高脂饮食对有肥胖倾向者的糖尿病预防最佳


  【24drs.com】一篇采用低热量饮食者的研究,主要对象是美国白人、过重或肥胖、非糖尿病患,在为期两年的研究结束时,遗传上较容易肥胖者,相较于使用低脂饮食者,使用高脂饮食者的beta-cell功能与胰岛素阻抗性改善。
  
  研究者表示,这些初步研究结果认为,地中海饮食这类饮食模式,富含多元不饱和脂肪,对于与肥胖有关之遗传变异者特别有帮助,可帮助他们免于发展为前期糖尿病与第二型糖尿病。
  
  新加坡国立大学助理教授Tao Huang博士在6月11日的美国糖尿病协会(ADA)2016年科学研讨会中的口头墙报会议中发表此篇研究。
  
  Huang博士等人分析了「Preventing Overweight Using Dietary Strategies (POUNDS LOST)」这项试验中744名参与者的资料,这些人被随机分组到4种减重饮食中的1种,2种是高脂(40%脂肪)、2种是低脂(20%脂肪);皆有身体质量指数(BMI)资料–与遗传变异相关。
  
  Huang博士解释,我们检测了32种单核苷酸多型性[SNPs]或DNA中与肥胖(高BMI)风险有关的遗传变化;他指出,如果是在10个人做遗传检测,或许有2人带有2种高风险基因的SNPs;其它5人带有8种高风险SNPs,其它人[风险最高且]有超过20种高风险SNPs —这组人的遗传风险高,且从高脂饮食获得的效益较多。
  
  根据Huang博士表示,这是DNA检测如何帮助引导个制化医疗(或在此情况中,个制化饮食)的范例。
  
  口头墙报会议主持人、格鲁吉亚州亚特兰大Emory大学Global糖尿病研究中心助理教授Mary Beth Weber博士指出,FTO基因和肥胖有强烈关联,其它一些基因和肥胖有某种强度之关联,而其它则是没多少影响,所以,只有少数遗传变异可能会影响结果。
  
  她同意研究显示依循地中海式饮食,虽然脂肪较高,但是健康的多元不饱和脂肪,会是有利的,特别是那些肥胖遗传风险高者。然而,尽管有很多人在争论遗传检测以及个制化药物,她提醒道,我倾向同意,我们在临床上还没能做到这点。
  
  她指出,除非我们在基因和结果之间有相当明确的关联,例如BRCA [之于乳癌/卵巢癌],当我们讨论是否值得进行某种基因检测时,需很小心。同时,这篇研究为已知的知识增加佐证:地中海式高脂、低热量饮食对大众相当有好处。
  
  Huang博士解释,饮食介入显示可有效改善胰岛素阻抗性和beta-cell功能;不过,很少了解整体的肥胖遗传敏感性是否受到调整饮食之影响。
  
  所以他和研究伙伴分析了2004-2007年间于麻塞诸塞州、波士顿与路易西安那州、Baton Rouge进行的POUNDS LOST试验的资料,研究对象是BMI值25-40的成年人,被随机指派进行4种饮食之一,这几种饮食在脂肪、蛋白质、碳水化合物的含量各有不同。
  
  整体而言,研究对象平均年龄51岁、BMI值33、60%是女性。
  
  研究者依据32种肥胖相关的遗传变异计算了参与者的风险分数,来自血液或唾液样本的DNA分析检测。
  
  参与者根据他们的肥胖遗传风险评分,被分成4组。
  
  饮食中的脂肪与BMI遗传风险分数有显著相互影响,包括:改变空腹胰岛素、beta-cell功能(HOMA-B)稳态模型评估、6个月时的胰岛素阻抗性(HOMA-IR)(交互影响P值分别 = .006, .005, .01)。
  
  肥胖遗传风险最高的前四分之一者中,相较于低脂饮食者,摄取低热量高脂饮食者的空腹胰岛素值(P = .05)和胰岛素阻抗性(P = .04)大幅降低,且在6个月的体重减轻期间,beta-cell 功能(P = .09)大幅增加。
  
  两年时的空腹胰岛素、HOMA-B和HOMA-IR有类似但稍弱的情况(P值分别 = .06, .05, .06,)。
  
  Huang博士等人结论指出,我们的资料认为,肥胖遗传风险高者更可以从低热量高脂减重饮食中获益,在长期减重期间改善胰岛素阻抗性与beta-cell功能。
  
  资料来源:http://www.24drs.com/
  
  Native link:High-Fat Diet Best for Diabetes Prevention in Obesity Prone

High-Fat Diet Best for Diabetes Prevention in Obesity Prone

By Marlene Busko
Medscape Medical News

NEW ORLEANS — In a study of mainly white, overweight or obese, nondiabetic Americans on reduced-calorie diets, those who had a high genetic susceptibility to obesity who were on a high-fat as opposed to a low-fat diet had improved beta-cell function and insulin resistance at the end of 2 years.

These preliminary findings suggest that a diet such as the Mediterranean diet, which is high in polyunsaturated fat, would be especially beneficial for people who have a greater number of genetic variants that are associated with obesity and could help prevent them from progressing to prediabetes and type 2 diabetes, the researchers say.

Tao Huang, PhD, assistant professor, National University of Singapore, presented this study in an oral moderated poster session on June 11 here at the American Diabetes Association (ADA) 2016 Scientific Sessions.

Dr Huang and colleagues analyzed data from 744 participants in the Preventing Overweight Using Dietary Strategies (POUNDS LOST) trial who had been randomized to one of four weight-loss diets, including two that were high fat (40% fat) and two that were low fat (20% fat) and for whom data were available on body mass index (BMI)–associated genetic variants.

"We tested 32 single nucleotide polymorphisms [SNPs]," or genetic variants in DNA, that are associated with a risk of obesity (high BMI), Dr Huang explained to Medscape Medical News. If genetic testing is done "in 10 people, maybe two people carry 2 SNPs of high-risk genes; another five people carry eight high-risk SNPs. The others [are at the highest risk and] may have more than 20 high-risk SNPs — and this group with high genetic risk may benefit more from the high-fat diet," he noted.

This is an example of how DNA testing can lead to personalized medicine (or in this case, a personalized diet), according to Dr Huang.

To Medscape Medical News, the moderator of the oral poster session, Mary Beth Weber, PhD, assistant professor, Global Diabetes Research Center, Emory University, Atlanta, Georgia, commented that the FTO gene has a strong association with obesity, and a couple of other genes have a somewhat strong association with obesity, but others have a much lesser effect, so a few genetic variants are probably driving the results.

She agreed that the study shows that "following a Mediterranean diet that, although is higher in fat, is healthy polyunsaturated fat, could be beneficial," especially if for those with a high genetic risk for obesity.

However, although a lot of people are arguing for genetic testing and personalized medicine, "I would tend to agree that we are not [yet] at that point clinically," she cautioned.

"Unless we have a very certain link between the gene and the outcome, something like BRCA [in breast/ovarian cancer], you should consider very carefully whether taking a genetic test is worth it," she added.

In the meantime, this study adds to the knowledge that is already understood, that a Mediterranean type high-fat, lower-calorie diet can be very beneficial in general, she noted.

POUNDS LOST Trial Included Two High-Fat, Two Low-Fat Diets

Dr Huang explained that diet interventions have shown effectiveness in improvement of insulin resistance and beta-cell function; however, little is known about whether the overall genetic susceptibility to obesity modifies the dietary effects.

So he and his colleagues analyzed data from the POUNDS LOST trial that was conducted from 2004 through 2007 in Boston, Massachusetts and Baton Rouge, Louisiana among adults who had a BMI of 25 to 40 who were randomly assigned to one of the four diets with differences in fat, protein, and carbohydrate content.

On average, the participants were 51 years old and had a BMI of 33, and 60% were women.

The investigators calculated the participants' risk score, based on the presence of 32 obesity–associated genetic variants, which were determined from DNA analysis from a blood or saliva sample.

The participants were divided into tertiles, based on their genetic risk score for obesity.

Dietary fat significantly interacted with the BMI genetic risk score on changes in fasting insulin, the homeostatic model assessment of beta-cell function (HOMA-B), and insulin resistance (HOMA-IR) at 6 months (P for interaction = .006, .005, and .01, respectively).

Among those in the highest tertile of genetic risk scores for obesity, those who consumed a low-calorie, high-fat diet had a greater decrease in fasting insulin (P = .05) and insulin resistance (P = .04) compared with those who consumed a low-fat diet, along with a greater increase in beta-cell function (P = .09) during the 6-month weight-loss period.

Similar but attenuated patterns were observed for fasting insulin, HOMA-B, and HOMA-IR at 2 years (P = .06, .05, and .06, respectively).

"Our data suggest that individuals with a higher genetic susceptibility to obesity may benefit more from consuming a hypocaloric and high-fat weight-loss diet in improving insulin resistance and beta-cell function during the long-term weight-loss period," Dr Huang and colleagues concluded.

The authors have no relevant financial relationships.

    
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