Associations between the intake of dairy fat and calcium and abdominal obesity

Metabolic effects of milk fatty acids: A literature review

Milk and dairy products are known to have a significant role in human development and tissue maintenance due to their high nutritional value. With the higher incidence of obesity and metabolic diseases, nutrition and public health authorities have recommended the intake of fat-free or low-fat dairy due to the saturated fatty acid content of whole-fat products and their effect on serum cholesterol levels. However, recent studies have questioned the association between milk fat consumption and cardiometabolic risk. This literature review aims to compile the scientific evidence of the metabolic effects of milk fatty acids in clinical and basic research studies, as well as their relationship with metabolic disorders and gut microbiota composition. Research shows that various milk fatty acids exert effects on metabolic alterations (obesity, type 2 diabetes and cardiovascular diseases) by modifying glucose homeostasis, inflammation and lipid profile-related factors. Additionally, recent studies have associated the consumption of milk fatty acids with the production of metabolites and the promotion of healthy gut microbiota. From mainly observational studies, evidence suggests that milk and dairy fatty acids are not directly linked to cardiometabolic risk, but further controlled research is necessary to clarify such findings and to assess whether dietary recommendations to choose low-fat dairy foods are necessary for the population for the prevention of obesity and cardiometabolic disease.

Fatty acid composition of cholesterol esters reflects dietary fat intake after dietary interventions in a multinational population

BACKGROUND

The effects of different dietary fatty acids (FA) on cardiovascular risk still needs clarification. Plasma lipids composition may be a biomarker of FA dietary intake.

PURPOSE

To evaluate in a composite population the relationships between changes in dietary fat intake and changes in FA levels in serum cholesterol esters.

METHODS

In a multinational, parallel-design, dietary intervention (KANWU study), dietary intakes (3-day food record) and FA composition of serum cholesterol esters (gas-liquid chromatography) were evaluated at baseline and after 3 months in 162 healthy individuals, randomly assigned to a diet containing a high proportion of saturated (SFA) or monounsaturated (MUFA) fat, with a second random assignment to fish oil or placebo supplements.

RESULTS

Main differences in serum lipid composition after the two diets included saturated (especially myristic, C14:0, and pentadecanoic, C15:0) and monounsaturated (oleic acid, C18:1 n-9) FA. C14:0 and C15:0 were related to SFA intake, while C18:1 n-9 was associated with MUFA intake. Fish oil supplementation induced a marked increase in eicosapentaenoic (C20:5 n-3) and docosahexaenoic (C22:6 n-3) acids. After the 3-month intervention, Δ-9 desaturase activity, calculated as palmitoleic acid/palmitic acid (C16:1/C16:0) ratio, was more reduced after the MUFA (0.31±0.10 vs 0.25±0.09, p<0.0001) than SFA diet (0.31±0.09 vs 0.29±0.08, p=0.006), with a statistically significant difference between the two groups (p<0.0001).

CONCLUSIONS

This study shows that serum cholesterol ester FA composition can be used during randomized controlled trials as an objective indicator of adherence to experimental diets based on saturated and monounsaturated fat modifications, as well as fish oil supplementation.

Milk-Fat Intake and Differences in Abdominal Adiposity and BMI: Evidence Based on 13,544 Randomly-Selected Adults

The primary purpose of this investigation was to evaluate the relationship between milk-fat intake and obesity, particularly abdominal obesity, in 13,544 U.S. adults. A lesser objective was to measure the degree to which the association was influenced by multiple potential confounding variables. This cross-sectional study used data from the 2011-2016 National Health and Nutrition Examination Survey (NHANES). Quantity of milk-fat regularly consumed was the exposure variable. Sagittal abdominal diameter (SAD), a measure of abdominal obesity, and body mass index (BMI) were the outcome variables. Sagittal abdominal diameter is a strong predictor of visceral abdominal fat, when measured by computed tomography, and has been shown to predict cardiometabolic disorders better than BMI. After controlling for age, race, gender, physical activity, leisure computer use and gaming, alcohol habits, and cigarette use, significantly lower BMIs were associated with consistent non-fat and full-fat milk consumption (F = 4.1, p = 0.0063). A significantly lower SAD was associated only with regular consumption of non-fat milk (F = 5.0, p = 0.0019). No significant differences were detected between the other milk-fat groups or milk abstainers. In this nationally representative sample, only 19.6% of adults regularly consumed low-fat milk. In conclusion, consistent non-fat milk intake was predictive of lower levels of abdominal adiposity compared to consumption of higher levels of milk-fat.

Dairy Consumption at Snack Meal Occasions and the Overall Quality of Diet during Childhood. Prospective and Cross-Sectional Analyses from the IDEFICS/I.Family Cohort

There is scarce information on the influence of dairy consumption between main meals on the overall diet quality through childhood, constituting the main aim of this research. From the Identification and prevention of Dietary- and lifestyle induced health EFfects In Children and infantS (IDEFICS) study, and based on the data availability in each period due to drop outs, 8807 children aged 2 to 9.9 years from eight European countries at baseline (T0: 2007-2008); 5085 children after two years (T1); and 1991 after four years (T3), were included in these analyses. Dietary intake and the Diet Quality Index (DQI) were assessed by two 24 hours dietary recalls (24-HDR) and food frequency questionnaire. Consumption of milk and yogurt (p = 0.04) and cheese (p < 0.001) at snack meal occasions was associated with higher DQI scores in T0; milk and yogurt (p < 0.001), and cheese (p < 0.001) in T1; and cheese (p = 0.05) in T3. Consumers of milk (p = 0.02), yogurt (p < 0.001), or cheese (p < 0.001) throughout T0 and T1 at all snack moments had significantly higher scores of DQI compared to non-consumers. This was also observed with the consumption of cheese between T1 and T3 (p = 0.03). Consumption of dairy products at snack moments through childhood is associated with a better overall diet quality, being a good strategy to improve it in this period.

Association between carbohydrate intake and fatty acids in the de novo lipogenic pathway in serum phospholipids and adipose tissue in a population of Swedish men

PURPOSE

Fatty acid composition in blood and adipose tissue (AT) is a useful biomarker of dietary fat quality. However, circulating saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) have been proposed to also reflect carbohydrate-induced de novo lipogenesis (DNL) and stearoyl-CoA desaturase (SCD) activity. We aimed to test the hypothesis that high carbohydrate intake is related to SFA and MUFA in serum or AT in a Swedish population.

METHODS

Fatty acid composition was measured in serum phospholipids (PL) and AT by gas chromatography in 63-year-old men (n = 299). Carbohydrate and alcohol intake was assessed (validated 7-day food records) in relation to total SFA, 16:0 (palmitate), 16:1 (palmitoleate), and estimated SCD activity (16:1n-7/16:0-ratio) in serum PL and in AT, respectively.

RESULTS

Total carbohydrate intake was inversely associated with 16:0 in PL (P = 0.005), independently of BMI. Disaccharides were non-linearly (restricted cubic splines) and weakly associated with 16:1 and SCD activity in PL (nonlinear trend, P ≤ 0.02) but not AT. Carbohydrate intake and SCD expression were not associated (P ≥ 0.08, n = 81). Alcohol intake was, however, linearly associated with 16:0 in PL (P < 0.001), and with 16:1 (P < 0.001) and SCD activity (P ≤ 0.005) in both PL and AT.

CONCLUSIONS

Higher carbohydrate intake from sugar-rich foods or beverages was not clearly reflected by higher SFA or SCD activity in serum PL or AT. Alcohol was, however, associated with higher SFA and MUFA.

Potential Biomarkers for Fat from Dairy and Fish and Their Association with Cardiovascular Risk Factors: Cross-sectional Data from the LifeLines Biobank and Cohort Study

Dairy fat intake, reflected by the biomarkers C14:0, C15:0, C17:0, trans-C16:1 (n-7), trans-C18:1 (n-7) and CLA, may have beneficial effects on cardiovascular health. It has, however, been questioned whether this association is genuine, since C15:0 and C17:0 are also biomarkers from fish. We investigated whether the above biomarkers are reliable markers for dairy fat intake in 864 healthy subjects. Subsequently, we explored the association between these biomarkers and cardiovascular risk factors. Intakes of dairy and fish were determined by Food Frequency Questionnaires FFQs. Fatty acids were analyzed in plasma triglycerides (TG) and phospholipids (PL). Median intakes of dairy and fish fat were 12.3 (8.4–17.4) g/day and 1.14 (0.53–1.75) g/day. All fatty acids, except TG C17:0, were associated with dairy fat (std.β range TG: 0.12 for C14:0 till 0.25 for C15:0 and Trans-C18:1 (n-7); and std.β range PL: 0.12 for C17:0 and Trans-C16:1 (n-7) till 0.24 for Trans-C18:1 (n-7) and CLA; p < 0.001). TG C17:0 was associated with fish fat (std.β = 0.08; p = 0.03), whereas PL C17:0 was not. Associations remained after adjustment for fish/dairy fat intake. Strongest inverse associations with biological variables were found with PL C17:0 and Trans-C18:1 (n-7) (Std.βs: waist circumference: −0.18, p < 0.001 and −0.10, p < 0.05; BMI: −0.17, p < 0.001, −0.11, p < 0.01; glucose: −0.10, p <0.01 and −0.08, p <0.05; high sensitive C-reactive protein (hs-CRP): −0.22, p < 0.001 and −0.16, p < 0.01; uric acid: −0.27, p < 0.001 and −0.24, p < 0.001). In conclusion, fatty acid biomarkers, except plasma TG C17:0, were associated with dairy fat intake, independent of fish fat intake. PL C17:0 and trans-C18:1 (n-7) were inversely associated with adiposity, diabetes, inflammation and uric acid.

Dairy product consumption and its association with metabolic disturbance in a prospective study of urban adults

The role of dairy foods and related nutrients in cardiometabolic health aetiology is poorly understood. We investigated longitudinal associations between the metabolic syndrome (MetS) and its components with key dairy product exposures. We used prospective data from a bi-racial cohort of urban adults (30-64 years at baseline (n 1371)), the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS), in Baltimore City, MD (2004-2013). The average of two 24-h dietary recalls measured 4-10 d apart was computed at baseline (V1) and follow-up (V2) waves. Annual rates of change (Δ) in dairy foods and key nutrients were estimated. Incident obesity, central obesity and the MetS were determined. Among key findings, in the overall urban adult population, both cheese and yogurt (V1 and Δ) were associated with an increased risk of central obesity (hazard ratio (HR) 1·13; 95 % CI 1·05, 1·23 per oz equivalent of cheese (V1); HR 1·21; 95 % CI 1·01, 1·44 per fl oz equivalent of yogurt (V1)]. Baseline fluid milk intake (V1 in cup equivalents) was inversely related to the MetS (HR 0·86; 95 % CI 0·78, 0·94), specifically to dyslipidaemia-TAG (HR 0·89; 95 % CI 0·81, 0·99), although it was directly associated with dyslipidaemia-HDL-cholesterol (HR 1·10; 95 % CI 1·01, 1·21). Furthermore, ΔCa and ΔP were inversely related to dyslipidaemia-HDL and MetS incidence, respectively, whereas Δdairy product fat was positively associated with incident TAG-dyslipidaemia and HDL-cholesterol-dyslipidaemia and the MetS. A few of those associations were sex and race specific. In sum, various dairy product exposures had differential associations with metabolic disturbances. Future intervention studies should uncover how changes in dairy product components over time may affect metabolic disorders.

Circulating fatty acids as biomarkers of dairy fat intake: data from the lifelines biobank and cohort study

Background: C14:0, C15:0, C17:0 and trans-C16:1(n-7) are often used as biomarkers for dairy fat intake. Trans-C18:1(n-7) and CLA, two fatty acids which are also present in dairy, have hardly been explored. We investigated whether trans-C18:1(n-7) and CLA can enrich the existing biomarker portfolio. Methods: Data were obtained from Lifelines (n = 769). Dairy fat intake was determined by FFQ. Fatty acids were measured in fasting plasma triglycerides (TG), phospholipids (PL) and cholesterol esters (CE). Results: Median (25th-75th percentile) intakes of dairy and dairy fat were 322(209-447) and 12.3(8.4-17.4) g/d respectively. A pilot study showed that trans-C18:1(n-7) and CLA were only detectable in TG and PL. Of the established markers, TG C15:0 was most strongly associated with dairy fat intake (standardized β (std.β) = 0.286, R² = 0.111). Of the less established markers, TG trans-C18:1(n-7) was most strongly associated with dairy fat intake (Std.β = 0.292, R² = 0.115), followed by PL CLA (Std.β = 0.272, R² = 0.103) and PL trans-C18:1(n-7) (Std.β = 0.269, R² = 0.099). In TG, a combination of C15:0 and trans-C18:1(n-7) performed best (R² = 0.128). In PL, a combination of C14:0, C15:0, trans-C18:1(n-7) and CLA performed best (R² = 0.143). Conclusion: Trans-C18:1(n-7) and CLA can be used as biomarkers of dairy fat intake. Additionally, combining established with less established markers allowed even stronger predictions for dairy fat intake.

Vitamin D Levels and Cardiometabolic Markers in Indigenous Argentinean Children Living at Different Altitudes

The objective of this study was to assess the association between vitamin D and cardiometabolic markers in 2 indigenous communities from similar ethnic backgrounds, but living at different altitudes. A cross-sectional study compared 152 (72 females) indigenous schoolchildren from San Antonio de los Cobres (SAC), 3750 m above sea level, with 175 (86 females) from Chicoana (CH), 1400 m above sea level, mean age 9 years. Anthropometry, blood pressure, lipids, glucose, insulin, and vitamin D were assessed in spring season. The prevalence of children’s overweight/obesity was significantly lower in SAC, 9.2% (13), than in CH, 41.5% (71). There was a significantly higher prevalence of vitamin D deficiency (<20 ng/mL) in SAC (n = 103, 67.7%) than in CH (n = 62, 36.3%). SAC showed an inverse correlation between vitamin D and insulinemia (r = −0.17, P < .05), whereas CH showed an inverse correlation between vitamin D and systolic blood pressure (r = −0.19, P < .05), z-BMI (body mass index; r = −0.25, P < .01), triglycerides (r = −0.15, P < .05), glucose (r = −0.35, P < .05), and insulinemia (r = −0.24, P < .01). Multiple linear regression analysis showed that vitamin D (β = −.47; R² = .21) was significantly associated with SAC location, adjusted for confounding variables. Vitamin D levels were significantly and directly associated with altitude and inversely with metabolic markers, suggesting that populations living at high altitudes are at higher risk for future cardiovascular diseases.

Calcium intake and the associations with faecal fat and energy excretion, and lipid profile in a free-living population

The aim of the present study was to investigate the associations between the habitual Ca intake and faecal fat and energy excretion as well as blood lipid profile in free-living normal-weight and overweight individuals. The participants were enrolled for an 8-d period where data from a 7-d diet registration (days 1–7), a 5-d faeces collection (days 3–7), a 2-d urine collection (days 5–7), and anthropometric measurements and a fasting blood sample (day 8) were collected. Analyses showed that dietary Ca intake (g/10 MJ per d) was positively associated with excretion of faecal fat (P = 0·004) and energy (P = 0·031) when adjusted for BMI, age, sex and intake of Ca-containing supplements. However, after adjustment for intake of fibre, the effect of Ca intake disappeared. Nevertheless, total cholesterol (CHOL) and LDL-CHOL concentrations were associated negatively with Ca intake (β −0·62 (95 % CI −0·96, −0·28) mmol/l, P < 0·001, and β −0·49 (95 % CI −0·78, −0·20) mmol/l, P = 0·001, respectively, per 1000 mg/10 MJ per d increase in Ca intake). In conclusion, incorporation of Ca-rich food products in a habitual diet was associated with reduced total CHOL and LDL-CHOL concentrations, which may lower the risk of CVD in the long term.

The relationship between high-fat dairy consumption and obesity, cardiovascular, and metabolic disease

PURPOSE

To comprehensively review the data on the relationship between the consumption of dairy fat and high-fat dairy foods, obesity, and cardiometabolic disease.

METHODS

We have conducted a systematic literature review of observational studies on the relationship between dairy fat and high-fat dairy foods, obesity, and cardiometabolic disease. We have integrated these findings with data from controlled studies showing effects of several minor dairy fatty acids on adiposity and cardiometabolic risk factors, and data on how bovine feeding practices influence the composition of dairy fat.

RESULTS

In 11 of 16 studies, high-fat dairy intake was inversely associated with measures of adiposity. Studies examining the relationship between high-fat dairy consumption and metabolic health reported either an inverse or no association. Studies investigating the connection between high-fat dairy intake and diabetes or cardiovascular disease incidence were inconsistent. We discuss factors that may have contributed to the variability between studies, including differences in (1) the potential for residual confounding; (2) the types of high-fat dairy foods consumed; and (3) bovine feeding practices (pasture- vs. grain-based) known to influence the composition of dairy fat.

CONCLUSIONS

The observational evidence does not support the hypothesis that dairy fat or high-fat dairy foods contribute to obesity or cardiometabolic risk, and suggests that high-fat dairy consumption within typical dietary patterns is inversely associated with obesity risk. Although not conclusive, these findings may provide a rationale for future research into the bioactive properties of dairy fat and the impact of bovine feeding practices on the health effects of dairy fat.

Elevated serum 25(OH)D concentrations, vitamin D, and calcium intakes are associated with reduced adipocyte size in women

Recent studies have suggested a beneficial effect of vitamin D and calcium on adipocyte metabolism and the metabolic profile. Our objective was to examine associations of vitamin D intake, calcium and dairy products as well as serum 25(OH)D concentration with adiposity measures and adipocyte size in women. Omental and subcutaneous adipose tissue samples were obtained from 43 women undergoing gynecological surgeries. Adipocyte size was measured using adipocyte suspensions from collagenase-digested fat tissues. Total and visceral adiposity were assessed by dual-energy X-ray absorptiometry and computed tomography, respectively. Serum 25(OH)D was measured by radioimmmunoassay. Dietary intakes were assessed using a food frequency questionnaire. Women consuming two or more dairy product portions daily had smaller adipocytes in the omental depot compared to women consuming less than two portions daily (79 ± 12 vs. 94 ± 16 µm, P ≤ 0.01). Dietary intakes of calcium (r = -0.55) and vitamin D (r = -0.43) as well as serum 25(OH)D (r = -0.35) were also inversely and significantly associated with omental adipocyte size (P ≤ 0.05 for all). Dietary vitamin D intake was inversely associated with visceral adipose tissue area (r = -0.34, P ≤ 0.05). Serum 25(OH)D was also inversely associated with visceral adipose tissue area (r = -0.32) as well as with total adipose tissue area (r = -0.44), subcutaneous adipose tissue area (r = -0.36), BMI (r =-0.43) and total body fat mass (r = -0.41, P ≤ 0.05 for all). In conclusion, elevated dietary vitamin D intake and serum 25(OH)D values are related to lower visceral adiposity and omental adipocyte size in women.

Metabolic syndrome after liver transplantation: prevalence and predictive factors

OBJECTIVES

Metabolic syndrome (MetS) is a disorder in which obesity, insulin resistance, high blood pressure and dyslipidemia coexist. This study assessed the prevalence of MetS and its associated factors in patients who underwent orthotopic liver transplantation (OLTx).

METHODS

Post-OLTx patients were assessed for the presence of MetS according to the diagnostic criteria proposed by the International Diabetes Federation (IDF) and National Heart, Lung, and Blood Institute/American Heart Association (NHLBI/AHA). Demographic, socioeconomic, lifestyle, clinical, anthropometric, and dietary variables were collected to identify predictors for MetS using logistic regression analysis.

RESULTS

Among the 148 patients assessed, the prevalence of MetS was 50% (IDF criteria) and 38.5% (NHLBI/AHA criteria). For both the IDF and the NHLBI/AHA classifications, the independent factors associated with MetS were older age, shorter time since transplantation, and history of excessive weight prior to OLTx. Other predictors for MetS by IDF criteria were alcohol abuse as the indication for OLTx, physical activity reduction as the cause of weight gain after transplantation, and calcium intake below recommended levels. The presence of MetS (NHLBI/AHA) was also associated with decreased intake of potassium, fiber, and folic acid.

CONCLUSIONS

MetS is highly prevalent among post-OLTx patients and it is predicted by older age, shorter time since transplantation, alcohol abuse as the cause of cirrhosis, excessive weight prior to OLTx, and some potentially modifiable factors such as physical activity reduction after OLTx and low intake of calcium, potassium, fiber, and folic acid.

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

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

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 10 d diets: low Ca and low fat (LC/LF: approximately 700 mg Ca/d, 25 % of energy (fat); high Ca and LF (HC/LF: approximately 2800 mg Ca/d, 25 % of energy fat); LC and high fat (LC/HF: approximately 700 mg Ca/d, 49 E% fat); or HC and HF (approximately 2800 mg Ca/d, 49 E% 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.

Dietary calcium intake is associated with less gain in intra-abdominal adipose tissue over 1 year

Calcium intake is reported to enhance weight loss with a preferential loss in trunk fat. Discrepant findings exist as to the effects of calcium intake on longitudinal changes in total fat mass and central fat deposition. Therefore, the purpose of this study was to determine associations between dietary calcium intake and 1-year change in body composition and fat distribution, specifically intra-abdominal adipose tissue (IAAT). A total of 119 healthy, premenopausal women were evaluated at baseline and 1 year later. Average dietary calcium was determined via 4-day food records. Total fat was determined by dual-energy X-ray absorptiometry (DXA) and subcutaneous abdominal adipose tissue (SAAT) and IAAT by computed tomography. Over the study period, participants' reported daily calcium and energy intakes were 610.0 ± 229.9 mg and 1,623.1 ± 348.5 kcal, respectively. The mean change in weight, total fat, IAAT, and SAAT was 4.9 ± 4.4 kg, 5.3 ± 4.0 kg, 7.7 ± 19.5 cm(2), and 49.3 ± 81.1 cm(2), respectively. Average calcium intake was significantly, inversely associated with 1-year change in IAAT (standardized β: -0.23, P < 0.05) after adjusting for confounding variables. For every 100 mg/day of calcium consumed, gain in IAAT was reduced by 2.7 cm(2). No significant associations were observed for average calcium intake with change in weight, total fat, or SAAT. In conclusion, dietary calcium intake was significantly associated with less gain in IAAT over 1 year in premenopausal women. Further investigation is needed to verify these findings and determine the calcium intake needed to exert beneficial effects on fat distribution.

Dairy beverages and energy balance

High dairy intakes have been associated with lower rates of obesity in observational studies, but mechanisms to explain the association are lacking. A high intake of dairy protein reduces spontaneous food intake and may be one important mechanism, but more specific effects of dairy calcium seem to exist. We have found that high versus low calcium intakes from dairy products had no effect on 24-h energy expenditure or substrate oxidation rates, but fecal fat excretion increased approximately 2.5-fold on the high-calcium diets. In a meta-analysis of intervention studies we found that increasing dairy calcium intake by 1200mg/day resulted in increased fecal fat excretion by 5.2 (1.6-8.8) g/day. Newer research shows that humans possess taste receptors for calcium in the gastrointestinal tract and that signaling may be linked to appetite regulation. A new line of evidence suggests that an inadequate calcium intake during an energy restricted weight loss program may trigger hunger and impair compliance to the diet. These mechanisms may be part of the explanation for the protective effects of dairy products with regard to obesity and metabolic syndrome.

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.

Associations between estimated fatty acid desaturase activities in serum lipids and adipose tissue in humans: links to obesity and insulin resistance

Fatty acid composition of serum lipids and adipose tissue triacylglycerols (AT-TAG) partly reflect dietary fatty acid intake. The fatty acid composition is, besides the diet, also influenced by desaturating enzymes that can be estimated using product-to-precursor fatty acid ratios. The interrelationships between desaturase indices derived from different serum lipid fractions and adipose tissue are unclear, as well as their associations with obesity and insulin resistance. We aimed to investigate cross-sectional correlations between desaturase indices as measured in serum lipid fractions (phospholipids; PL and free fatty acids; FFA) and in adipose tissue (AT-TAG). In a population-based sample of 301 healthy 60-year-old men various desaturase indices were assessed: stearoyl-CoA-desaturase (16:1n-7/16:0; SCD-16 and 18:1n-9/18:0; SCD-18, respectively), delta-6-desaturase (20:3n-6/18:2n-6; D6D) and delta-5-desaturase (20:4n-6/20:3n-6; D5D). Correlations with BMI and insulin resistance (HOMA-IR) were also examined. SCD-16 and D5D were significantly correlated between fractions and tissues (all r > 0.30), whereas SCD-18 and D6D were not. Desaturase indices in serum FFA and AT-TAG were significantly correlated; SCD-16 (r = 0.63), SCD-18 (r = 0.37), and D5D (r = 0.43). In phospholipids, SCD-16 was positively correlated to BMI (r = 0.15), while D5D negatively to both BMI (r = -0.30) and HOMA-IR (r = -0.31), all p < 0.01. D6D in both phospholipids and AT-TAG was positively correlated to HOMA-IR and BMI (all p < 0.01). In conclusion, SCD-1 and D5D activity indices showed overall strong correlations between lipid pools. SCD-1 activity index in adipose tissue is best reflected by 16:1/16:0-ratio in serum FFA, but associations with obesity and insulin resistance differ between these pools. D5D in PL was inversely related to obesity and insulin resistance, whereas D6D index showed positive associations.

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

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

Dairy and weight loss hypothesis: an evaluation of the clinical trials

This review evaluates evidence from clinical trials that assessed the effect of dairy product or calcium intake, with or without concomitant energy restriction, on body weight and adiposity. Of 49 randomized trials assessing the effect of dairy products or calcium supplementation on body weight, 41 showed no effect, two demonstrated weight gain, one showed a lower rate of gain, and five showed weight loss. Four of 24 trials report differential fat loss. Consequently, the majority of the current evidence from clinical trials does not support the hypothesis that calcium or dairy consumption aids in weight or fat loss.

Ethnic differences in dairy and related nutrient consumption among US adults and their association with obesity, central obesity, and the metabolic syndrome

BACKGROUND

Recent studies suggest dairy consumption and associated nutrients may be protective against some of the components of the metabolic syndrome (MetS).

OBJECTIVES

We examined the association between consumption of a variety of dairy products and their related nutrients with obesity, central obesity, and MetS, and attempted to explain some of the ethnic differences in metabolic outcomes through dairy consumption using national data.

DESIGN

Nationally representative indicators of obesity, central obesity, and MetS among US adults were constructed from National Health and Nutrition Examination Survey 1999-2004 data, including direct anthropometric assessments, blood pressure, and laboratory tests. Sample sizes ranged from 4519 for MetS to 14 618 for obesity. Associations between diet (assessed using 24-h recalls) and metabolic and other outcomes were tested using multivariate linear and logistic models and structural equation models.

RESULTS

We found a significant inverse association between intake of whole milk, yogurt, calcium, and magnesium and metabolic disorders. Odds ratios for one more daily serving of yogurt and 100 mg Mg for MetS were 0.40 (95% CI: 0.18, 0.89) and 0.83 (95% CI: 0.72, 0.96), respectively. The opposite was found for intakes of cheese, low-fat milk, and phosphorus. Using structural equation models, ethnic differences in some MetS outcomes, such as body mass index and systolic blood pressure, were partly explained by variations in dairy-related nutrients.

CONCLUSIONS

Various dairy products may have differential associations with metabolic disorders, including obesity. Ethnic differences in dairy consumption may explain in part the ethnic disparities in metabolic disorders in the US population.

Autoantibodies against modified apolipoprotein B-100 in relation to low-density lipoprotein size and the metabolic syndrome in otherwise healthy men

The role of inflammation in atherosclerotic disease is well established, but the role of autoantibodies against modified apolipoprotein (apo) B-100 remains unclear. The metabolic syndrome is associated with a proinflammatory state, a predominance of small dense low-density lipoprotein (LDL) particles, and an increased risk for atherosclerotic diseases. Previous studies have shown specific autoantibodies against modified apo B-100 (within LDL) to be related to human atherosclerotic disease. The objective of the present study was to investigate whether autoantibodies against modified apo B-100 are related to parameters of the metabolic syndrome, such as small dense LDL. Two hundred ninety-one healthy men were investigated for different metabolic, anthropometric, and inflammatory variables; LDL peak particle size; and distribution of LDL in 4 subfractions. Subjects were grouped according to LDL peak size > or = 23.5 nm (pattern A, n = 230) or <23.5 nm (pattern B, n = 61). Immunoglobulin (Ig) G and IgM antibodies against 2 aldehyde-modified peptide sequences, denoted as 45 and 210, within apo B-100 were quantified. Levels of IgG(45), but not the other autoantibodies, were significantly higher in pattern B individuals (with a predominance of small dense LDL particles) compared with pattern A (P < .01). Relationships for both IgG(45) and IgG(210) with parameters typically associated with the metabolic syndrome were found. Only IgG(45) tended to be higher in individuals with the metabolic syndrome compared with those without (P = .07). We conclude that subjects with a predominance of small dense LDL particles have elevated concentrations of IgG(45) in the circulation, which reflect an activated immune response to a specific epitope of modified apo B-100.

Fatty acid desaturases in human adipose tissue: relationships between gene expression, desaturation indexes and insulin resistance

AIMS/HYPOTHESIS

Fatty acid desaturases introduce double bonds into growing fatty acid chains. The key desaturases in humans are Delta5-desaturase (D5D), Delta6-desaturase (D6D) and stearoyl-CoA desaturase (SCD). Animal and human data implicate hepatic desaturase activities in insulin resistance, obesity and dyslipidaemia. However, the role of desaturase activity in adipose tissue is uncertain. We therefore evaluated relationships between adipose mRNA expression, estimated desaturase activities (fatty acid ratios) in adipose tissue and insulin resistance.

METHODS

Subcutaneous adipose tissue mRNA expression of D5D (also known as FADS1), D6D (also known as FADS2) and SCD was determined in 75 individuals representative of the study population of 294 healthy 63-year-old men. Desaturation indexes (product/substrate fatty acid ratios) were generated from adipose tissue fatty acid composition in all individuals. Insulin resistance was defined as the upper quartile of the updated homeostasis model assessment (HOMA-2) index.

RESULTS

The relevant desaturation indexes (16:1/16:0, 18:1/18:0, 20:4/20:3 and 18:3/18:2) reflected expression of SCD, but not of D5D or D6D in adipose tissue. Insulin-resistant individuals had a higher adipose tissue 18:1/18:0, but not 16:1/16:0 ratio than insulin-sensitive individuals. Individuals with a high adipose tissue 18:1/18:0 ratio were 4.4-fold (95% CI 1.8-11.8) more likely to be insulin resistant [threefold (95% CI 1.1-8.6) after adjustment for waist circumference and plasma triacylglycerol]. In a multiple regression model predicting HOMA-2, the independent effect of the 18:1/18:0 ratio was borderline (p=0.086).

CONCLUSIONS/INTERPRETATION

Adipose tissue desaturation indexes of SCD reflect the expression of the gene encoding the enzyme in this tissue. Elevated SCD activity within adipose tissue is closely coupled to the development of insulin resistance.

Markers of endothelial activity are related to components of the metabolic syndrome, but not to circulating concentrations of the advanced glycation end-product Nɛ-carboxymethyl-lysine in healthy Swedish men

Endothelial function is considered important in the development of cardiovascular diseases and type 2 diabetes. Circulating advanced glycation end-products (AGEs) and dietary components have been shown to affect endothelial function in type 2 diabetics, but determinants of endothelial function in a non-diabetic population are more poorly investigated. Therefore, we investigated relationships between dietary habits, AGEs and endothelial activation in men with isolated metabolic disturbances. Circulating markers of endothelial activation (soluble forms of vascular cell adhesion molecule-1, intercellular adhesion molecule-1, E-selectin and von Willebrand factor) and plasma N epsilon-carboxymethyl-lysine (CML, the predominant AGE in human plasma) were analyzed in a cross-sectional study of 294 healthy men. Individuals completed a 7-day dietary record, and metabolic and inflammatory parameters were determined. NCEP/ATPIII-criteria were used to define the metabolic syndrome. Endothelial activation was higher in individuals with the metabolic syndrome, and was positively related to certain features of the syndrome (insulin, glucose, inflammation and obesity), but not to others (triacylglycerol and blood pressure). Dietary factors were related to endothelial activation, but CML was not. Multivariate analysis revealed energy and alcohol intake, along with insulin and markers of oxidative stress and inflammation, to be positive predictors of endothelial activation. In this cohort of otherwise healthy men, endothelial activation was increased in individuals with the full metabolic syndrome, but not in those with only some of the components of the metabolic syndrome. Insulin resistance, inflammation, oxidative stress, the dietary intake of energy and alcohol, but not plasma CML, predicted endothelial activation in these men.

Effects of dietary lactose on long-term high-fat-diet-induced obesity in rats

OBJECTIVE

In this study, we examined the effects of lactose on long-term high-fat-diet-induced obesity in rats.

RESEARCH METHODS AND PROCEDURES

A total of 112 Sprague-Dawley strain female rats (6 weeks old) were divided into four groups: a basic control diet group (Cont), 10% lactose diet group (Lac), high-fat diet group (Fat), and high-fat with 10% lactose diet group (Fat+Lac). After 0, 7, 14, and 84 days from starting the experimental diet, the animals were fasted overnight and killed by bleeding from the abdominal aorta under anesthesia (n = 8 or 9/group).

RESULTS

After 84 days, the addition of lactose to the high-fat diet decreased the final body weight, body weight gain, fat accumulation, and the levels of serum leptin, serum triglycerides, and serum glucose significantly (p < 0.05). Although there was no significant difference in the levels of serum calcium and phosphorus between the Fat and Fat+Lac groups, lumbar vertebral bone mineral density was significantly higher in the Fat+Lac group than in the Cont group on Day 82. Interestingly, the level of serum 1alpha, 25-dihydroxyvitamin D(3) in the Fat+Lac group on Day 84 was reduced by 74% compared with the Fat group (p < 0.01), while there was no significant difference in serum parathyroid hormone levels between the Fat and Fat+Lac groups.

DISCUSSION

This is the first study to suggest that the addition of lactose to a long-term high-fat diet may regulate not only calcium metabolism but also fat deposition. Further studies on the mechanism of dietary lactose in the regulation of adiposity would provide valuable data for the prevention of long-term high-fat-diet-induced obesity.

Effect of dairy supplementation on body composition and insulin resistance in mice

OBJECTIVE

This study examined whether yogurt supplementation attenuated the weight gain and insulin resistance in mice fed a moderate-fat diet.

METHODS

Nine-week-old male mice (F1 BTBR x C57Bl6/J) were housed individually for the duration of the study. After initial measurements of body weight and composition, mice were randomly assigned to receive one of two isocaloric diets (19.4% kcal protein, 45.5% kcal carbohydrate, and 35.1% kcal fat). One diet was supplemented with dried yogurt powder (10.75 g/100 g of diet). In the first experiment, mice received the diets for 4 wk, after which body weight and body composition were reassessed. In the second experiment, an insulin tolerance test was performed at week 4 and glucose uptake in gonadal fat was assessed at week 5.

RESULTS

Baseline body weight was not significantly different between control and yogurt mice (P = 0.85). Body weight and fat mass increased significantly over time (P < 0.001) and there was a significant effect of diet on the increase in body weight (P < 0.05) and fat mass (P < 0.001), with the yogurt mice gaining less weight and fat than the control mice. Food intake was not significantly affected by the yogurt supplementation (P = 0.906). Digestive efficiency was significantly lower in the yogurt mice (P < 0.05) due to greater fecal production (P < 0.01). There was no significant effect of diet on the glucose area under the curve during the insulin tolerance test (P = 0.24). Glucose uptake in the gonadal fat was significantly higher in the yogurt mice than in controls under basal (P < 0.05) and insulin-stimulated (P < 0.05) conditions.

CONCLUSION

Yogurt supplementation resulted in less weight and fat gain in mice fed isocaloric diets due to a decrease in digestive efficiency. Yogurt also enhanced the uptake of glucose in fat but did not significantly improve insulin sensitivity.

Dietary and non-dietary determinants of central adiposity among Tehrani women

OBJECTIVE

To determine the correlates of central adiposity.

DESIGN

Population-based cross-sectional study.

SUBJECTS

A total of 926 women (aged 40-60 years) from all districts of Tehran.

METHODS

Demographic data were collected and anthropometric indices were measured according to standard protocols. Dietary intakes were assessed by means of a semi-quantitative food-frequency questionnaire. The suggested cut-off point for waist-to-hip ratio (WHR>or=0.84) for Tehrani people, adjusted for their age group, was used to determine central adiposity. Logistic regression analysis was used to determine the correlates of WHR, which were adjusted for age, taking medications and body mass index (BMI). The components of dietary intake were determined by factor analysis. Pearson correlation was used to determine the association between the dietary components and WHR. Analysis of covariance was employed to compare the mean values of WHR in different lifestyle groups, with adjustment for BMI and age.

RESULTS

Mean WHR was 0.82 +/- 0.06. The possibility of being centrally obese was higher in women with light physical activity (odds ratio: 2.11; 95% confidence interval: 1.40-2.53), depressed women (1.36; 1.02-1.93), smokers (1.21; 1.02-1.56) and unemployed women (1.41; 1.13-1.72). Marriage (1.31; 1.10-1.82), menopause (1.22; 1.02-1.61), low vitamin C intake (2.31; 1.25-4.25) and low calcium intake (1.30; 1.07-3.78) were associated with central fat accumulation. Dairy consumption was inversely correlated with central fat accumulation (r = -0.2, P < 0.05).

CONCLUSION

Central adiposity is associated with poor lifestyle factors including low physical activity, depression, smoking, low intake of vitamin C, low intake of calcium and dairy products and high fat consumption. Thus lifestyle modifications should be encouraged to achieve a healthier body shape.

Food preference questionnaire as a screening tool for assessing dietary risk of cardiovascular disease within health risk appraisals

OBJECTIVE

Nutrition components of health risk appraisals (HRAs) aim to rapidly and accurately assess dietary behaviors that increase disease risk. Because cognitive research suggests that recalling food likes/dislikes may be simpler and more accurate than recalling intake, we tested whether a preference measure was predictive of cardiovascular disease risk factors within an HRA.

METHODS

HRA participants (422 primarily non-Hispanic white men, mean age 46+/-10 years) from a manufacturing company completed surveys to assess fat and sweet food/beverage preference; frequency of consuming fat and sweet foods/beverages, alcoholic beverages, fiber-rich foods (whole grains, fruits, and vegetables); and physical activity. Per measured risk factors, 34% had central obesity (waist circumference>or=102 cm), 32% had hypertension (>or=140 and/or>or=90 mm Hg), 52% had prehypertension (>or=120 to 139 and/or>or=80 to 89 mm Hg), and 52% had an elevated total cholesterol level (>or=200 mg/dL [5.2 mmol/L]).

STATISTICAL ANALYSES

Multiple linear regression models explaining variability in waist circumference, blood pressure, and serum lipids were tested.

RESULTS

Although preference and intake pairs for fat and sweets were significantly correlated, intake of fat and sweets failed to associate significantly with any risk factor. Significant variance in waist circumference was explained by age, fat preference, fiber intake, and physical activity. Those with greater circumferences liked fat more, consumed less fiber, and exercised less. Waist circumference in turn contributed significantly to models predicting serum lipid levels and blood pressure. Alcohol intake explained variability in serum lipid levels-higher intakes were associated with higher high-density lipoprotein cholesterol levels. The models predicting risk were generally more explanatory in younger (<50 years) than in older men.

CONCLUSIONS

Including a preference measure within an HRA appears to enhance cardiovascular disease risk factor assessment. Fat preference, intake of fiber-rich foods, and alcohol proved the best dietary determinants of cardiovascular disease risk factors.

Effect of dietary calcium intake on weight gain in type 2 diabetic patients following initiation of insulin therapy

OBJECTIVES

This pilot study analyses weight gain in type 2 diabetic patients at initiation of insulin therapy, according to daily calcium intake.

METHODS

Type 2 diabetic patients consecutively admitted for initiation of insulin therapy were studied between January and March 2004 in a monocenter study. Dietary intake was assessed by a 7-day food history before insulin treatment (initial visit) and 4 to 6 months later (final visit).

RESULTS

Thirty-one patients were studied (18 males and 13 females; mean age 62+/-9 years, with diabetes duration 14+/-10 years). Weight significantly increased between initial and final visits (81.9+/-16.2 vs. 84.8+/-17.8 kg; P=0.0272). Median weight gain was 2.4 kg (IQR: -1.15 to +5.27 kg). Waist circumference increased by 2 cm (IQR: 0 to +4 cm). There was no difference between weight change and tertile of calcium intake adjusted on energy intake. We did not find any correlation between weight change and total calcium intake (Rho=0.186; P=0.3165) or dairy calcium intake (Rho=0191; P=0.3040). Similarly, we did not find any correlation between waist circumference change and total calcium intake (Rho=0.324; P=0.1205) or dairy calcium intake (Rho=0.285; P=0.0755).

CONCLUSION

We found no relation between total or dairy calcium intake and weight change during initiation of insulin therapy in type 2 diabetic patients. Dietary calcium intake does probably not play a major role on insulin-induced body weight gain.

Dairy foods, dietary calcium and obesity: a short review of the evidence

The possible association between dairy products consumption and body weight regulation has been the subject of several recent publications. The interest in this issue arose after biologically plausible mechanisms for this association were identified: most of these suggested a key role for calcium intake from dairy products, although calcium-independent mechanisms have also been proposed. Data from cross-sectional epidemiological studies support the hypothesis that a dairy food-rich diet is associated with lower fat accumulation in adults and children; however, prospective studies and randomised controlled intervention trials have yielded inconsistent results. Different reasons could explain these findings that regard the evaluation of either the "exposure" (i.e. the methodological problems in the assessment of dietary intake of nutrients over a long time) and the "outcome" (i.e. multiple factors involved in the regulation of body weight). Moreover, it could also be hypothesised that high consumption of dairy foods would be a marker of healthier lifestyles, or that nutritional differences exist within dairy products. Available data do not unequivocally support the hypothesis that a causal relationship exists between high dairy food intake--and/or high dietary calcium intake--and lower fat mass deposition. However, research in this field should aim to define the health impact of dairy foods even beyond obesity.

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.

Trends in energy and macronutrient intakes in non-under-reporters vary with the method used to identify under-reporters

OBJECTIVE

To investigate effects of using different methods to identify under-reporters on trends in dietary intake and physical activity level (PAL) in non-under-reporters.

DESIGN

Dietary intake and activity pattern were recorded by 887 female university students from 1988 to 2003. Energy expenditure (EE) and PAL were measured using a factorial method. Nine methods were used to identify under-reporters. Trends between 1988 and 2003 were determined from linear regression of median data for each year.

RESULTS

Prevalence of under-reporting varied with the method used, ranging from 22.2% to 66.7%. Trends that were consistent using all methods were a decrease in per cent of energy from fat and no change in alcohol intake or PAL (P<0.05). Trends in energy and macronutrient intakes varied with the method used. Using the four methods that excluded the most under-reporters there were increases in energy and gram carbohydrate (CHO) intakes (P<0.05), but no change in gram fat intake. Using the four methods that excluded the fewest under-reporters there was no change in energy or gram CHO intake, but a decrease in gram fat intake (P<0.05).

CONCLUSION

Trends in energy, fat and CHO intakes in non-under-reporters varied with the method used to identify under-reporters.