Synergistic lipid-lowering effects of alfalfa meal as an adjuvant to the partial ileal bypass operation

Partial ileal bypass (PIB) and ingestion of alfalfa are both known to lower plasma cholesterol (C) levels. During an 18-week period, the combined effects of both were studied in four randomized groups of rabbits receiving C-free, hypercholesterolemia-inducing, semisynthetic diets 3 weeks after sham or PIB surgery. The diets, with or without alfalfa, had similar overall compositions of fat, protein, carbohydrate, and fiber. We measured blood C, triglycerides (T), and lipoprotein fractions of both C and T at biweekly intervals. In vivo liver and small-bowel synthesis of C, fatty acids (FA), and nonsaponifiable lipids (NSL) were determined with radioactive ¹⁴C-acetate at the end of the study. The results were evaluated by means of analysis of variance using unweighted cell means. The combined PIB and alfalfa modalities significantly lower C levels in serum, plasma, low-density lipoproteins, and high-density lipoproteins by 66%, 71%, 85%, and 35%, respectively. However, due to alfalfa, a significant increase of 49% was observed in plasma T when both treatments were combined. Liver FA synthesis was significantly decreased (65%) with PIB and increased (161%) with alfalfa; when the two treatments are combined, a nonsignificant response was observed. Similarly, this inverse relationship for PIB and alfalfa was seen for C and NSL synthesis. Small-bowel FA synthesis was significantly decreased (72%) by the combination of PIB and alfalfa. We conclude that alfalfa suppresses, in part, the physiologic rebound effect of PIB surgery by increasing hepatic C and NSL synthesis; inversely, PIB surgery inhibits the additive effect in the liver synthesis of FA produced by alfalfa. Alfalfa and PIB alone, and synergistically, decrease total small-bowel lipid synthesis, specifically that of FA. Alfalfa is an effective adjuvant to PIB for reducing total and lipoprotein C fractions.