A high legume low glycemic index diet improves serum lipid profiles in men

Abstract

Clinical studies have shown that fiber consumption facilitates weight loss and improves lipid profiles; however, the beneficial effects of high fermentable fiber low glycemic index (GI) diets under conditions of weight maintenance are unclear. In the Legume Inflammation Feeding Experiment, a randomized controlled cross-over feeding study, 64 middle-aged men who had undergone colonoscopies within the previous 2 years received both a healthy American (HA) diet (no legume consumption, fiber consumption = 9 g/1,000 kcal, and GI = 69) and a legume enriched (1.5 servings/1,000 kcal), high fiber (21 g/1,000 kcal), low GI (GI = 38) diet (LG) in random order. Diets were isocaloric and controlled for macronutrients including saturated fat; they were consumed each for 4 weeks with a 2-4 week break separating dietary treatments. Compared to the HA diet, the LG diet led to greater declines in both fasting serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) (P < 0.001 and P < 0.01, respectively). Insulin-resistant (IR) subjects had greater reductions in high density lipoprotein cholesterol (HDL-C; P < 0.01), and triglycerides (TAG)/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. Insulin-sensitive (IS) subjects had greater reductions in TC (P < 0.001), LDL-C (P < 0.01), TC/HDL-C (P < 0.01), and LDL-C/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. In conclusion, a high legume, high fiber, low GI diet improves serum lipid profiles in men, compared to a healthy American diet. However, IR individuals do not achieve the full benefits of the same diet on cardiovascular disease (CVD) lipid risk factors.

Conflict of interest statement

All of the authors have read and approved the final submitted manuscript and there was no conflict of interest with the present paper. The authors’ contributions were as follows: ZZ conducted research with participants, data analysis, and write up of manuscript; EL designed the research, contributed to data interpretation and manuscript preparation; PMKE and NHC contributed to data interpretation and manuscript preparation; DB conducted research with participants and and was involved with the write up of the manuscript; MJR contributed to data analysis and the write up of the manuscript; JSU, GB, and RSC contributed to data interpretation and the write up of the manuscript; and TJH designed research, contributed to data interpretation and manuscript preparation, and study oversight.

Figures

Fig. 1

Relationship between HOMA-IR index at study entry and differences in TC/HDL cholesterol ratio changes (Delta TC/HDL-C ratio) on the two diets. Delta TC/HDL cholesterol was calculated by subtracting the change scores over the HA diet from the change score over the LG diet, thus changeLG – changeHA (n = 64; β = 0.266, R2 = 0.11, P = 0.025)