Eating Yogurt Daily Increases “Good” Cholesterol in Women
Women who eat yogurt every day may experience an increase in the level of “good” cholesterol, according to a clinical trial published in the European Journal of Clinical Nutrition (2002;56:843–9). This beneficial effect can be magnified by supplementing the yogurt with probiotics and a prebiotic compound called oligofructose.
In this study, 29 women ate 300 grams (about 10.6 ounces) of a full-fat (3.5% fat by weight) yogurt product daily for 21 weeks. Blood cholesterol measurements were repeated every seven weeks during the study.
Over the 21-week trial, a small increase in the total cholesterol level was observed that was not statistically significant. A larger, and statistically significant, 38% increase was observed in HDL, or “good” cholesterol levels after eating the yogurt. No change was observed in LDL, or “bad,” cholesterol levels. Despite the small increase in total cholesterol levels, the increase in HDL cholesterol would presumably decrease the risk of developing heart disease, as past research has shown this type of cholesterol to be protective.
Can Probiotic and Prebiotic Agents Influence Cholesterol Levels?
These findings were surprising in light of the fact that this trial was designed to see if yogurt ingestion could decrease total cholesterol levels. In particular, the researchers had theorized that a yogurt product with added probiotic bacteria (Lactobacillus acidophilus and Bifidobacterium longum) and a prebiotic agent (oligofructose) could reduce cholesterol levels as observed in earlier research studies.
To observe the effect of the enriched yogurt, each woman also ate the probiotic- and prebiotic-containing product for a 7-week stretch during the 21-week trial. During the period when the women consumed the supplemented yogurt, there was a further increase in HDL cholesterol beyond that seen from simply eating plain yogurt. Probiotic agents are live bacteria that have the ability to influence the concentration of different bacterial species in the intestines. Prebiotic agents also influence the concentrations of bacteria in the gut by acting as a food source for beneficial organisms. Although the bacteria in our intestines are necessary for normal digestion, it is not clear how influencing the concentrations of these organisms affects cholesterol levels.
Animal and human studies have found many other benefits from yogurt ingestion, including prevention of diarrhea, stimulation of the immune system, and prevention of vaginal yeast infections. It is not known whether supplementing yogurt with probiotics and prebiotics, as the researchers did here, would enhance these other health benefits of yogurt.
“Good” and “Bad” Cholesterol
All cholesterol is not created equal. Increased levels of LDL cholesterol, often referred to as “bad” cholesterol, are directly linked to increased risk of heart disease. HDL cholesterol, on the other hand, is considered protective against heart disease. Some research indicates that the ratio of HDL cholesterol to total cholesterol is more important than the total cholesterol level for the prediction of heart disease risk.
There are several ways that HDL cholesterol levels can be increased. Exercise, weight loss, and moderate drinking (one or two drinks per day, for example), and supplementing with magnesium, vitamin C, or lecithin, may all increase HDL levels. The most common class of medications (statin drugs) used to lower total cholesterol, on the other hand, does not increase HDL cholesterol levels.
Based on the results of this new study, women with low concentrations of HDL cholesterol should consider adding yogurt to their diet on a regular basis. If available, yogurt supplemented with probiotic and prebiotic constituents may provide further benefit. More research is needed to determine whether the same effects could be expected in men.
Matt Brignall, ND is a graduate of the University of Michigan and Bastyr University. He works at the Seattle Cancer Treatment and Wellness Center, where he specializes in complementary medicine approaches to cancer. He has been published in several journals, including Alternative Medicine Review, Coping With Cancer, and the Journal of the National Cancer Institute. Dr. Brignall also teaches clinical nutrition at Bastyr University in Kenmore, WA. He is a regular contributor to Healthnotes, Healthnotes Newswire, and the Healthnotes Quick!Reference series.
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