【关键词】  Cholesterol

    the Center for Human Performance and Nutrition Research, The Cooper Institute Centers for Integrated Health Research, Dallas, TX (CPE, ANJ, and TSC)
    Brinker International, Dallas, TX (MS), and Proliant, Inc, Ankeny, IA (EW)

    ABSTRACT

    Background: The consumption of milk products has been shown to lower cholesterol. The mechanism of action surrounding this observation has been attributed to the protein fraction of milk and serum.

    Objective: We examined the effect of an oral serum bovine immunoglobulin protein fraction (bIg) derived from US Department of Agricultureapproved beef (aged <30 mo) on lipid indexes in humans.

    Design: Participants included men and women (aged 2570 y) with hypercholesterolemia (5.446.99 mmol/L) who were not receiving cholesterol-lowering medication. Treatment consisted of the randomized, double-blind, parallel-group, placebo-controlled administration of 5 g bIg for 6 wk in 52 participants (n = 26 each in treatment and control groups).

    Results: Mean (±SD) total cholesterol (TC) at baseline was 6.33 ± 0.1 mmol/L for bIg and 6.16 ± 0.1 mmol/L for placebo. A repeated-measures multivariate analysis of covariance covaried for change in total energy and alcohol intake and Tukey’s post hoc examination of our data showed that the bIg-treated group had a significant reduction in TC at 3 wk (5.98 ± 0.5 mmol/L; P < 0.05) and 6 wk (5.97 ± 0.7 mmol/L; P < 0.05). The concentration at 6 wk was significantly different from that in the placebo group (P < 0.05). This reduction was largely due to a decrease in LDL cholesterol in the bIg-treated group from baseline (4.12 ± 0.6 mmol/L) at 3 wk (3.92 ± 0.7 mmol/L, P < 0.05) and at 6 wk (3.84 ± 0.6 mmol/L, P < 0.05); the 6-wk concentration differed significantly between the treatment and placebo groups (P < 0.05). We observed no significant changes in the placebo group or in any other lipid indexes or markers associated with hepatorenal or cardiovascular function.

    Conclusion: Consumption of bIg appears to positively modulate the primary lipid indexes associated with cardiovascular disease.

    Key Words: Cholesterol  cardiovascular disease  LDL  lipids  bovine serum immunoglobulin  bIg

    INTRODUCTION

    Hypercholesterolemia is an important risk factor for cardiovascular disease. Accordingly, guidelines from the National Cholesterol Education Program suggest weight reduction and dietary management as preferred alternatives for lowering cholesterol and managing heart disease (1). Barring lifestyle changes, the use of medications such as statin drugs is effective, although some persons experience negative sequelae that contraindicate their use (2, 3). Thus, a continual investigation for alternative solutions is warranted. An area for potential investigation is the constituents found in milk (4-7), although the mechanism of action surrounding milk consumption has not been adequately identified (8). Of the principal proteins present in milk, those found in whey protein present an interesting avenue for investigation, because casein is actually thought to be hypercholesterolemic when compared with other protein sources (9, 10). Moreover, 2 studies have reported that the administration of 90 g dried skim milk from hyperimmunized cows lowers cholesterol in humans with mildly elevated cholesterol concentrations (11, 12). In those studies, the primary difference between the control skim milk and the skim milk from hyperimmunized cows was the protein content of bovine immunoglobulin (bIg).

    Whereas milk and whey contain low concentrations of bIg (<1% and 34%, respectively), immunoglobulin comprises at least 25% of the protein content of serum. This is an important consideration because the intake of 90 g skim milk solids may be impractical for consumers. However, the purification of bIg from US Department of Agriculture (USDA)approved edible bovine serum produces a higher bIg concentration so that persons can consume smaller quantities. Serum protein also contains other factors that could alter cholesterol absorption. These factors include antibodies that are reactive with cholesterol and lipoproteins (13), which might interfere with cholesterol absorption (14). In an 8-wk pilot study (E Weaver, C Siefken, and R Strohbehn, unpublished observations, 2002), our group found that participants with mild hypercholesterolemia showed a significant reduction in total cholesterol (TC) after the administration of 5 g bIg/d. The objective of our current trial was to examine bIg supplementation on blood lipids in a larger cohort by using a formal randomized, double-blind clinical trial.

    SUBJECTS AND METHODS

    Study population

    We examined 52