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Garlic and Cholesterol

A key risk factor for the increase of cardiovascular and cerebrovascular disease is high serum cholesterol concentration. Studies conducted prior to this experiment showed that garlic aided the reduction of serum cholesterol and was active in reducing hypocholesterolemia. It was recognized that many studies neglected to monitor vital signs, body weight, blood chemistry, and liver functions. Any one of these factors has a great affect on serum cholesterol levels and therefore should be monitored in order to have accurate results.

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The authors of this study (Steiner M, Khan AH, Holbert D, Lin RI, 1996) attempted to measure the effects of garlic on the total cholesterol levels in a given sample of subjects in a double-blind crossover study. The test group was made up of fifty-two men of ages 32 to 68 . Their total cholesterol concentration needed to be between 5.7 and 7.5 mmol/L. Blood lipids were measured several times throughout the experiment, as well as cholesterol levels, body weight, and blood pressure. The subjects were given nine pills to be evenly divided into three doses taken daily. The groups were randomly divided into a garlic group and a placebo group. The garlic group was given pills that contained 800mg of aged garlic extract (AGE), the placebo group received an identical looking pill containing 600mg cornstarch, 99.5 mg microcrystaline cellulose, 0.5mg caramel, and 3.5mg magnesium stearate (plecebo). Both groups were monitored for six months. At the end of the first six month period the groups were reversed (crossed over). The results from both groups in the first six month period were compared, as were the two groups in the final four month period.

Total serum cholesterol concentration was significantly lowered in the groups using AGE. The highest reduction in blood serum cholesterol in relation to the placebo group was observed at 6.1%. The results were higher when compared to the baseline group, with a reduction of 7.0%. Low density lipoprotein (LDL) levels were observed to be reduced by 4.0% when compared to the baseline and 4.6% when compared to the placebo group. This lowering of LDL was apparent in the time frame from the first to the fortieth day. After the fortieth day the effects of garlic on LDL began to level off. When high density lipoprotein (HDL) levels were examined there was no significant changes in any of the groups observed.

Experiments done prior to this study reported results of a 9 to12 percent reduction in blood cholesterol levels. The authors of this study concluded that those levels were too high. Their results fell into a range of 5 to 8 percent. This study also was able to conclude that there was no significant effect of garlic on HDL levels. However it was shown that garlic reduced LDL levels. The authors, by consistent monitoring, were able to conclude that aged garlic extract did not influence the general blood chemistry. There was also no changes to thyroid or liver functions as a result of the presence of garlic. The authors did acknowledge the need for better compliance to specified dosages. They felt that as a result of poor compliance these results could have been acquired using lower dosages.

  1. Reference
  2. Steiner M, Khan AH, Holbert D, Lin RI. 1996. A double-blind crossover study in moderately hypercholesterolemic men that compared the effect of aged garlic extract and placebo administration on blood lipids. Am J Clin Nutr.64:866-70.1

 

Bryan Muscat and Sara Farnworth
Biological Science Program
University of Guelph
Guelph, Ontario, Canada.

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