Epidemiological studies show an inverse association between dairy consumption and obesity. While the reason for this is not fully understood, evidence also showing an inverse association between calcium intake and obesity, suggests that dairy might be protective of obesity because of the calcium it contains. The weight loss effect of dairy was found by accident in a clinical trial investigating the effects of a yoghurt drink on skeletal health. Those subjects in the treatment group unexpectedly lost weight, suggesting that the increased calcium or dairy consumption had inhibitory effects on weight gain. Obesity and its related disorders such as cardiovascular disease and diabetes are increasingly being seen as disorders of inflammation, possible via generation of systemic oxidative stress. Factors that can reduce systemic oxidation and inflammation may therefore be beneficial to these diseases. This may also explain the benefits of calcium and dairy in the protection from obesity.
For example, researchers1 have used a cross-sectional survey of 1514 Greek men and 1528 Greek women (aged 18 to 89 years) to investigate the associations between consumption of dairy products and levels of various inflammatory markers. Subjects were otherwise healthy and had no clinical symptoms of cardiovascular disease. Fasting blood samples were collected in order to assess inflammatory markers and a frequent food questionnaire was used to assess the intake of dairy products including milk, cheese and yoghurt. The results showed that C-reactive protein (CRP), interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-α) were 16, 5 and 12% lower in those subjects consuming 11 and 14 servings of dairy products per week, compared to those consuming less than 8 servings per week. Those consuming more than 14 servings per week had CRP, IL-6 and TNF-α levels 29, 9 and 20% lower than those consuming fewer than 8 servings.
These findings remained significant even after adjustment for age, sex, smoking, physical activity, body mass index and dietary habits. This is strong evidence that high dairy product consumption is able to influence obesity. One possible explanation for the ability of dairy to reduce inflammation is on account of the presence of B vitamins within cow’s milk. Vitamin B6, vitamin B12 and folate are able to reduce plasma homocysteine levels, high levels of which are a known cause of systemic oxidative stress. Dairy may therefore have some benefits through the supply of small amounts of some of the B vitamins. Alternatively the calcium, or other components of dairy such as the conjugated linoleic acid, may have other regulatory mechanisms upon inflammation. Some evidence suggests that calcium can regulate appetite through release of calcitonin. Dairy may therefore have multiple mechanisms of action in preventing weight gain.
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