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09-08-2011 | General practice | Article

Garlic, grape seed supplements may reduce hematologic malignancy risk


Free abstract

MedWire News: Use of garlic and grape seed supplements may be associated with a reduced risk for blood cancers, US study data show.

Roland Walter (Fred Hutchinson Cancer Research Center, Seattle, Washington) and colleagues say that their findings "suggest a possible role of these supplements in the chemoprevention of hematologic malignancies."

The researchers explain that over-the-counter multivitamins are the most widely used dietary supplements in the US, but few studies have examined the preventive effect of nutrients from supplements on blood cancers.

Walter and team therefore investigated the association between vitamin, mineral, and specialty supplement intake and hematologic malignancy risk in 66,227 men and women aged 50 to 76 years, who enrolled in the VITamins And Lifestyle (VITAL) cohort study between 2000 and 2002.

All participants completed a self-administered questionnaire on supplement and medication use, health history and risk factors, and diet. Using this information, the researchers computed a 10-year average daily dose of each supplemental nutrient.

During a mean follow-up period of 6.5 years, 588 (0.89%) participants developed a hematologic malignancy, classed as myeloid neoplasms, mature B-cell neoplasms, Hodgkin lymphoma, or mature T- and NK-cell neoplasms.

These individuals were older at baseline, more likely to be male, and more often had two or more first-degree relatives with a family history of leukemia or lymphoma than participants who did not develop a hematologic malignancy.

After adjustment for these potential confounders, the researchers observed that high use of garlic supplements (≥4 days/week for ≥3 years) was associated with a significant 45% reduced risk for developing a hematologic malignancy during follow-up, compared with no use.

Participants who reported ever use of grape seed supplements had a significant 43% reduced risk for hematologic malignancies compared with those who reported never using the supplements.

In addition, high use (8-10 pill-years) of multivitamins was associated with a 20% reduced risk for hematologic malignancies, but the finding was not statistically significant.

The researchers found no association between risk for total hematologic malignancies and use of any of the individual vitamins, minerals, or other specialty supplements assessed.

Walter and co-authors note that several experimental studies have suggested that garlic or specific garlic compounds, most prominently organic sulfur compounds, could prevent cancer through the modulation of carcinogen metabolism, inhibition of DNA adduct formation, upregulation of antioxidant defenses and DNA repair systems, and the promotion of mitotic arrest and apoptotic cell death of cancer cells.

They add that grape seeds are a rich source of proanthocyanidins, which possess potent antioxidant properties and, like many phytochemicals, have shown promising chemopreventive effects in vitro and in animal models.

This could be the first cohort study to suggest a possible role of garlic and grape seed supplements in the chemoprevention of hematologic malignancies, say the researchers in Cancer, Epidemiology, Biomarkers, and Prevention.

Therefore "further, controlled studies will need to confirm these findings."

By Laura Dean

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