2016-12-02 07:43:22 National Academy of Science
Science Newsfrom research organizations
Aspartame may prevent, not promote, weight loss by blocking intestinal enzyme's activity
Study identifies possible mechanism behind sugar substitute's lack of effectiveness
Date:
November 22, 2016
Source:
Massachusetts General Hospital
Summary:
A team of investigators has found a possible mechanism explaining why use of the sugar substitute aspartame might not promote weight loss. In their report, the researchers show how the aspartame breakdown product phenylalanine interferes with the action of an enzyme previously shown to prevent metabolic syndrome - a group of symptoms associated with type 2 diabetes and cardiovascular disease.
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A team of Massachusetts General Hospital (MGH) investigators has found a possible mechanism explaining why use of the sugar substitute aspartame might not promote weight loss. In their report published online in Applied Physiology, Nutrition and Metabolism, the researchers show how the aspartame breakdown product phenylalanine interferes with the action of an enzyme previously shown to prevent metabolic syndrome -- a group of symptoms associated with type 2 diabetes and cardiovascular disease. They also showed that mice receiving aspartame in their drinking water gained more weight and developed other symptoms of metabolic syndrome than animals fed similar diets lacking aspartame.
"Sugar substitutes like aspartame are designed to promote weight loss and decrease the incidence of metabolic syndrome, but a number of clinical and epidemiologic studies have suggested that these products don't work very well and may actually make things worse," says Richard Hodin, MD, of the MGH Department of Surgery, the study's senior author. "We found that aspartame blocks a gut enzyme called intestinal alkaline phosphatase (IAP) that we previously showed can prevent obesity, diabetes and metabolic syndrome; so we think that aspartame might not work because, even as it is substituting for sugar, it blocks the beneficial aspects of IAP."
In a 2013 study published in Proceedings of the National Academy of Sciences, Hodin's team found that feeding IAP to mice kept on a high-fat diet could prevent the development of metabolic syndrome and reduce symptoms in animals that already had the condition. Phenylalanine is known to inhibit the action of IAP, and the fact that phenylalanine is produced when aspartame is digested led the researchers to investigate whether its inhibitory properties could explain aspartame's lack of a weight-loss effect.
In a series of experiments the team first found that the activity of IAP was reduced when the enzyme was added to a solution containing an aspartame-sweetened soft drink but remained unchanged if added to a solution with a sugar-sweetened beverage. IAP is primarily produced in the small intestine, and the researchers found that injecting an aspartame solution into segments of the small intestines of mice significantly reduced the enzyme's activity. In contrast, IAP activity remained unchanged in bowel segments injected with a saline solution.
To better represent the effects of consuming beverages or other products containing aspartame, the researchers followed four groups of mice for 18 weeks. Two groups were fed a normal diet, one receiving drinking water with aspartame, the other receiving plain water. The other two groups were fed a high-fat diet, along with either aspartame-infused or plain water. Animals in the normal diet group that received aspartame consumed an amount equivalent to an adult human's drinking about three and a half cans of diet soda daily, and aspartame-receiving animals in the high-fat group consumed the equivalent of almost two cans.
At the end of the study period, while there was little difference between the weights of the two groups fed a normal diet, mice on a high-fat diet that received aspartame gained more weight than did those on the same diet that received plain water. Aspartame-receiving mice in both diet groups had higher blood sugar levels than did those fed the same diets without aspartame, which indicates glucose intolerance, and both aspartame-receiving groups had higher levels of the inflammatory protein TNF-alpha in their blood, which suggests the kind of systemic inflammation associated with metabolic syndrome.
"People do not really understand why these artificial sweeteners don't work. There has been some evidence that they actually can make you more hungry and may be associated with increased calorie consumption. Our findings regarding aspartame's inhibition of IAP may help explain why the use of aspartame is counterproductive," says Hodin, who is a professor of Surgery at Harvard Medical School. "While we can't rule out other contributing mechanisms, our experiments clearly show that aspartame blocks IAP activity, independent of other effects."
Story Source:
Materials provided by Massachusetts General Hospital. Note: Content may be edited for style and length.
Journal Reference:
Sarah Shireen Gul, A. Rebecca L. Hamilton, Alexander R Munoz, Tanit Phupitakphol, Liu Wei, Sanjiv K Hyoju, Konstantinos P Economopoulos, Sara Morrison, Dong Hu, Weifeng Zhang, Mohammad Hadi Gharedaghi, Haizhong Huo, Sulaiman R Hamarneh, Richard A. Hodin. Inhibition of the gut enzyme intestinal alkaline phosphatase may explain how aspartame promotes glucose intolerance and obesity in mice. Applied Physiology, Nutrition, and Metabolism, 2016; DOI: 10.1139/apnm-2016-0346
2016-12-02 07:43:22 National Academy of Science
カロリーゼロのはずが…人工甘味料のアスパルテームがメタボを促進？
2016.11.30 07:03
サイエンス食べ物/飲み物フィットネス/ヘルスケア人体
カロリーゼロのはずが…人工甘味料のアスパルテームがメタボを促進？ 1
ダイエットコーラはダイエットにならない？
近年の健康ブームに置き去りとなってしまわないよう、清涼飲料水メーカーも、身体に優しいイメージの商品開発が目立ちます。たっぷりと砂糖が入ったコカコーラではなく、人工甘味料のアスパルテームを用い、ダイエットコーラやコカコーラ・ゼロといった商品群が準備されてきたことなどは、その一例でしょうかね…。
ところが、このほどマサチューセッツ総合病院（MGH）の研究チームは、健康によいと謳われているアスパルテームについて、NRC Newsで驚きの研究発表をしました。というのは、アスパルテームを摂取すると、ダイエットが進むどころか、かえって健康には悪影響かも！ということ。
同研究では、実験用マウスを4グループに分けて、アスパルテームがおよぼす影響をテスト。高カロリーの食事を与えつつ、アスパルテーム入りの水を飲んだグループと、通常の水を飲むグループを設けました。すると、4週間の実験期間の終わりに、アスパルテーム入りの水を飲んだマウスたちは、通常の水を飲んでいたマウスたちよりも体重が増え、高血圧や血糖値の上昇をはじめとする悪い健康状態が目立ちました。別に通常の食事を与えた2グループは、アスパルテーム入りの水を飲んでも、通常の水を飲んでも、あまり健康状態に差は見られなかったんだとか。
同研究チームを率いた、MGHのRichard Hodin博士は、Science Daily上でこのようなコメントを発表しています。
アスパルテームのような甘味料は、体重を減らしたり、メタボリックシンドロームの症状を改善したりできることを目指して開発が進められた。しかしながら、数々の臨床試験および疫学研究データから、実際には想定されたような効果はなく、かえって悪影響をおよぼす可能性もあることが判明している。
今回の実験でマウスが摂取したアスパルテーム入りの飲料は、人間でいうならば、毎日3.5本のダイエットコーラ缶を飲み続けることに相当するようですね。砂糖が入っていない健康的な飲み物と思って、わざわざダイエットコーラのような製品を選び続けても、ほとんど健康面でメリットはなかったりするのかもしれませんよ〜。
Hodin博士は、アスパルテームが、肥満を予防する働きをするIAP（腸アルカリホスファターゼ）を阻害してしまうことを発見。さらには、血中のTNF-αを増やし、メタボリックシンドロームを加速させる危険性があると指摘しています。ダイエットコーラのダイエット効果を信じて飲み続けていた人が、どれほど本当に存在するのかは謎ですが、衝撃の研究発表を受けて、騙されたと感じた北米の消費者たちによる訴訟にまで発展していくことだって考えられますよね。
関連記事：
・エナジードリンクの飲み過ぎは、肝炎などの健康被害の恐れにつながる
・ソイレントの製品で具合が悪くなるのは何故なのか? 現在まで判明していること
image by mantinov / Shutterstock.com
source: NRC News, Science Daily
Eve Peyser - Gizmodo US
（湯木進悟）
〓 ref. 「enhance」
Apple の新しいテレビ広告で耳にした「enhance」の意味とは？
June 12, 2013キクエイゴEdit
6月10日に開幕したアップル（Apple）の開発者向けイベント『Worldwide Developers Conference（WWDC）』。
SPONSORED LINK
Apple WWDC 2013 私は初日の基調講演は見ていなかったのですが、Twitter やニュースで話題を追っていると、Apple の新しいテレビ広告を目にしました。
さっそく見てみると、"We spend a lot of time on a few great thing. Until every idea we touch enhances each life it touches." というナレーションがありました。
