研究：每日五蔬果 健康好身体

British nutritionists threw down the gauntlet to dietary guidelines in April by declaring seven daily portions of fresh fruit and vegetables, rather than the recommended five, were the key to health.

But a new foray into the arena of sound eating says the famous five-a-day recommendation made by the UN's World Health Organisation (WHO) in 2003 should be fine.

Researchers in China and the United States trawled through 16 published investigations into diet and health involving more than 830,000 participants, who were followed for periods ranging from four and a half years to 26 years.

Every additional daily serving of fruit and vegetables reduced the average risk of premature death from all causes by five percent, the scientists found.

Over the period of the studies, 56,000 of the participants died, researchers said.

In the case of death from a heart attack or a stroke, each additional serving curbed risk by four percent.

But there was no evidence of an additional fall in risk beyond five portions, according to the review, published online Tuesday by the British Medical Journal (BMJ).

"We found a threshold of around five servings a day of fruit and vegetables, after which the risk of death did not reduce further," said the investigators, led by Frank Hu of the Harvard School of Public Health in Boston, Massachusetts.

High consumption of fruit and veg did not translate into a significant reduction in the risk of death from cancer, the study also found.

In addition to advising patients about the virtues of healthy eating, doctors should also push home the message about risks from obesity, inactivity, smoking and excessive drinking, said the paper.

In April, researchers at University College London found that eating seven daily portions or more could reduce the risk of cancer by 25 percent and of heart disease by 31 percent, compared to people who consumed less than one portion a day.

The study was based on the eating habits of more than 65,000 people in England between 2001 and 2008.

The London researchers admitted to being surprised by what they found and cautioned the results may not be applicable to other countries.

Britain has one of the highest rates of heart disease in Europe, a fact blamed in part on a diet high in fat and sugar.

The WHO guidelines are based on the equivalent of five 80-gram (three-ounce) portions. One portion is roughly equivalent to a medium-sized apple, a bowl of mixed salad or three dessert spoonfuls of raw, cooked, canned or frozen vegetables.

英国营养学家在四月份向既定的食谱指南发起挑战，宣称保持身体健康的关键是每日七种蔬果搭配而不是以往推荐的五种蔬果。

但是一项新的关于健康饮食的调查显示，联合国世界卫生组织（(WHO)）在2003年推荐的著名的每日五蔬果搭配是合理的。

中国和美国的研究者搜索了16种已经出版的饮食和健康调查，涉及到超过83万的参与者，这些人参与并接受了从4年半到26年不等的跟踪调查。

科学家们发现，每日每多摄入一份蔬菜和水果，由各种因素引起的早死亡率就会降低5%。

研究者称，有5.6万参与者在这项研究进行的过程中去世。

在那些死于心脏病和中风的病例中，每天多吃一种蔬果，疾病的威胁就降低4%。

但是根据英国医学杂志(BMJ)周二在网上发表的评论，仍然没有证据能表明多增加一种可以比五种的搭配更能降低死亡率。

“我们发现一天五蔬果是一个临界值，在此基础上增加再多的份量对降低死亡风险也无济于事。”位于马萨诸塞，波士顿的哈佛大学公共卫生学院的弗兰克•胡（Frank Hu）所领导的研究团队称。

研究也发现，多摄入蔬菜和水果并不代表就能显著降低患癌死亡的风险。

这篇论文提到，除了建议病人健康饮食外，医生也应该尽量告诫他们在家庭生活中应注意肥胖，缺少锻炼，吸烟以及过度酗酒对身体带来的风险。

在四月份，英国伦敦大学学院（University College London）的研究者们发现，一天摄入七种蔬果或以上份量的人同那些一天摄入量少于一种的人相比，患癌症的风险降低25%，患心脏病的风险降低31%。

这项研究是依据2001年到2008年间英国6.5万多人的饮食习惯而得出的。

伦敦的研究者们承认他们对自己的发现感到十分惊喜，同时谨慎地提醒这项结果可能并不适用于其它国家。

英国是欧洲心脏病发生率最高的国家，部分原因应归咎于含过多脂肪和糖分的饮食习惯。

世界卫生组织以5份80克（3盎司）的摄入量为指南。每一份差不多相当于一个中等大小的苹果，一碗什锦沙拉或是三个甜点勺那么多生的、熟的、罐装的或速冻的蔬菜。