Non-dietary Factors Research Articles

Serum and adipose tissue fatty acid composition as biomarkers of habitual dietary fat intake in elderly men with chronic kidney disease

Fatty acid (FA) composition in serum cholesterol esters (CE) and adipose tissue (AT) reflect the long-term FA intake in the general population. Because both dietary intake and FA biomarkers associate with renal function, our aim was to identify which CE and AT FAs are useful biomarkers of habitual FA intake in individuals with chronic kidney disease (CKD). Cross-sectional analysis was performed in 506 men (aged 70 years) with a glomerular filtration rate (GFR) of <60 mL/min per 1.73 m(2) from the Uppsala Longitudinal Study of Adult Men cohort. Dietary habits were evaluated with a 7-day dietary record. FA compositions in CE and AT were analyzed by gas-liquid chromatography in two random subsamples of 248 and 318 individuals, respectively. Both CE and AT linoleic acid and docosahexaenoic acid (DHA) were strongly associated with their corresponding intake, after adjustments for non-dietary factors. The proportions of eicosapentaenoic acid (EPA) and palmitic acid in CE and AT moderately correlated with dietary intake, whereas correlations of other FAs were weaker or absent. Proportions of EPA and DHA in CE and AT were positively associated with the total energy-adjusted fish intake. Results were confirmed in adequate reporters as identified by the Goldberg cutoff method. These relationships held constant, regardless of a GFR above or below 45 mL/min per 1.73 m(2) or the prevalence of microalbuminuria. Proportions of EPA, DHA, palmitic and linoleic acid in serum CE and AT are good indicators of their dietary intake in men with CKD. They can be considered valid biomarkers for epidemiological studies and assessment of compliance.

Accounting for the effects of lipids in stable isotope (δ13C and δ15N values) analysis of skin and blubber of balaenopterid whales

Stable isotope values (δ(13)C and δ(15)N) of darted skin and blubber biopsies can shed light on habitat use and diet of cetaceans, which are otherwise difficult to study. Non-dietary factors affect isotopic variability, chiefly the depletion of (13)C due to the presence of (12)C-rich lipids. The efficacy of post hoc lipid-correction models (normalization) must be tested. For tissues with high natural lipid content (e.g., whale skin and blubber), chemical lipid extraction or normalization is necessary. C:N ratios, δ(13)C values and δ(15)N values were determined for duplicate control and lipid-extracted skin and blubber of fin (Balaenoptera physalus), humpback (Megaptera novaeangliae) and minke whales (B. acutorostrata) by continuous-flow elemental analysis isotope ratio mass spectrometry (CF-EA-IRMS). Six different normalization models were tested to correct δ(13)C values for the presence of lipids. Following lipid extraction, significant increases in δ(13)C values were observed for both tissues in the three species. Significant increases were also found for δ(15)N values in minke whale skin and fin whale blubber. In fin whale skin, the δ(15)N values decreased, with no change observed in humpback whale skin. Non-linear models generally out-performed linear models and the suitability of models varied by species and tissue, indicating the need for high model specificity, even among these closely related taxa. Given the poor predictive power of the models to estimate lipid-free δ(13)C values, and the unpredictable changes in δ(15)N values due to lipid-extraction, we recommend against arithmetical normalization in accounting for lipid effects on δ(13)C values for balaenopterid skin or blubber samples. Rather, we recommend that duplicate analysis of lipid-extracted (δ(13)C values) and non-treated tissues (δ(15)N values) be used.

Prospective cohort studies of vitamin B-6 intake and colorectal cancer incidence: modification by time?

The relation between vitamin B-6 intake and colorectal cancer risk remains uncertain. We prospectively evaluated whether a higher vitamin B-6 intake in the remote past is more strongly associated with a lower risk of colorectal cancer than is an intake in the recent past in the Nurses' Health Study and the Health Professionals Follow-Up Study. We assessed vitamin B-6 intake every 4 y by using validated food-frequency questionnaires and followed 86,440 women and 44,410 men for ≤28 y. Cox proportional hazards regression was used to estimate multivariable RRs and 95% CIs. The total vitamin B-6 intake was significantly associated with an ∼20-30% lower risk of colorectal cancer in age-adjusted results, but this association became attenuated and nonsignificant after additional adjustment for nondietary and dietary factors. When the highest to lowest quintiles of cumulative total vitamin B-6 intake were compared, RRs (95% CIs) for colorectal cancer were 0.99 (0.80, 1.24; P-trend = 0.55) for women and 0.95 (0.73, 1.23; P-trend = 0.75) for men. For the same comparison, RRs were 0.92 (0.73, 1.16) for total vitamin B-6 intake 0-4 y before diagnosis, 0.99 (0.78, 1.26) for intake 4-8 y before diagnosis, 0.92 (0.71, 1.21) for intake 8-12 y before diagnosis, and 0.93 (0.69, 1.26) for intake 12-16 y before diagnosis in women. Corresponding RRs for men were 0.86 (0.63, 1.17), 0.96 (0.70, 1.32), 0.90 (0.63, 1.29), and 1.16 (0.75, 1.79). Results did not differ by cancer subsite, source of vitamin B-6 (food or supplement), alcohol consumption, or folate intake. Our data do not support a strong role of adulthood vitamin B-6 intake in colorectal carcinogenesis in these US health professionals.

Dietary Guidelines

Dietary Guidelines

Impact of dietary selenium intake on cardiac health: Experimental approaches and human studies

Selenium, a dietary trace mineral, essential for humans and animals, exerts its effects mainly through its incorporation into selenoproteins. Adequate selenium intake is needed to maximize the activity of selenoproteins, among which glutathione peroxidases have been shown to play a major role in cellular defense against oxidative stress initiated by excess reactive oxygen species. In humans, a low selenium status has been linked to increased risk of various diseases, including heart disease. The main objective of this review is to present current knowledge on the role of selenium in cardiac health. Experimental studies have shown that selenium may exert protective effects on cardiac tissue in animal models involving oxidative stress. Because of the narrow safety margin of this mineral, most interventional studies in humans have reported inconsistent findings. Major determinants of selenium status in humans are not well understood and several nondietary factors might be associated with reduced selenium status. In this review, we discuss recent studies regarding the role of selenoproteins in the cardiovascular system, the effect of dietary intake on selenium status, the impact of selenium status on cardiac health, and the cellular mechanisms that can be involved in the physiological and toxic effects of selenium.

Lifestyle-Related Risk Factors, Smoking Status and Cardiovascular Disease

Cardiovascular disease represents one of the most important causes of morbidity and mortality in highly developed countries and is known to be associated with some lifestyle-related risk factors (e.g. alcohol consumption, smoking status, diet, physical activity, bodyweight). There is still incomplete information about their combined effect on cardiovascular risk in hypertensive patients with optimal pharmacological blood pressure control. The objective of this study was to evaluate the correlation of some lifestyle behaviours, using a specific questionnaire, with development of cardiovascular disease in treated hypertensive patients. 617 hypertensive, non-diabetic participants (aged 53.1 ± 7.6 years, 44.9% male; mean age 53.1 ± 7.6 years) free of prevalent cardiovascular disease, cancer, liver cirrhosis and/or failure, chronic kidney disease more than grade 3 (glomerular filtration rate by the Modification of Diet in Renal Disease study <30 mL/min/1.73 m2) were analysed. Metabolic syndrome was defined according to the Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). Left ventricular hypertrophy was defined when left ventricular mass index was >51 g/m2. Carotid artery atherosclerosis was assessed as an increased intima medial thickness (IMT) by B-mode ultrasonography. IMT values between 0.9 and 1.3 mm were defined as 'thickening' and those >1.3 mm as 'plaque'. Assessment of smoking status, dietary and non-dietary factors was established by administration of a specific questionnaire. In the initial population of examined patients, 288 were smokers and 329 were non-smokers. At baseline, the patients belonging to smoking group were less often overweight than those belonging to the non-smoking group, showing a lower initial body mass index (BMI) [27.54 ± 4.0 vs 28.28 ± 4.3; p < 0.029], lower plasma levels of high-density lipoprotein cholesterol (HDL-C) [48.14 ± 12.6 vs 51.39 ± 14.1 mg/dL; p < 0.006] and were more often affected by carotid artery atherosclerosis (93.9 % vs 86.1%; p < 0.002) than non-smoking patients. When analysed for dietary and other lifestyle-related risk factors, we found a higher prevalence of carotid atherosclerotic disease in patients consuming less than two meals per day than in those consuming more than two meals per day (96.6% vs 85.7%; p < 0.001), without any significant difference in the mean number of medications taken and in specific classes of medications. Total amount of cigarettes smoked, calculated as packs per year (39.14 ± 16.5 vs 20.81 ± 13.6; p < 0.0001) was higher in patients with a diagnosis of atherosclerotic disease of the carotid artery than in patients free of this disorder, whereas the average age at which people began smoking was lower (17.58 ± 6.3 vs 21.53 ± 10.2 years). In a binary model of logistic regression adjusted for BMI, HDL-C, smoking status and number of daily meals, only smoking status was confirmed to be strongly correlated to clinical evidence of carotid atherosclerosis (p < 0.025). In hypertensive patients, in optimal blood pressure control, smoking status has been shown to be independently associated with an increased maximum arterial IMT (IMTmax). In particular, an increase of the IMT was associated with the total amount of cigarettes smoked (calculated as packs per year) and the average age at which people began smoking.

Abstract 663: Circulating lipids and fatty acids and non-Hodgkin lymphoma risk in a nested case-control study: The Multiethnic Cohort

Abstract Objective: Dietary fatty acids provide important components of immune cells, cytokines, and prostaglandins. Intake of n-3 and n-6 polyunsaturated fatty acids may influence inflammatory responses that contribute to the risk of non-Hodgkin lymphoma (NHL). Because saturated and polyunsaturated fatty acid (SFA and PUFA) intake has been linked with NHL, this analysis evaluated biomarkers of dietary fat intake in relation to risk. Methods: We conducted a nested-case control analysis (275 cases and 549 controls) within the Multiethnic Cohort Study (Caucasians, Japanese Americans, Latinos, African Americans, and Native Hawaiians) to examine NHL risk by tertile of erythrocyte membrane fatty acid composition and serum lipid concentrations. Cases were matched to 2 controls by sex, year of birth, ethnicity, location (CA or HI), date and time of blood draw, and fasting hours before blood draw. Fatty acids were measured as the percentage of total measured erythrocyte membrane fatty acids using gas chromatography, and absolute serum levels of total, high density-lipoprotein (HDL), and low density-lipoprotein (LDL) cholesterol and triglycerides were measured using an automated chemical analyzer (Cobas MiraPlus, Roche Diagnostics, Switzerland). Conditional logistic regression was applied to estimate odds ratios (OR) and 95% confidence intervals (CI) with adjustment for potential confounders. Results: The mean ages at blood draw were 70.1±7.4 and 70.2±7.4 years for cases and controls, respectively. The cases (82 diffuse large B-cell, 52 small cell/chronic lymphocytic leukemia, 49 follicular, 15 T-cell, and 77 others) were diagnosed 3.1±2.3 years after the blood draw. Higher prediagnostic serum lipids, in particular total (ORT3 vs T1: 0.5 [95% CI: 0.4, 0.8]; ptrend &amp;lt;0.001) and HDL cholesterol (ORT3 vs T1: 0.5 [0.3, 0.8]; ptrend &amp;lt;0.01) but not triglycerides were associated with a lower NHL risk. No significant associations were found for individual fatty acids, the n-3/n-6 fatty acid or the PUFA/SFA ratio. Stratification by sex and ethnicity suggested significant heterogeneity. For example, in women but not in men, n-6 fatty acids were associated with a higher NHL risk (ptrend =0.09) and the PUFA/SFA ratio with a lower risk (ptrend =0.05). Monounsaturated fatty acids reduced risk in Caucasians (ptrend =0.01) while higher risks were observed for stearic acid (C18:0; ptrend &amp;lt;0.01) in Japanese Americans and for palmitic acid (C16:0; ptrend &amp;lt;0.01) in African Americans. Conclusions: Individual fatty acids showed no relation with overall NHL risk in this multiethnic population, but possible sex- or ethnicity-specific influences may exist. Total and HDL cholesterol levels, which reflect dietary and non-dietary factors, were associated with a reduced risk. Replication of these findings in other cohort studies is warranted. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 663. doi:1538-7445.AM2012-663

Magnesium intake, plasma C-peptide, and colorectal cancer incidence in US women: a 28-year follow-up study

Background:Laboratory studies suggest a possible role of magnesium intake in colorectal carcinogenesis but epidemiological evidence is inconclusive.Method:We tested magnesium–colorectal cancer hypothesis in the Nurses’ Health Study, in which 85 924 women free of cancer in 1980 were followed until June 2008. Cox proportional hazards regression models were used to estimate multivariable relative risks (MV RRs, 95% confidence intervals).Results:In the age-adjusted model, magnesium intake was significantly inversely associated with colorectal cancer risk; the RRs from lowest to highest decile of total magnesium intake were 1.0 (ref), 0.93, 0.81, 0.72, 0.74, 0.77, 0.72, 0.75, 0.80, and 0.67 (Ptrend<0.001). However, in the MV model adjusted for known dietary and non-dietary risk factors for colorectal cancer, the association was significantly attenuated; the MV RRs were 1.0 (ref), 0.96, 0.85, 0.78, 0.82, 0.86, 0.84, 0.91, 1.02, and 0.93 (Ptrend=0.77). Similarly, magnesium intakes were significantly inversely associated with concentrations of plasma C-peptide in age-adjusted model (Ptrend=0.002) but not in multivariate-adjusted model (Ptrend=0.61). Results did not differ by subsite or modified by calcium intakes or body mass index.Conclusion:These prospective results do not support an independent association of magnesium intake with either colorectal cancer risk or plasma C-peptide levels in women.

Dietary fatty acid intake, its food sources and determinants in European adolescents: the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study

Dietary fatty acids (FA) play a role in several (patho)physiological processes at any age, and different FA have different effects on lipid status and health outcome. The present study aims to describe the FA intake and its main food sources in a population of healthy European adolescents and to assess the variation in intake as a function of non-dietary factors. FA intake was assessed with 24h recall interviews in 1804 adolescents aged 12·5-17·5 years. Usual intakes were calculated using the multiple source method. Multilevel analyses, adjusting for study centre, were used to investigate the influence of non-dietary factors. The mean total fat intake was 33·3 (sd 1·2)% of total energy intake (%E). The mean SFA intake was 13·8 (sd 1·2)%E, with 99·8% of the population exceeding the recommendations. SFA was mainly delivered by meat and cake, pies and biscuits. In most adolescents, the PUFA intake was too low, and 35·5% of the population did not achieve the minimum recommended intake for α-linolenic acid (ALA). The main determinants of FA intake in the present study population were age and sex, as well as physical activity in the male subgroup. No contributions of body composition, socio-economic status or sexual maturation to the variance in FA intake were observed. In conclusion, the most important public health concerns regarding FA intake in this adolescent population were the low intake of ALA and the high intake of SFA, mainly seen in the younger-aged boys. In this group the major contributor to SFA was meat.

Carcinoma of the stomach: A review of epidemiology, pathogenesis, molecular genetics and chemoprevention.

Carcinoma of the stomach is still the second most common cause of cancer death worldwide, although the incidence and mortality have fallen dramatically over the last 50 years in many regions. The incidence of gastric cancer varies in different parts of the world and among various ethnic groups. Despite advances in diagnosis and treatment, the 5-year survival rate of stomach cancer is only 20 per cent. Stomach cancer can be classified into intestinal and diffuse types based on epidemiological and clinicopathological features. The etiology of gastric cancer is multifactorial and includes both dietary and nondietary factors. The major diet-related risk factors implicated in stomach cancer development include high content of nitrates and high salt intake. Accumulating evidence has implicated the role of Helicobacter pylori (H. pylori) infection in the pathogenesis of gastric cancer. The development of gastric cancer is a complex, multistep process involving multiple genetic and epigenetic alterations of oncogenes, tumor suppressor genes, DNA repair genes, cell cycle regulators, and signaling molecules. A plausible program for gastric cancer prevention involves intake of a balanced diet containing fruits and vegetables, improved sanitation and hygiene, screening and treatment of H. pylori infection, and follow-up of precancerous lesions. The fact that diet plays an important role in the etiology of gastric cancer offers scope for nutritional chemoprevention. Animal models have been extensively used to analyze the stepwise evolution of gastric carcinogenesis and to test dietary chemopreventive agents. Development of multitargeted preventive and therapeutic strategies for gastric cancer is a major challenge for the future.

A Prospective Study of Prepregnancy Dietary Iron Intake and Risk for Gestational Diabetes Mellitus

OBJECTIVEIt is important to identify modifiable factors that may lower gestational diabetes mellitus (GDM) risk. Dietary iron is of particular interest given that iron is a strong prooxidant, and high body iron levels can damage pancreatic β-cell function and impair glucose metabolism. The current study is to determine if prepregnancy dietary and supplemental iron intakes are associated with the risk of GDM.RESEARCH DESIGN AND METHODSA prospective study was conducted among 13,475 women who reported a singleton pregnancy between 1991 and 2001 in the Nurses’ Health Study II. A total of 867 incident GDM cases were reported. Pooled logistic regression was used to estimate the relative risk (RR) of GDM by quintiles of iron intake controlling for dietary and nondietary risk factors.RESULTSDietary heme iron intake was positively and significantly associated with GDM risk. After adjusting for age, BMI, and other risk factors, RRs (95% CIs) across increasing quintiles of heme iron were 1.0 (reference), 1.11 (0.87–1.43), 1.31 (1.03–1.68), 1.51 (1.17–1.93), and 1.58 (1.21–2.08), respectively (P for linear trend 0.0001). The multivariate adjusted RR for GDM associated with every 0.5-mg per day of increase in intake was 1.22 (1.10–1.36). No significant associations were observed between total dietary, nonheme, or supplemental iron intake and GDM risk.CONCLUSIONSThese findings suggest that higher prepregnancy intake of dietary heme iron is associated with an increased GDM risk.

Influence of gender on DHA synthesis: the response of rat liver to low dietary α-linolenic acid evidences higher ω3 ∆4-desaturation index in females

The conversion rate of α-linolenic acid (ALA) into docosahexaenoic acid (DHA) is determined by dietary and non-dietary factors. Higher capacity of DHA synthesis has been evidenced in females, indicating that sex factors influence the conversion pathway. To evaluate the extent to which sexual dimorphism of DHA synthesis is subordinated to nutritional handling, we measured the ω3 ∆4-desaturation index in male and female rats receiving adequate or inadequate amounts of ALA. The ω3 ∆4-desaturation index was drawn from the DHA to docosapentaenoic acid (ω3DPA) ratio in liver phospholipids. Male and female rats born to ω3-deficient dams were fed a supplemented diet supplying low, inadequate, intermediate, or adequate ALA (5, 20, 100, or 300mg ALA/100g diet, respectively). Control rats from both gender received the adequate diet from fetal life. Compared with control, low ALA feeding induced the ω3 ∆4-desaturation index to increase by 38 and 70% in the phosphatidylethanolamine fraction of males and females, respectively, and by 67% in phosphatidylcholine in females only. Supplementations with increased doses of ALA progressively smoothed this gender effect. Moreover, the analysis of our data from a previous study shows that ovariectomy decreased, whereas estradiol treatment increased the ω3 index to values comparable with those of diet-matched males and intact females, respectively. Females are more prone than males to increase their index of ω3 ∆4-desaturation, especially in response to low supplies in ALA. Estradiol supports the ω3 index, suggesting that this hormone plays a role in the effect of gender on DHA synthesis.

Non-dietary environmental risk factors in prostate cancer

IntroductionThe aim is to update and disclose the main environmental risk factors, excluding dietary factors, involved in the etiopathology of prostate cancer. Materials and methodsBibliographic review of the last 25years of non-dietary environmental risk factors associated with prostate cancer between 1985 and 2010, obtained from MedLine, CancerLit, Science Citation Index and Embase. The search profiles were Environmental Risk Factors/Tobacco/Infectious-Inflammatory Factors/Pesticides/Vasectomy/Occupational Exposures/Chemoprevention Agents/Radiation and Prostate Cancer. ResultsWhile some non-dietary environmental risk factors increase the risk of acquiring the disease, others decrease it. Of the former, it is worth mentioning exposal to tobacco smoke, chronic infectious-inflammatory prostatic processes and occupational exposure to cadmium, herbicides and pesticides. The first factors that reduce the risk are the use of chemopreventive drugs (Finasterida, Dutasteride) and exposure to ultraviolet solar radiation. With the current data, a vasectomy does not influence the risk of developing the disease. ConclusionsThe slow process of prostate carcinogenesis is the final result of the interaction of constitutional risk and environmental factors. Non-dietary environmental factors play an important role in the etiopathology of this disease. To appropriately assess the risk factors, extensive case studies that include all the possible variables must be analyzed.

Dietary Pattern and Bone Density Changes in Elderly Women: A Longitudinal Study

Objective: Few data are available on the effect of the diet in general on bone health. The objective of this study was to identify dietary patterns and to evaluate the association between such patterns and bone mineral density (BMD) changes over time.Methods: We analyzed a sample of women aged ≥65 years participating in the InCHIANTI Study. BMD was evaluated using computed tomography of the tibia and nutritional intake using the EPIC questionnaire. We used a cluster analysis to identify patterns of dietary intake. The clusters were compared with respect to nutritional intake; risk factors for osteoporosis; comorbidity; total, trabecular, and cortical BMD; and BMD changes over 6 years.Results: The sample size was 434, with a mean age of 75.2 years (SD, 7.01 years; range, 65–94 years). Based on dietary variables, 2 clusters were identified with a marked difference in energy intake (30 kcal/kg of ideal body weight [IBW] in cluster 1 vs 44 kcal/kg IBW in cluster 2). We found no meaningful differences between clusters with regard to nondietary risk factors for osteoporosis, BMD measured at baseline, and changes in BMD over the 6-year follow-up; cluster 2 showed a greater increase in cortical BMD (+30.2 mg/cm3 vs +16.7 mg/cm3). Members of cluster 2 were less likely to have a lower cortical BMD increase (adjusted odds ratio, 0.452; 95% confidence interval, 0.215–0.950).Conclusions: Cortical BMD increases more in participants eating a diet exceeding the RDA for macronutrients. Cortical BMD may be more sensitive to diet and dietary interventions than trabecular bone.

Anemia in Postmenopausal Women: Dietary Inadequacy or Nondietary Factors?

Anemia in Postmenopausal Women: Dietary Inadequacy or Nondietary Factors?

Factores de riesgo ambientales no dietéticos en el cáncer de próstata

Introduction The aim is to update and disclose the main environmental risk factors, excluding dietary factors, involved in the etiopathology of prostate cancer. Materials and method Bibliographic review of the last 25 years of non-dietary environmental risk factors associated with prostate cancer between 1985 and 2010, obtained from MedLine, CancerLit, Science Citation Index and Embase. The search profiles were Environmental Risk Factors/Tobacco/Infectious-Inflammatory Factors/Pesticides/Vasectomy/Occupational Exposures/Chemoprevention Agents/Radiation and Prostate Cancer. Results While some non-dietary environmental risk factors increase the risk of acquiring the disease, others decrease it. Of the former, it is worth mentioning exposal to tobacco smoke, chronic infectious-inflammatory prostatic processes and occupational exposure to cadmium, herbicides and pesticides. The first factors that reduce the risk are the use of chemopreventive drugs (Finasterida, Dutasteride) and exposure to ultraviolet solar radiation. With the current data, a vasectomy does not influence the risk of developing the disease. Conclusions The slow process of prostate carcinogenesis is the final result of the interaction of constitutional risk and environmental factors. Non-dietary environmental factors play an important role in the etiopathology of this disease. To appropriately assess the risk factors, extensive case studies that include all the possible variables must be analysed.

Differences in coronary heart disease, stroke and cancer mortality rates between England, Wales, Scotland and Northern Ireland: the role of diet and nutrition

IntroductionIt is unclear how much of the geographical variation in coronary heart disease (CHD), stroke and cancer mortality rates within the UK is associated with diet. The aim of this...

Demographic and lifestyle factors and selenium levels in men and women in the U.S.

Selenium is an antioxidant trace element linked to cardiovascular disease and cancer. Although diet is a major source, relatively little else is known about independent determinants of selenium levels in free-living humans. In this study, we aimed to investigate the independent demographic, lifestyle, and dietary determinants of selenium levels in 1,997 men and 1,905 women in two large prospective U.S. cohorts. Toenail selenium levels were quantified using neutron activation analysis. Diet, geographic residence, demographic, and environmental factors were assessed by validated self-administered questionnaires. Multivariate generalized linear models were conducted to assess the independent relations of these factors with toenail selenium levels, correcting for measurement error in the diet. In multivariable-adjusted analyses, independent predictors of higher selenium were male gender (6.3% higher levels); living in West and Northern-Midwest U.S. regions (8.9% and 7.4% higher than Southern-Midwest regions, respectively); consumption of beef and bread products (between 0.7 - 2.5% higher per daily serving); and selenium supplement use (6.9% higher than non-users); whereas cigarette smoking (5-10% lower than never smokers) , older age (0.6% lower per 5 years), and consumption of eggs, white rice, dairy products, coffee, and alcohol (between 0.1 to 2.0% lower per daily serving) were associated with lower selenium. Multiple dietary and non-dietary factors independently predicted selenium levels, suggesting that both consumption and non-dietary processes (e.g., related to oxidant status) may affect levels. Significant geographic variation in selenium levels exists in the US.

Gut Bacteria Help Infants to Digest Milk More Effectively Than Adults

Infants are more efficient at digesting and utilizing nutritional components of milk than adults owing to a difference in the strains of bacteria that dominate their digestive tracts. Researchers from the University of California, Davis, and Utah State University report the genomic analysis of these strains in the November 2010 issue of the journal Applied and Environmental Microbiology, identifying the genes that are most likely responsible for this difference (see http://aem.asm.org/cgi/content/full/76/22/7373). “Human milk provides all the nutrients needed to satisfy the neonate energy expenditure and a cadre of molecules with non-nutritional but biologically relevant functions,” the researchers state. “Neonatal health is likely dependent on the timely and complex interactions among bioactive components in human milk, the mucosal immune system, and specialized gut microbial communities.” In pointing out that human milk oligosaccharides (HMOs) are the third-largest solid component of milk, the authors note that the structural complexity of HMOs renders them nondigestible to the host. “Bifidobacteria and, frequently, Bifidobacterium longum strains often predominate the colonic microbiota of exclusively breast-fed infants. Among the three subspecies of B. longum, only B. longum subsp. infantis grows robustly on human milk oligosaccharides (HMOs)” and is associated with early colonization of the infant gut. In the study, the researchers used whole-genome microarray comparisons to associate genotypic biomarkers among 15 B longum strains exhibiting various HMO utilization patterns. They identified 5 distinct gene clusters on B longum that were conserved across all strains capable of growth on HMOs and which have also diverged in strains incapable of growing on HMOs. The results of this study suggest that B longum has ≥2 distinct subspecies: B longum subsp infantis, adapted to utilize milk carbon and found primarily in the digestive tract of children, and B longum subsp longum, specialized for plant-derived carbon metabolism and associated with the adult digestive tract. “Although early gut colonization is likely dependent on a multitude of dietary and nondietary factors, the delivery of complex oligosaccharides through milk creates an ideal and unique nutrient niche for the establishment of, and colonization by, B. longum subsp. infantis strains,” say the researchers. “During weaning, a gradual transitioning from milk-based to plant-based diets generates a shift in carbon availability in the gastrointestinal tract favorable for the expansion and formation of an adult-like gastrointestinal tract microbiota.”

Determinants of plasma alkylresorcinol concentration in Danish post-menopausal women

Alkylresorcinols (AR), a group of phenolic lipids present in the outer parts of wheat and rye grain kernels, have been suggested as biomarkers of whole-grain wheat and rye intake. In this study, we investigated potential determinants of plasma AR concentration in a free-living population. Non-fasting samples from post-menopausal women enrolled in the Danish Diet, Cancer and Health study (n = 360) were selected. Diet was assessed using a semi-quantitative food frequency questionnaires (FFQ) and the association between food items likely to contain AR and relevant non-dietary factors were studied by analysis of covariance models. The median AR concentration was 78 nmol/l (interquartile range = 106.9 nmol/l). Intake of rye bread, identified as the main determinant, was associated with 87% higher plasma total AR concentration per 100 g of bread (95% confidence interval = 46-139%). About 8-12% of the total variation (depending on the AR homologue) in plasma AR concentration was explained by the selected dietary variables. At a nutrient level, total dietary fiber and cereal fiber were significantly associated with plasma total AR concentration (P = 0.05), but only ≈2% of the total plasma AR concentration was explained by the dietary fiber or cereal fiber intake. In the studied population, AR plasma concentration was mainly affected by rye bread intake among investigated determinants.