2.3. Dietary Assessment and Dietary Inflammatory Index (DII)

The details of dietary assessment and DII calculation have been described previously [22]. Generally, daily and weekly intakes of 280 food items in the past year were assessed by RA at baseline using a locally developed and validated semi-quantitative food frequency questionnaire (FFQ) [26]. Mean nutrient quantitation and energy intakes per day were calculated mainly referring to food composition tables derived from the Chinese Medical Sciences Institute [9,13] and the Centre for Food Safety in Hong Kong [27], and supplementally referring to the food composition tables from Taiwan Food and Drug Administration [12] and the US Department of Agriculture (USDA) [28]. DII was developed by Dr. Hébert and et al., and the details have been provided elsewhere [19]. Briefly, a scoring algorithm for 45 food parameters, referring to their effects on the levels of inflammatory markers (IL-1β, IL-4, IL-6, IL-10, CRP, and TNF-α) was developed. In the present study, based on FFQ-derived dietary data, 30 out of 45 food parameters were available to calculate DII. The 30 food parameters were energy, protein, carbohydrate, total fat, saturated fat, monounsaturated fatty acid, polyunsaturated fatty acid, fibre, cholesterol, vitamin B12, vitamin B6, folic acid, thiamin, niacin, riboflavin, vitamin A, b-carotene, vitamin C, vitamin D, vitamin E, iron, magnesium, selenium, zinc, isoflavones, alcohol, caffeine, onion, pepper, and green/black tea. Baseline DII score was the sum of the transformed mean intake of each food composition parameters multiplied by their related inflammatory effect score [19]. A higher and positive DII score indicates a more pro-inflammatory diet, while a lower and negative one indicates a more anti-inflammatory diet. In the present study, a pro-inflammatory diet is defined as a diet in the highest tertile of DII in this community-dwelling older population [22].