Impact of Vitamin A and Carotenoids on the Risk of Tuberculosis Progression.

BACKGROUND: Low and deficient levels of vitamin A are common in low- and middle-income countries where tuberculosis burden is high. We assessed the impact of baseline levels of vitamin A and carotenoids on tuberculosis disease risk. METHODS: We conducted a case-control study nested within a longitudinal cohort of household contacts (HHCs) of pulmonary tuberculosis case patients in Lima, Peru. We defined case patients as human immunodeficiency virus (HIV)-negative HHCs with blood samples in whom tuberculosis disease developed ≥15 days after enrollment of the index patient. For each case patient, we randomly selected 4 controls from among contacts in whom tuberculosis disease did not develop, matching for sex and year of age. We used conditional logistic regression to estimate odds ratios for incident tuberculosis disease by vitamin A and carotenoids levels, controlling for other nutritional and socioeconomic factors. RESULTS: Among 6751 HIV-negative HHCs with baseline blood samples, 192 had secondary tuberculosis disease during follow-up. We analyzed 180 case patients with viable samples and 709 matched controls. After controlling for possible confounders, we found that baseline vitamin A deficiency was associated with a 10-fold increase in risk of tuberculosis disease among HHCs (adjusted odds ratio, 10.53; 95% confidence interval, 3.73-29.70; P < .001). This association was dose dependent, with stepwise increases in tuberculosis disease risk with each decreasing quartile of vitamin A level. CONCLUSIONS: Vitamin A deficiency strongly predicted the risk of incident tuberculosis disease among HHCs of patients with tuberculosis. Vitamin A supplementation among individuals at high risk of tuberculosis may provide an effective means of preventing tuberculosis disease.

Intake of selected minerals and risk of premenstrual syndrome.

Iron, potassium, zinc, and other minerals might impact the development of premenstrual syndrome (PMS) through multiple mechanisms, but few studies have evaluated these relations. We conducted a case-control study nested within the prospective Nurses' Health Study II (1991-2001). Participants were free from PMS at baseline. After 10 years, 1,057 women were confirmed as PMS cases and 1,968 as controls. Mineral intake was assessed using food frequency questionnaires completed in 1991, 1995, and 1999. After adjustment for calcium intake and other factors, women in the highest quintile of nonheme iron intake had a relative risk of PMS of 0.64 (95% confidence interval (CI): 0.44, 0.92; P for trend = 0.04) compared with women in the lowest quintile. Women in the highest quintile of potassium intake had a relative risk of 1.46 (95% CI: 0.99, 2.15; P for trend = 0.04) compared with women in the lowest quintile. High intake of zinc from supplements was marginally associated with PMS (for intake of ≥25 mg/day vs. none, relative risk = 0.69, 95% CI: 0.46, 1.02; P for trend = 0.05). Intakes of sodium, magnesium, and manganese were unrelated to PMS risk. These findings suggest that dietary minerals may be useful in preventing PMS. Additional studies are needed to confirm these relations.

Dietary B vitamin intake and incident premenstrual syndrome.

BACKGROUND: Thiamine, riboflavin, niacin, vitamin B-6, folate, and vitamin B-12 are required to synthesize neurotransmitters that are potentially involved in the pathophysiology of premenstrual syndrome (PMS). OBJECTIVE: The objective was to evaluate whether B vitamin intake from food sources and supplements is associated with the initial development of PMS. DESIGN: We conducted a case-control study nested within the Nurses' Health Study II cohort. Participants were free of PMS at baseline (1991). After 10 y of follow up, 1057 women were confirmed as cases and 1968 were confirmed as controls. Dietary information was collected in 1991, 1995, and 1999 by using food-frequency questionnaires. RESULTS: Intakes of thiamine and riboflavin from food sources were each inversely associated with incident PMS. For example, women in the highest quintile of riboflavin intake 2-4 y before the diagnosis year had a 35% lower risk of developing PMS than did those in the lowest quintile (relative risk: 0.65; 95% CI: 0.45, 0.92; P for trend = 0.02). No significant associations between incident PMS and dietary intakes of niacin, vitamin B-6, folate, and vitamin B-12 were observed. Intake of B vitamins from supplements was not associated with a lower risk of PMS. CONCLUSIONS: We observed a significantly lower risk of PMS in women with high intakes of thiamine and riboflavin from food sources only. Further research is needed to evaluate the effects of B vitamins in the development of premenstrual syndrome.

Dietary vitamin D intake, 25-hydroxyvitamin D3 levels and premenstrual syndrome in a college-aged population.

High dietary intake of vitamin D may reduce the risk of premenstrual syndrome (PMS), perhaps by affecting calcium levels, cyclic sex steroid hormone fluctuations, and/or neurotransmitter function. Only a small number of previous studies have evaluated this relationship and none have focused on young women. We assessed this relationship in a cross-sectional analysis within the UMass Vitamin D Status Study. Between 2006 and 2008, 186 women aged 18-30 (mean age=21.6 years) completed a validated food frequency questionnaire, additional questionnaires to assess menstrual symptoms and other health and lifestyle factors, and provided a fasting blood sample collected during the late luteal phase of their menstrual cycle. Among all study participants, results suggested the possibility of an inverse association between intake of vitamin D from food sources and overall menstrual symptom severity, though were not statistically significant; mean intakes in women reporting menstrual symptom severity of none/minimal, mild, and moderate/severe were 253, 214, and 194 IU/day, respectively (P=0.18). From among all study participants, 44 women meeting standard criteria for PMS and 46 women meeting control criteria were included in additional case-control analyses. In these women, after adjustment for age, body mass index, smoking status and total calcium intake, higher intake of vitamin D from foods was associated with a significant lower prevalence of PMS. Women reporting vitamin D intake from food sources of >or=100 IU/day had a prevalence odds ratio of 0.31 compared to those reporting<100 IU/day (95% confidence interval=0.10-0.98). Late luteal phase 25-hydroxyvitamin D3 levels were not associated with prevalent PMS. Results from this pilot study suggest that a relationship between vitamin D and PMS is possible, though larger studies are needed to further evaluate this relationship and to investigate whether 25-hydroxyvitamin D3 levels in the follicular or early luteal phases of the menstrual cycle may be related to PMS risk.

Can folate intake reduce arsenic toxicity?

Arsenic-contaminated groundwater is a global environmental health concern. Inorganic arsenic is a known carcinogen, and epidemiologic studies suggest that persons with impaired arsenic metabolism are at increased risk for certain cancers, including skin and bladder carcinoma. Arsenic metabolism involves methylation to monomethylarsonic acid and dimethylarsinic acid (DMA) by a folate-dependent process. Persons possessing polymorphisms in certain genes involved in folate metabolism excrete a lower proportion of urinary arsenic as DMA, which may influence susceptibility to arsenic toxicity. A double-blind placebo-controlled trial in a population with low plasma folate observed that after 12 weeks of folic acid supplementation, the proportion of total urinary arsenic excreted as DMA increased and blood arsenic concentration decreased, suggesting an improvement in arsenic metabolism. Although no studies have directly shown that high folate intake reduces the risk of arsenic toxicity, these findings provide evidence to support an interaction between folate and arsenic metabolism.

Preconception folate and vitamin B(6) status and clinical spontaneous abortion in Chinese women.

OBJECTIVE: To assess the association between preconception homocysteine and B vitamin status and risk of clinical spontaneous abortion in women from Anqing, China. METHODS: All women were aged 21-34 years, had never smoked, and were primigravid. Patients (n = 49) were women with a clinically recognized pregnancy who experienced a fetal death before 100 days' gestation. Controls (n = 409) were women who maintained a pregnancy that ended in a live birth. Homocysteine, folate, and vitamins B(6) and B(12) concentrations were measured in plasma obtained before conception. RESULTS: Mean vitamin B(6) concentration was lower in patients than in controls (34.0 versus 37.9 nmol/L, P =.04). In addition, the risk of spontaneous abortion tended to increase with decreasing plasma vitamin B(6) and folate concentration (P for trend =.06 and.07, respectively), although the significance of these trends was further reduced in logistic models that included age, body mass index, and both vitamins. The risk of spontaneous abortion was four-fold higher among women with suboptimal plasma concentrations of both folate and vitamin B(6) (folate less than or equal to 8.4 nmol/L and vitamin B(6) less than or equal to 49 nmol/L) than in those with higher plasma concentrations of both vitamins (odds ratio 4.1, 95% confidence interval 1.2, 14.4). Homocysteine and vitamin B(12) status were not associated with spontaneous abortion risk. CONCLUSION: Suboptimal preconception folate and vitamin B(6) status, especially when they occur together, may increase the risk of clinical spontaneous abortion. Additional prospective studies are needed to confirm these findings and to determine whether antenatal B vitamin supplementation reduces spontaneous abortion risk.