Nutrition Updates

VITAMIN B₆ REQUIREMENTS AND INFLAMMATION

Morris MS, Sakakeeny L, Jacques PF, Picciano MF, and Selhub J. Vitamin B-6 intake is inversely related to, and the requirement is affected by, inflammation status. J Nutr. 2010;140:103–110.

Low vitamin B₆ status is linked with increased rates of cardiovascular disease, and this relationship appears to be independent of the role of B₆ in homocysteine metabolism. Some research indicates that low levels of vitamin B₆ are associated with inflammatory conditions including rheumatoid arthritis and cardiovascular disease. Plasma levels of pyridoxal 5′-phosphate (PLP), the active form of vitamin B₆, decrease briefly following myocardial infarction and may be lowered in inflammation. It has been proposed that PLP is reduced by inflammation and that low B₆ status increases the risk for inflammatory diseases. Therefore, it is hypothesized that individuals with inflammation require a greater amount of vitamin B₆ to maintain adequate levels of PLP relative to healthy individuals. However, the relationship between low B₆ intake and inflammatory markers is less well explored. The analysis reported by Morris et al. evaluates associations among B₆ intake, plasma PLP, and plasma C-reactive protein concentrations in the 2003–2004 National Health and Nutrition Examination Survey (NHANES ) dataset.

Data for approximately 2,686 participants (47% women) in NHANES were used in the analysis. Participant data were included if individuals were aged 19 or older, were free from diabetes, were not pregnant, and were not using oral contraceptives or steroidal anti-inflammatory medication. Normal food consumption patterns and supplement intake were assessed using two 24-h dietary intake records. Usual intake of protein, energy, and B₆ were estimated from food-intake data. Primary biochemical measures included plasma PLP and C-reactive protein (CRP). Vitamin B₆ adequacy was defined as plasma PLP ≥ 20 nmol/L. Inflammation status was categorized into CRP ≤ 3 mg/L; 3.1–10 mg/L; and >10 mg/L, with a higher value indicating greater inflammation. Dietary intake of vitamin B₆ was positively associated with B₆ status. When comparing across levels of inflammation, the requirement for vitamin B₆ to prevent inadequacy was significantly higher in individuals with the highest levels of CRP. Additionally, high intake of vitamin B₆ was protective against elevations in CRP. These data indicate that vitamin B₆ intake in the general population may be protective against inflammation, and that the presence of inflammation may drive up the requirement for vitamin B₆.

DIETARY FOLATE AND B₁₂ AND GASTRIC CANCER MORTALITY IN MTHFR 677TT CARRIERS

Galván-Portillo MV, Oñate-Ocaña LF, Pérez-Pérez GI, Chen J, Herrera-Goepfert R, Chihu-Amparan L, Flores-Luna L, Mohar-Betancourt A, and López-Carrillo L. Dietary folate and vitamin B12 intake before diagnosis decreases gastric cancer mortality risk among susceptible MTHFR 677TT carriers. Nutr. 2010;26:201–208.

Gastric cancer has a relatively low survival rate, with <25% survival after 5 years. Poor survival outcomes are related to location and type of tumor, and better outcomes are associated with screening and early detection. Dietary intake of alcohol negatively affects survival, whereas intake of vitamin E, raw vegetables, tofu, and chicken are all linked with decreased mortality. Intake of natural folates may be protective against cancer via methylation reactions involving DNA and RNA synthesis. Some observations link folate deficiency with DNA hypomethylation that may, in turn, promote cancer development and proliferation. Genetic variations among individuals may result in impairments in folate-mediated methylation reactions. Specifically, individuals homozygous for the methylenetetrahydrofolate reductase 677C→T polymorphism (MTHFR 677TT genotype) have a reduced MTHFR enzyme activity compared to individuals with the wild-type (MTHFR 677CC) genotype. The present prospective study by Galván-Portillo et al. examined the relationship between MTHFR 677C→T status, dietary methyl intake (folate, betaine, choline, methionine, and vitamin B₁₂), and gastric cancer survival.

Individuals (N = 257) living in the Mexico City region of Mexico were enrolled in the 2-year prospective trial. Data were collected for clinical history and dietary habits for the 3 years preceding the onset of gastric cancer symptoms. Dietary intake of methyl donors was estimated using food-frequency questionnaires validated for the Mexican diet. MTHFR 677C→T genotyping was determined using polymerase chain reaction/restriction fragment length polymorphism, and individuals were stratified into genetic groups (CC, CT, TT). Survival status and response to treatment at the end of the study were determined using clinical records and patient interviews. During the 2-year study, 128 participants died of gastric cancer. Total survival decreased over time (64% at 6 months, 45% at 1 year, and 31% at 2 years). No significant differences in survival were observed for intake of methyl donors in the total study population. When stratified across the MTHFR 677C→T genotype, poorer survival was observed in 677TT carriers with low reported intakes of folate and vitamin B₁₂. In this genetic group, high folate and B₁₂ intake were associated with a reduced risk of mortality. There was a trend for intake of betaine and choline to be protective in the 677TT carriers, and there were no effects of methionine intake on gastric cancer survival. The data presented by Galván-Portillo et al. demonstrate a gene-nutrient interaction between MTHFR status, folate intake, and gastric cancer survival. The authors suggest that folate and B vitamins might be a useful intervention to improve survival in gastric cancer in individuals with the 677TT genotype.

CALCIUM SUPPLEMENTATION AND LIPIDS, BLOOD PRESSURE, AND BODY COMPOSITION

Reid IR, Ames R, Mason B, Bolland MJ, Bacon CJ, Reid HE, Kyle C, Gamble GD, Grey A, and Horne A. Effects of calcium supplementation on lipids, blood pressure, and body composition in healthy older men: a randomized controlled trial. Am J Clin Nutr. 2010;91:131–139.

Calcium supplements are widely used for the prevention of osteoporosis in men and women. Recent work suggests that calcium may also have beneficial effects on blood pressure, blood lipids, and body composition. Some studies show an inverse relationship between calcium intake and body weight. Other research shows a reduction in blood pressure with calcium supplementation. With respect to blood lipids, it has been demonstrated that calcium binds to fatty acids in the gut, which leads to a reduction in fat absorption. The current study by Reid et al. examined the effects of calcium supplementation on body composition, blood lipids, and blood pressure in healthy men over the age of 40 years.

Participants (N = 323) were randomized into one of two calcium supplementation conditions (600 mg/d or 1,200 mg/d) or placebo. Participants were followed for 2 years. Primary outcome measures included body weight, fat mass, lean mass, HDL and LDL levels, triglycerides, and systolic and diastolic blood pressure. There was a tendency for systolic and diastolic blood pressure to decrease with calcium supplementation. When participants were categorized into lower and higher baseline calcium intake using a median split (median intake at baseline, 785 mg/d), there was a beneficial effect on systolic and diastolic blood pressure in those individuals with lower baseline calcium intake who were in the 1,200 mg/d condition. There were no effects of calcium supplementation on measures of body composition or blood lipids. The authors report that other research that found positive effects of calcium on body composition typically conducted their investigations using a dietary intervention or calcium plus cholecalciferol rather than elemental calcium alone, as used in the present study. Additionally, they propose that the benefits of calcium on blood lipids seen in women may be less pronounced in men. The data from the present study suggests that supplementation with calcium may have positive effects on blood pressure in men with low calcium intake.

NUTRITIONAL STATUS AND COGNITIVE CAPACITY IN INSTITUTIONALIZED ELDERLY

Aparicio Vizuete A, Robles F, Rodríguez-Rodríguez E, López-Sobaler AM, and Ortega RM. Association between food and nutrient intakes and cognitive capacity in a group of institutionalized elderly people. Eur J Nutr. doi: 10.1007/s00394-009-0086-y

As the global population ages, an increasing number of individuals with age-related cognitive decline is observed. Loss of mental function related to aging is one of the leading reasons for loss of independence and transition to managed care. It has been hypothesized that poor nutritional status may be one factor affecting the cognitive decline seen in aging individuals. A number of studies have linked inadequate levels of vitamins B₆, B₁₂, and folate with poorer cognitive function. Other research suggests that intake of the antioxidant vitamins C, E, and beta-carotene protect against the neurological effects of oxidative stress and free radical damage. The current study by Aparicio Vizuete et al. compared associations between food and nutrient intake and cognitive capacity in institutionalized elderly subjects.

One-hundred and seventy-eight elderly (≥65 years) men and women were sampled from four nursing homes in the Madrid region of Spain. Participants were eligible for inclusion in the study if they were free from health problems that would affect nutrient absorption, and if their Mini Mental State Examination scores were greater than 23. Participants were allowed to choose their daily menus from the offerings regularly available in the nursing homes. Food intake and supplement use was recorded for 7 days. Daily food and supplement intake was analyzed according to g/d by major food group (e.g., pulses, fruit, meat) and according to micro- and macronutrient content. Cognitive capacity was assessed using the Short Portable Mental State Questionnaire (SPMSQ) and performance was categorized into no errors (SPMSQ = 0) or one or more errors (SPMSQ > 0). Cognitive capacity scores were further categorized by age, either above or below the 50^th percentile for age (83 years). Individuals with no errors on the SPMSQ consumed more cereals, eggs, fish, oils, and fats than those with one or more errors. Additionally, these individuals consumed more energy, carbohydrates, fats, polyunsaturated fatty acids, cholesterol, and vitamin E than those with one or more errors. Correlations between nutrient intake and total number of errors showed an improved performance with most nutrients analyzed including fiber, monounsaturated fatty acids, polyunsaturated fatty acids, vitamins B₆, C, D, and E, calcium, folic acid, magnesium, and zinc. Intake of meat and intake of saturated fatty acids was associated with a greater number of errors. Although the present institutionalized population was generally healthy, it is important to stress that the findings do not include dietary intake over the life-span, but are limited to the 7-day observational period and to foods available within the nursing homes. The present correlations may indicate that individuals with better cognitive functioning may make more informed dietary choices. The present data suggest that self-selected diets rich in eggs, vegetables, cereals, and fish are associated with cognitive capacity in elderly institutionalized individuals.

NUTS IMPROVE INSULIN SENSITIVITY IN METABOLIC SYNDROME

Casas-Agustench P, López-Uriarte P, Bulló M, Ros E, Cabré-Vila JJ, and Salas-Salvadó J. Effects of one serving of mixed nuts on serum lipids, insulin resistance and inflammatory markers in patients with the metabolic syndrome. Nutr Metab Cardiovasc Dis. doi:10.1016/j.numecd.2009.08.005

Metabolic syndrome is characterized by a constellation of symptoms including inflammation, cardiovascular risk factors, impaired glucose handling, and hyperlipidemia. Dietary intake of nuts has been shown in other studies to reduce cardiovascular disease markers, improve blood lipid profiles, decrease diabetes rates, and improve insulin sensitivity. Casas-Agustench et al. propose that nuts, which are rich in mono- and polyunsaturated fats, vitamin E, and protein, may improve some of the accompanying symptoms seen in metabolic syndrome.

Men and women with metabolic syndrome (N = 50) were randomized into one of two dietary intervention conditions for 12 weeks. All participants were provided with recommendations for a diet rich in fruits, vegetables, whole grains, and fish, and low in red meats, added sugars, and salt. Individuals in the nut condition (n = 25) were given daily provisions of 30 g raw, unpeeled nuts (15 g walnuts, 7.5 g almonds, and 7.5 g hazelnuts). Individuals in the control condition (n = 25) were advised against tree nut and peanut intake for the duration of the study. Primary outcome measures included changes in adiposity, blood pressure, cholesterol, C-reactive protein, monocyte chemotactic protein-1 (MCP-1), insulin, interleukin-6 (IL-6), IL-18, and adiponectin. In both diet conditions, participants showed moderate decreases in body fat and body weight as well as lower blood pressure. Lipid profiles were improved in the control diet relative to the nut diet. Participants in the nut condition had improved fasting insulin levels and improvements in insulin resistance relative to the control condition. There was a trend for inflammatory markers to be improved with nut intake. While the initial observation for nut intake on inflammation was significant, adjustment for changes in body weight modified the findings. The present data suggest that dietary changes to include more fruits, vegetables, and lean protein and to decrease added salt and sugar has positive effects on adiposity, body weight, and blood pressure in individuals with metabolic syndrome. Lipid profiles may be more favorably influenced by a more healthy diet with reduced fat intake when compared to a similar diet containing nuts. The addition of 30 g/d of mixed nuts produces improvements in insulin resistance over and above changes seen with adopting a more healthy diet.