台灣地區老年人葉酸營養狀況與慢性疾病之相關性探討

Association of Folate Status and Chronic Diseases in Elderly Taiwanese

陳冠如(Kuan-Ju Chen)

指導教授 ： 林璧鳳

共同指導教授 ： 潘文涵

國立臺灣大學/生命科學院/微生物與生化學研究所/博士(2006年)

https://doi.org/10.6342/NTU.2006.03102

摘要

中文摘要
本研究以衛生署1999年至2000年進行的「台灣地區老人營養健康狀況調查1999-2000」（Elderly Nutrition and Heath Survey in Taiwan, Elderly NAHSIT）計畫中的65歲以上老年人為研究對象，蒐集男性樣本1213人和女性樣本1169人，共計2382人，以全自動免疫分析儀測定血漿葉酸、同半胱胺酸濃度，並配合Elderly NAHSIT資料庫中的人體測量、生化檢驗、飲食資料、疾病史與暫時性腦缺血發作問卷 (transient ischemic attack; TIA questionnaire) 等資料，以探討台灣老人之 (1)葉酸營養與富含葉酸食物攝取狀況 (2)葉酸等維生素B對同半胱胺酸濃度的影響 (3)葉酸等維生素B與同半胱胺酸濃度的影響因素 (4)葉酸等維生素B、同半胱胺酸與高血壓、中風、腎功能不全及白內障的相關性。
此次調查指出台灣老人血漿葉酸濃度，女性 (12.8±0.6 ng/mL) 顯著高於男性 (10.4±0.6 ng/mL)。葉酸缺乏率 (血漿葉酸濃度小於3 ng/mL) 接近零，但是葉酸瀕臨缺乏率 (血漿葉酸濃度介於3-6 ng/mL) 仍高達12~18%。飲食葉酸攝取量，男性 (379±18 µg/d) 與女性 (351±27 µg/d) 無顯著差異；只有一半的老人族群葉酸攝取量達到2/3 RDA (400 µg/d)。增加蔬菜、菇蕈與水果類的攝取頻率，與提高飲食葉酸攝取量有關；女性老人隨著年齡增長對水果的攝取逐漸減少，而顯著影響葉酸營養狀況。
台灣老人的血漿同半胱胺酸濃度，男性 (13.3 µmole/L) 顯著高於女性 (10.6 µmole/L)。血漿同半胱胺酸濃度高於15 µmol/L盛行率，男性為23.4%，顯著高於女性的11.2%。葉酸、維生素B6與B12，是與台灣老人血漿同半胱胺酸濃度有關的營養因子。同時有二種以上維生素B不足者 (葉酸與維生素B6 vs葉酸與維生素B12) ，高同半胱胺酸血症的危險性高於單一維生素B不足者。
探討台灣老人葉酸等維生素B、血漿同半胱胺酸濃度的相關因素，結果顯示抽煙、服用營養補充劑、規律運動會影響葉酸、維生素B2或B6營養狀況，亦會影響血漿同半胱胺酸濃度。此外血漿同半胱胺酸濃度，有隨著年齡、收縮壓、血清肌酸酐濃度、咖啡攝取頻率的增加而上升，茶攝取頻率的增加而減少的趨勢。雖然素食者的血漿葉酸濃度較高，不過，素食者的血漿同半胱胺酸濃度高於非素食者，可能與素食者的維生素B12濃度較低有關，值得注意。攝取較多蔬菜、菇蕈及水果類的飲食因素，有助於改善葉酸，維生素B2營養狀況，亦與低血漿同半胱胺酸濃度有關。老年族群血中葉酸等維生素B與同半胱胺酸濃度，除了受生理、生活型態與飲食因素影響外，應尚受其他未知因素所影響。
對罹患慢性疾病的相關因子探討結果顯示， C-反應蛋白正常者，同半胱胺酸濃度上升仍與高血壓、中風、腎功能不全的危險性有關。此外，血漿同半胱胺酸濃度較高者， C-反應蛋白濃度也高時，比單一同半胱胺酸或C-反應蛋白濃度上升的老人顯著增加罹患高血壓、中風和腎功能不全的危險性。年齡增加、低舒張壓、糖尿病、葉酸不足，與老人白內障的危險性有關。即使VitB2、VitB6與VitB12營養皆充足時，葉酸不足仍與老人中風、白內障的危險性有關；推測葉酸不足與老人中風、白內障的危險性，可能受到維生素B營養狀況所影響。年齡≧75歲且葉酸缺乏之男性老人的白內障危險性，高於單一年齡≧75 歲或葉酸缺乏者，故建議75歲以上老人更應注意葉酸營養狀況，以避免白內障的危險性增加。
以上的結果顯示台灣老人的葉酸營養狀況、高同半胱胺酸血症的盛行率仍應注意。葉酸、維生素B6及B12，與維持正常血漿同半胱胺酸濃度有關。本橫斷面研究結果雖未能說明因果關係，不過，規律運動、減少抽煙、咖啡，並增加蔬菜與水果類的攝取，以改善葉酸等維生素B的營養狀況，降低血漿同半胱胺酸濃度，對減少中風、高血壓、腎功能不全與白內障的危險性，應有所助益。

關鍵字

葉酸 ； 同半胱胺酸 ； 中風 ； 高血壓 ； 腎功能不全 ； 白內障

並列摘要

Abstract
To investigate the relationship between folate status and dietary folate intake, homocysteine (Hcy) and B vitamins status, B vitamins status and chronic diseases such as hypertension, stroke, renal insufficiency and cataract in elderly Taiwanese, we analyzed plasma folate levels, Hcy and dietary folate intake in elderly subjects aged higher than 65 y, sampled from the Elderly Nutrition and Health Survey in Taiwan (1999-2000) (Elderly NAHSIT).
Results showed that the mean plasma folate levels were 10.1 ± 0.6 ng/mL for males and 13.0 ± 0.7 ng/mL for females. The average plasma folate concentrations of males from all age groups were significantly lower than those of females. None of the study subjects had a plasma folate level below 3 ng/mL. However, 18.6% of males and 12.1% of females had marginal folate deficiency, with plasma folate between 3-6 ng/mL. The average estimated folate intakes were 379 ± 18 µg/d in males and 351 ± 27 µg/d in females. Moreover, 45.5% of males and 48.8% of females had a dietary folate intake below 2/3 of the RDA of 400 µg/d. Our results indicated that dietary folate intake increased with increased intakes of vegetables, mushrooms and fruit. A lower intake of fruit appeared to be responsible for the higher prevalence of marginal folate deficiency among females over the age of 80 years.
The average plasma Hcy levels of males (13.3 ± 0.6 µmol/L) were significantly higher than those of females (10.6 ±0.7 µmol/L). The overall prevalence of hyperhomocysteinemia (Hcy > 15 µmol/L) was 23.4% for elderly males and 11.2% for elderly females. In subjects with normal renal function, vitamin B6, B12 and folate status were independent nutritional factors associated with elevated Hcy levels in elderly Taiwanese. A combination of insufficiency in two B vitamins had an additive effect on the risk of hyperhomocysteinemia.
To investigate the effect of life style and dietary factor on the vitamin B status and Hcy levels, our results showed that smoking, consumption of nutrient supplement and physical activity were major lifestyle factors associated with folate, vitamin B2, B6 status and plasma Hcy. The average plasma Hcy levels increased with increased age, systolic pressure, serum creatinine level and coffee consumption, and decreased with increased tea consumption. Compared with the nonvegetarians, the vegetarians had significantly higher levels of plasma folate, but lower levels of vitamin B12. The plasma Hcy levels of vegetarians were significantly higher than those of nonvegetarians presumably due to lower levels of plasma vitamin B12. A higher intake of vegetables, mushrooms and fruit appeared to be responsible for the good status of folate and vitamin B2, and lower levels of Hcy.
In a multiple logistic regression model, we found that elderly persons with normal C-reactive protein (CRP), the higher plasma Hcy was associated with hypertension, stroke and renal insufficiency. Further analysis showed that the strength of the association between higher plasma Hcy levels and hypertension, stroke, renal insufficiency was increased when combined with higher plasma CRP levels. The cataract was associated with aging, lower diastolic pressure, diabetes and folate insufficiency. We also found that folate insufficiency was associated with cataract in elderly persons who had adequate vitamin B2, B6 and B12 status. This suggests that the association between folate status and cataract is influenced by vitamin B2, B6 and B12 status. A combination of the elderly persons aged higher than 75 y with folate insufficiency had an additive effect on the risk of cataract. To maintain a good folate status should be especially promoted for those aged higher than 75 y.
In summary, it should be noted that up to 18.6% of males and 12.1% of females had marginal folate deficiency, the prevalence of plasma Hcy above 15 µmol/L was particularly high in elderly males at 23.4%. In addition, half of elderly Taiwanese still had inadequate folate intake. Vitamin B6, B12 and folate were independent nutritional factors associated with elevated Hcy levels in elderly Taiwanese. In this cross-sectional study, though cause and effect was unable to be clarified, the risk of elderly with chronic disease such as hypertension, stroke, renal insufficiency and cataract may be lowered through prevention of hyperhomocysteinemia and improving folate, vitamin B6 and B12 status by physical activity, avoiding smoking and encouraging intake of vegetables and fruits.

並列關鍵字

folate ； homocysteine ； stroke ； hypertension ； renal insufficiency ； cataract

參考文獻

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