高脂飲食對有肥胖傾向者的糖尿病預防最佳


  【24drs.com】一篇採用低熱量飲食者的研究,主要對象是美國白人、過重或肥胖、非糖尿病患,在為期兩年的研究結束時,遺傳上較容易肥胖者,相較於使用低脂飲食者,使用高脂飲食者的beta-cell功能與胰島素阻抗性改善。
  
  研究者表示,這些初步研究結果認為,地中海飲食這類飲食模式,富含多元不飽和脂肪,對於與肥胖有關之遺傳變異者特別有幫助,可幫助他們免於發展為前期糖尿病與第二型糖尿病。
  
  新加坡國立大學助理教授Tao Huang博士在6月11日的美國糖尿病協會(ADA)2016年科學研討會中的口頭壁報會議中發表此篇研究。
  
  Huang博士等人分析了「Preventing Overweight Using Dietary Strategies (POUNDS LOST)」這項試驗中744名參與者的資料,這些人被隨機分組到4種減重飲食中的1種,2種是高脂(40%脂肪)、2種是低脂(20%脂肪);皆有身體質量指數(BMI)資料–與遺傳變異相關。
  
  Huang博士解釋,我們檢測了32種單核苷酸多型性[SNPs]或DNA中與肥胖(高BMI)風險有關的遺傳變化;他指出,如果是在10個人做遺傳檢測,或許有2人帶有2種高風險基因的SNPs;其他5人帶有8種高風險SNPs,其他人[風險最高且]有超過20種高風險SNPs —這組人的遺傳風險高,且從高脂飲食獲得的效益較多。
  
  根據Huang博士表示,這是DNA檢測如何幫助引導個製化醫療(或在此情況中,個製化飲食)的範例。
  
  口頭壁報會議主持人、喬治亞州亞特蘭大Emory大學Global糖尿病研究中心助理教授Mary Beth Weber博士指出,FTO基因和肥胖有強烈關聯,其他一些基因和肥胖有某種強度之關聯,而其他則是沒多少影響,所以,只有少數遺傳變異可能會影響結果。
  
  她同意研究顯示依循地中海式飲食,雖然脂肪較高,但是健康的多元不飽和脂肪,會是有利的,特別是那些肥胖遺傳風險高者。然而,儘管有很多人在爭論遺傳檢測以及個製化藥物,她提醒道,我傾向同意,我們在臨床上還沒能做到這點。
  
  她指出,除非我們在基因和結果之間有相當明確的關聯,例如BRCA [之於乳癌/卵巢癌],當我們討論是否值得進行某種基因檢測時,需很小心。同時,這篇研究為已知的知識增加佐證:地中海式高脂、低熱量飲食對大眾相當有好處。
  
  Huang博士解釋,飲食介入顯示可有效改善胰島素阻抗性和beta-cell功能;不過,很少瞭解整體的肥胖遺傳敏感性是否受到調整飲食之影響。
  
  所以他和研究夥伴分析了2004-2007年間於麻塞諸塞州、波士頓與路易西安那州、Baton Rouge進行的POUNDS LOST試驗的資料,研究對象是BMI值25-40的成年人,被隨機指派進行4種飲食之一,這幾種飲食在脂肪、蛋白質、碳水化合物的含量各有不同。
  
  整體而言,研究對象平均年齡51歲、BMI值33、60%是女性。
  
  研究者依據32種肥胖相關的遺傳變異計算了參與者的風險分數,來自血液或唾液樣本的DNA分析檢測。
  
  參與者根據他們的肥胖遺傳風險評分,被分成4組。
  
  飲食中的脂肪與BMI遺傳風險分數有顯著相互影響,包括:改變空腹胰島素、beta-cell功能(HOMA-B)穩態模型評估、6個月時的胰島素阻抗性(HOMA-IR)(交互影響P值分別 = .006, .005, .01)。
  
  肥胖遺傳風險最高的前四分之一者中,相較於低脂飲食者,攝取低熱量高脂飲食者的空腹胰島素值(P = .05)和胰島素阻抗性(P = .04)大幅降低,且在6個月的體重減輕期間,beta-cell 功能(P = .09)大幅增加。
  
  兩年時的空腹胰島素、HOMA-B和HOMA-IR有類似但稍弱的情況(P值分別 = .06, .05, .06,)。
  
  Huang博士等人結論指出,我們的資料認為,肥胖遺傳風險高者更可以從低熱量高脂減重飲食中獲益,在長期減重期間改善胰島素阻抗性與beta-cell功能。
  
  資料來源: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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