Low fat yoghurt cuts risk of type 2 diabetes

Swapping snacks — such as potato chips — for low-fat yogurt can cut the risk of developing type 2 diabetes by almost half, according to the results of a new observational study.

The findings, involving a randomly selected subgroup from the larger EPIC-Norfolk study, were published online February 5 inDiabetologia by Nita G. Forouhi, MBB, PhD, from the Medical Research Council (MRC) Epidemiology Unit, University of Cambridge School of Clinical Medicine, United Kingdom, and colleagues.

"A good place to include yogurt in your diet to reap the benefits against onset of diabetes would be instead of a packet of crisps [potato chips].We found that swapping crisps for yogurt offered protection against onset of diabetes. This may form a practical dietary change suggestion for patients at risk of diabetes as well as among the general population," Dr. Forouhi revealed in an email.

In the study — the first to examine the relationship of dairy consumption with incident type 2 diabetes using prospective 7-day food diaries — subjects with the highest low-fat yogurt consumption had a 28% lower risk of developing type 2 diabetes over 11 years of follow-up compared with those who ate very little or no yogurt, after adjustment for a variety of possible confounders.

"Current US dietary guidelines recommend increasing intake of fat-free or low-fat milk and milk products such as milk, yogurt, and cheese… Recommending yogurt intake is therefore in keeping with dietary guidelines for all patients," Dr. Forouhi said.

And, she noted, "At a time when other research has shown that certain foods raise health risks, such as consuming high amounts of added sugar, it is reassuring to have messages about other foods, like yogurt and low-fat fermented dairy products, that could be good for our health."

Dietary Dairy Examined
The study compared a detailed daily record of all the food and drink consumed over a week at the time of study entry among 753 people who developed new-onset type 2 diabetes over 11 years of follow-up, with 3502 randomly selected study participants from EPIC-Norfolk, which comprised more than 25,000 men and women.

At baseline, subjects had a mean age of 59 years and body mass index (BMI) of 26 kg/m 2; they filled in detailed diary questionnaires that asked about all foods containing dairy as the main ingredient and the type of dairy product (yogurt, cheese, or milk). These were divided into high-fat and low-fat based on a 3.9% cutoff for total fat content. Fermented dairy products (all yogurt, all cheese, sour cream, and crème fraiche) were also categorized separately into high- and low-fat.

Milk was the most-consumed dairy product, accounting for 82%, followed by cheese (9%) and yogurt (8%). Total average dairy consumption was 269 g/day, of which 65% was low-fat.

Total overall dairy consumption was not associated with the development of diabetes, but low-fat dairy intake was, after adjustment for age and sex. Yet even this became nonsignificant after further adjustment for other confounders including BMI, smoking, alcohol consumption, social class, physical activity, and other dietary components.

Similarly, total fermented dairy-product consumption was associated with a 19% lower risk, but this also became nonsignificant after adjustment for possible confounders.

Low-Fat Fermented Dairy Products Linked to Lower Risk
But after full adjustment, a significant relationship remained between intake of low-fat fermented dairy products and the development of type 2 diabetes, with a hazard ratio of 0.76 for the highest vs lowest tertiles (P for trend = .049).

"In public-health terms this equates to 4.5 standard-size portions (125 g) per week of low-fat fermented dairy products, largely composed of yogurt (all types) and including low-fat unripened cheese such as low-fat cottage cheese and fromage frais," the researchers say.

Low-fat yogurt in particular was associated with a 35% reduced risk after adjustment for age and sex ( P for trend < .001), and this relationship remained significant even after adjustment for other potential confounders (HR 0.72, P for trend = .017).

In a separate analysis, the effect of substituting dairy products for snacks — such as cake, pudding, biscuits, or chips — was examined. Eating yogurt instead of such snacks resulted in a 47% lower risk for diabetes, but none of the other substitutions resulted in a significant reduction in diabetes risk.

Several possible mechanisms could explain the relationship between fermented dairy and diabetes, including promotion of the synthesis of menaquinone (vitamin K 2), which has been linked to reduced rates of type 2 diabetes, or the actions of probiotic bacteria, which have been found to improve lipid profiles and antioxidant status in patients with type 2 diabetes, the researchers suggest.

Moreover, low-fat fermented dairy products are "naturally low in fat and high in water content and are, therefore, low energy-dense foods. Studies have shown an independent association of low energy-dense foods with lower fasting insulin levels and the metabolic syndrome and a lower risk of type 2 diabetes," they say.

Dr. Forouhi said that the use of 7-day food diaries allows for a much more careful analysis of dairy intake than has been done in prior studies.

"This work gives us important…and more detailed information than our own past research and that of others. We were able to estimate people's diets in much more detail and in real time with all food and drink that was consumed being recorded with a 7-day food diary.

"This gets around an important limitation of the past research, which has relied on participants' recall of foods they have eaten in the past. This gives us greater confidence that low-fat fermented dairy and yogurt specifically within that group can be important for the prevention of diabetes as part of an overall healthy lifestyle," she concluded.

Vitamin D-fortified yoghurt improves cholesterol levels in diabetics

Regular consumption of a vitamin D-fortified yoghurt drink may improve cholesterol levels and markers of blood vessel functioning in diabetic people, according to new research.

The study reports that twice daily consumption of a yoghurt drink enriched with vitamin D3 results in improved blood sugar management, lowered insulin resistance, normalised cholesterol levels, and improved markers of endothelial dysfunction – a precursor of heart disease.

"Patients who had taken the vitamin D yoghurt also had improved cholesterol levels with lower total cholesterol and LDL levels and an increase in HDL. All the improvements in cholesterol seemed to be due to the reduction in insulin resistance,” said Dr Tirang Neyestani of the researchers, based at the National Research Institute and Faculty of Nutrition and Food Technology at Shahid Beheshti University of Medical Sciences, Iran.

“Biomarkers of endothelial dysfunction, serum endothelin-1, E-Selectin and MMP-9, levels were also lower for the patients taking vitamin D," he added.


D deficiency
The researchers noted that low vitamin D status is known to affect the inner lining of blood vessels (endothelial cells),eventually leading to atherosclerosis and cardiovascular disease. In addition they noted that people with diabetes are known to have an increased risk of heart disease.

The researchers suggested that endothelial function “may therefore be the focus of preventive efforts against both diabetes and its fatal complications.” They noted that by improving vitamin D status in diabetic people, it may be possible to improve endothelial biomarkers, possibly reducing the risk of heart disease.


Study details
In the double-blind trial, the researchers from Tehran gave diabetic patients either a plain yoghurt drink (Doogh) or the same drink fortified with vitamin D3 twice a day for 12 weeks. The team measured the effects of vitamin D on glycemic status, cholesterol levels and endothelial biomarkers.

The team found that vitamin D improved the fasting glucose, insulin resistance, cholesterol, and measures of endothelial function.

“The intervention resulted in a significant improvement in fasting glucose, the Quantitative InsulinCheck Index (QUICKI), glycated hemoglobin (HbA1c), triacylglycerols, high-density lipoprotein cholesterol (HDL-C), endothelin-1, E-selectin and MMP-9 in the fortified yoghurt drink compared to the plain yoghurt drink,” wrote the researchers.

The team noted that most patients in the trial were deficient in vitamin D at the start, but the fortified yoghurt drink elevated most of their levels to normal. However, they said that even amongst those who took the vitamin D supplement, around 5% remained deficient, and did not show any signs of improvements associated with increased status.


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Vitamin D-fortified yoghurt improves cholesterol levels in diabetics
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Source: BMC Medicine, published open access online, doi: “Regular consumption of vitamin D-fortified yogurt drink (Doogh) improved endothelial biomarkers in subjects with type 2 diabetes: a randomized double-blind clinical trial” Authors: S. Shab-Bidar, T.R. Neyestani, A. Djazayery, M.R. Eshraghian, A. Houshiarrad, et al

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