If you favor those milk chocolate bon-bons over the dark variety, you might be better off switching. Eating dark chocolate -- but not milk chocolate -- raises levels of antioxidant in the blood, which could help protect against heart disease.

    Researchers found that the rise in antioxidant levels is much lower when milk chocolate is eaten or when dark chocolate is eaten along with milk. Although the exact reason is unclear, it may be that milk interferes with the absorption of antioxidants from chocolate.

    The findings, reported in scientific journal Nature, come from a study of 12 healthy volunteers who, on different days, ate 100 grams of dark chocolate alone, 100 grams of dark chocolate with milk, or 200 grams of milk chocolate.

    Blood analysis one-hour after dark chocolate was eaten showed a significant rise in antioxidant levels, including levels of epicatechin, a well-known dietary flavonoid, report Dr. Mauro Serafini, from the National Institute for Food and Nutrition Research in Rome, and associates.

    In contrast, not much change in antioxidant levels was seen after eating of milk chocolate or dark chocolate with milk. Moreover, epicatechin absorption into the bloodstream was much lower than when dark chocolate was eaten alone.

    The researchers say their findings highlight the possibility that other items in the diet could reduce the antioxidant activity of flavonoids in the body.

    "There is therefore a need to take into account dietary habits when designing studies to assess the association between flavonoid-rich foods, antioxidant activity and degenerative disease," they add.

    如果你喜歡牛奶巧克力勝過黑巧克力，你最好還是改變一下。黑巧克力能夠提高血液中抗氧化劑的含量，有助于預防心臟病，而白巧克力則不能。

    研究人員發現吃牛奶巧克力或加奶的黑巧克力時，增加的抗氧化劑含量就少得多。現在還不清楚確切的原因，有可能是牛奶妨礙人體吸收巧克力所含的抗氧化成分。

    科學雜志《自然》刊登了這項研究結果。該研究在12個健康的志愿者中進行。他們在不同的時期內分別吃了100克黑巧克力，100克加奶的黑巧克力和200克牛奶巧克力。

    羅馬國家食品與營養研究學會的毛羅·塞拉菲尼和他的助手說，受試者吃了黑巧克力一小時后，血液分析顯示抗氧化成分的含量顯著升高，包括表兒茶酸的含量。表兒茶酸是一種常見的食物類黃酮。

    相反，吃了牛奶巧克力或加奶的黑巧克力過后抗氧化劑的水平變化并不大。此外，血液吸收的表兒茶酸也比光吃黑巧克力低得多。

    研究人員說他們的結論增加了其他食品會削弱人體中類黃酮抗氧化活性的可能性。

    他們還補充說：“因此，在設計研究評估富含類黃酮的食物、抗氧化活性和變性疾病之間聯系時，有必要將飲食習慣考慮進去。”