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zoom RSS 白米が糖尿病リスクを増大?/米国

<<   作成日時 : 2010/06/18 19:51   >>

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 ハーバード大の研究によると、週に5回以上白米を食べる人はU型糖尿病のリスクが17%増加する。週に数回玄米を食べる人は糖尿病リスクが16%減少する。
 玄米を食べる人は健康に注意し果物や野菜を摂取する傾向が強いので、そうしたライフスタイルが関連している可能性があるが、それだけでは説明できないともいう。
 米を精米するとマグネシウム、クロム、その他の無機質とビタミンを含む栄養素の多くを剥ぎ取ってしまい、インシュリン需要の高いでんぷんのみが残ってしまう。
 全体の食事・運動・喫煙・家族歴などの影響を除外しても玄米と糖尿病リスク減少の関連性は残るがその程度は低く、治療食ではない。
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Does Eating Brown Rice Lower Diabetes Risk?
Eaters of Brown Rice Have Lower Risk of Type 2 Diabetes, Study Finds
http://abcnews.go.com/Health/Diabetes/eaters-brown-rice-lower-risk-type-diabetes-study/story?id=10888438
By LAUREN COX and COURTNEY HUTCHISON
June 15, 2010

画像White or brown rice might be a matter of taste. But people who substitute brown rice for white rice for health reasons may be onto something, a new study from Harvard University implies.
Study finds eating brown rice rather than white can lower the risk of diabetes.

Yet doctors warn that there's more to this effect than the nutrition in rice alone.

Researchers drew on data from over 200,000 subjects and found that those who ate five or more servings of white rice a week had a 17 percent increased risk of developing type 2 diabetes compared with those who rarely ate white rice.

What's more, they found that those who ate brown rice regularly were overall less likely to develop diabetes.

With those results, researchers estimated that subbing in a few servings a week of white rice with brown would result in a 16 percent decrease in diabetes risk.

But diet and diabetes experts say these results may have more to do with type of person who tends to prefer brown rice than how the food itself affects health.

"Maybe people who eat brown rice are more health conscious," said Dr. Charles Clark , professor of medicine at Indiana University School of Medicine. Because the study can only gauge associations between lifestyle choices and later disease, it's impossible to tell whether it's the rice that makes a difference or some other shared quality among brown rice eaters, he said.

Indeed, researchers found that brown rice eaters as a group tended to be more physically active, leaner, less likely to smoke, and perhaps most importantly, had a higher intake of fruits, vegetables, and whole grains -- all choices that help lower risk of developing diabetes.

"I think whole grains may be the big player and not brown rice alone," says Carla Wolper, a researcher at the N.Y. Obesity Research Center.

But making the switch from white to brown rice may be a relatively painless way for Americans to incorporate more whole grains in their diet, says Dr. Walter Willet, a co-author on the study. This was one of the reasons researchers decided to zero in on this particular grain.

Health Nuts and Brown Rice

Showing that eating whole grains is healthier for you than eating refined grains is nothing new, but given the growing consumption of white rice in the United States and globally, Willett says, this particular diet change is worth looking into.

"When we refine rice, we strip away the majority of many of the nutrients," says Willett, "including magnesium, chromium and other minerals and vitamins."

"You're left with a form of starch that is rapidly broken down, leads to greater spikes in blood sugar, and increases the demand for insulin. Over time this exhausts the pancreas and leads to diabetes," he said.

Doctors largely agreed that a whole grain, like brown rice, is better than a refined grain like white rice or white bread.

"The overall consumption of brown rice was relatively low in this population," said Dr. Carl J. Lavie, medical director of Cardiac Rehabilitation and Prevention at John Ochsner Heart and Vascular Institute in New Orleans.

"Instead of consuming high quantities of white rice, it would be preferable to replace this with either brown rice and even better to replace white rice with other whole grains…" he said.

Clark said brown rice is high in fiber and "diets high in fiber are protective for a number of risks including colon cancer, obesity, and diabetes." So adding more whole grains, such as brown rice, is always a good thing.

The fact that those who chose brown rice tended to live more health-conscious lives than white rice eaters exaggerated the reduced risk of diabetes seen in the study, but it does not explain it away, Willett said.

Could the Brown Rice Alone Change Diabetes Risk?

Researchers controlled for the lifestyle choices that may impact diabetes risk, such as overall diet, exercise level, smoking habits, and a family history of the disease.

Taking into account all these behaviors, the association between brown rice consumption and a lower risk of diabetes was diminished but did not disappear, said Willett.

But those diminished benefits of brown rice alone did not impress all doctors.

Richard Feinman, a professor of Cell Biology at SUNY Downstate Medical Center, called the direct link between eating brown rice and lower diabetes risk "weak."

"It [the article] is written in a technical way that consumers won't understand so the limited results are obscured," said Feinman. "But the conclusions stated in the abstract are not justified by the results."

Feinman said by looking at the study, he'd estimate that 1 person out of 1,000 people who subbed brown rice for white rice would be able to prevent diabetes.

Keith Thomas Ayoob, of Albert Einstein College of Medicine, acknowledged that brown rice alone might have an effect on a person's risk for diabetes and brown rice isn't a remedy for disease risk.

Ayoob said he doesn't want consumers to think that switching to brown rice could replace the other habits necessary for good health such as portion control, exercise, and overall diet.

"I'm all for people swapping out refined grains for whole grains, but the issue of diabetes is more complex than can be seen by this study," he said.

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Page last updated at 23:48 GMT, Monday, 14 June 2010 00:48 UK
White rice White rice has a higher glycaemic index than brown rice
http://news.bbc.co.uk/2/hi/health/10307790.stm

Replacing white rice with brown rice and wholemeal bread could cut the risk of diabetes by a third, US experts say.

White rice poses a diabetes threat because it causes steep rises in blood sugar, say Harvard researchers in Archives of Internal Medicine.

Brown rice and other wholegrain foods are a healthier option as they release glucose more gradually, they say.

The study is based on questionnaires; some say the data is not robust enough to base firm conclusions on.

It may be that people who eat less white rice tend to live healthier lifestyles, for example.
'Brown is better'

In the study of nearly 200,000 US people, white rice consumption was linked to type 2 diabetes.

After adjusting for age and other diabetes risk factors, those who ate five or more 150g servings of white rice per week had a 17% increased risk of diabetes compared with people who consumed less than one serving - about a cup of rice - per month.

Although few people - only 2% - in the study ate this much white rice, the finding was significant.
Continue reading the main story

The best way to prevent type 2 diabetes is by keeping active and eating a healthy balanced diet that is low in fat, salt and sugar with plenty of fruit and vegetables

Dr Victoria King Diabetes UK

Yet eating brown rice appeared to have the opposite effect, cutting the risk of type 2 diabetes.

People who ate two or more servings of brown rice per week had an 11% reduced risk of developing the condition compared with those who ate less than one serving a month.

Based on the results, the researchers estimate that replacing 50g or one-third of a typical serving of white rice with the same amount of brown rice would lead to a 16% lower risk of type 2 diabetes.

And replacing the white rice with wholegrains, including brown rice and pasta, wholemeal bread and rolled oats, could cut the risk by more than a third.
Food composition

Dr Qi Sun and other researchers say the explanation lies in the composition of the food.

Like other wholegrain foods, brown rice is high in fibre and releases its energy slowly.

In contrast, white rice has had all the bran and some of the germ removed during milling.

This gives white rice a higher glycaemic index (GI) - a measure of how much a food raises blood sugar levels compared with the same amount of glucose or white bread.

"From a public health point of view, replacing refined grains such as white rice by whole grains, including brown rice, should be recommended to facilitate the prevention of type 2 diabetes," according to the researchers.

Experts generally recommend that at least half of carbohydrate intake should come from whole grains like brown rice.

More than 70% of the rice consumed in developed countries such as the US and UK is white.

Dr Victoria King of Diabetes UK said that, since the results were from self-reported food diaries and questionnaires, it was not possible to make conclusive recommendations on how much of certain foods, such as brown rice, might protect against type 2 diabetes at this stage.

"The best way to prevent type 2 diabetes is by keeping active and eating a healthy balanced diet that is low in fat, salt and sugar with plenty of fruit and vegetables," she said.


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White Rice, Brown Rice, and Risk of Type 2 Diabetes in US Men and Women

Qi Sun, MD, ScD; Donna Spiegelman, ScD; Rob M. van Dam, PhD; Michelle D. Holmes, MD, DrPH; Vasanti S. Malik, MSc; Walter C. Willett, MD, DrPH; Frank B. Hu, MD, PhD

Arch Intern Med. 2010;170(11):961-969.

Background Because of differences in processing and nutrients, brown rice and white rice may have different effects on risk of type 2 diabetes mellitus. We examined white and brown rice consumption in relation to type 2 diabetes risk prospectively in the Health Professionals Follow-up Study and the Nurses' Health Study I and II.

Methods We prospectively ascertained and updated diet, lifestyle practices, and disease status among 39 765 men and 157 463 women in these cohorts.

Results After multivariate adjustment for age and other lifestyle and dietary risk factors, higher intake of white rice (≥5 servings per week vs <1 per month) was associated with a higher risk of type 2 diabetes: pooled relative risk (95% confidence interval [CI]), 1.17 (1.02-1.36). In contrast, high brown rice intake (≥2 servings per week vs <1 per month) was associated with a lower risk of type 2 diabetes: pooled relative risk, 0.89 (95% CI, 0.81-0.97). We estimated that replacing 50 g/d (uncooked, equivalent to one-third serving per day) intake of white rice with the same amount of brown rice was associated with a 16% (95% CI, 9%-21%) lower risk of type 2 diabetes, whereas the same replacement with whole grains as a group was associated with a 36% (30%-42%) lower diabetes risk.

Conclusions Substitution of whole grains, including brown rice, for white rice may lower risk of type 2 diabetes. These data support the recommendation that most carbohydrate intake should come from whole grains rather than refined grains to help prevent type 2 diabetes.


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