令和元年国民健康栄養調査によると、20代女性の朝食欠食率は18.1%、30歳代では22.4%であり、若年勤労女性の約5名に1名が朝食を欠食している。朝食欠食は若年女性における除脂肪量の低値、骨密度の低下及び主観的体調不良など様々な健康問題に関連することから、糖代謝、脂質代謝及び鉄代謝不良など他の健康問題を誘発するリスクにもなり得ると考えられる。【目的】若年勤労女性を対象に朝食摂取習慣の有無と血液生化学指標との関連を明らかにすることとした。【方法】対象者は正常月経周期を有する若年勤労女性22名であり、朝食摂取群(n=11、年齢30±3歳、BMI20.6±1.8kg/m2)と朝食欠食群(n=11、年齢28±6歳、BMI20.2±1.6kg/m2)に分類した。調査項目は食事記録法によるエネルギー、栄養素及び食品群別摂取量、早朝空腹時の血液検査及び生体電気インピーダンス法による身体組成であり、2群間で各項目を比較した。【結果】朝食欠食群は朝食摂取群と比較してエネルギー(kcal/日)、たんぱく質(g/日)、炭水化物(g/日)及び穀類(g/日)の摂取量が有意に低値を示した。また血液生化学指標において朝食欠食群の血清フェリチン(ng/dL)及びMCH(pg)が有意に低値を示した。血清フェリチン<20ng/dL及びMCH<28.6pgを鉄欠乏のスクリーニングとすると両血中指標ともに朝食欠食群は朝食摂取群と比較してカットオフ値を下回る者の割合が高値を示した。【結論】朝食摂取習慣の有無は若年女性における鉄欠乏と関連することが示唆された。潜在性鉄欠乏は本邦の若年女性において罹患率の高い疾病の1つであり、様々な不定愁訴と関連することから、その予防策として朝食摂取の重要性を普及する必要がある。(著者抄録)

[Purpose] The current study aimed to determine the association between serum uncarboxylated osteocalcin (ucOC) levels and dietary vitamin K intake in female Japanese athletes.[Methods] The nutritional profile and food group intake of 52 Japanese female athletes were investigated using a digital photographic method with data obtained from 3-day dietary records. The food groups were categorized into 18 groups in line with the standard tables of food composition in Japan. Fasting blood samples were collected for serum ucOC levels, and dual-energy X-ray absorptiometry (DXA) evaluated body composition and bone parameters.[Results] The results showed that dietary vitamin K intake level was 235 ± 148 µg/day, and approximately 70% (n = 36) of participants consumed more than the adequate intake (AI) level, based on the Dietary Reference Intakes for Japanese females aged 18–29. Serum ucOC levels were negatively associated with daily vitamin K intake (r = −0.388, &lt;i&gt;P&lt;/i&gt; = 0.004) and calcium (r = −0.596, &lt;i&gt;P&lt;/i&gt; = 0.004) after adjusting for energy intake.[Conclusion] Our study revealed that serum ucOC levels were negatively associated with dietary vitamin K intake in female Japanese athletes. Serum ucOC levels reflected dietary vitamin K intake in female athletes. In summary, female athletes consume more vitamin K than the general population to maintain bone health. Furthermore, our results indicated that serum ucOC levels might be linked to dietary calcium intake.

The aim of the present study was to clarify the influence of inulin and lactulose-fortified prebiotic food intakes on bone metabolism turnover among Japanese female athletes. The participants included 29 female athletes aged 18–25 years. They were requested to consume their habitual foods or drinks with one pack of prebiotic food every day for 12 weeks. Dietary intake, training time, body composition, blood sample, and fecal microbiota were assessed during this intervention period. Body composition, total energy intake, and training time of the participants revealed no significant changes during the intervention period. The occupation ratio of Bifidobacterium spp. was significantly increased at 3 and 4 weeks (18.0 ± 8.3% and 17.6 ± 8.5%, respectively) compared to that of pre-intervention (11.7 ± 7.3%) (p = 0.019 and p = 0.035, respectively). The serum TRACP-5b level was significantly decreased at 12 weeks (363 ± 112 mU/dL) compared to that at baseline (430 ± 154 mU/dL) (p = 0.018). These results suggest that the prebiotic food used in this study might have beneficial effects on bone health and gut microbial environment among female athletes. Further studies are warranted to identify the mechanism of the prebiotics–gut–bone axis.