飲食中的巨量營養素組成與腦中灰質在健康年輕成人與老年人的不同關係

Abstract

在生命發展的過程中，來自飲食攝取的能量及其營養素是對神經結構發展與功能極其重要的因子。但對於飲食中的巨量營養素與腦部結構與功能在非肥胖或非飲食失功能的人類身上，其間的關聯，目前的資訊是有限的。我們假設隨著人類攝取的巨量營養素的不同程度，會使腦中灰質體積大小與認知功能表現有差異。更重要地，飲食與腦的關係會隨著年齡的不同，而有需求上的不同。在本研究中，我們徵求了在台灣本地32位年輕成人(年齡在20~30歲之間)與21位年長成人(年齡在60歲以上)，讓他們參與(a)至少三天的系統性飲食紀錄(b)受測關於認知功能表現的神經心理學測驗，以及(c)結構性腦部核磁共振照影，以得知參與者腦中灰質體積大小。參與者必須無臨床上的身心疾病，且無飲食失調狀況。研究方法(a)我們依照台灣地區衛福部食品藥物管理署的資料庫，算出每位受試者其飲食內容中的碳水化合物含量、蛋白質含量，及脂質含量(b)我們使用的神經心理學測驗有簡短智能測驗(MMSE)、魏氏智力測驗III(WAIS III)、魏氏記憶測驗III (WMS III)、早期失智症篩檢量表(AD-8) (c)計算腦中灰質體積大小則是用版本5.2.0的Freesurfer 軟體，以得知全腦不同腦區的灰質體積。我們的研究結果發現在健康年輕成人當中，飲食中攝取較多比例的碳水化合物者，腦中易有較小的灰質體積;而在健康老年人當中，飲食中攝取較多比例的碳水化合物者，腦中卻易有較大的灰質體積。而在攝取蛋白質含量的多寡，對健康年輕成人來說其腦中灰質體積較不易受影響;但對老年人來說，攝取蛋白質含量越高，其腦中灰質體積就越小。在巨量營養素與腦中灰質在健康年輕成人與健康老年人的關係，年紀不同對於營養攝取的需求不同占了一個關鍵性的角色。

Energy and molecular substrates from dietary intake are important factors for neuronal structural development and function over the lifespan. There is limited information, however, on how human dietary macronutrient levels are associated with brain structure and function, particularly for those not affected by obesity or other dietary dysfunctions. We hypothesized that macronutrient intake levels in humans should have measurable associations with gray matter volume and cognitive ability even in individuals maintaining healthy dietary habits. Importantly, diet-brain associations may differ across age due to differential nutritional requirements. In this study, 32 young (age20-30) and 21 older (age above 60) Taiwanese adults participated in (a) systematic dietary monitoring at least 3 days, (b) neuropsychological tests of cognitive abilities, and (c) T1-weighted magnetic resonance imaging (MRI) of gray matter volumes (256*256 mm in-plane field of view, 1*1*1 mm3 voxels, TR = 2 s, inversion time = 0.9 s, flip angle = 9°). Participants were physically healthy at time of testing with no dietary dysfunction or neurocognitive counter-indications. Individual intake levels of calorie, carbohydrates, lipids, and proteins were scored based on the local food and drug administration database. The neuropsychological test battery included: the mini-mental State Examination (MMSE), the Wechsler Adult Intelligence Scale III (WAIS III), the Wechsler Memory Scale III (WMS III), and the Alzheimer Disease-8 (AD-8) questionnaire.T1 images were analyzed using Freesurfer software ver. 5.2.0 to parcellate regional gray matter volumes across the whole brain. We found in healthy adults, higher proportion of dietary carbohydrates decreased brain volumes in young adults, but increased brain volumes in older adults. Proportion of dietary proteins had minimal effects on young adult brain volumes, but decreased brain volumes in older adults. Age requirements play a critical role in the effect of macronutrients on brain volume in young and older adults.