Relationship between intake and plasma concentrations of vitamin B12 and folate in 873 adults with a physically active lifestyle: a cross-sectional study.

BACKGROUND: Vitamin B12 and folate function as co-factors in pathways used during physical activity. Physical activity may therefore increase vitamin requirements, leading to a risk of deficient plasma concentrations. We aimed to investigate the relationship between intake and plasma concentrations of vitamin B12 and folate in physically active adults, as well as identify other determinants of vitamin B12 and folate plasma concentrations. METHODS: The study population consisted of 873 adults (528 men and 345 women), aged 19-78 years, who participated in a 4-day walking event. The relationship between intake and plasma concentrations of vitamin B12 and folate was assessed using correlation and linear regression analyses. In addition, potential other determinants (sex, age, body mass index, energy intake and physical activity) of vitamin plasma concentrations were investigated. RESULTS: Significant positive correlations were observed between intake and plasma concentrations of vitamin B12 [Pearson's correlation coefficient = 0.15; 95% confidence interval (CI) = 0.08-0.21] and folate (Pearson's correlation coefficient = 0.18; 95% CI = 0.12-0.25). In addition to vitamin intake, sex, age and energy intake were also determinants of both vitamin B12 and folate plasma concentrations in multivariable regression models. CONCLUSIONS: The results suggest a positive association between intake and plasma concentrations for both vitamin B12 and folate in physically active people. By contrast to our hypothesis, physical activity was not a determinant of vitamin B12 and folate plasma concentrations. However, sex, age and energy intake were found to be determinants. Thus, when studying the relationship between intake and plasma concentrations of vitamin B12 or folate, these factors should be taken into account.

Prediction of low haemoglobin levels in whole blood donors.

BACKGROUND AND OBJECTIVES: Each year, a relevant proportion of whole blood donors is deferred from donation because of low haemoglobin (Hb) levels. Such temporary deferrals are demoralizing, and donors may never return for a donation. Reliable predictions of Hb levels may guide the decision whether donors can be invited for the next donation. In this study, a prediction model was developed for the risk of low Hb levels. MATERIALS AND METHODS: Individual data from 5191 whole blood donors were analysed; 143 donors had a low Hb level. Eleven candidate predictors were considered in logistic regression models to predict low Hb levels. The performance of the prediction model was studied with the receiver operating characteristic (ROC) curve. Internal validity was assessed with a bootstrap procedure. RESULTS: Strong predictors were sex, seasonality, Hb level measured at the previous visit, difference in Hb levels between the previous two visits, time since the previous visit, deferral at the previous visit, and the total number of whole blood donations in the past 2 years. Internal validation showed an area under the ROC curve of 0·87. CONCLUSION: The developed prediction model provides accurate discrimination between donors with low and appropriate Hb levels. The model predictions may be valuable to determine whether donors can be invited for a next donation, or whether some interventions such as postponement of the invitation are warranted. Potentially, this could decrease the number of donor deferrals for low Hb levels.

Selection of a food classification system and a food composition database for future food consumption surveys.

OBJECTIVE: To harmonize food classification and food composition databases, allowing comparability of consumption at both food and nutrient levels in Europe. DESIGN: To establish the level of comparability at the food level, the EFCOSUM group benefited from the work already carried out within other European projects, which established a Euro Food Groups (EFG) classification system. Four food groups, ie bread, vegetables (excluding potatoes), fruits (excluding fruit juice) and fish and seafood, were judged on their applicability for making food consumption data comparable across countries at the food level. CONCLUSIONS: It was concluded that the EFG system could be used but that still much work has to be done. For food consumption data to be collected in the future, the software that will be used should enable conversion of foods 'as consumed' to foods at the 'raw edible' level. With respect to comparability of nutrient intake estimations, EFCOSUM advises waiting for the European Nutrient Composition Database (ENDB) currently being prepared by the EPIC group. Until this is available, comparison of consumption data at the nutrient level cannot be carried out between countries.

Dietary calcium and bone density in adolescent girls and young women in Europe.

The objective of this study was to investigate the association between dietary calcium intake and radial bone density among young women, over the whole range of intake and at different levels of calcium intake. The study design was a cross-sectional, observational multicenter investigation in six European countries. One thousand one hundred and sixteen healthy Caucasian girls aged 11-15 years and 526 women aged 20-23 years participated, after having been selected from larger population samples to represent a large range in calcium intake. Bone mineral density (BMD) was measured with dual-energy X-ray absorptiometry at the ultradistal and middistal radius. Calcium intake was assessed with 3-day food records. Other potential determinants of BMD were measured by anthropometry or questionnaires. Mean calcium intake among the girls varied between 609 mg/day in Italy and 1267 mg/day in Finland; intakes for women were in a similar range. After adjustment for height, weight, and age at menarche for the women, and adjustment for age, height, weight, Tanner stage, and bone area for the girls, radial BMD at both sites did not significantly vary among quartiles of calcium intakes for both age groups. In multivariate linear regression, calcium was weakly positively associated with BMD at both sites in the girls (per 100 mg of calcium: beta = 0.57 mg/cm2, p = 0.03 for middistal BMD and beta = 0.56 mg/cm2, p = 0.01 for ultradistal BMD). For middistal BMD, the association was observed predominantly in pre-menarcheal girls. The associations were no longer statistically significant after full adjustment for all determinants of BMD, except again in pre-menarcheal girls. Radial BMD in the women was not associated with calcium intake, except after full adjustment for determinants of BMD, when ultradistal BMD became inversely associated with calcium intake (per 100 mg beta = -1.02, p = 0.03); this finding was due to results in one of the countries and not found in other countries. There was no evidence for a different relation between calcium and BMD at different levels of intake; although there was a positive association at calcium intake levels < 600 mg/day, the interaction was not significant and there was no consistent trend over intake categories. These results do not support the hypothesis that dietary calcium is a determinant of peak BMD in European women, for a wide range of intake. This study does not provide evidence that Recommended Dietary Allowances for calcium should be increased.

Food consumption methods. Development, reproducibility and validation of a food frequency questionnaire for vitamin B6.

OBJECTIVE: The correct classification of adults with a habitual low vitamin B6 intake by means of a food frequency questionnaire (FFQ). Assessment of reproducibility of the food frequency questionnaire and of the relative validity as compared to 3 d diet records (DR). DESIGN: A self-administered food frequency questionnaire (FFQ) to measure habitual vitamin B6 intake was developed using the data base of the first Dutch National Food Consumption Survey 1987/88 (DNFCS). The frequency and quantity of consumption of 92 (combinations of) food products, contributing to about 95% of vitamin B6 intake, were asked for. Recent food consumption was measured with 3 d diet records. Reproducibility of the FFQ was assessed after 10 months (n = 330). SUBJECTS: Randomly selected men and women aged 20-79 y, stratified for 10 y age classes and sex. RESULTS: A total number of 2867 FFQs was adequately completed (response rate 46%). A low vitamin B6 group was selected from the lowest tertile of age-gender specific vitamin B6 intake (36 men and 36 women, aged 20-49 and 36 men and 36 women, aged 50-79) and a so-called reference group (n = 300) was selected at random. The ratio of vitamin B6 intake according to FFQ and DR (FFQ/DR) varied between 0.77 and 0.99 for the various age-gender-study groups; for vitamin B6/g protein the FFQ/DR ratio varied between 1.00 and 1.10. After correction for intraindividual variance Pearson correlation coefficients between vitamin B6 intake according to FFQ and DR varied between 0.27 and 0.95 for the various age-gender-study groups, for vitamin B6/g protein the corrected Pearson correlation coefficients varied between 0.27 and 0.65. Of the subjects selected in the low B6 groups, 61-81% fell in the lowest tertile of vitamin B6 intake according to diet records and 3-6% fell in the extreme opposite tertile. The percentage subjects selected in the same/opposite quartile of vitamin B6 intake according to FFQ and DR was 50/11 for men, and 45/18 for women. Pearson correlation coefficients for vitamin B6 intake according to the first and the second FFQ were 0.64 and 0.72 for men and women, respectively; for vitamin B6/g protein these values were 0.70 and 0.51 for men and women, respectively. The proportion of subjects classified in the same/extreme opposite tertile of vitamin B6 intake was 56/6 and 62/5 for men and women, respectively. CONCLUSIONS: It is concluded that the FFQ was adequate for the selection of subjects with a habitually low vitamin B6 intake.

Alcohol consumption in relation to food intake and smoking habits in the Dutch National Food Consumption Survey.

The interrelationships between alcohol consumption, energy and food intake and smoking habits were studied in 1145 men and 1171 women, aged 22-49 years, in the Dutch National Food Consumption Survey, in which a 48-h dietary record method was used. The aim of the study was to investigate the effects of alcohol consumption on dietary habits and smoking. A strong relationship between alcohol consumption and energy intake was found. The energy derived from alcohol was not compensated for by lower intake of other nutrients. There was no increase in Quetelet's index with increasing alcohol consumption, except for non-smoking men who were heavy drinking on midweek days. Possible explanations for this apparent lack of an overall effect of alcohol calories are discussed. Alcohol consumption was much higher on weekend days than on midweek days. No differences in nutrient intake were found between non-drinkers, moderate drinkers and heavy drinkers on midweek days. On weekend days, however, there was a slightly higher total fat and saturated fat intake in moderately drinking men. For women cholesterol intake was found to be higher in moderate and heavy drinkers. Finally, a strong positive relationship between alcohol consumption and smoking was observed. It is concluded that the observations with respect to energy and nutrient intake and smoking habits are not indicative of a healthier lifestyle in moderate alcohol users between 22 and 49 years of age. Consequently, the more favourable prognosis of moderate drinkers cannot be ascribed to a more healthy lifestyle.

Nationwide survey on nutritional habits in elite athletes. Part II. Mineral and vitamin intake.

The nutritional habits of elite athletes competing at a national and international top level were determined. Groups of endurance strength, and team sport athletes participated. All athletes trained at least 1-2 h daily. The purpose of the study was to quantify the mineral and vitamin intake and to identify the magnitude of the nutrient supplementation use. Information on food intake was obtained by a 4- or 7-day food diary. It was found that calcium and iron intake was positively related to energy intake. In low energy intakes (less than 10 MJ) iron intake might be insufficient. In general, vitamin intake with food was in agreement with the Dutch recommendations. However, if energy intake is high (greater than 20 MJ) the amount of refined carbohydrate is increased. Consequently, the nutrient density for vitamin B1 drops. Therefore, under these conditions, supplementation for vitamin B1 must be considered. The low vitamin intake found in lower energy intakes can be improved by proper nutritional advice. In body building and in professional cycling, high dosages of vitamins are used. The other groups of athletes used only moderate quantities of vitamin supplements. It is concluded that vitamin and mineral intake is sufficient, when energy intake ranges between 10 and 20 MJ/day.

Nationwide survey on nutritional habits in elite athletes. Part I. Energy, carbohydrate, protein, and fat intake.

Information about habitual food intake was systematically obtained from elite endurance, strength, and team sport athletes. The athletes (n = 419) trained at least 1-2 h daily and competed on an international level. A 4- or 7-day food diary was kept. For analysis of the data, a computerized food table was used. Mean energy intake varied from 12.1-24.7 MJ per day for male and 6.8-12.9 MJ per day for female athletes. Protein intake was in agreement with or higher than the Dutch recommendations. Contribution of carbohydrate intake to total energy intake varied from 40%-63%. Fat intake tended to meet the criteria for a prudent diet (less than 35%). Snacks contributed about 35% to the total energy intake and the bread/cereals and dairy food groups were the most important energy sources. It is concluded that in general there are two major concerns. In those sports in which body composition plays an important role, energy and thus nutrient intake is often marginal. In all groups of athletes intake of carbohydrate is insufficient.

Nutrition of premenarcheal athletes: relation with the lipid and apolipoprotein profiles.

The lipid and apolipoprotein profiles in plasma and the nutritional intake were investigated in 25 female elite gymnasts, 23 recreational gymnasts, 21 girl swimmers, and 16 controls. The girls were matched for sexual development, assessed by means of breast development. The age of the girls varied from 10.0 to 15.0 years. The recreational gymnasts and the girl swimmers had the highest levels of HDL-C, while those of the elite gymnasts and the controls were equally low (P less than or equal to 0.05). The same trend was seen in the case of the HDL-C/TC, HDL-C/LDL-C, and HDL-C/apo A-I ratios (P less than or equal to 0.05). The swimmers and the controls had similar high levels of apo A-I, and the swimmers also had a low apo B level. The differences with the elite group reached statistical significance (P less than or equal to 0.05). The recreational gymnasts had a lower level of apo E than the elite gymnasts and the swimmers had (P less than or equal to 0.05). The composition of the diet, expressed in energy %, was similar for all groups. The recreational gymnasts had a higher P/S ratio than the controls. It is concluded that the differences in lipid and apolipoprotein profiles found between young, female athletes and controls are not associated with differences in dietary intake and may be due to differences in physical activity. Also, genetic factors may have contributed to the variation found in the mentioned profiles. Yet, in this pediatric population, the nutritional intake played a small but significant role relative to the plasma lipids and apolipoproteins.