Milk enriched with “healthy fatty acids” improves cardiovascular risk markers and nutritional status in human volunteers

Abstract

Objective

The main goal of the present study was to evaluate the effect of a commercially available milk containing small amounts of eicosapentaenoic acid and docosahexaenoic acid, oleic acid, and vitamins A, B6, D, E, and folic acid compared with semi-skimmed and skimmed milk in volunteers with moderate cardiovascular risk.

Methods

Two hundred ninety-seven subjects 25 to 65 y of age with moderate cardiovascular risk were randomly allocated into three groups. In addition to their diets, one group consumed 500 mL/d of the enriched milk, another group consumed 500 mL/d of skimmed milk, and a control group consumed 500 mL/d of semi-skimmed milk. All groups consumed the dairy drinks for 1 y and blood samples were taken at 0 and 12 mo.

Results

Consumption of enriched milk for 1 y produced significant (P < 0.05) increases in serum folate (58%) and high-density lipoprotein cholesterol (4%). Plasma triacylglycerols (10%), total cholesterol (4%), and low-density lipoprotein cholesterol (6%) were reduced significantly only in the supplemented group. Serum glucose, homocysteine, and C-reactive protein remained unchanged. In the skimmed milk and semi-skimmed milk groups, the only significant decreases were in serum folate (17% and 11%, respectively).

Conclusion

Daily intake of a milk enriched with fish oil, oleic acid, and vitamins improved the nutritional status and cardiovascular risk markers of volunteers, whereas skimmed milk and semi-skimmed milk did not.

Introduction

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide. In Europe, CVDs in 2000 accounted for 49% of all deaths and 30% of all deaths before the age of 65 y. These data clearly indicate that CVDs are a major public health problem [1]. The diet is known to influence some of the risk factors described for CVDs [2].

Over recent decades, numerous nutritional and epidemiologic studies have linked ω-3 polyunsaturated fatty acid (ω-3 PUFA) consumption (namely α-linolenic acid, eicosapentaenoic acid [EPA], and docosahexanoic acid [DHA]) to a significant decrease in some CVD risk factors.

Although the exact mechanism by which ω-3 PUFAs exert an atheroprotective effect is still unclear, a number of possible mechanisms have been studied, including the ability of ω-3 PUFAs to beneficially influence blood clotting and thrombosis, plasma lipid profile, blood pressure, arrhythmia, and inflammation. Antiatherosclerotic effects derived from ω-3 PUFA intake are mostly derived from their incorporation into the phospholipids of cell membranes, replacing arachidonic acid as initial substrate for eicosanoid production [3]. Consumption of ω-3 PUFAs also affects blood lipids. Several studies have indicated that dietary DHA and EPA lower the rise of blood triacylglycerols after a meal and, hence, produce a beneficial effect [4], [5], [6].

It has been shown that diets, like the Mediterranean diet, rich in monounsaturated fatty acids and poor in saturated fat have favorable effects on the CV risk profile [7], [8]. Moreover, high blood homocysteine levels appear to be associated with higher risks of coronary, cerebral, and peripheral vascular diseases and are inversely related to blood levels of folate and of vitamins B12 and B6 [9], [10], implying that coronary heart disease risk may be decreased by dietary vitamin supplementation.

Evidence has been gathered by the most recent World Health Organization report [11], which recommends 1) regular fish consumption to provide 200–500 mg of EPA + DHA/wk, 2) a replacement of saturated fat by monounsaturated fat, and 3) an increase in the consumption of fruit and vegetables to achieve proper antioxidant and folate status.

We previously reported that the regular consumption of a dairy product (Puleva Omega 3, Puleva Food S.A., Granada, Spain) supplemented with oleic acid, ω-3 PUFAs, and vitamins E, B6, B12, and folic acid (versus semi-skimmed milk) produced a significant decrease in total and low-density lipoprotein (LDL) cholesterol levels, increased plasma levels of vitamin B12, increased plasma and erythrocyte levels of folic acid accompanied by a significant reduction in plasma levels of triacylglycerols, homocysteine, and Vascular Cell Adhesion Molecule-1 (VCAM-1) and C-reactive protein (CRP) in normolipidemic healthy volunteers and patients with peripheral vascular disease or after a heart stroke [12], [13], [14], [15].

All these studies were done with subjects with very specific features, in small groups, sometimes with dietetic restrictions, short periods of intervention, and always using semi-skimmed milk as a control. The goal of the present study was to determine the effects of a 1-y consumption of ω-3 PUFA, oleic acid, and vitamins E, B6, B12, and folic acid within a food matrix (skimmed milk) on CV risk factors in a large sample of human volunteers with a moderate CV risk. Semi-skimmed and skimmed milk were used as controls.