Genetic and environmental contributions to serum retinol and alpha-tocopherol concentrations: the Stanislas Family Study

BACKGROUND: Although numerous environmental factors are documented to influence serum retinol and alpha-tocopherol concentrations, little is known about the genetic versus the environmental contributions to variations in these traits. OBJECTIVE: The aim of this study was to estimate additive genetic heritability and household effects for serum retinol and alpha-tocopherol concentrations in a variance component analysis. DESIGN: In a sample of 387 French families, information on serum retinol and alpha-tocopherol concentrations, usual dietary intake, lifestyle, and serum lipid profiles and related polymorphisms (apolipoprotein E, apolipoprotein C-III, apolipoprotein B, cholesteryl ester transfer protein, and lipoprotein lipase) was obtained. RESULTS: For serum retinol--after adjustment for sex, age, body mass index, alcohol consumption, oral contraceptive use, and serum albumin, triacylglycerol, and apolipoprotein A-I concentrations--additive genetic effects and shared common environment contributed 30.5% and 14.2% of the total variance, respectively. For serum alpha-tocopherol, approximately 22.1% of the total variance was due to the additive effects of genes and 18.7% to those of household environment, after adjustment for the covariates sex, age, vitamin E intake, oral contraceptive use, and cholesterol, triacylglycerol, and apolipoprotein A-I concentrations. For both vitamins, the influence of measured polymorphisms was not significant. Moreover, heritability and household effect estimates were not significantly different between the 4 classes of relatives and did not vary significantly when families shared more meals at home. CONCLUSIONS: The results show that serum retinol and alpha-tocopherol concentrations are under genetic control in healthy families.     

Which plasma antioxidants are most related to fruit and vegetable consumption?

Substantial evidence suggests that fruit and vegetable intake reduces the risk of some cancers and other chronic diseases. While a varied diet containing fruits and vegetables may confer benefits greater than those of any single nutrient, it would be useful to have data on the plasma nutrients most influenced by fruit and vegetable intake. The authors examined the correlation between fruit and vegetable intake as measured by the abbreviated CLUE II food frequency questionnaire and several plasma antioxidants. This study includes 116 male subjects aged 35-72 years who were nonsmokers and nonusers of vitamin supplements and who provided blood samples in the CLUE II Study in Washington County, Maryland. Plasma was assayed for ascorbic acid, beta-carotene, beta-cryptoxanthin, and alpha- and gamma-tocopherol. Lipid- and energy-adjusted partial correlation for the relation with fruit and vegetable intake was r = 0.64 for ascorbic acid, r = 0.44 for beta-carotene, and r = 0.50 for beta-cryptoxanthin. While this study does not address efficacy, the stronger association of ascorbic acid with fruit and vegetable intake seen here may imply that ascorbic acid is an important component of the protective effect seen for fruits and vegetables in numerous epidemiologic studies.     

Dietary intake and other determinants of blood vitamins in an elderly population

The relationships of diet, plasma lipids, age, gender, ponderal index, cigarette and alcohol consumption, drug use and infections to blood concentrations of retinol, beta-carotene, alpha-tocopherol, ascorbic acid and vitamins B1, B2, B6 status were studied among 291 men and women aged 60-82 years. Statistically significant correlations between dietary intake and blood indicator levels were found respectively for beta-carotene, alpha-tocopherol, ascorbic acid, vitamins B2 and B6, but not for retinol and thiamin, when the effects of other parameters were controlled. The main other determinants were cigarette consumption which had a negative effect on status for retinol, beta-carotene, alpha-tocopherol, ascorbic acid and vitamin B2; alcohol consumption for retinol, vitamin B6 (positive effect on status) and beta-carotene (decrease of plasma level); plasma lipids and use of hypolipaemic drugs for fat-soluble vitamins; ponderal index for beta-carotene and vitamin B6; gender and use of antibiotics for ascorbic acid. The apparent relation between gender and level of retinol, beta-carotene, alpha-tocopherol and vitamin B6 status was not any more significant after adjustment for alcohol or cigarette consumption. Tobacco and alcohol appear to be associated factors which should be controlled for in studies investigating relations between these vitamins and diseases influenced by smoking and drinking habits.     

Smoking and exposure to environmental tobacco smoke decrease some plasma antioxidants and increase gamma-tocopherol in vivo after adjustment for dietary antioxidant intakes

BACKGROUND: Free radicals in cigarette smoke may cause oxidative damage to macromolecules, contributing to cardiovascular diseases and cancer. Decreased plasma antioxidant concentrations may indicate cigarette smoke-related oxidative stress. OBJECTIVE: We compared the effects on plasma antioxidant concentrations in cotinine-confirmed active and passive smokers with those in nonsmokers, independent of differences in dietary intakes and other covariates. DESIGN: Plasma samples from 83 smokers, 40 passive smokers, and 36 nonsmokers were analyzed for total ascorbic acid, alpha- and gamma-tocopherols, 5 carotenoids, retinol, and cotinine. Groups were compared by using analysis of variance with adjustment for sex, age, race, body mass index, alcohol intake, triacylglycerol concentration, fruit and vegetable intakes, and dietary antioxidants. RESULTS: After adjustment for dietary antioxidant intakes and other covariates, smokers and passive smokers had significantly lower plasma beta-carotene concentrations than did nonsmokers (0.15, 0.17, and 0.24 micro mol/L, respectively) and significantly higher gamma-tocopherol concentrations (7.8, 7.8, and 6.5 micro mol/L, respectively). Smokers had significantly lower plasma ascorbic acid and beta-cryptoxanthin concentrations than did nonsmokers and passive smokers (ascorbic acid: 43.6, 54.5, and 54.6 micro mol/L, respectively; beta-cryptoxanthin: 0.12, 0.16, and 0.16 micro mol/L, respectively) and significantly lower concentrations of lutein and zeaxanthin than did nonsmokers (0.33 compared with 0.41 micro mol/L). The P values for all the differences described above were < 0.05. No significant differences in plasma concentrations of alpha-tocopherol, alpha-carotene, total carotenoids, lycopene, or retinol were observed. CONCLUSIONS: These results indicate that cigarette smokers and nonsmokers exposed to cigarette smoke have a significantly lower plasma antioxidant status than do unexposed nonsmokers, independent of differences in dietary antioxidant intakes. Further research is required to explain why plasma gamma-tocopherol concentrations were significantly higher in smokers and passive smokers than in nonsmokers.     

Measurement of fruit and vegetable consumption with diet questionnaires and implications for analyses and interpretation

Measurement error can have an important impact on the estimation of the true relation between diet and disease. The authors examined the performance of models regressing plasma vitamin C level on fruit and vegetable consumption and the effect of categorization of fruit and vegetable consumption on the association with plasma vitamin C. They used diet information reported by 4,487 participants in the Norfolk, United Kingdom, portion of the European Prospective Investigation into Cancer and Nutrition by means of a 7-day diet diary and a food frequency questionnaire (FFQ) (1993-1998). The authors found substantial differences in mean fruit and vegetable consumption assessed by the two diet instruments. Consumption estimated with the FFQ was about twice as high as that obtained with the 7-day diary, and the ranking of individuals according to estimates of fruit and vegetable consumption from the 7-day diary and the FFQ differed substantially. When fruit and vegetable consumption were categorized into quintiles, the two questionnaires produced similar associations of relative intake with plasma vitamin C, but estimation of the association of absolute intake with plasma vitamin C differed.     

Plasma C-reactive protein and homocysteine concentrations are related to frequent fruit and vegetable intake in Hispanic and non-Hispanic white elders

Elevated C-reactive protein (CRP) and plasma total homocysteine (Hcy) were recently identified as risk factors for cardiovascular disease. However, few studies have related fruit and vegetable consumption to these markers of inflammation and B vitamin deficiency, particularly in the Hispanic population. We examined the relation of fruit and vegetable intake with plasma CRP and Hcy concentrations in a cross-sectional study. Subjects were 445 Hispanic elders and 154 neighborhood-based non-Hispanic white elders living in Massachusetts. Diet was assessed with a FFQ designed for this population. There were significant inverse dose-response associations between fruit and vegetable intake and plasma CRP (P for trend = 0.010) and Hcy (P for trend = 0.033) concentrations, after adjustment for potential confounders. The prevalence of high plasma CRP (> 10 mg/L), and high Hcy (>10.4 micromol/L for women and >11.4 micromol/L for men), was significantly greater among subjects in the lowest quartile of fruit and vegetable consumption relative to those in the highest quartile, 17.9 vs. 9.1% and 58.7 vs. 44.4%, respectively. With each additional serving of fruit and vegetable intake, adjusted odd ratios for high plasma CRP and Hcy were 0.79 (95% CI: 0.65 to 0.97) and 0.83 (95% CI: 0.72 to 0.96), respectively. Greater frequency of fruit and vegetable intake was associated with significantly lower plasma CRP and Hcy concentrations. Because both of these metabolites are known risk factors for CVD, these findings contribute to the evidence that a higher intake of fruit and vegetables may reduce the risk of CVD.     

Relationships between different types of fruit and vegetable consumption and serum concentrations of antioxidant vitamins

Increased fruit and vegetable consumption has become a health priority in many countries. Therefore, data investigating the influence of different types of fruits and vegetables on serum antioxidant levels would be useful. The objective of the study was to assess the relationship between fruit and vegetable consumption and vitamin serum antioxidant concentrations. Specific fruit and vegetable groups are evaluated. A total of 3521 subjects (1487 men and 2034 women), aged 35-60 years, participating in the SU.VI.MAX cohort were included in this study. Blood samples of participants were analysed for beta-carotene, vitamin C and alpha-tocopherol. Each subject had completed at least six dietary records during the first 2 years of the study. It was found that women had higher mean beta-carotene and vitamin C serum concentrations than men, but lower alpha-tocopherol serum concentrations. Serum beta-carotene and vitamin C concentrations were positively correlated with consumption of both fruit and vegetables, as well as with most of the fruit and vegetable groups tested. These relationships persisted after adjustment for confounding factors. Regression analysis showed a linear dose-response relationship. Root vegetables and citrus fruits were particularly associated with beta-carotene serum status as were citrus fruits for vitamin C. Fruit and vegetable consumption was either not or weakly associated with alpha-tocopherol serum concentrations. These results describe antioxidant serum concentrations according to fruit and vegetable consumption in a large sample and support the findings of previous studies involving a more limited number of subjects.     

Maternal nutritional status and the risk for orofacial cleft offspring in humans

Periconceptional folate and folic acid intake prevents orofacial clefts (OFC) in the offspring. It has been suggested that other nutrients also play a role. We investigated the preconceptional intake of macronutrients (protein, fat, carbohydrate, fiber, and cholesterol), vitamins (vitamin A, retinol, beta-carotene, ascorbic acid, and alpha-tocopherol), minerals (calcium, phosphorus, iron, magnesium, and zinc) and food groups in mothers of OFC children and controls. At approximately 14 mo after the index pregnancy, 206 mothers of a child with a nonsyndromic OFC and 203 control mothers completed a FFQ on current food intake and a general questionnaire. After exclusion of pregnant and lactating mothers, mothers who reported a change in diet compared with the preconceptional period, and those for whom periconceptional folic acid supplement use was unclear, 182 OFC mothers and 173 control mothers were evaluated. Macronutrient, vitamin, mineral, and food group intakes were compared. After adjustment for energy, quintiles of dietary nutrient intake and odds ratios with 95% CI were calculated. The preconceptional intake of all macronutrients, vitamins, minerals, and food groups with the exception of milk (products), potatoes, pies/cookies were lower in OFC mothers than in controls. The energy-adjusted intakes of vegetable protein, fiber, beta-carotene, ascorbic acid, alpha-tocopherol, iron, and magnesium were significantly lower in cases compared with controls. Increasing intakes of vegetable protein, fiber, ascorbic acid, iron, and magnesium decreased OFC risk. In conclusion, a higher preconceptional intake of nutrients predominantly present in fruits and vegetables reduces the risk of offspring affected by OFC.     

Comparison of plasma biomarkers with dietary assessment methods for fruit and vegetable intake

OBJECTIVE: To assess the variability and validity of plasma-based biomarkers of antioxidant vitamin, and fruit and vegetable intake. SETTING: Leeds, Wakefield, Huddersfield and Bradford, England. SUBJECTS: A total of 54 free-living, nonsmoking women recruited from participants of the UK Women's Cohort Study (UKWCS). METHODS: Two fasting blood samples were taken at two time points, 18 months apart. A 4-day food diary was completed prior to the first blood sample and a 24-h recall was conducted at the time of the second blood collection. All blood samples were analysed for ascorbic acid and four carotenoids. Associations between antioxidant vitamin intake from all food sources and supplements, as well as fruit and vegetable intake, and plasma levels of the antioxidant vitamins were assessed. RESULTS: Using the 4-day diary, positive associations were found between micronutrient intake from all food sources and plasma concentrations of ascorbic acid (P<0.01) and beta-carotene (P<0.01). No associations were seen between plasma micronutrient levels and specifically fruit and vegetable intakes. In general, associations between plasma levels and intakes assessed by the 24-h recall were less marked than those based on the 4-day diary. CONCLUSIONS: Plasma ascorbic acid and beta-carotene are good indicators of previous vitamin C and beta-carotene intake, from all food sources. However, caution is required in extrapolating these results to include individual food groups, rich in these vitamins. The results imply that the practice of using plasma biomarkers simply as a proxy measure of dietary intake is not valid and emphasise that plasma biomarkers are not simply a reflection of dietary intake, but also of a number of physiological processes. Biomarkers in nutrition epidemiological studies are however useful to measure nutrient status at the tissue level.     

The relationships among socioeconomic status, fruit and vegetable intake, and alcohol consumption

Abstract Purpose . We examined the relationships among fruit and vegetable intake, alcohol consumption, and socioeconomic status (SES). We hypothesized that fruit and vegetable consumption would be inversely associated with alcohol consumption and the relationship would differ by SES. Design . A cross-sectional analysis. Setting . Large, urban Midwestern county. Subjects . A unique, racially/ethnically diverse sample of 9959 adults (response rate: 66.3%). Measures . Fruit and vegetable intake was measured using two items that assessed servings per day. Alcohol consumption was measured in terms of volume of alcohol consumed and binge drinking. Individual measures of SES included education and household income. Analysis . Weighted multivariate linear and Poisson regression were used to estimate effects. Results . The relationship between fruit and vegetable intake and alcohol consumption varied by SES. Those with lower household incomes who consumed five or more servings of fruits and vegetables per day were less likely to engage in binge drinking relative to those consuming zero to one servings of fruits and vegetables per day (risk ratio = .66; 95% confidence interval: .46, .95). No association was observed for higher-household-income individuals. Conclusion . We observed an inverse relationship between fruit and vegetable consumption and alcohol intake in those with lower household incomes but not in those with higher household incomes. Results suggest that the relationship between diet and alcohol consumption may be more relevant in populations with more restricted economic choices. Results are, however, based on cross-sectional data.     

Parental pressure, dietary patterns, and weight status among girls who are "picky eaters"

OBJECTIVE: To determine whether mothers' fruit and vegetable intake and mothers' use of pressure in the feeding domain when their daughters were 7 years old predicted picky eating and dietary intake when their daughters were 9 years old, and to examine diet and weight status in picky and nonpicky eaters. DESIGN/SUBJECTS: Participants were 173 9-year-old non-Hispanic white girls and their mothers. A longitudinal analysis was used to assess maternal influences on picky eating and diet. A cross-sectional analysis was used to examine diet and weight status between picky and nonpicky eaters. Measures included maternal feeding practices, daughters' pickiness, mothers' fruit and vegetable intake, daughters' food intake, and weight status. STATISTICAL ANALYSES: t tests examined differences between picky and nonpicky eaters. Structural equation modeling examined relationships among mothers' fruit and vegetable intake; child feeding practices; daughters' pickiness; and fruit, vegetable, micronutrient, and fiber intakes. RESULTS: Mothers consuming more fruits and vegetables were less likely to pressure their daughters to eat and had daughters who were less picky and consumed more fruits and vegetables. Picky eaters consumed fewer fruits and vegetables, but also fewer fats and sweets. All girls consumed low amounts of vitamin E, calcium, and magnesium, but more picky girls were at risk for not meeting recommendations for vitamins E and C and also consumed significantly less fiber. In addition, picky eaters were less likely to be overweight. CONCLUSIONS: Mothers influenced daughters' fruit and vegetable intake via their own patterns of fruit and vegetable intake and by influencing their daughters' tendencies to be picky eaters. Both picky and nonpicky eaters had aspects of their diets that did not meet recommendations. Taken together, these findings suggest that parents should focus less on "picky eating" behavior and more on modeling fruit and vegetable consumption for their children.     

Plasma ascorbic acid concentrations and fat distribution in 19,068 British men and women in the European Prospective Investigation into Cancer and Nutrition Norfolk cohort study

BACKGROUND: Antioxidants, such as ascorbic acid, play a role in scavenging free radicals to protect against oxidative endothelial damage. Excess fat may promote fatty acid oxidation and increase free radical concentrations, which could result in increased antioxidant use. Whether plasma ascorbic acid concentrations are associated with fat distribution remains unclear. OBJECTIVE: Our aim was to examine the association between abdominal obesity, as measured by the waist-to-hip ratio, and plasma ascorbic acid concentrations in the general population. DESIGN: We examined the cross-sectional relation between anthropometric measurements of fat distribution and plasma ascorbic acid concentrations in 19 068 men and women aged 45-79 y without known chronic illness. Dietary ascorbic acid intake was estimated for a subgroup of 8178 men and women who kept 7-d food diaries coded for nutrient intake. RESULTS: The waist-to-hip ratio was inversely related to plasma ascorbic acid concentrations in both men and women. This association was independent of body mass index, age, vitamin supplement use, cigarette smoking, and socioeconomic group. Waist and hip circumferences showed separate and opposite associations with plasma ascorbic acid concentrations, independent of body mass index and other covariates. Dietary ascorbic acid intake only partly explained the observed associations. CONCLUSIONS: Plasma ascorbic acid was associated with fat distribution independent of body mass index. Differences in dietary intake and lifestyle habits, underlying systemic oxidative stress, or both may explain the inverse relation between fat distribution and plasma ascorbic acid concentrations. Additional studies are needed to determine the underlying explanation of these observations.     

Vitamin intake in an average diet of Warsaw adult inhabitants

The study aimed to establish the intake of vitamins in an average diet of Warsaw adult inhabitants using 3-day records method. The consumption of vitamin B1 was about 40% lower than recommended, the intake level of vitamin C, B2, PP and B6 was about 20-30% lower than recommended, whilst, folate in the diet realized the norms only in 50%. The intake of vitamins E, A and B12 was higher than recommended. In order to ensure the proper intake of vitamin C, it is recommended to increase the intake of fruit and vegetables rich in this vitamin and their products. In order to increase the participation of vitamin B1, PP, B6 and folate in the diet, a higher consumption of vegetable and vegetable products and bread and cereal products is recommended, however, in order to supply the proper amount of vitamin B2 in the diet it is recommended to increase the intake level of milk and milk products, vegetables and bread and cereal products.     

A household food inventory is not a good measure of fruit and vegetable intake among ethnically diverse rural women

Environmental measures of food availability are surrogates of consumption. Such measures may be useful among populations for whom standard dietary assessment is difficult. The objective of this cross-sectional study was to test whether a measure of the household dietary environment would perform as well as or better than a standard fruit and vegetable assessment among ethnically diverse rural women. Participants were 154 non-Hispanic white, 157 Hispanic, and 102 Native American adult women residing in rural Washington state. Participants completed an interviewer-administered household inventory of fruits and vegetables and a standard measure of fruit and vegetable intake used in the 5 A Day for Better Health Program. Pearson correlation coefficients assessed the validity of the measures against biomarkers of fruit and vegetable consumption (serum carotenoids). Pearson correlations were poor to modest between the household inventory and serum carotenoids (r=0.06 to 0.22) and between the 5 A Day responses and serum carotenoids (r=-0.08 to 0.17). There were no differences by ethnic group; both short tools performed poorly compared with the biomarkers across Hispanic, non-Hispanic white, and Native-American participants. In conclusion, both the household inventory and the popular 5 A Day measure were poor indicators of fruit and vegetable intake in this sample of ethnically diverse rural women.     

Changes in plasma antioxidant status following consumption of diets high or low in fruit and vegetables or following dietary supplementation with an antioxidant mixture

The aim of the present study was to examine the effect of consumption of a high-fruit and vegetable diet, or a spray-dried extract of selected fruits and vegetables of high antioxidant content, on indices of antioxidant status of individuals consuming a background diet with minimal antioxidant intake. Plasma antioxidant concentrations were determined in twenty-five men following a 2-week depletion period during which they consumed self-selected low-antioxidant diets (less than three servings of fruit and vegetables with no tea, coffee, red wine or fruit juice). Following this period the volunteers consumed either a self-selected diet containing five to seven servings of fruit and vegetables/d, or 30 g of a spray-dried supplement designed to provide the equivalent antioxidant activity of five to seven servings of fruit and vegetables for 2 weeks in a crossover trial. Following consumption of a high-antioxidant diet for 2 weeks, plasma concentrations of ascorbic acid, alpha- and beta-carotene and lutein+zeaxanthin were all significantly increased (P < 0.05) over the depletion period. However, concentrations of lycopene, retinol and tocopherol were not affected. Consumption of the supplement also raised the concentrations of these same antioxidants in plasma. Despite the increases in the concentrations of measured antioxidant nutrients, the 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid-equivalent antioxidant capacity of plasma, as estimated by inhibition of metmyoglobin activity, was not significantly affected by any of the dietary treatments.     

Household food security and fruit and vegetable intake among low-income fourth-graders

Objective

To examine the relationship between household food security and children’s and parents’ fruit, vegetable, and breakfast consumption and fruit and vegetable availability.

Design

Cross-sectional study using matched parent-child surveys.

Setting

Title I elementary schools in Maryland.

Participants

Ninety-two low-income parent-child dyads recruited from fourth-grade nutrition education programs completing a baseline evaluation.

Main Outcome Measures

Fruit and vegetable intake, breakfast consumption, and fruit and vegetable availability in home and school.

Analysis

Chi-square tests, 1-way ANOVA.

Results

Thirty-six percent of parents reported low/very low household food security, and both parents and students reported low fruit and vegetable intake. Students from households with low food security who were not participating in school nutrition programs had the lowest vegetable consumption and the fewest number of days consuming breakfast, indicating a relatively greater need for enrollment than their peers.

Conclusions and Implications

Few differences between children in food-secure and food-insecure households were observed, which underscores the need for research on food insecurity and children’s eating behaviors. Examination of other factors influencing fruit and vegetable intake and improvements in food environments and programs are needed. Efforts to increase enrollment among eligible students in school nutrition programs may reduce negative consequences of household food insecurity.     

Daily polyphenol intake in France from fruit and vegetables

The objective of this study was to create a French database on the polyphenol content of fruit and vegetables as uncooked fruits and vegetables and then to evaluate polyphenol intake through fruit and vegetable consumption in France. To achieve this, we used the Folin-Ciocalteu method adapted to fruit and vegetable polyphenol quantitation (1). Vegetables with the highest polyphenol concentration were artichokes, parsley, and brussels sprouts [>250 mg of gallic acid equivalent (GAE)/100 g fresh edible portion (FEP)]; fruits with the highest concentrations were strawberries, lychees, and grapes (>180 mg of GAE/100 g FEP). Conversely, melons (Cantaloupe cv.) and avocados had the lowest polyphenol concentration for fruits and vegetables, respectively. Based on fruit consumption data, apples and strawberries are the main sources of polyphenols in the French diet, whereas potatoes, lettuces, and onions are the most important vegetable sources. Total polyphenol intake from fruit is about 3 times higher than from vegetables, due to the lower polyphenol concentration in vegetables. The calculation of polyphenol intake, based on both assessment methods used [(Société d'Etudes de la Communication, Distribution et Publicité (SECODIP) and Supplémentation en Vitamines et Minéraux Antioxydants (SUVIMAX)], showed that apples and potatoes provide approximatively half of the total polyphenol intake from fruit and vegetables in the French diet.     

Megadose effects of vitamin C on vitamin B-12 status in the rat

Effects of ascorbic acid ingestion on the severity of vitamin B-12 deficiency were investigated by feeding weanling rats experimental diets containing 0-100 micrograms of vitamin B-12 activity per kg of diet, with or without 6.0 mg of ascorbic acid per ml supplied in drinking water for 15 wk. This daily consumption of up to 150 mg of ascorbic acid did not impair growth, but did result in significantly higher concentrations of ascorbic acid in plasma, liver, adrenal glands and feces. When rats were fed diets deficient or marginally deficient in vitamin B-12, liver concentrations of vitamin B-12 were markedly lower than in liver of rats fed adequate vitamin B-12. Ascorbic acid ingestion raised values significantly in the vitamin B-12-deficient diet group. Urinary methylmalonic acid was significantly elevated in the deficient rats. However, it was significantly reduced to more normal values by ascorbic acid in rats with both low and marginal vitamin B-12 status, as defined by dietary and liver concentrations of vitamin B-12 activity. Although coprophagy was not prevented, rats showed no increased consumption of feces with the higher ascorbic acid content. Thus, the results of this research indicate that vitamin C ingestion partially protects rats from vitamin B-12 deficiency.     

Changes in markers of inflammation,antioxidant capacity and oxidative stress in smokers following consumption of milk,and milk supplemented with fruit and vegetable extracts and vitamin C

Two milk-based beverages delivering twice the average daily antioxidant intake were formulated, based on synergistic combinations of fruit and vegetable extracts, and containing vitamin C (1.00 mg/ml) for shelf stability. Smokers (n = 42) consumed prototype milk A, B or non-supplemented milk (no extracts or vitamin C; 200 ml) twice daily for 6 weeks. Fasting and post-prandial (2 h after milk consumption) blood samples were collected at baseline and the end of each treatment. Non-supplemented milk significantly reduced fasting inflammatory cytokines (interleukin (IL) 6, IL-1β, tumour necrosis factor-α) compared to baseline. Both supplemented milk-based beverages significantly increased fasting plasma vitamin C concentrations and antioxidant potential and decreased serum uric acid, compared to non-supplemented milk. The beverages did not induce post-prandial oxidative stress or inflammation. Therefore, regular consumption of the supplemented milks may confer health benefits because of increased antioxidant potential or through mechanisms resulting from increased vitamin C or decreased uric acid concentrations.     

Vitamins, lipids and lipoproteins in a healthy elderly population

Vitamin status may be related to serum lipid-lipoprotein levels. We tested this hypothesis in a group of 270 healthy elderly men and women over 60 years of age. Vitamin status was determined from dietary intakes and biochemical analysis of plasma. Fasting lipid profile included triglycerides, total cholesterol, low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein-cholesterol (HDL-C). Correlations have been adjusted by partial correlation for age, physical activity, body mass index, and alcohol consumption. Neither vitamin E intake nor ascorbic acid intake nor ascorbic acid plasma levels correlated with any lipids measured. HDL-C levels did not correlate with any vitamin parameters. In men, vitamin A blood levels correlated with LDL-C, triglyceride, and total cholesterol levels. In women, total cholesterol levels correlated inversely with thiamine and riboflavin blood status and with dietary intake of vitamins B6, D, and niacin. LDL-C plasma values were also inversely correlated with both intake and plasma vitamin D levels and intakes of riboflavin and vitamin B12 in women.