high-Ca whey v. 1.4 (SEM 0.2) % in the low-Ca casein group; P < 0.05), which may partly explain the effect on body weight.

Dietary calcium attenuation of body fat gain during high-fat feeding in mice

Human epidemiological studies have supported the hypothesis that a dairy food-rich diet is associated with lower fat accumulation, although prospective studies and intervention trials are not so conclusive and contradictory data exist in animal models. The purpose of this study was to assess the effects on body weight and fat depots of dairy calcium (12 g/kg diet) in wild-type mice under ad libitum high-fat (43%) and normal-fat (12%) diets and to gain comprehension on the underlying mechanism of dairy calcium effects. Our results show that calcium intake decreases body weight and body fat depot gain under high-fat diet and accelerates weight loss under normal-fat diet, without differences in food intake. No differences in gene or protein expression of UCP1 in brown adipose tissue or UCP2 in white adipose tissue were found that could be related with calcium feeding, suggesting that calcium intake contributed to modulate body weight in wild-type mice by a mechanism that is not associated with activation of brown adipose tissue thermogenesis. UCP3 protein but not gene expression increased in muscle due to calcium feeding. In white adipose tissue there were effects of calcium intake decreasing the expression of proteins related to calcium signalling, in particular of stanniocalcin 2. CaSR levels could play a role in decreasing cytosolic calcium in adipocytes and, therefore, contribute to the diminution of fat accretion. Results support the anti-obesity effect of dietary calcium in male mice and indicate that, at least at the time-point studied, activation of thermogenesis is not involved.

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.

Effects of long-term calcium intake on body weight, body fat and bone in growing rats

Increased calcium intake may reduce body weight and fat in non-growing individuals. This study explored the long-term effects of high versus low calcium intake on body weight, body fat, BMC, BMD and bone size in growing male and female rats. Ninety male and 90 female Sprague-Dawley rats were randomly assigned either to a high calcium (1%) or low calcium (0.25%) diet from age 3 weeks until 40 weeks. Half of the animals were fed ad libitum, and half of the animals were on an adjusted feeding schedule (the food intake of the low calcium animals was reduced to maintain equal body weight with high calcium animals of the same gender). DXA and radiographic measurements (femur and skull length and width) were collected at the age of 4, 13 and 34 weeks. Growing male rats fed the low calcium diet ad libitum gained more weight and more fat than rats on a high calcium diet. When food intake was controlled, male rats on the low calcium diet still had a greater fat mass (despite their similar body weight) and smaller skeletal measurements than the high calcium animals. Growing female rats initially responded like the males: when fed ad libitum low calcium animals had an increased body weight and fat mass; when food intake was controlled the low calcium animals had a greater fat mass and smaller skeletal measurements. However, these differences were found at 13 weeks and not at 34 weeks, suggesting a transient effect with no long-term differences between high and low calcium intake in the growing female rats.

Calcium deficiency cannot induce obesity in rats

If intake of a required nutrient--here calcium--affects body weight, the effect must be mediated by a change in the body weight set-point. Thus, the controversial 'anti-obesity' influence of high calcium intake should decrease the body weight set-point. Diets differing in calcium content were assigned to three groups of rats. The effects of the diets on body weight, BMI, fat content, plasma calcium, body weight set-point, food intake, and preference for various calcium solutions were measured after 6 weeks of calcium deprivation or supplementation, and again after a further 6 weeks of recovery on a regular diet. After 6 weeks, the low-calcium diet had induced calcium deficiency but had failed to raise the body weight set-point. Nor had it produced obesity or fat accumulation. After 6 weeks of recovery, body weight and fat content were no higher in calcium-deprived rats than in the control or supplemented rats. In this experiment, low-calcium intake failed to cause obesity and did not raise the body weight set-point. The results indicate that calcium intake probably does not affect body weight.

Lack of Relationship between Calcium Intake and Body Size in an Obesity-Prone Population

OBJECTIVE

Dietary calcium intake, especially from dairy products, may have a protective effect against obesity. This study aimed to determine if calcium intake is associated with body weight and adiposity in Pima Indians, an obesity-prone population.

RESEARCH METHODS AND PROCEDURES

Subjects were 65 Pima Indian adults (35 men/30 women, age 33+/-8 years [mean+/-standard deviation]) participating in a study of eating behavior and 78 Pima Indian children (36 boys/42 girls, age 10.4+/-0.3 years) participating in a study of childhood obesity. Height and weight were measured, and body composition was determined by dual-energy x-ray absorptiometry. Food intake in adults was assessed using the Block 1998 Food Questionnaire; food intake in children was assessed using a 24-hour recall with parental assistance.

RESULTS

In adults, mean energy intake was 3,163+/-1,037 kcal/day, mean percentage of energy from fat was 41%+/-7%, and calcium intake was 914+/-333 mg/day. In children, mean energy intake was 1,988+/-733 kcal/day, mean percentage of energy from fat was 36%+/-9%, and calcium intake was 637+/-352 mg/day, half the recommended daily intake for this age group. There were no significant associations between calcium intake and body weight (r=0.05, P=.71; r=0.04, P=.73), body fat (r=0.16, P=.19; r=0.12, P=.42), or body mass index (r=0.01, P=.97; r=0.04, P=.77) in either adults or children, respectively.

DISCUSSION

One explanation for the lack of association between reported calcium intake and body size in Pima Indians may be that the high-fat, high-energy diet consumed by the population overwhelmed the "anti-obesigenic" effect of calcium.

CONCLUSIONS

We were unable to find an association between calcium intake and body size or adiposity in Pima Indian adults and children. Although the essentiality of calcium to bone health is well established, the role of calcium and dairy product intake in obesity and weight management remains uncertain.