ジャンクフードは老化早める可能性　染色体のテロメアに差

【パリＡＦＰ＝時事】工業的に加工されたジャンクフードをたくさん食べる人は、老化に関連する染色体上の遺伝子マーカーが変化する可能性が高いとする研究結果が1日、オンラインで行われた欧州・国際肥満学会議（ECO-ICO）で発表された。（写真は資料写真）
　いわゆる「超加工食品」を１日に３品以上食べる人は、そうした食品をめったに食べない人に比べて、染色体の末端部位にありＤＮＡとタンパク質から成る「テロメア」が短くなる確率が２倍になるという。
　テロメアの短さは細胞レベルでの生物学的老化の指標であり、今回の研究では食事が細胞の老化を早める要因であることが示唆された。ただし、加工度が高い食品の摂取とテロメアの短縮の相関関係は強いが、因果関係についてはいまだ推測の域を出ないと論文の著者らは警告している。
　人間の体細胞には、遺伝情報を含む２３対の染色体が存在する。テロメアには遺伝情報はないが、染色体の安定性と完全性を維持するために不可欠で、ひいては体内の全細胞の機能がテロメアにかかっている。私たちが年を取るにつれ、テロメアは自然に短くなる。このテロメアの短縮は長年、生物学的年齢の指標とみなされてきた。
　スペイン・ナバラ大学のマリア・ベスラストロヨ、アメリア・マルティ両教授が率いるチームは、加工度の高いジャンクフードの定期的な摂取とテロメアの短縮の間に疑われる関連性について調査を進めた。
　研究チームは２００８年に５５歳以上でＤＮＡサンプルを提供し、その後２年ごとに食生活に関する詳細なデータも提供した８８６人について調べた。この男性６４５人、女性２４１人を超加工食品の消費量に応じて、４グループに均等に分けた。
　このうち超加工食品の摂取が多いグループは、家族歴に心血管疾患、糖尿病、血中脂肪異常がみられる可能性がより高かった。一方、超加工食品の摂取が少ないグループは、食物繊維、オリーブオイル、果物、野菜やナッツ類の摂取が多い地中海食と関連付けられた。
　さらに超加工食品の摂取が最も少ないグループに対し、他の３グループが短いテロメアを持っている確率は、超加工食品の摂取量が多くなるにつれて２９％、４０％、８２％と増えていった。
　研究結果は今年、米臨床栄養学会誌「アメリカン・ジャーナル・オブ・クリニカル・ニュートリション」に掲載された。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2020/09/02-15:07）

People who eat a lot of industrially processed junk food are more likely to exhibit a change in their chromosomes linked to ageing, according to research presented Tuesday at an online medical conference.
Three or more servings of so-called ultra-processed food per day doubled the odds that strands of DNA and proteins called telomeres, found on the end of chromosomes, would be shorter compared to people who rarely consumed such foods, scientists reported at the European and International Conference on Obesity.
Short telomeres are a marker of biological ageing at the cellular level, and the study suggests that diet is a factor in driving the cells to age faster.
While the correlation is strong, however, the causal relationship between eating highly processed foods and diminished telomeres remains speculative, the authors cautioned.
Each human cell has 23 pairs of chromosomes that contain our genetic code.
Telomeres do not carry genetic information, but are vital for preserving the stability and integrity of chromosomes and, by extension, the DNA that all the cells in our body relies on to function.
As we get older, our telomeres shorten naturally because each time a cell divides, part of the telomere is lost.
That reduction in length has long been recognised as a marker of biological age.
Scientists led by professors Maria Bes-Rastrollo and Amelia Marti, both of the University of Navarra in Spain, wanted to explore a suspected connection between the regular consumption of highly processed junk food and shrinking telomeres.
- Not real food -
Earlier studies had pointed to a possible link with sugar-sweetened drinks, processed meats and other foods loaded with saturated fats and sugar, but the findings were inconclusive.
Ultra-processed foods are industrially manufactured substances composed of some mix of oils, fats, sugars, starch and proteins that contain little if any whole or natural foods.
They often include artificial flavourings, colourings, emulsifiers, preservatives and other additives that increase shelf-life and profit margins.
These same properties, however, also mean that such foods are nutritionally poor compared to less processed alternatives, the researchers said.
Earlier studies have shown strong correlations between ultra-processed foods and hypertension, obesity, depression, type 2 diabetes and some forms of cancer.
These conditions are often age-related in so far as they are linked to oxidative stress and inflammation known to influence telomere length.
Marti and colleagues looked at health data for nearly 900 people aged 55 or older who provided DNA samples in 2008 and provided detailed data about their eating habits every two years thereafter.
The 645 men and 241 women were equally divided into four groups, depending on their consumption of ultra-processed foods.
Those in the high-intake group were more likely to have a family history of cardiovascular disease, diabetes and abnormal blood fats.
That also consumed less foods associated with the Mediterranean diet -- fibre, olive oil, fruits, vegetable and nuts.
Compared to the group who ate the fewest ultra-processed foods, the other three showed an increased likelihood -- 29, 40 and 82 percent, respectively -- of having shortened telomeres.
The findings were published earlier this year in the peer-reviewed American Journal of Clinical Nutrition.