Dietary Polyphenol Intake in US Adults and 10-Year Trends: 2007-2016.

BACKGROUND: Polyphenols are a class of phytochemicals that have antioxidant, anti-inflammatory, anticancer, and antiviral properties. Previous research suggests that dietary polyphenol intake is protective against major chronic diseases. To our knowledge, no data on polyphenol intake for the US adult population are available. OBJECTIVE: This study explored usual dietary polyphenol intake among US adults in 2013-2016 and examined trends in intake during 2007-2016 by demographic characteristics, and identified major dietary sources of polyphenols. DESIGN: The National Health and Nutrition Examination Survey is a series of cross-sectional surveys representative of the civilian noninstitutionalized US population. PARTICIPANTS/SETTING: This study included 9,773 adults aged 20 years and older. MAIN OUTCOME MEASURES: Dietary and supplement data were obtained from two 24-hour dietary recalls. Polyphenol intake was estimated using the Phenol Explorer Database and adjusted for total energy intake. STATISTICAL ANALYSIS PERFORMED: Usual intake was estimated both overall and by demographic characteristics using the National Cancer Institute method. Trends in intake on a given day over 10 years were evaluated using regression analysis. The complex survey design was incorporated in all analyses. RESULTS: In 2013-2016, the usual intake of dietary polyphenols was a mean (standard error) of 884.1 (20.4) mg per 1,000 kcal/d. Polyphenol intake was higher in adults 40 years and older, women, non-Hispanic White adults, and college graduates. During 2007-2016, the mean daily polyphenol intake did not change significantly over time for overall and demographic groups. Main polyphenol classes consumed were phenolic acids (mean [standard error] of 1,005.6 [34.3] mg/d) and flavonoids (mean [standard error] of 379.1 [10.7] mg/d). Foods and beverages contributed 99.8% of polyphenol intake, with coffee (39.6%), beans (9.8%), and tea (7.6%) as major dietary contributors. CONCLUSION: Findings from this study suggest that polyphenol intake is consistent with the low intake of fruits, vegetables, and whole grains in the US population, and provide more evidence of the need for increased consumption of these food groups.

Caffeine Consumption Contributes to Skin Intrinsic Fluorescence in Type 1 Diabetes.

BACKGROUND: A variant (rs1495741) in the gene for the N-acetyltransferase 2 (NAT2) protein is associated with skin intrinsic fluorescence (SIF), a noninvasive measure of advanced glycation end products and other fluorophores in the skin. Because NAT2 is involved in caffeine metabolism, we aimed to determine whether caffeine consumption is associated with SIF and whether rs1495741 is associated with SIF independently of caffeine. MATERIALS AND METHODS: SIF was measured in 1,181 participants with type 1 diabetes from the Epidemiology of Diabetes Interventions and Complications study. Two measures of SIF were used: SIF1, using a 375-nm excitation light-emitting diode (LED), and SIF14 (456-nm LED). Food frequency questionnaires were used to estimate mean caffeine intake. To establish replication, we examined a second type 1 diabetes cohort. RESULTS: Higher caffeine intake was significantly associated with higher SIF1(LED 375 nm[0.6, 0.2]) (P=2×10(-32)) and SIF14L(ED 456 nm[0.4, 0.8]) (P=7×10(-31)) and accounted for 4% of the variance in each after adjusting for covariates. When analyzed together, caffeine intake and rs1495741 both remained highly significantly associated with SIF1(LED 375 nm[0.6, 0.2]) and SIF14(LED 456 nm[0.4, 0.8]). Mean caffeinated coffee intake was also positively associated with SIF1(LED 375 nm[0.6, 0.2]) (P=9×10(-12)) and SIF14(LED 456 nm[0.4, 0.8]) (P=4×10(-12)), but no association was observed for decaffeinated coffee intake. Finally, caffeine was also positively associated with SIF1(LED 375 nm[0.6, 0.2]) and SIF14(LED 456 nm[0.4, 0.8]) (P<0.0001) in the replication cohort. CONCLUSIONS: Caffeine contributes to SIF. The effect of rs1495741 on SIF appears to be partially independent of caffeine consumption. Because SIF and coffee intake are each associated with cardiovascular disease, our findings suggest that accounting for coffee and/or caffeine intake may improve risk prediction models for SIF and cardiovascular disease in individuals with diabetes.