| Summary: | 碩士 === 國立臺灣師範大學 === 人類發展與家庭學系 === 101 === 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 surveys facilitates 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.
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