The Effect of Dietary Protein Source on Serum Lipids

Presentation Number: OR28-3
Date of Presentation: March 7th, 2015

Anda Raluca Gonciulea*1 and Deborah Sellmeyer2
1Johns Hopkins School of Medicine, Baltimore, MD, 2Johns Hopkins Bayview Medical Center, Baltimore, MD

Abstract

Hypercholesterolemia and elevated LDL-C are leading risk factors for cardiovascular disease. Vegetable based diets can improve serum cholesterol profiles with specific beneficial effects attributed to soy foods.  However, there are limited data comparing the effects of soy based and non-soy based vegetable diets on lipids, particularly using whole food diets. We conducted a secondary data analysis using data from a randomized trial that evaluated the effect of dietary protein source on calcium metabolism.  Postmenopausal women without renal, GI, or bone disease, or insulin requiring DM (n=176, age = 63 ± 7 years) were randomized to one of four weighed metabolic diets for eight weeks. Diets were equivalent in energy (2149 ± 157 kcals/d), protein (73 ± 4 g/d), and fat (73 ± 20 g/d) with >80% of the protein coming from either non-dairy animal, non-soy vegetable, dairy or soy sources.  Total cholesterol content was 0 mg/d in vegetable and soy diets and 238 ± 87 mg/day in animal and dairy diets.  Saturated fat was 12 ± 5, 8 ± 1, 29 ± 4, 9 ± 4 g/d in the animal, vegetable, dairy, and soy diets respectively (p<0.05 for dairy vs. other groups).  Polyunsaturated fat was 9 ± 4, 27 ± 6, 5 ± 2, 23 ± 3 g/d in the animal, vegetable, dairy, and soy diets respectively (p<0.05 for each of animal and dairy vs. each of vegetable and soy).  Fasting blood samples, obtained at baseline and week 8 were assayed for total cholesterol, LDL-C, HDL-C, triglycerides, glucose and insulin.  Change in each variable was calculated by subtracting the baseline value from the week 8 value.  Parameters were compared across diet groups using ANOVA.  Baseline lipid concentrations were not different among diet groups.  Total cholesterol decreased by 39 ± 3 mg/d in the soy group (p<0.001 vs. dairy, p=0.002 vs. animal) and 31 ± 5 in the vegetable group (p=0.004 vs. dairy, 0.15 vs. animal).  LDL-C decreased by 28 ± 3 mg/d in the soy group (p<0.001 vs. dairy, p=0.01 vs. animal) and 21 ± 4 in the vegetable group (p=0.006 vs. dairy, 0.38 vs. animal).  There were no significant differences in lipid effects between the soy and vegetable diets.  There were no significant differences among the groups in change in triglyceride, VLDL, HOMA-IR, fasting glucose, or insulin.  HDL-C decreased by 12 ± 1 mg/d in the soy group (p<0.008 vs. dairy, p=0.02 vs. animal) although there were no significant differences in change in total cholesterol:HDL ratio.  There were no significant changes in HDL-C in any other diet group.  In conclusion, both the soy and vegetable diets resulted in significant reductions in total cholesterol and LDL although the reductions in the vegetable group, while significant compared to the dairy group, were not statistically significant compared to the animal group.  Given that there were no significant differences between the soy and vegetable groups, these data do not support a specific lipid lowering component in soy foods, but suggest a beneficial effect of plant based diets in general.

 

Nothing to Disclose: ARG, DS