Ock K. Chun

Estimation of Antioxidant Intakes from Diet and Supplements in U.S. Adults

The importance of antioxidants in reducing risks of chronic diseases has been well established; however, antioxidant intakes by a free-living population have not yet been estimated adequately. In this study, we aimed to estimate total antioxidant intakes from diets and supplement sources in the U.S. population. The USDA Flavonoid Database, food consumption data, and dietary supplement use data of 8809 U.S. adults aged >/=19 y in NHANES 1999-2000 and 2001-2002 were used in this study. Daily total antioxidant intake was 208 mg vitamin C (46 and 54% from diets and supplements, respectively), 20 mg alpha-tocopherol (36 and 64), 223 mug retinol activity equivalents carotenes (86 and 14), 122 mug selenium (89 and 11), and 210 mg flavonoids (98 and 2). Antioxidant intakes differed among sociodemographic subgroups and lifestyle behaviors. Energy-adjusted dietary antioxidant intakes were higher in women, older adults, Caucasians, nonconsumers of alcohol (only for vitamin C and carotenes), nonsmokers (only for vitamin C, vitamin E, and carotenes), and in those with a higher income and exercise level (except for flavonoids) than in their counterparts (P < 0.05). Consumption of fruits, vegetables, and whole grains may be a good strategy to increase antioxidant intake. The possible association between antioxidant intake and the prevalence of chronic diseases should be investigated further.

Plasma and Dietary Antioxidant Status as Cardiovascular Disease Risk Factors: A Review of Human Studies

Extensive evidence has demonstrated that many antioxidants such as vitamin C, vitamin E, carotenoids and polyphenols have protective effects in preventing cardiovascular disease (CVD), a chronic disease that is mediated by oxidative stress and inflammation. This review focuses on evidence from prospective cohort studies and clinical trials in regard to the associations between plasma/dietary antioxidants and cardiovascular events. Long-term, large-scale, population-based cohort studies have found that higher levels of serum albumin, bilirubin, glutathione, vitamin E, vitamin C, and carotenoids were associated with a lower risk of CVD. Evidence from the cohort studies in regard to dietary antioxidants also supported the protective effects of dietary vitamin E, vitamin C, carotenoids, and polyphenols on CVD risk. However, results from large randomized controlled trials did not support long-term use of single antioxidant supplements for CVD prevention due to their null or even adverse effects on major cardiovascular events or cancer. Diet quality indexes that consider overall diet quality rather than single nutrients have been drawing increasing attention. Cohort studies and intervention studies that focused on diet patterns such as high total antioxidant capacity have documented protective effects on CVD risk. This review provides a perspective for future studies that investigate antioxidant intake and risk of CVD.

Estimation of Daily Proanthocyanidin Intake and Major Food Sources in the U.S. Diet

Proanthocyanidins (PA), the polymers of flavan-3-ols, have cardioprotective and cancer preventive properties as shown in clinical studies. The PA intake in a free-living population has not yet been reported, however. We aimed to estimate the dietary intake of PA and identify its major sources by combining the recently released and expanded USDA PA database with food consumption data of 8809 U.S. adults in the NHANES 1999-2002. U.S. adults over 19 y had a total PA intake of 95 mg/d, in the order of polymers (30%), monomers (22%), dimers (16%), 4-6 mers (15%), 7-10 mers (11%), and trimers (5%). When adjusted for energy intake, the total PA intake increased with age (P < 0.001), was higher in women than men (P < 0.01) and in alcohol consumers compared with nonconsumers (P < 0.05), and was lower in non-Hispanic blacks compared with other ethnicities (P < 0.001). Three major food sources, tea, legumes, and wines, contributed 45 mg (48%) of daily PA intake. The marked differences in PA intake among various sociodemographic subgroups need further investigation in relation to health disparities and chronic disease prevalence in the US.

Food Matrix Affecting Anthocyanin Bioavailability: Review

Anthocyanins, abundant in deep-colored fruits and vegetables, have received considerable attention due to their potential health benefits. However, the bioavailability of anthocyanins is relatively low compared to that of other flavonoids. While previous reviews focused on the absorption, metabolism and excretion of anthocyanins, little information is available on the effects of food matrix on anthocyanin bioavailability, particularly food matrices of the usual diet. The present review includes the recent studies on interactive effects of anthocyanins and certain food components. Evidence suggests that the bioavailability of anthocyanins varies markedly depending on food matrices, including other antioxidants and macronutrients present in foods consumed, which consequently affects the absorption and antioxidant capacity of anthocyanins. Further studies are needed to gain insight into the mechanisms underlying the interactive effects of anthocyanins and food components in their bioavailability and antioxidant capacity of anthocyanins at the physiological level.

Berry anthocyanins suppress the expression and secretion of proinflammatory mediators in macrophages by inhibiting nuclear translocation of NF-κB independent of NRF2-mediated mechanism

The objectives of this study were to compare the anti-inflammatory effects of anthocyanins from blueberry (BBA), blackberry (BKA), and blackcurrant (BCA) and to determine the relationship between their antioxidant capacity and anti-inflammatory effect in macrophages. Major anthocyanins in BBA, BKA and BCA were malvidin-3-glucoside (16%), cyanidin-3-glucoside (98%) and delphinidin-3-rutinoside (44%), respectively. BKA showed higher total antioxidant capacity than BBA and BCA. RAW 264.7 macrophages were incubated with 0-20 μg/ml of BBA, BKA and BCA, and subsequently activated by lipopolysaccharide (LPS) to measure proinflammatory cytokine production. Interleukin 1β (IL-1β) messenger RNA (mRNA) levels were significantly decreased by all berry anthocyanins at 10 μg/ml or higher. Tumor necrosis factor α (TNFα) mRNA levels and secretion were also significantly decreased in LPS-treated macrophages. The levels of the repression were comparable for all berry anthocyanins. LPS-induced nuclear factor κB (NF-κB) p65 translocation to the nucleus was markedly attenuated by all of the berry anthocyanins. In bone marrow-derived macrophages (BMMs) from nuclear factor E2-related factor 2 wild-type (Nrf2(+/+)) mice, BBA, BKA and BCA significantly decreased cellular reactive oxygen species (ROS) levels with a concomitant decrease in IL-1β mRNA levels upon LPS stimulation. However, in the BMM from Nrf2(-/-) mice, the anthocyanin fractions were able to significantly decrease IL-1β mRNA despite the fact that ROS levels were not significantly affected. In conclusion, BBA, BKA and BCA exert their anti-inflammatory effects in macrophages, at least in part, by inhibiting nuclear translocation of NF-κB independent of the NRF2-mediated pathways.

Estimation of risks of pesticide exposure, by food intake, to Koreans

The aim of this study was to evaluate theoretical maximum daily intake (TMDI) and estimated daily intake (EDI) for Korean by using maximum residue levels (MRLs), food intake, residue data and correction factors, and compare with acceptable daily intake (ADI) in order to estimate the health risk based on the pesticide exposure. Then, the oncogenic risks of the pesticides were assessed from TMDI and estimated daily intake with treatment (adjusted EDI). The percent ratio of TMDI to ADI for 262 pesticides was mostly below 80%, but 42 pesticides (16.0%) exceeded the ADI. EDI without treatment (non-adjusted EDI) and estimated daily intake with treatment (adjusted EDI) were summed up to about 6.41 ml/day/capita and 2.94 ml/day/capita, respectively. The percentage of ADI was TMDI (101.04%) > non-adjusted EDI (0.08%) > adjusted EDI (0.01%), and the exposure level of Korean population to whole pesticides was below the level to produce health risk. The dietary oncogenic risk for Koreans was estimated to be 7.3x10(-4) on the basis of TMDI, 1.8x10(-7) on the basis of adjusted EDI, and although the level from TMDI exceeded the risk level (1x10(-6)) of the Environment Protection Agency (EPA), the level from adjusted EDI, real exposure level, was below it.

Urinary Isoflavones and Their Metabolites Validate the Dietary Isoflavone Intakes in US Adults

BACKGROUND Isoflavones are derived from dietary sources and considered to promote health by preventing the onset of such chronic diseases as cardiovascular disease, cancer, and osteoporosis. Valid and reliable estimation of isoflavone intake is a prerequisite to establishing biological functions of isoflavones on health risks. OBJECTIVE This study aimed to validate the approach of estimating dietary isoflavone intake with respective urinary isoflavone concentrations in US adults. DESIGN Data from the US Department of Agriculture isoflavone database and dietary recalls of 2,908 US adults with urinary isoflavone data in the 1999-2002 National Health and Nutrition Examination Survey were used. RESULTS Dietary isoflavone was consumed by only 35% of adults in a day with an average intake of 3.1 mg/day, which resulted in a mean intake of 1.0 mg/day for all US adults. The isoflavone intakes were from genistein (55%), diadzein (35%), glycitein (7%), biochanin A (2%), and formononetin (2%). Both daily total and energy adjusted isoflavone intake differed by race/ethnicity subgroups (P<0.05) and was associated positively with income (P<0.01) and inversely with body mass index (P<0.05). Geometric mean urinary isoflavone concentration was 5.0 ng/mL among isoflavone consumers and the urinary genistein and daidzein excretion correlated with their isoflavone intake levels (P<0.01). CONCLUSIONS In large population-based studies, estimated dietary isoflavone intake can be validated by urinary isoflavones. Further studies are needed at an individual level to validate dietary isoflavone intake by urinary isoflavone concentration.

Dietary Antioxidants and Prostate Cancer: A Review

Prostate cancer is the most common noncutaneous cancer in men in the United States. Several studies have examined the relationship between prostate cancer and antioxidants; however, the results of these studies are inconsistent. This article provides a systematic review of studies on prostate cancer and antioxidant intake from diet and supplements. Tea and coffee appear to offer protection against advanced prostate cancer. Different forms of vitamin E appear to exert different effects on prostate cancer, with alpha-tocopherol potentially increasing and gamma-tocopherol potentially decreasing risk of the disease. There is no strong evidence for a beneficial effect of selenium, vitamin C, or beta-carotene, whereas lycopene appears to be negatively associated with risk of the disease. The effect of dietary antioxidants on prostate cancer remains undefined and inconclusive, with different antioxidants affecting prostate cancer risk differentially. Further studies are needed to clarify the relationship between antioxidants and prostate cancer risk and to delineate the underlying mechanisms.

Dietary fat increases quercetin bioavailability in overweight adults.

SCOPE Epidemiologic evidence supports that dietary quercetin reduces cardiovascular disease (CVD) risk, but its oral bioavailability is paradoxically low. The aim of this study was to determine whether dietary fat would improve quercetin bioavailability in adults at high risk for CVD and to assess lipid-mediated micellarization of quercetin in vitro. METHODS AND RESULTS In a randomized, cross-over study, overweight/obese men and postmenopausal women (n = 4 M/5 F; 55.9 ± 2.1 years; 30.8 ± 1.4 kg/m(2) ) ingested 1095 mg of quercetin aglycone with a standardized breakfast that was fat-free (<0.5 g), low-fat (4.0 g), or high-fat (15.4 g). Plasma was obtained at timed intervals for 24 h to measure quercetin and its methylated metabolites isorhamnetin and tamarixetin. Compared to the fat-free trial, plasma quercetin maximum concentration (Cmax ), and area under curve (AUC0-24 h ) increased (p < 0.05) by 45 and 32%, respectively, during the high-fat trial. During the high-fat trial, isorhamnetin Cmax and AUC0-24 h also increased by 40 and 19%, respectively, whereas Cmax and AUC0-24 h of tamarixetin increased by 46 and 43%, respectively. Dietary fat dose-dependently increased micellarization efficiency of quercetin aglycone in vitro. CONCLUSION Dietary fat improves quercetin bioavailability by increasing its absorption, likely by enhancing its micellarization at the small intestine.

Estimation of total antioxidant capacity from diet and supplements in US adults.

Given the importance of dietary antioxidants in reducing the risks of chronic diseases, the present study aimed to estimate the intake of total antioxidant capacity (TAC) from diet and dietary supplements of US adults. We utilised the US Department of Agriculture flavonoid and proanthocyanidin databases, dietary supplement data and food consumption data of 4391 US adults aged 19+ years in the National Health and Nutrition Examination Survey 2001-2. In order to convert the intake data of individual antioxidant compounds to TAC values, the vitamin C equivalent (VCE) of forty-three antioxidant nutrients measured previously was also applied. Daily TAC averaged 503.3 mg VCE/d (approximately 75 % from diet and 25 % from supplements). The energy-adjusted daily TAC level from diet and supplements was higher in women (except for carotenoids), older adults, Caucasian (except for carotenoids), non-alcohol consumers (for vitamin E and proanthocyanidins), subjects with higher income (except for carotenoids) and higher exercise levels than their counterparts (P < 0.05). TAC was positively associated with daily consumption of fruits and fruit juices, vegetables and vegetable products, beverages, wines and teas (P < 0.001). Teas, dietary supplements, and fruits and fruit juices were the major sources of dietary TAC of the US population (28, 25 and 17 %, respectively), while the contribution of vegetables and vegetable products to TAC was minimal ( < 2 %). The present study indicates that antioxidant intake from various diet and supplements contributes to TAC status. TAC levels are different in sociodemographic subgroups of the US population. The relationship between TAC intake and risks of chronic disease warrants further investigation.