Cow's milk is the primary source of vitamin D for children, but dairy products can interfere with the absorption of iron. Pediatricians have never known how much milk a child should drink. Now researchers have established that for most children, two cups a day achieves the right balance.
牛奶是兒童獲取維生素D的主要來源，但是乳制品會阻礙鐵的吸收。一直以來，兒科醫(yī)師并沒有明確了解兒童牛奶的飲用量應(yīng)為多少。如今，研究人員發(fā)現(xiàn)，對于大多數(shù)兒童而言，每天兩杯牛奶（總計500毫升——編注）便可以達(dá)到合理的平衡。

Canadian scientists studied more than 1,300 healthy 2- to 5-year-olds, collecting data on diet and physical activity. They took blood samples to measure iron and vitamin D levels.
加拿大科學(xué)家調(diào)查了1300多名兩歲到五歲的健康兒童，收集了他們的飲食和運(yùn)動數(shù)據(jù)，并且抽取了兒童血液樣本來測量鐵和維生素D的含量水平。

The study, published online in the journal Pediatrics last week, found that after adjusting for other factors, two cups a day was enough to maintain sufficient vitamin D (more than 30 nanograms per milliliter of blood) without affecting iron levels. But bottle use, season of the year, skin pigmentation and body mass index had significant effects on the optimal amounts of milk. Children with darker skin, for example, needed three to four cups of milk to get sufficient vitamin D in winter. Those who used only a bottle failed to maintain sufficient stores of vitamin D and iron.
這項研究于上周在《兒科》(Pediatrics)期刊的在線版刊登。該研究發(fā)現(xiàn)，在調(diào)整其他因素之后，每天兩杯牛奶的攝入量完全可以維持充足的維生素D儲備（每毫升血液中超過30微克），同時不影響鐵含量。但是奶瓶的使用、季節(jié)、膚色和體重指數(shù)對于牛奶的最攝入量有著非常大的影響。例如，膚色較深的兒童在冬天需要飲用3到4杯的牛奶才能保證充足的維生素D攝入量。那些只喝一瓶奶的兒童則難以維持足夠的維生素D和鐵含量水平。

The lead author, Dr. Jonathon L. Maguire, an assistant professor of pediatrics at the University of Toronto, said that children over 2 should not be given a bottle. "It's easy to give children the bottle to pacify them," he said, "but in terms of these two nutrients, there's no benefit in it."
多倫多大學(xué)(University of Toronto)兒科學(xué)副教授、該研究第一作家喬納森·L·馬奎爾博士(Dr. Jonathon L. Maguire)指出，兩歲以上的兒童不應(yīng)再使用奶瓶。他說，“家長喜歡拿奶瓶來安撫孩子。但是就這兩種營養(yǎng)物質(zhì)的吸收而言，奶瓶喂奶是沒有益處的?！?/div>