建立國人n-6及n-3脂肪酸膳食評估運算方法

Abstract

目前國內少有針對膳食n-6及n-3脂肪酸進行探討，而國際間在分析膳食n-6及n-3脂肪酸時，其加總項目並無一定論；在n-6/n-3攝取比值方面，則因臨床數據不充足，建議值的訂定仍需要有更多研究進行探討。本研究目的在建立本土的n-6及n-3脂肪酸食品營養成份資料庫，以及藉由24小時飲食回憶及飲食頻率問卷，了解國人n-6及n-3脂肪酸攝取狀況及飲食型態，同時檢測兩方法之相對效度，並進一步模擬出符合n-6及n-3脂肪酸建議量之飲食型態。 本研究受試者主要來自民國98年11月至民國99年3月，於臺北市立婦幼醫院招募之孕婦，並於民國101年4月至12月（其新生兒滿2歲時），在詢問婦女後續受訪意願下，同時並進行配偶的招募，共針對36位幼兒父母（父母親各18位）進行研究分析。利用24小時飲食回憶及飲食頻率問卷，收集幼兒父母的整日飲食內容，並運用本研究室研發之運算系統NUFOOD.2進行分析。本研究同時建立n-6及n-3多元不飽和脂肪酸資料庫，以精進n-6及n-3脂肪酸攝取量之估算，資料收集為將運算系統NUFOOD.2內建之733種食物原料，增設8種多元不飽和脂肪酸，並完成數據補遺，其脂肪酸分別為C18:2 n-6、C18:3 n-3、C18:3 n-6、C18:4 n-3、C20:4 n-6、C20:5 n-3、C22:5 n-3、C22:6 n-3。為模擬「達到n-6及n-3脂肪酸建議攝取量之飲食型態」，本研究另利用受試者之24小時飲食回憶資料，進行飲食型態之調整。統計分析以SPSS 20.0進行處理。 結果發現，在24小時飲食回憶評估方面，成人每日平均熱量攝取為1983 kcal，蛋白質77 g、脂質70 g、醣類260 g，各占總熱量攝取的15.7%、30.9%、53.4%；在n-6及n-3脂肪酸的部分，n-6脂肪酸21614 mg、n-3脂肪酸2544 mg、n-6/n-3比值為8.9。而在飲食頻率問卷評估方面，成人每日平均熱量攝取為2848 kcal，蛋白質109 g、脂質123 g、醣類327 g，各占總熱量攝取的15.1%、38.2%、46.7%；在n-6及n-3脂肪酸的部分，n-6脂肪酸35359 mg、n-3脂肪酸4446 mg、n-6/n-3比值則為8.1。分析本研究受試者n-6及n-3脂肪酸主要食物來源，則發現最主要來自於植物油類、牛肉類、蛋類、豬肉類及魚類。在食物攝取份量及頻率上，植物油類每日平均攝取34.8 g（約6茶匙）；牛肉類每日平均攝取16 g（約1/4個掌心大），平均每月攝取1.8次；蛋類每日平均攝取46.7 g（約1個），平均每週攝取3.1次；豬肉類每日平均攝取77.0 g（約1個掌心大），平均每週攝取2.4次；魚類每日平均攝取18.2 g（約1/4個掌心大），平均每週攝取1.9次。針對24小時飲食回憶及飲食頻率問卷，進行兩方法之相對效度分析，結果發現，若以皮爾森積差相關分析，則EPA及DHA呈顯著正相關(p< .01)，相關係數分別為.53及.48；若以斯皮爾曼等級相關分析，則是DHA及n-6/n-3攝取比值呈顯著正相關(p < .05)，相關係數分別為.45及.37。其次將飲食頻率問卷資料以24小時飲食回憶熱量校正(calibrated FFQ)，則發現兩方法之相對效度，除了C18:3 n-6及C18:4 n-3統計上未達顯著以外，其餘脂肪酸皆呈現顯著正相關 (p < .05)，相關係數介於.37到.73之間。在飲食型態的部分，若將受試者六大類食物調整成新版每日飲食指南建議份量，並在豆魚肉蛋類替換入12公克（約1/4掌心大）的鯖魚，或是95公克（約一個手掌大）的鱈魚，在油脂類則是替換入1茶匙的芥花油，則必需脂肪酸C18:2 n-6及C18:3 n-3可達到臺灣建議之總熱量4-8％及0.6-1.2％，EPA及DHA總量則可達到日本官方建議之1000 mg，n-6/n-3攝取比值則降至5.1-5.3。 由結果顯示，飲食頻率問卷所評估之脂肪酸攝取量，相較於24小時飲食回憶，會有部分高估的情況(p < .05)。在受試者的飲食型態發現，必需脂肪酸C18:2 n-6及C18:3 n-3的主要食物來源以植物油居多；而EPA及DHA主要食物來源以魚類居多，此結果與世界衛生組織(2008)的主要食物來源報告內容一致。經過24小時飲食回憶之熱量校正後，更能呈現出飲食頻率問卷的良好相對效度；說明在以飲食頻率問卷進行膳食評估調查時，宜再收集受試者之24小時飲食回憶資料，以協助後續相對效度分析之校正。在模擬「達到n-6及n-3脂肪酸建議攝取量之飲食型態」的部分，將受試者之飲食型態調整成新版每日飲食指南的型式後，僅須再提高富含EPA及DHA魚類的攝取份量，以及增加富含C18:3 n-3植物油的使用份量，即可達到n-6及n-3脂肪酸建議量；而模擬後之n-6/n-3攝取比值約為5，此結果或許可以作為國內實踐n-6及n-3脂肪酸建議攝取量之n-6/n-3建議攝取比值。 基於適當的n-6及n-3脂肪酸攝取量，能降低心血管疾病的死亡率及發炎相關疾病的嚴重性，針對國人n-3脂肪酸未達建議值的現象，建議提倡民眾提高富含EPA及DHA魚類的攝取份量，並增加富含C18:3 n-3植物油的使用份量，以維護國人的健康。Currently, research on dietary n-6 and n-3 fatty acid in Taiwan is scare, and related international studies have not reached a consensus on the analysis of these two types of fatty acids. Furthermore, because clinical data regarding the dietary n-6/n-3 fatty acid ratio are insufficient, the establishment of recommended values requires further research and discussion. The objective of this study was to establish a domestic database on the nutritional composition of foods containing n-6 and n-3 fatty acids and to obtain the dietary patterns and n-6 and n-3 fatty acid intake in the Taiwanese population. Questionnaires that evaluated participant 24-hour dietary recalls and food frequency questionnaires were conducted. In addition, we assessed the relative validity of the two questionnaires and simulated dietary patterns that fulfilled the recommended intakes of n-6 and n-3 fatty acids. The participants of the study were pregnant women recruited at the Heping Fuyou branch of Taipei City Hospital, from November 2009 to March 2010. Between April and December 2012 (when the newborns of the participants reached the age of 2 y), the spouses of the participants were also recruited after assessing the participants’ willingness to conduct follow-up interviews. We employed the NUFOOD.2 computational system (researched and developed in our laboratory) to analyze the daily dietary intake of 36 parents (18 fathers and mothers, respectively) that was collected by using 24-hour dietary recalls and food frequency questionnaires (FFQ). In addition, we established a database of n-6 and n-3 polyunsaturated fatty acids to enhance the estimation precision of n-6 and n-3 fatty acid intake. Data were collected to establish 733 types of food ingredients in the NUFOOD.2 system; 8 types of polyunsaturated fatty acids were added (ie, C18:2 n-6, C18:3 n-3, C18:3 n-6, C18:4 n-3, C20:4 n-6, C20:5 n-3, C22:5 n-3, and C22:6 n-3); and missing data were provided. To simulate dietary patterns promoting the recommended intake of n-6 and n-3 fatty acids, we used the 24-hour dietary recall data of the participants to adjust their dietary patterns. Statistical analyses were conducted using SPSS 20.0 software. The results of the 24-hour dietary recalls evaluation indicated that the participants’ average daily calorie intake was 1983 kcal; the average intake of protein, fat, and carbohydrates was 77 g, 70 g, and 260 g, respectively, and accounted for 15.7%, 30.9%, and 53.4% of the total calorie intake, respectively; the average intake of n-6 and n-3 fatty acids was 21614 mg and 2544 mg, respectively (the n-6/n-3 ratio was 8.9). The results of the FFQ indicated that participant average daily calorie intake was 2848 kcal; the average intake of protein, fat, and carbohydrates was 109 g, 123 g, and 327 g, respectively, and accounted for 15.1%, 38.2%, and 46.7% of the total calorie intake, respectively; the average intake of n-6 and n-3 fatty acids was 35359 mg and 4446 mg, respectively (the n-6/n-3 ratio was 8.1). Analysis showed that participants’ primary food sources for n-6 and n-3 fatty acids were vegetable oil, beef, eggs, pork, and fish. The average daily intake and frequency of related food sources were as follows: 34.8 g (approximately 6 t.) of vegetable oil; 16 g (approximately 1/4 of a human palm) of beef, 1.8 times per month on average; 46.7 g (approximately 1 serving) of eggs (average of 3.1/wk); 77 g (approximately a human palm) of pork (average of 2.4/wk); and 18.2 g (approximately 1/4 of a human palm) of fish (average of 1.9/wk). Regarding the relative validity of the 24-hour dietary recalls and FFQ, the Pearson product-moment correlation analysis indicated that eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) exhibited a positive correlation (p< .01), with respective correlation coefficients of .53 and .48. The Spearman’s rank correlation coefficient analysis showed a positive correlation (p < .05) between DHA and the dietary n-6/n-3 fatty acid ratio, with correlation coefficients of .45 and .37, respectively. The FFQ data were calibrated using the 24-hour dietary recall data; the calorie-adjusted results indicated that the relative validity of the 2 questionnaires exhibited a positive correlation for all fatty acids (p < .05), with correlation coefficients ranging between .37 and .73, whereas C18:3 n-6 and C18:4 n-3 did not achieve statistical significance. For dietary patterns, the recommended intake of C18:2 n-6 and C18:3 n-3 essential fatty acids (respectively accounting for 4-8% and 0.6-1.2% of total calories) for the Taiwanese population can be achieved by adjusting the 6 major food groups of the participants’ diet to the recommended intake based on a new food guide, that is, substituting 12 g (approximately 1/4 of a human palm) of Mackerel or 95 g (approximately a human palm) of codfish into the soybean/fish/meat/eggs group and substituting 1 t. of canola oil into the fats and oil group. In addition, the suggested combined intake (1000 mg) of EPA and DHA based on the official Japanese recommendations can be attained through this adjustment, and the dietary n-6/n-3 fatty acid ratio is reduced to 5.1-5.3. The results showed that the fatty acid intake evaluated through the FFQ was partially overestimated compared to the 24-hour dietary recalls (p< .05). Participant dietary patterns indicated that the primary food source of C18:2 n-6 and C18:3 n-3 essential fatty acids was vegetable oil, and the food source for EPA and DHA was fish, which is consistent with the World Health Organization 2008 report on primary food sources. The excellent relative validity of the FFQ was further demonstrated following the 24-hour dietary recall calibration. The concurrent collection of 24-hour dietary recalls data and FFQ during dietary assessment surveysfacilitates the calibration of relative validity in subsequent analyses. Regarding the simulation of dietary patterns that promote recommended n-6 and n-3 fatty acid intake, the results show that an increased intake of fish (high in EPA and DHA) and vegetable oil (high in C18:3 n-3) is required after participant dietary patterns were adjusted based on the new food guide model, which provides the recommended intake of n-6 and n-3 fatty acids. After the simulation, the dietary n-6/n-3 fatty acid ratio was found to be approximately 5. This result can possibly be adopted as a recommended n-6/n-3 intake ratio in the domestic implementation of n-6 and n-3 fatty acid suggested intake amounts. Since an appropriate n-6 and n-3 fatty acid intake can reduce cardiovascular mortality and severity of inflammation-related diseases, for people n-3 fatty acid intake below the recommended value of the phenomenon, it is recommended to promote public rich in EPA and DHA increased intake of fish, and increase rich in C18:3 n-3 servings of vegetable oils used to protect people's health.