Dairy Ca Research Articles

Quantifying the evolution of animal dairy intake in humans using calcium isotopes

The contribution of dairy products to modern human diets has a debated role in the expansion of Neolithic economies and the dynamics of demographic transitions. While current methods allow discussing dairy production and processing, no approach allows reconstructing quantitatively its effective consumption. Calcium isotopes (δ44/42Ca) potentially represent such a marker due to the abundance of isotopically fractionated Ca in dairy products. Here, we test Ca isotope sensitivity to dietary intake of dairy product: we first used a dietary model based on a compilation of available data of dietary Ca sources; we then compared the modelled outputs to available and newly acquired skeletal δ44/42Ca values of individuals from populations with documented and markedly distinct dairy consumption habits. Our model predicts a marked decrease of skeletal δ44/42Ca values with dairy Ca intake. We measure a significant difference in δ44/42Ca values between populations eating no dairy products and those with high proportions of dairy Ca in their diet. The average dairy Ca intakes inferred by the model agree well with the documented dietary habits of these populations. Finally, we observe a significant drift across Neolithic and Iron Age periods up to modern times in societies producing dairy, contrasting with the populations consuming no dairy products. This trend marks a dramatic change in the utilization of dietary Ca. Given the available data, our model supports a marked increase in dairy intake starting from the late Neolithic period in Western Europe. Calcium isotopes could yield significant insight into the evolutions of dairy product intakes and the biocultural revolutions experienced by Neolithic populations.

Barriers and facilitators of household provision of dairy and plant-based dairy alternatives in families with preschool-age children.

This study aimed to explore barriers and facilitators of the provision of dairy and plant-based dairy alternatives (PBDA) by parents of preschool-age children, a previously unexplored area of research. Five focus groups of parents were conducted and audio-recorded. Verbatim transcripts were analysed using thematic analysis. University of Guelph, in Guelph, ON, Canada in 2019. Thirty-two (n 19 mothers, 13 fathers) parents of preschool-age children. Most (59 %) were university or college educated. Facilitators common to both dairy and PBDA provision included perceived nutritional benefits, such as dairy's Ca, protein and fat content, and PBDA's protein content, and the perception that PBDA adds variety to the diet. Facilitators unique to dairy v. PBDA provision included the taste of, familiarity with, and greater variety and accessibility of dairy products, specifically child-friendly products. A facilitator unique to PBDA v. dairy provision was ethical concerns regarding dairy farming practices. Barriers common to both dairy and PBDA provision included perceived cost, concerns regarding the environmental impact of production, and high sugar content. Barriers specific to dairy included use of antibiotics and hormones in dairy production. A barrier specific to PBDA was the use of pesticides. Behaviour change messages targeting parents of preschoolers can emphasise the nutrition non-equivalence of dairy and some PBDA and can educate parents on sources of affordable, unsweetened dairy and PBDA.

High prevalence of low dairy calcium intake and association with insomnia, anxiety, depression and musculoskeletal pain in university students from Jordan.

To assess dairy Ca intake and investigate its relationship with insomnia and other common co-morbidities including anxiety, depression and musculoskeletal pain (MSP) among university students. Cross-sectional study. University, Irbid, Jordan. Male and female individuals (n 1000), aged 20·87 ± 2·69 years. Low dairy Ca intake (<1000 mg/d) was reported by 96·5 % of participants, and moderate to severe insomnia reported by 15·6 % of participants. Abnormal anxiety and depression scores were reported by 26·2 and 18·0 % of participants, respectively. MSP was reported by 42·9 % of participants. Participants with moderate to severe insomnia had lower dairy Ca, higher anxiety and depression scores and higher measures of MSP compared to participants with no insomnia (P-values < 0·05). Dairy Ca was weakly inversely correlated with Insomnia Severity Index (ISI) score, depression score and measures of MSP (P-values < 0·05). Regression analysis indicated that insomnia was predicted by low dairy Ca, anxiety, depression, MSP and smoking (P-values < 0·05). Both anxiety and depression were predicted by increased ISI score (P-values < 0·05), while depression alone was predicted by low dairy Ca (P-value < 0·01). MSP was predicted by increased ISI and anxiety scores (P-values < 0·05). Low dairy Ca was highly prevalent and associated with insomnia and depression among university students. Individuals should be advised to increase dietary Ca intake to achieve the recommended daily amount. Further research is required to investigate a potential causal relationship between low Ca and both insomnia and its related co-morbidities.

Milk and the city: Raw milk challenging the value claims of value chains

ABSTRACTThis article assesses two models of dairy production and distribution to the large city of Dar es Salaam. One is urban and peri-urban raw milk production through territorial markets and the symbiotic food system and the other a dairy value chain intervention. The raw milk system is remarkably resilient and gives lower prices to milk drinkers and better returns to small-scale farmers. The value chain intervention provides opportunities for some dairy farmers but can’t compete and favors corporate entities less aligned with most farmers’ and city residents’ interests. Policy maker’s preference for value chain interventions appears to be ideological as it is not justified by the outcomes, but support for alternatives is growing and needs to be built on.

Low dairy calcium intake is associated with overweight and elevated blood pressure in Polish adults, notably in premenopausal women.

Dietary Ca is now being recognized to play an important role not only in skeletal integrity, but also in the regulation of energy and metabolism. The aim of the present study was to estimate the relationship of dairy Ca intake with BMI and blood pressure (BP) in a sample derived from the Polish population. Ca intake was calculated from an interviewer-administered semi-quantitative FFQ. BMI was calculated from measured weight and height, and BP was measured by a physician. Cross-sectional epidemiological study on osteoporosis risk factors in Poland. Randomly selected healthy adult persons (n 1259; 750 women and 509 men). Dairy Ca intake was significantly lower in individuals with overweight/obesity (BMI≥25·00 kg/m2) and/or with elevated BP (systolic/diastolic ≥140/≥90 mmHg) than in those with normal body mass and BP, respectively. Ca intake was negatively correlated with BMI (r=-0·12, P<0·001), systolic BP (r=-0·11, P<0·001) and diastolic BP (r=-0·08, P<0·01). Daily dairy Ca intake below 1000 mg was a predictor for BMI≥25·0 kg/m2 (OR=1·44, P<0·005). This relationship was stronger in women, particularly premenopausal women. The obtained results indicate the role of low dairy Ca intake in the development of obesity and hypertension, notably in premenopausal women.

Low fat dairy foods improve lipid profile and proinflammatory markers in overweight/obese early postmenopausal women after a 6-month weight loss intervention

W previously showed that consumption of low fat dairy foods (4-5 servings/day), resulted in better body composition (lean and fat tissue) outcomes compared to calcium (Ca) supplement or control group in postmenopausal women after a 6-month weight loss intervention. Here we report the effect of dairy foods and/or Ca supplementation on lipid profile and proinflammatory markers in the same population. A total of n=97 overweight/obese early postmenopausal women completed the 6 months follow up and had complete datasets. They were divided into 3 groups: Supplement (pills containing 630 mg Ca+400 IU of vitamin D/day); Dairy (low fat dairy consumption, 4-5 servings/day) and Control (placebo pills). Each group included moderate energy restriction (~85% of energy needs). Glucose, insulin, lipid profile (cholesterol, triglycerides, LDL, HDL) as well as Apo A1, Apo B and CRP were analyzed in fasting blood samples by commercially available Enzyme Linked Immunosorbent Assay (ELISA) kits. There was improvement in each measured parameter, probably due to weight loss, except in glucose, HDL and Apo B which remained the same. Dairy group showed the highest % decrease in total cholesterol and LDL, 6.1% and 7.7%, respectively, compared to Supplement (3.2% and 3.4%) and Control (3.8% and 1.7%) groups. Additionally, Apo A decreased in Dairy group while it increased in Supplement and Dairy groups. In conclusion, the intervention with low fat dairy foods complemented with hypo caloric diet resulted in the best outcomes for lipid profile and highest reduction in Apo A. Increasing the low fat dairy foods to 4-5 servings/day may be beneficial for metabolic profile in postmenopausal women during weight loss.

Calcium intake and osteoporosis: the influence of calcium intake from dairy products on hip bone mineral density and fracture incidence - a population-based study in women over 55 years of age.

The incidence of osteoporosis increases with age and is most frequently observed in postmenopausal women. The objective of the present population-based cohort study was to assess the influence of Ca intake from dairy sources on hip bone mineral density and hip fracture incidence in a group of Polish women over 55 years of age. The main outcome measures included: bone mineral density, the number of previous fractures and the reported Ca intake from dairy sources, assessed by a diet questionnaire. The RAC-OST-POL Study was conducted in the District of Raciborz in the south of Poland. The study was carried out in a group of 625 women, randomly recruited from the general population of women aged >55 years. Median Ca intake from dairy products was lower in the group of women with femoral neck T-score ≤-2·5 than in the group with T-score >-2·5 (275 v. 383 mg/d; P = 0·0019). For total hip score, the difference was close to borderline significance (P = 0·0698). Median Ca intake from dairy products was lower in the group of women with previous fractures than in those without fracture history (336 v. 395 mg/d; P = 0·0254). The main dairy source of Ca in the analysed group included milk drinks, rennet cheese and milk. Higher dairy Ca intake is recommended, since a number of the women analysed were unable to satisfy their Ca requirement exclusively from their diet.

Dairy food intake of Australian children and adolescents 2-16 years of age: 2007 Australian National Children's Nutrition and Physical Activity Survey.

Dairy food consumption is important for Australian children as it contributes key nutrients such as protein and Ca. The aim of the present paper is to describe dietary intake from dairy foods for Australian children aged 2-16 years in 2007. Secondary analysis of a quota-sampled survey using population-weighted, 1 d (24 h) dietary recall data. Australian national survey conducted from February to August 2007. Children (n 4487) aged 2-16 years. Most Australian children consumed dairy foods (84-98 %), with the proportion consuming tending to decrease with age and males consuming significantly more than females from the age of 4 years. Milk was the most commonly consumed dairy food (58-88 %) and consumed in the greatest amount (243-384 g/d). Most children consumed regular-fat dairy products. The contribution of dairy foods to total energy intake decreased with age; from 22 % of total energy at age 2-3 years to 11 % at age 14-16 years. This trend was similar for all nutrients analysed. Dairy food intake peaked between 06.00 and 10.00 hours (typical breakfast hours) corresponding with the peak in dairy Ca intake. Australian children (older than 4 years) did not reach recommendations for dairy food intake, consuming ≤2 servings/d. The under-consumption of dairy foods by Australian children has important implications for intake of key nutrients and should be addressed by multiple strategies.

Lower dairy calcium and dairy vitamin D intakes are associated with increased skeletal muscle fatty infiltration in adolescent girls

BACKGROUNDFat infiltration within skeletal muscle is strongly associated with type 2 diabetes mellitus. Insufficient calcium (Ca) and vitamin D (VitD) intake is common in youth and has been associated with the development of obesity and osteoporosis. Dairy Ca and VitD are better absorbed compared to other dietary sources and have been linked to decreased adiposity.OBJECTIVEExamine the relationships between dairy Ca and VitD with skeletal muscle fat infiltration (SMFI) in 212 healthy girls aged 8–13 years.METHODSMuscle density (mg/cm3), an index of fat infiltration, was measured at the 66% tibia and 20% femur sites (relative to distal growth plates) on the non‐dominant limb using peripheral quantitative computed tomography (pQCT). Dairy Ca and VitD were assessed using the Harvard youth adolescent questionnaire (YAQ).RESULTSMultiple linear regressions with dairy Ca and VitD, maturity, total caloric intake, and activity (pedometer steps) were used to predict SMFI and showed that dairy Ca was positively associated with muscle densities of the calf (P ≤ 0.01, partial r (ρ)=0.185, β=0.216) and thigh (P ≤ 0.05, ρ=0.135, β=0.157 ). Dairy VitD was independently associated with higher muscle densities of the calf (P≤ 0.01, ρ=0.183, β=0.194) and thigh (P ≤ 0.05, ρ=0.159, β=0.168).CONCLUSIONLower dairy consumption is associated with increased SMFI in young girls.Grant Funding Source : NIH: HD050775

Calcium effects on bodyweight appear to be mediated in part by changes in gut microflora and altered by dietary matrix

Calcium (Ca) intake variably affects bodyweight (BW) regulation. Delivery matrix may affect Ca effects. Gut microflora is now a considered variable in BW regulation. Three isonitrogenous, isocaloric, 45 kcal% fat diets were fed to male C57/BL6J mice (n=10/group) in two diet‐induced obesity tests. Isolated soy protein was used for diets containing adequate (0.5 wt%, D1) or high (1.5 wt%, D2) amounts of Ca as CaCO3, while non‐fat dry milk was used in a second 1.5 wt% Ca diet (NFDM), providing 0.5 wt% Ca as intrinsic dairy Ca. Test 1: 5 wk old mice were fed test diets for 12 wks. Mice fed D1 and NFDM consumed similar amounts of feed, but NFDM fed mice gained less BW and body fat (p&lt;0.05). Mice fed D2 consumed the most feed, gained the most BW and body fat (p &lt;0.05). Gut microflora community structure was determined by 16SrRNA pyrosequencing of feces collected during the last 48 hrs of study. UniFrac analysis and PCA clustering of mice with similar microflora clearly separated D1, D2, and NFDM at the genera level. Test 2: Test 1 protocol, except that mice were pre‐fed D1 for 12wks prior to being fed D1, D2, or NFDM for an additional 8wk period. Similar responses in feed intake, BW, body fat and microflora shifts were seen. Dairy was most effective in obesity prevention (Test 1) and its effects were correlated to changes in gut microflora. 1.5 wt% CaCO3 increased obesogenic tendencies. Funded by the Dairy Research Institute.

Dairy calcium intake modifies responsiveness of fat metabolism and blood lipids to a high-fat diet

Intervention studies have demonstrated that saturated fat increases total and LDL-cholesterol concentrations, and it is therefore recommended that the intake of high-fat dairy products be limited. However, observational studies have found an inverse relationship between the intake of dairy products and incidence of CVD. We aimed to study whether the Ca content of dairy products influences the effect of dairy fat on the lipid profile. The study had a randomised cross-over design. Subjects (n 9) were randomised to one of the sequence of four isoenergetic 10d diets: low Ca and low fat (LC/LF: approximately 700mg Ca/d, 25% of energy (fat); high Ca and LF (HC/LF: approximately 2800mg Ca/d, 25% of energy fat); LC and high fat (LC/HF: approximately 700 mg Ca/d, 49E% fat); or HC and HF (approximately 2800mg Ca/d, 49E% fat). Blood variables were measured before and after each diet period, and faeces and urine were collected at the end of each diet period. A two-way ANOVA was used to examine the effect of Ca and fat intake. Independent of Ca intake, the HF diet increased the concentrations of total (9%; P<0·0001), LDL (14%; P<0·0001)- and HDL (13%; P=0·0002)-cholesterol compared with the LF diet. However, independent of fat intake, the HC diet decreased the concentrations of total (4%; P=0·0051) and LDL-cholesterol (10%; P<0·0001) but not HDL-cholesterol compared with the LC diet. In addition, total:HDL-cholesterol was decreased (5%; P=0·0299), and HDL:LDL was increased (12%; P=0·0097) by the HC diet compared with the LC diet. Faecal fat excretion was increased by both the HC (P<0·0001) and HF (P=0·0052) diets. In conclusion, we observed that dairy Ca seems to partly counteract the raising effect of dairy fat on total and LDL-cholesterol, without reducing HDL-cholesterol.

An Adequate Calcium Intake Could Help Achieve Weight Loss in Overweight/Obese Women following Hypocaloric Diets

Aim: To investigate the effect of calcium (Ca) intake and dairy product consumption modification on body composition in overweight/obese women following two types of hypocaloric diet. Methods: Study subjects were 57 women who were randomly assigned to follow one of two hypocaloric diets: diet V, in which the relative consumption of vegetables was increased, and diet C, which involved increasing the relative consumption of cereals (especially breakfast cereals). Dietetic and anthropometric data were collected at the start and at the end of the 6-week intervention period. Results: Ca density, Ca index of nutritional quality and Ca/protein improved with both diets. Dairy products, Ca intake, dairy Ca intake and Ca/protein were inversely correlated with body mass index at the end of the study. Among the women with an initial calcium intake below the 50th percentile, those who achieved a reduction in body mass index above the 50th percentile were those who most increased their total calcium intake, calcium intake from dairy sources, calcium density, calcium/protein ratio and the intake of total and skimmed dairy product consumption. Conclusion: Correcting an inadequate calcium intake could help improve weight loss in women following hypocaloric diets.

Dietary calcium and dairy modulation of oxidative stress and mortality in aP2-agouti and wild-type mice.

Oxidative and inflammatory stress have been implicated as major contributors to the aging process. Dietary Ca reduced both factors in short-term interventions, while milk exerted a greater effect than supplemental Ca. In this work, we examined the effects of life-long supplemental and dairy calcium on lifespan and life-span related biomarkers in aP2-agouti transgenic (model of diet-induced obesity) and wild-type mice fed obesigenic diets until their death. These data demonstrate that dairy Ca exerts sustained effects resulting in attenuated adiposity, protection against age-related muscle loss and reduction of oxidative and inflammatory stress in both mouse strains. Although these effects did not alter maximum lifespan, they did suppress early mortality in wild-type mice, but not in aP2-agouti transgenic mice.

Calcium intake among different college-student populations

Previous surveys showed that women fall short of the recommended level for calcium (Ca) consumption, particularly female college students. The aims of the study were to compare dietary calcium (Ca) intake and its sources, as well as multivitamin/mineral supplement use between African American and Caucasian American female students with a nutrition/ health background and African American and Croatian female general student-populations. Additionally, we examined the relationship between Ca intake and weight/BMI within each population. Participants - volunteers (N=314, age 18–37 yr) completed a validated food frequency questionnaire, assessing their usual Ca intake and supplements ; 57 African Americans and 54 Caucasian Americans recruited from Nutrition and/or other Health Sciences departments (NHS), and 100 African American and 103 Croatian women representing the general student population (GSP). 63% of the African American and 57% of the Caucasian American NHS participants met or exceeded the recommended Ca intake (DRI 1000 mg/day), while only 24% of the African American and 30% of the Croatian GSP participants met or exceeded this Ca requirement. Results showed thar African American and Caucasian NHS populations consumed significantly more Ca, specifically as dairy Ca, and were more likely to take supplements than either GSP group, suggesting that nutrition/ health education can negate various other influences known to affect Ca intake.

Impact of increasing calcium intake with dairy vs. calcium carbonate on calcium retention in overweight adolescents

This study assessed the effect of calcium supplementation from dairy vs. calcium carbonate sources on calcium (Ca) retention in overweight and obese adolescent boys and girls. Twenty-three girls (BMI 33 ± 5 kg/m2) and seventeen boys (BMI 28 ± 5 kg/m2), aged 12–15 years, participated in two 3-week controlled feeding trials, separated by a 3-week washout period. Each subject consumed a controlled basal diet during both trials that provided their individualized energy need and 778 ± 147 mg Ca/day. Using a two period crossover design, subjects received no additional Ca in a soy-based product (Control) during one 3-week testing period and were randomized to receive an additional 675 mg Ca/day as dairy Ca (Dairy) or Ca carbonate (CC) in the other testing period. Ca intake and source of Ca were manipulated through a frozen product consumed twice each day. All urine and feces were collected during each 3-week period. Diet, fecal, and urine samples were each pooled for 24-hour periods and measured for Ca content by Inductively Coupled Plasma Spectrophotometry. Subjects retained (intake-feces-urine) more (p<0.0001) Ca when they consumed the higher Ca product (552 ± 213 mg Ca/day for the CC group and 578 ± 221 mg Ca/day for the Dairy group) compared to the lower Ca period (296 ± 169 mg Ca/day for Control). Thus, doubling Ca intake through either dairy or Ca carbonate supplementation led to a nearly two-fold increase in Ca retention. The proportion of intake retained (~38%) during pubertal growth in obese adolescents was not dependent on Ca intake, as observed in adults. Supported by NIH DK066108, National Dairy Council and test products were a gift from The Schwan Food Company.

The acute effects of different sources of dietary calcium on postprandial energy metabolism

Dairy Ca intake has been shown to be superior to elemental Ca in increasing the loss of body fat during energy restriction. We questioned whether the mechanisms involved an increase in postprandial energy expenditure, fat oxidation and/or a greater lipolysis. The acute effects of different sources of Ca were examined in eight subjects, aged 47-66 years and BMI 27.6-36.1 kg/m2, in a three-way cross-over study. Subjects were randomly provided breakfast meals either low in dairy Ca and vitamin D (LD; control), high in non-dairy Ca (calcium citrate) but low in vitamin D (HC) or high in dairy Ca and vitamin D (HD). Diet-induced thermogenesis, fat oxidation rates (FOR), carbohydrate oxidation rates (COR), insulin, glucose, NEFA and glycerol were measured hourly over a 6 h postprandial period. Postprandial data were calculated as a change (Delta) from the fasting value. Results showed that DeltaNEFA was significantly different between meals (LD -1.50 (sem 0.26), HC -1.22 (sem 0.32), HD -0.94 (sem 0.27) mmol/l x 6 h; P = 0.035), with a lesser suppression following both high-Ca meals. DeltaFOR was significantly higher following the two high-Ca meals (LD -6.5 (sem 2.2), HC 2.93 (sem 2.34), HD 3.3 (sem 2.5) g x 6 h; P = 0.005), while reciprocally DeltaCOR was significantly lower. DeltaGlycerol was less suppressed following the high-Ca meals but statistical significance was not achieved. No differences in diet-induced thermogenesis, insulin or glucose were observed. Regardless of source, Ca intake acutely stimulated postprandial fat oxidation; and there was a lesser suppression of NEFA following these meals.

Dairy augmentation of total and central fat loss in obese subjects

We have previously demonstrated an antiobesity effect of dietary Ca; this is largely mediated by Ca suppression of calcitriol levels, resulting in reduced adipocyte intracellular Ca2+ and, consequently, a coordinated increase in lipid utilization and decrease in lipogenesis. Notably, dairy Ca is markedly more effective than other Ca sources. Obese subjects were placed on balanced deficit (-500 kcal/day) diets and randomized to control (400-500 mg Ca/day; n = 16) or yogurt (1100 mg Ca/day; n = 18) treatments for 12 weeks. Dietary macronutrients and fiber were held constant at the US average. Body weight, body fat and fat distribution (by dual-energy X-ray absorptiometry), blood pressure and circulating lipids were measured at baseline and after 12 weeks of intervention. Fat loss was markedly increased on the yogurt diet (-4.43+/-0.47 vs -2.75+/-0.73 kg in yogurt and control groups; P<0.005) while lean tissue loss was reduced by 31% on the yogurt diet. Trunk fat loss was augmented by 81% on the yogurt vs control diet (P<0.001), and this was reflected in a markedly greater reduction in waist circumference (-3.99+/-0.48 vs -0.58+/-1.04 cm, P<0.001). Further, the fraction of fat lost from the trunk was higher on the yogurt diet vs control (P<0.005). Isocaloric substitution of yogurt for other foods significantly augments fat loss and reduces central adiposity during energy restriction..

Anaerobically Digested Dairy Manure as Fertilizer for Maize in Acid and Alkaline Soils

Anaerobically digested animal manure is a potentially useful by-product from CH4 generation facilities on farm businesses. Two greenhouse experiments were conducted using an acid and alkaline soil to determine the relative effectiveness of anaerobically digested dairy manure compared to undigested dairy manure and inorganic N for increasing maize (Zea mays L.) growth in the early vegetative stage of development. The first experiment compared digested manure with (NH4)2SO4 at 0 to 400 mg total N kg−1 dry soil applied to Mardin (pH 4.9; coarse-loamy, mixed, active, mesic Typic Fragiudepts) or Honeoye (pH 7.2; fine-loamy, mixed, mesic Glossoboric Hapludalfs) soils. In the second experiment, digested manure at 200 mg total N kg−1 dry soil was applied to the soils and compared with fresh dairy manure, Ca(NO3)2, NH4NO3, and (NH4)2SO4 applied at the same total N rate. Also, an unamended treatment was included. In both experiments, shoot dry wt and total plant N after manure applications were equal or greater than inorganic fertilizer applications across both soil types, and maize yields from digested manure in the acid soil were as good or better than the yields in the alkaline soil. Differences could not be attributed solely to plant available nitrogen (N) (NH4-N + NO3-N) in the soil as there was similar or greater quantities of available N in the inorganic fertilizer treatments as in the digested manure treatment. Anaerobically digested dairy manure appears to be more effective for increased maize growth in early stages of development than inorganic fertilizer N sources if applied to an acid soil rather than to an alkaline soil.

Calcium and Dairy Products Inhibit Weight and Fat Regain during Ad Libitum Consumption Following Energy Restriction in Ap2-Agouti Transgenic Mice

We demonstrated previously that dietary calcium suppression of calcitriol reduces adipocyte Ca(2+), suppresses lipogenesis, and increases lipid utilization during energy restriction. Notably, dairy calcium sources exert markedly greater effects. To determine the effects of dietary calcium and dairy products on energy partitioning during subsequent refeeding, we induced obesity in aP2-agouti transgenic mice with a high-fat/high-sucrose diet, then restricted energy intake from a high-calcium (1.3%) diet for 6 wk to induce fat loss, and then provided free access to a low-calcium (0.4%) diet or to high-calcium (1.3%) diets that utilized either calcium-fortified foods or dairy products (milk or yogurt) for 6 wk. Refeeding the low-calcium diet caused the regain of all weight and fat, whereas all high-calcium diets reduced fat gain by 55% (P < 0.01). All high-calcium diets stimulated adipose tissue uncoupling protein (UCP)2 and skeletal muscle UCP3 expression (P < 0.001) and slightly increased core temperature (P = 0.136), but only the dairy-based diets elicited a marked (>10-fold, P < 0.001) increase in skeletal muscle peroxisome proliferator-activated receptor-alpha expression. All 3 high-calcium diets produced significant increases in lipolysis, decreases in fatty acid synthase expression and activity, and reduced fat regain (P < 0.03), but the 2 dairy-containing high-calcium diets exerted significantly greater effects on regain (P < 0.01). Thus, high-Ca diets elicit a shift in energy partitioning and reduction of weight gain during refeeding, with dairy Ca sources exerting markedly greater effects.

Relation between calcium intake and fat oxidation in adult humans.

To determine if total calcium (Ca(2+)) intake and intake of Ca(2+) from dairy sources are related to whole-body fat oxidation. : Cross-sectional study. A total of 35 (21 m, 14 f) non-obese, healthy adults (mean+/-s.d., age: 31+/-6 y; weight: 71.2+/-12.3 kg; BMI: 23.7+/-2.9 kg m(-2); body fat: 21.4+/-5.4%). Daily (24 h) energy expenditure (EE) and macronutrient oxidation using whole-room indirect calorimetry; habitual Ca(2+) intake estimated from analysis of 4-day food records; acute Ca(2+) intake estimated from measured food intake during a 24-h stay in a room calorimeter. Acute Ca(2+) intake (mg. kcal(-1)) was positively correlated with fat oxidation over 24 h (r=0.38, P=0.03), during sleep (r=0.36, P=0.04), and during light physical activity (r=0.32, P=0.07). Acute Ca(2+) intake was inversely correlated with 24-h respiratory quotient (RQ) (r=-0.36, P=0.04) and RQ during sleep (r=-0.31, P=0.07). After adjustment for fat mass, fat-free mass, energy balance, acute fat intake, and habitual fat intake, acute Ca(2+) intake explained approximately 10% of the variance in 24-h fat oxidation. Habitual Ca(2+) intake was not significantly correlated to fat oxidation or RQ. Total Ca(2+) intake and Ca(2+) intake from dairy sources were similarly correlated with fat oxidation. In backwards stepwise models, total Ca(2+) intake was a stronger predictor of 24 h fat oxidation than dairy Ca(2+) intake. Higher acute Ca(2+) intake is associated with higher rates of whole-body fat oxidation. These effects were apparent over 24 h, during sleep and, to a lesser extent, during light physical activity. Calcium intake from dairy sources was not a more important predictor of fat oxidation than total Ca(2+) intake.