甘い飲料をよく飲む女児では初潮が早まる

砂糖入り飲料を多量に摂取する女児では、思春期が早まる可能性が報告された。この知見は「Human Reproduction」オンライン版に1月28日掲載された。

　この研究は、9～14歳の女児5,600人弱を1996年から2001年まで追跡したもの。食物摂取の詳細なアンケートから、飲料から摂取された砂糖量が算出された。

　その結果、1日1.5サービングを超える砂糖入り飲料を摂取した女児は、週2サービング以下を摂取した女児に比べ、最初の月経（初潮）が2.7カ月早かった。この関連は、女児のBMI（身長と体重から算出する肥満指数）、食物摂取量や運動とは独立していた。平均初潮年齢は、砂糖入り飲料摂取が最も多い群で12.8歳、最も少ない群で13歳だった。ダイエット飲料は、初潮年齢の差には関連していなかったという。

　「早期の月経開始は、思春期のうつ病、成人後の乳がんのリスクファクターであることから、この知見は単に初潮を早く迎えるという以上の意味をもつ」と、筆頭著者である米ハーバード大学（ボストン）公衆衛生学部博士研究員のJenny Carwile氏は述べている。

　指導著者である同大医学部准教授のKarin Michels氏は、「この研究は砂糖入り飲料が早期初潮の直接の原因だと示すものではなく、関連が示されただけにすぎない。だが、加糖飲料は果汁のような自然に甘い飲料よりもグリセミック指数が高く、高グリセミック食品は体内のインスリン濃度を急速に高め、これが性ホルモンの濃度を上昇させることにより、早期の月経開始に関連しうる」と推測している。

　米国飲料協会（ABA）は、この研究では因果関係の知見が欠けていると指摘。「女児の思春期開始は前世代より早まっており、その理由について科学的に一致した意見はない」と述べている。

　別の専門家は、「砂糖入り飲料には栄養的価値はない。初潮が早まる理由が何であれ、何歳であっても、砂糖入り飲料を定期的に飲む理由などない」としている。

PMID:25628346

Sugar-sweetened beverage consumption and age at menarche in a prospective study of US girls.

Journal

Human reproduction (Oxford, England). 2015 Jan 27; pii: deu349.

Author

J L Carwile, W C Willett, D Spiegelman, E Hertzmark, J Rich-Edwards, A L Frazier, K B Michels

Abstract

STUDY QUESTION : Is sugar-sweetened beverage (SSB) consumption associated with age at menarche?

SUMMARY ANSWER : More frequent SSB consumption was associated with earlier menarche in a population of US girls.

WHAT IS KNOWN ALREADY : SSB consumption is associated with metabolic changes that could potentially impact menarcheal timing, but direct associations with age at menarche have yet to be investigated.

STUDY DESIGN, SIZE, DURATION : The Growing up Today Study, a prospective cohort study of 16 875 children of Nurses' Health Study II participants residing in all 50 US states. This analysis followed 5583 girls, aged 9-14 years and premenarcheal at baseline, between 1996 and 2001. During 10 555 person-years of follow-up, 94% (n = 5227) of girls reported their age at menarche, and 3% (n = 159) remained premenarcheal in 2001; 4% (n = 197) of eligible girls were censored, primarily for missing age at menarche.

PARTICIPANTS/MATERIALS, SETTING, METHODS : Cumulative updated SSB consumption (composed of non-carbonated fruit drinks, sugar-sweetened soda and iced tea) was calculated using annual Youth/Adolescent Food Frequency Questionnaires from 1996 to 1998. Age at menarche was self-reported annually. The association between SSB consumption and age at menarche was assessed using Cox proportional hazards regression.

MAIN RESULTS AND THE ROLE OF CHANCE : More frequent SSB consumption predicted earlier menarche. At any given age between 9 and 18.5 years, premenarcheal girls who reported consuming >1.5 servings of SSBs per day were, on average, 24% more likely [95% confidence interval (CI): 13, 36%; P-trend: <0.001] to attain menarche in the next month relative to girls consuming ≤2 servings of SSBs weekly, adjusting for potential confounders including height, but not BMI (considered an intermediate). Correspondingly, girls consuming >1.5 SSBs daily had an estimated 2.7-month earlier menarche (95% CI: -4.1, -1.3 months) relative to those consuming ≤2 SSBs weekly. The frequency of non-carbonated fruit drink (P-trend: 0.03) and sugar-sweetened soda (P-trend: 0.001), but not iced tea (P-trend: 0.49), consumption also predicted earlier menarche. The effect of SSB consumption on age at menarche was observed in every tertile of baseline BMI. Diet soda and fruit juice consumption were not associated with age at menarche.

LIMITATIONS, REASONS FOR CAUTION : Although we adjusted for a variety of suspected confounders, residual confounding is possible. We did not measure SSB consumption during early childhood, which may be an important window of exposure.

WIDER IMPLICATIONS OF THE FINDINGS : More frequent SSB consumption may predict earlier menarche through mechanisms other than increased BMI. Our findings provide further support for public health efforts to reduce SSB consumption.

STUDY FUNDING/COMPETING INTERESTS : The Growing up Today Study is supported by grant R03 CA 106238. J.L.C. was supported by the Breast Cancer Research Foundation; Training Grant T32ES007069 in Environmental Epidemiology from the National Institute of Environmental Health Sciences, National Institutes of Health; and Training Grant T32HD060454 in Reproductive, Perinatal and Pediatric Epidemiology from the National Institute of Child Health and Human Development, National Institutes of Health. A.L.F. is supported by the American Cancer Society, Research Scholar Grant in Cancer Control. K.B.M. was supported in part by the National Cancer Institute at the National Institutes of Health (Public Health Service grants R01CA158313 and R03CA170952). There are no conflicts of interest to declare.