"The combined effect of omega-3 and omega-9 polyunsaturated fatty acid supplementation, with an equivalent decrease in saturated fatty acids, has not been evaluated yet in patients with metabolic syndrome," explained lead author Pedro Benito from Córdoba University and the Carlos Haya Hospital.
Metabolic syndrome (MetS) is a condition characterised by central obesity, hypertension, and disturbed glucose and insulin metabolism. The syndrome has been linked to increased risks of both type 2 diabetes and CVD.
Fifteen per cent of adult Europeans are estimated to be affected by MetS, while the US statistic is estimated to be a whopping 32 per cent. Obesity is established to be the main risk factor for MetS.
The new randomised, placebo-controlled open clinical trial, published on-line in the journal Clinical Nutrition (doi: 10.1016/j.clnu.2005.12.006), supplemented the diet of 72 volunteers with either half a litre per day of semi-skimmed milk (control group) or the same volume of a commercially available enriched milk.
All of the volunteers had at least three of the main risk factors for MetS, including abdominal obesity, triglyceride levels above 150mg/dL, HDL-cholesterol levels below 40 mg/dL in men and 50 mg/dL in women, blood pressure higher than 130/85 mmHg, and fasting blood glucose levels higher than 110 mg/dL.
The enriched milk, supplied by Covap, contained omega-3 fatty acids EPA (0.003 grams per 100 mL) and DHA (0.034 grams per 100 mL), oleic acid (1.14 grams per 100 mL), folic acid (30 micrograms per 100 mL), and vitamin E (1.5 milligrams per 100 mL).
After three months of supplementation, the researchers found that compliance, acceptance and tolerability of the enriched milk was very high.
"A significant reduction of 13 per cent in triglyceride levels, six per cent in total cholesterol levels, 7.5 per cent in LDL-cholesterol, and 5.7 per cent in alipoprotein B (apoB) was observed in the test group but not the control group," reported Benito.
A drop in blood pressure was also observed for the test group, but not the control group. This could be attributed to weight loss, but the researchers argue that this is more likely to be due to a combination of the omega-3s and oleic acid.
The reason that such an enriched milk appears to benefit people with MetS is the combination of nutrients, say the researchers: "High intakes of omega-3 and omega-9 PUFAs, folic acid, and vitamin E, are important characteristics of the Mediterranean diet, so that the enrichment of milk with these nutrients allows approaching the diets of our patients to the Mediterranean diet."
As explained by the researchers, this is the first such study to investigate the effects of supplementation with an enriched milk with respect to the cardiovascular risk factors associated with metabolic syndrome, and thus considerably more research must be performed before any firm conclusions can be drawn.
Indeed, Benito and his colleagues called for longer studies to take into account final cardiovascular outcomes.
Omega-3 enrichment of dairy products is on the increase in Europe with 20 new launches of enriched milk in 2005, and 19 omega-3 enriched yoghurts hitting European shelves during the same time. Data source: Mintel's Global New Product Database.