Although the incidence of gastric cancer (GC) has declined, it remains the second most common cancer in Korea. As a class of phytochemicals, carotenoids are fat-soluble pigments that are abundant in fruits and vegetables and have health-promoting properties, including cancer prevention effects. This case-control study investigated the effects of total dietary carotenoids, dietary carotenoid subclasses (α-carotene, β-carotene, β-cryptoxanthin, lutein/zeaxanthin, and lycopene), and foods contributing to the dietary intake of each carotenoid on the risk of GC. Four hundred and fifteen cases and 830 controls were recruited from the National Cancer Center Hospital in Korea between March 2011 and December 2014. A significant inverse association between total dietary carotenoids and GC risk was observed among women (odds ratio (OR) 0.56, 95% confidence interval (CI) 0.32–0.99). A higher intake of dietary lycopene was inversely associated with GC risk overall in the subjects (OR 0.60, 95% CI 0.42–0.85, p for trend = 0.012), men (OR 0.60, 95% CI 0.39–0.93), and women (OR 0.54, 95% CI 0.30–0.96, p for trend = 0.039). This significant association between dietary lycopene intake and GC risk was also observed in the subgroups of Helicobacter pylori (H. pylori)-positive subjects and those who had ever smoked. Among the major contributing foods of dietary lycopene, consumption of tomatoes and tomato ketchup was inversely associated with GC risk in the overall subjects, men, and women. Based on our findings, a higher intake of dietary lycopene and contributing foods of lycopene (tomatoes and tomato ketchup) may be inversely associated with the risk of GC.

It is possible that blood B vitamins level and cognitive function may be affected by dietary intake of these vitamins, no study however has yet been conducted on relationships between B vitamins intake and cognitive function among elderly population in Korea. This study examined the relationship between B vitamins intake and cognitive function among elderly in South Korea. Participants consisted of 100 adults with mild cognitive impairment (MCI), 100 with Alzheimer’s disease (AD), and 121 normal subjects. Dietary intake data that included the use of dietary supplements were obtained using a 24-hour recall method by well-trained interviewers. Plasma folate and vitamin B12 concentrations were analyzed by radioimmunoassay, and homocysteine (Hcy) was assessed by a high performance liquid chromatography-fluorescence method. Plasma levels of folate and vitamin B12 were positively correlated with B vitamins intake; and plasma Hcy was negatively correlated with total intake of vitamin B2, vitamin B6, vitamin B12 and folate. In the AD group, a multiple regression analysis after adjusting for covariates revealed positive relationships between vitamin B2 intake and test scores for the MMSE-KC, Boston Naming, Word Fluency, Word List Memory and Constructional Recall Tests; and between vitamin B6 intake and the MMSE-KC, Boston Naming, Word Fluency, Word List Memory, Word List Recognition, Constructional Recall and Constructional Praxis Tests. Positive associations were observed between vitamin B12 intake and the MMSE-KC, Boston Naming, Constructional Recall and Constructional Praxis Tests, and between folate intake and the Constructional Recall Test. In the MCI group, vitamin B2 intake was positively associated with the MMSE-KC and Boston Naming Test, vitamin B6 intake was positively associated with the Boston Naming Test, and folate intake was positively associated with the MMSE-KC and Word List Memory test. No associations were observed in the normal group. These results suggested that total B vitamins intake is associated with cognitive function in cognitively impaired AD and MCI elderly, and the association is stronger in AD patients.

Long-chain polyunsaturated fatty acids (LC-PUFAs) are essential for infant neurodevelopment. The nutritional adequacy of dietary LC-PUFAs depends not only on the LC-PUFAs intake but also on the n-6 to n-3 fatty acid ratio (n-6/n-3 PUFAs). This study aimed to identify the association between the maternal dietary n-6/n-3 PUFAs and motor and cognitive development of infants at 6 months of age. We used data from 960 participants in the Mothers and Children's Environmental Health (MOCEH) study, which is a multi-center prospective cohort study. Dietary intake of pregnant women was assessed by a one-day 24-h recall method. Food consumption of infants was estimated based on the volume of breast milk and weaning foods. The duration of each feed was used to estimate the likely volume of milk consumed. Dietary intake of infants at 6 months was also assessed by a 24-h recall method. Cognitive and motor development of infants at 6 months of age was assessed by the Korean Bayley scales of infant development edition II (BSID-II) including the mental developmental index (MDI) and the psychomotor developmental index (PDI). Maternal intakes of n-6/n-3 PUFAs and linoleic acid (LA)-to-α-linolenic acid (ALA) ratio (LA/ALA) were 9.7 ± 6.3 and 11.12 ± 6.9, respectively. Multiple regression analysis, after adjusting for covariates, showed that n-6/n-3 PUFAs was negatively associated with both the MDI (β = −0.1674, P = 0.0291) and PDI (β = −0.1947, P = 0.0380) at 6 months of age. These inverse associations were also observed between LA/ALA and both the MDI and PDI (MDI; β = −0.1567; P = 0.0310, PDI; β = −0.1855; P = 0.0367). Multiple logistic regression analysis, with the covariates, showed that infants whose mother’s LA/ALA were ranked in the 2nd, 3rd, and 4th quartile were at approximately twice the risk with more than twice the risk of delayed performance on the PDI compared to the lowest quartile (1st vs. 2nd; OR = 2.965; 95% CI = 1.376 − 6.390, 1st vs. 3rd; OR = 3.047; 95% CI = 1.374 − 6.756 and 1st vs. 4th; OR = 2.551; 95% CI = 1.160 − 5.607). Both the maternal dietary n-6/n-3 PUFAs and LA/ALA intake were significantly associated with the mental and psychomotor development of infants at 6 months of age. Thus, maintaining low n-6/n-3 PUFAs and LA/ALA is encouraged for women during pregnancy.

Age-related bone loss is a major public health problem. This cross-sectional study examined the association between the dietary intake of carotenoids and bone mineral density (BMD). Data from 8022 subjects (3763 males and 4259 females) aged 30–75 years included in the Korean National Health and Nutrition Examination Survey (2008–2011) were analyzed. BMD was measured by dual-energy X-ray absorptiometry. Intake of carotenoids was estimated using 24-h dietary recall. In multiple linear analysis, after adjusting for covariates, lutein + zeaxanthin and β-cryptoxanthin intake was positively associated with total hip BMD in males and premenopausal women respectively, while β-carotene intake was positively correlated with femoral neck, total hip, and whole-body BMD in postmenopausal women. Postmenopausal women in the highest quintile of daily β-carotene intake, showed a lower risk of osteopenia at the lumbar spine (odds ratio (OR): 0.35, 95% CI: 0.16–0.79, P for trend = 0.009) than those in the lowest quintile, after adjusting for covariates. Daily β-cryptoxanthin intake was significantly associated with a lower risk of osteopenia at the total hip (OR per 1 mg/day increase: 0.76; 95% CI: 0.59–0.97), and lumbar spine (OR per 1 mg/day increase: 0.79; 95% CI: 0.70–0.89) in postmenopausal women. These results suggest that the dietary intake of β-carotene and β-cryptoxanthin may have a positive effect on bone health.

There is increasing evidence emerging that suggests high sugar intake may adversely increase the incidence of chronic diseases. However, there are only a few related studies in Korea. Based on the current Dietary Reference Intakes for Koreans, this study examined whether total sugar intake above 20% of the total energy was a risk factor for metabolic syndrome in middle-aged Korean adults. This cross-sectional study involved 7005 adults (3751 men and 3254 women) aged 40–69 years, who participated in the Korean Genome and Epidemiology Study (KoGES), a large community-based cohort study. Daily total sugar intake was estimated using a validated food frequency questionnaire. About 9% and 16% of the men and women, respectively, derived >20% of energy intake from total sugar. The males in this category had a significantly higher odds of obesity defined as having a BMI ≥ 25 (OR = 1.491, 95% CI = 1.162–1.914), low HDL-cholesterol (OR = 1.313, 95% CI = 1.038–1.660), and metabolic syndrome (OR = 1.332, 95% CI = 1.038–1.709) than those who received a lower proportion of energy intake from total sugar. These results suggest that high (>20%) energy intake from total sugar may be associated with an increased risk of metabolic syndrome in middle-aged Korean men.

Short sleep duration or poor sleep quality has been associated with an increased risk of obesity. Although the underlying mechanism remains unclear, one proposed pathway is poor diet quality. This cross-sectional study investigated whether diet quality modifies the association between sleep status and obesity in Korean adults. We used the baseline data and samples of 737 men and 428 women (n = 1165) aged 19–64, who participated in the prospective Ewha–Boramae cohort study. Sleep duration was dichotomized into ≥7 h (adequate) and 5 (poor quality) and ≤5 (good quality). Diet quality was evaluated by the Recommended Food Score (RFS). Obesity was associated with higher rates of insufficient sleep and poor sleep quality in women, but not in men. After adjustment for covariates, women with poor sleep quality had a higher risk of obesity than women with good sleep quality (OR = 2.198; 95% CI = 1.027–4.704); this association occurred only in the group with RFS ≤ median score. Our findings support a significant association between sleep quality and obesity, and this association has been potentially modified by dietary quality in women.