高齢者に対する栄養介入研究

今日は、5th Cachexia Conferenceの資料の中から、高齢者に対する栄養介入研究の抄録を紹介します。このネタばかりですみません。

http://www.lms-events.com/19/5th_Cachexia_Conference_2009_Abstracts.pdf

Nutritional interventional studies in the elderly
Antoni Salvà
Institut de l’Envelliment (institute on Ageing), Universitat Autònoma de Barcelona, Spain

高齢者に対する栄養介入研究についてレビューすると、有効という論文と無効という論文があり、結論は出せる状況にはありません。ただ、大腿骨頚部骨折、肺炎、褥瘡に関しては栄養介入が有効というエビデンスが出てきています。

栄養介入研究でも栄養指標ではなく、身体機能や認知機能をアウトカムにした研究が出てきています。ただ、これらの多くは二次アウトカムですが。リハ栄養の立場で考えれば、栄養指標よりも身体機能、ADL、認知機能を一次アウトカムにすべきだと思います。

対象が健常高齢者ではなく、低栄養のハイリスク群、病院退院後、施設入所の患者であれば、栄養介入の身体機能に対する有効性が示されていますが、全般的には効果はないという報告が多いです。健常健常者で栄養状態が良好であれば、栄養介入は不要で運動療法のみで十分と言えます。

一方、身体機能低下、低栄養を認める患者には、栄養介入と運動・リハが重要です。リハ栄養はこのような患者が対象のため、より有効な可能性が高いと考えます。

認知機能に対する栄養介入（ビタミンB12、葉酸、抗酸化物質）は、無効という報告が多いようです。認知障害に対しては現状ではリハ栄養というよりも、認知リハと適応があれば薬物療法が中心になると思います。

Unintentional weight loss and undernutrition are major problems among older people. Under nutrition causes changes in body mass and composition which manifest particularly as weight loss and low BMI. Under nutrition, predict reduced physical performance and functional decline, and are associated with worse quality of life and increase of mortality. The relationships between under nutrition and health outcomes are well described specially for those patients in LTC facilities or in acute settings. In these situations there is evidence on the efficacy of a nutritional intervention including supplementation, in increasing nutritional markers and reducing mortality. There is also some evidence of the positive effect improving outcomes in hip fracture, pulmonary infections and pressure ulcers.

Beyond under nutrition, nutrition has a strong relationship with two important outcomes in the older people: physical function and cognition. The transition from independence to disability in older adults is characterized by detectable changes in body composition and physical function, including unexplained weight loss, reduced muscle strength, self-reported exhaustion, slow walking speed and low physical activity, which often cluster and have been grouped under the term “frailty”. Epidemiologic studies have shown that reduced caloric intake and weight loss and the reduced intake of specific nutrients (proteins, vitamins D, E, C, B6, B12, folate and selenium) are associated with these changes.

Intervention studies using nutritional supplementation have shown inconclusive results. The majority of studies aimed at assessing the effects of increased energy and proteins on nutritional status or intermediate outcomes (body composition measures, inflammation or other biological markers). Almost all the quoted studies included functional outcomes only as secondary outcomes. The results were, in general, negative for these kind of outcomes. Some positive results were observed in those studies enrolling more selected populations (for example participants with higher risk of under nutrition or after hospital discharge or institutionalized), or combining nutritional supplementation with exercise. Different studies also tested the effect of specific vitamins, mainly vitamin D. Besides the known effects on bone health and fractures, interventions with vitamin D showed positive results on muscle strength and falls. Few negative data are available on vitamin E and other antioxidant micronutrients (carotenoids etc), although observational studies showed a strong inverse correlation between their concentration and physical performance and frailty. Studies using supplementation with this kind of nutrients and also with omega-e, vitamin B12, folic acid and antioxidants have mostly evaluated their effect on cognitive function, in general with unsatisfying results.