Milk intake is inversely related to obesity in men and in young women: data from the Portuguese Health Interview Survey 1998–1999

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.

Effects of a fibre-enriched milk drink on insulin and glucose levels in healthy subjects

Background

The glycaemic response to foods is dependent on the quality and content of carbohydrates. Carbohydrates in the form of dietary fibre have favourable effects on insulin and glucose metabolism and may help to control energy intake. Dairy products have a relatively low carbohydrate content, and most of the carbohydrate is in the form of lactose which causes gastrointestinal symptoms in part of the population. In order to avoid these symptoms, dairy products can be replaced with lactose-free dairy products which are on the market in many parts of the world. However, the effects of lactose-free products on insulin and glucose metabolism have not been studied.

Methods

In the present study, we investigated the effects of 1) a lactose-free milk drink, 2) a novel fibre-enriched, fat- and lactose-free milk drink and 3) normal fat-free milk on serum glucose and insulin levels and satiety using a randomized block design. Following an overnight fast, 26 healthy volunteers ingested 200 ml of one of these drinks on three non-consecutive days. Insulin and glucose levels and subjective satiety ratings were measured before the ingestion of the milk product and 20, 40, 60, 120 and 180 minutes after ingestion. The responses were calculated as the area under the curve subtracted by the baseline value (AUC minus baseline).

Results

The insulin response was significantly lower for the fibre-enriched milk drink than it was for the other milk products (AUC, P = 0.007). There were no differences in the response for glucose or in the AUC for the subjective satiety ratings between the studied milk products.

Conclusion

The present results suggest that this novel milk drink could have positive effects on insulin response.

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.

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.

Worldwide trends in dairy production and consumption and calcium intake: is promoting consumption of dairy products a sustainable solution for inadequate calcium intake?

BACKGROUND

Adequate calcium intake is critical for good health. Inadequate calcium intake is a worldwide problem and is more serious in countries where consumption of dairy products is low.

OBJECTIVE

To analyze worldwide trends in production and consumption of dairy products and in calcium intake.

METHODS

Data were taken from Food and Agriculture Organization food balance sheets, from published studies, and from surveys of four countries with large populations and large dairy production (China, India, the United States, and Russia). Linear regression models were fitted to estimate average annual changes and to project future trends.

RESULTS

Overall global dairy production and supply (total and per capita) have increased since 1980, especially in developing countries. There are large between-region and between-country differences in the levels of production, supply, and consumption and in the trends. In 1997 India surpassed the United States to become the largest dairy producer. Consumption of dairy products in China has more than tripled since 1982 and has increased sevenfold among urban residents. The increase has been more dramatic during recent years. In spite of increases in dairy production and consumption in China and India, calcium intake has decreased in these countries. The average daily per capita consumption of dairy products was more than 200 g in the United States in 1999-2004 but less than 27g in China in 2002; the average daily per capita intake of calcium was 962 mg in US men and 756 mg in US women in 1999-2004, but less than 400 mg in China in 2002.

CONCLUSIONS

Global production and supply of dairy products have been increasing since 1980, which has an impact on the environment. Dairy consumption and calcium intake remain low in most countries examined as compared with recommended amounts of dairy products and calcium. Promotion of consumption of dairy products does not necessarily increase total calcium intake.

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.

Effects of dietary taurine supplementation on plasma and liver lipids in OVX rats fed calcium-deficient diet

Taurine supplementation has been shown to have an effect on lowering blood lipids in ovariectomized (OVX) rats. It therefore seemed desirable to find out whether the beneficial effect of taurine on OVX rats fed calcium-deficient diet could also be reproduced. Forty female Sprague-Dawley rats were divided into two groups. One group was OVX and the other group received a sham operation (Sham). Each rat group was further divided into the control diet and the taurine supplemented (2.0 g/100 g diet) diet group. All rats were fed on calcium-deficient diet and deionized water ad libitum for 6 weeks. Plasma and liver lipids were determined by using commercial kits. LDL-cholesterol concentrations were estimated with the equation of Friedewald et al. (1972). There were no significant differences in body weight gain and food intake between the control and taurine group within Sham and OVX groups, but body weight gain, food intake, and food efficiency ratio was higher in the OVX group. Concentrations of plasma total cholesterol, triglyceride, LDL-cholesterol were significantly lower in the taurine fed group of OVX rats fed Ca deficient diet, while HDL-cholesterol concentration was increased in the taurine fed group. Therefore, in this study, we examined whether taurine also prevented hypercholesterolemia induced by ovarian hormone deficiency in ovariectomized rats when they were fed a calcium-deficient diet. These results indicate that taurine may have some beneficial effects on hypercholesterolemia and hypertriglyceridemia in OVX rats fed calcium-deficient diet.

A prospective study of dairy consumption in relation to changes in metabolic risk factors: the Hoorn Study

OBJECTIVE

Higher dairy consumption has been suggested to reduce the risk of obesity and metabolic disturbances. The aim of our study was to investigate the prospective association between dairy consumption and changes in weight and metabolic disturbances.

METHODS AND PROCEDURES

Baseline dairy intake (servings/day) was assessed by a semi-quantitative food-frequency questionnaire in 1,124 participants of the Hoorn Study. Linear and logistic regression analyses were performed to investigate the association between dairy intake and 6.4-year change in weight, fat distribution, and metabolic risk factors (glucoses, lipids, blood pressure) and the incidence of metabolic syndrome (MS).

RESULTS

Baseline dairy consumption was not associated with changes in fasting and post-load glucose concentrations, serum lipid levels (high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, and triglycerides), or blood pressure, nor with the risk of developing the MS in 6.4 years (odds ratio with 95% confidence interval was 0.86 (0.52-1.42) comparing highest with lowest quartile of dairy consumption). In subjects with BMI < 25 kg/m(2), higher dairy consumption was significantly associated with an increase in BMI, weight, waist, and a decrease in high-density lipoprotein.

DISCUSSION

Our results do not support the hypothesis that a higher dairy consumption protects against weight gain and development of metabolic disturbances in a Dutch elderly population.

Trends in food availability in Portugal in 1966–2003

BACKGROUND

Dietary intake has changed considerably in South European countries, but whether those changes were similar between countries is currently unknown.

AIM OF THE STUDY

To assess the trends in food availability in Portugal and four other Mediterranean countries from 1966 to 2003.

METHODS

Food and Agricultural Organization food balance sheets from Portugal, France, Italy, Greece and Spain. Trends were assessed by linear regression.

RESULTS

The per capita availability of calories has increased in Portugal, France, Greece, Italy and Spain in the past 40 years. Portugal presented the most rapid growth with an annual increase of 28.5 +/- 2.2 kcal (slope +/- standard error), or +1000 kcal overall. In animal products, Portugal had an annual increase of 20.7 +/- 0.9 kcal, much higher than the other four countries. Conversely, the availabilities of vegetable and fruit only showed a slight growth of 1.0 +/- 0.1 kcal/year and 2.5 +/- 0.4 kcal/year, respectively, thus increasing the ration of animal to vegetable products. Olive oil availability increased in all countries with the notable exception of Portugal, where a significant decrease was noted. Wine supply decreased in all five countries; in contrast, beer supply started to take up more alcohol share. Percentage of total calories from fat increased from nearly 25% to almost 35% in Portugal during the study period, mainly at the expenses of calories from carbohydrates, whereas the share of protein showed just a slight increase. Furthermore, fat and protein were increasingly provided by animal products.

CONCLUSIONS

Portugal is gradually moving away from the traditional Mediterranean diet to a more Westernized diet as well as France, Greece, Italy and Spain. Noticeably, the trends of diet transition were observed relatively faster in Portugal than in the other four Mediterranean countries.

Is higher dairy consumption associated with lower body weight and fewer metabolic disturbances? The Hoorn Study

BACKGROUND

Dairy consumption has been postulated to reduce the risk of obesity and metabolic disturbances.

OBJECTIVE

The aim of this study was to evaluate the associations of dairy consumption with body weight and other components of the metabolic syndrome.

DESIGN

We used cross-sectional data for 2064 men and women aged 50-75 y who participated in the Hoorn Study. The metabolic syndrome was defined according to the National Cholesterol Education Program Expert Panel. Dairy consumption was assessed by using a semiquantitative food-frequency questionnaire.

RESULTS

The median consumption of total dairy products was 4.1 servings/d. After adjustment for potential confounders (ie, dietary factors, physical activity, smoking, income, educational level, and antihypertensive medication), total dairy consumption was significantly associated with lower diastolic blood pressure (beta +/- SE: -0.31 +/- 0.12 mm Hg/serving) and higher fasting glucose concentrations (0.04 +/- 0.02 mmol/L per serving), but not with body weight or other metabolic variables (ie, lipids, postload glucose, or insulin). When different dairy products were distinguished, borderline significant (P < 0.10) inverse associations were observed for dairy desserts, milk, and yogurt with systolic (-1.26 +/- 0.58, -0.57 +/- 0.34, and -1.28 +/- 0.74 mm Hg/serving, respectively) and diastolic (-0.58 +/- 0.31, -0.57 +/- 0.18, and -0.35 +/- 0.40 mm Hg/serving, respectively) blood pressure, whereas cheese consumption was positively associated with body mass index (0.15 +/- 0.08/serving).

CONCLUSION

In an elderly Dutch population, higher dairy consumption was not associated with lower weight or more favorable levels of components of the metabolic syndrome, except for a modest association with lower blood pressure.

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.

Trends of food intake in Portugal, 1987–1999: results from the National Health Surveys

OBJECTIVE

To assess trends of food intake in Portugal.

DESIGN

Analysis of three cross-sectional studies: 1987, 1995-1996 and 1998-1999.

SETTING

Representative samples of free-living individuals.

SUBJECTS

64 734 men and 71 282 women.

INTERVENTIONS

Food intake was assessed by questionnaires inquiring the number of meals and which foodstuffs (fish, meat, milk, rice/pasta/potatoes, soup, vegetables and fruit) had been consumed the day before.

RESULTS

Age-adjusted average number of meals decreased from 3.3+/-0.1 in 1987 to 2.9+/-0.1 in 1998-1999 in both genders (P<0.001). In men, the percentage of subjects consuming meat, milk and potatoes/rice/pasta increased from 73, 66 and 91% in 1987 to 83, 74 and 95% in 1998-1999, respectively. The percentage of subjects consuming soup and fish decreased from 70 and 56% in 1987 to 62 and 53% in 1998-1999, respectively. In women, the percentage of subjects consuming meat, milk, potatoes/rice/pasta and vegetable increased from 70, 66, 89 and 71% in 1987 to 78, 77, 93 and 83% in 1998-1999, respectively. The percentage of subjects consuming soup and fish decreased from 70 and 55% in 1987 to 64 and 53% in 1998-1999, respectively. These trends were more pronounced in the younger age, which also displayed a higher frequency of snacking. Multivariate analysis adjusting for age group, region and educational level showed that the consumption of meat, milk and vegetables increased and the consumption of soup, fish and fruit decreased in 1998-1999 relative to 1995-1996.

CONCLUSIONS

Within a decade, the Portuguese dietary pattern has changed considerably, shifting from a traditional, south European to a more Westernized, protein-rich diet.

SPONSORSHIP

The Unidade de Nutrição e Metabolismo of the Instituto de Medicina Molecular is partially funded by a grant from the FCT (Fundação para a Ciência e a Tecnologia) ref. RUN 437.