Research Advances (Part 2)
Posted Wednesday, October 29, 2008

This is the second installment of our series highlighting the Office of Dietary Supplements at the National Institutes of Health ninth annual report on the significant advances in dietary supplement research. Today we will sum up a new items about research with garlic, green tea, and vitamin A.


Garlic and Heart Disease

It has long been known that garlic may reduced one's risks for heart disease by increasing reactive oxygen species, helping high blood pressure and high cholesterol levels, platelet aggregation, and blood coagulation. How garlic does this however, has not been fully understood. When crushed, the allicin properties of garlic decompose into organic polysulfides. It has now been found that the polysulfides can then be metabolized, increasing the hydrogen sulfide in blood vessels. Hydrogen sulfide induces smooth muscle cell relaxation, as well as decreasing hypertension.

Only a handful of plants other than garlic contain these sulfur compounds, and garlic is the only one of these with a dietary use. With this new knowledge of what the active process is, researchers now believe that garlic supplements may be tailored based on their ability to produce hydrogen sulfide in relevant blood cells and tissues. This should bring about more efficient and reliable supplements, along with a firm, demonstrable case for including garlic in your long-term diet.

DSIB: Garlic

National Academy of Sciences: Hydrogen sulfide mediates the vasoactivity of garlic


Green Tea and Breast Cancer

Worldwide, green tea consumption is second only to water. Widely renown for its medicinal properties, green tea is a great source of polyphenols, especially the catechin epigallocatechin gallate (EGCG). The polyphenols have antioxidant properties which are believed to be responsible for the majority of the health benefits found in green tea.

Green tea and lower incidences of breast cancer have been shown in many studies, as well as the relationship between the tea and the risk of recurring breast cancer.

It has now been identified for the first time that FOXO3a, a gene activated by EGCG, has a role in the inhibition of an invasive phenotype in breast cancer cells. This new research showed that EGCG works to repress of pathways available to the cancer activating cells, thus diminishing their ability to transform into cancerous tumors. These findings offer new molecular evidence for the understanding of the anticarcinogenic effect of green tea.

DSIB: Green Tea

Cancer Research: Activation of FOXO3a by the Green Tea Polyphenol Epigallocatechin-3-Gallate Induces Estrogen Receptor {alpha} Expression Reversing Invasive Phenotype of Breast Cancer Cells



Vitamin A Guidelines

In 2002 the International Vitamin A Consultative Group (IVACG) recommened that dosage for new mothers in vitamin A deficent areas be increased from previous World Health Organization (WHO) outlines which were set forth in 1997. A study conducted with young mother and infants in rural Gambia was undertaken to test the effectiveness and necessity of these new recommendations.

There was some concern that the increase in dosage might be dangerous, that vitamin A in such quantities might have negative interactions on immunization vaccines and generate oxidative stress.

These concerns did not bare out in the study, there were no adverse events from either set of procedures, but it was found that there were not any observable outcome differences between the IVACG recommendations and the previous WHO scheduling doses. While the results did not show an increased risk with the higher doses, the study supported reverting to the previous WHO recommendations, as there were no noticiable benefits to the higher doses at present.

DSIB: Vitamin A

Lancet: Effectiveness of an early supplementation scheme of high-dose vitamin a versus standard who protocol in gambian mothers and infants : a randomised controlled trial



For more of this series, check out part 1 and part 3.


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