Dr James Anderson from the University of Kentucky and a colleague from Norwegian firm NutriPharma assessed the effects of two commercial meal replacement products -one based on soy, the other made from milk - on around 50 overweight or obese men and women following a low-energy diet (1200kcal per day).
Soy protein intake has favourable effects on body weight and fat distribution in experimental animals but these effects have not been demonstrated in humans.
The subjects consumed either five soy-based or two milk-based liquid meal replacements for a 12-week weight loss trial. Serum lipoprotein measurements were obtained at baseline, six and 12 weeks.
There were no significant differences in weight loss between either group, although the soy product did cut weight loss by slightly more each week. More importantly, reductions in serum cholesterol and LDL cholesterol values at six weeks were significantly greater in the soy group, report the authors in the June issue of the Journal of the American College of Nutrition (vol 24, no 3, pp210-216).
Those consuming soy had a 15.2 per cent reduction in cholesterol and 17.4 per cent drop in LDL cholesterol. The milk group had a 7.7 per cent change in LDL cholesterol.
Also soy meal replacement use was associated with significant reductions in serum triglycerides at six and 12 weeks while the dairy meal replacement did not have this effect, write the authors, and soy intake produced small but significant reductions in serum glucose values.
This evidence suggests that soy may be a valuable tool in maintaining overall health, lowering cholesterol, and even slowing the development of diabetes, say the authors.
"The bottom line is soy is healthy, and while incorporating it into weight loss may not have a more dramatic effect on your waistline than other nutrition plans, its benefits go beyond weight loss toward increasing overall health," Anderson said.