Pilar Galan

Prevalence of Vitamin D Insufficiency in an Adult Normal Population

Abstract: The vitamin D status of a general adult urban population was estimated between November and April in 1569 subjects selected from 20 French cities grouped in nine geographical regions (between latitude 43° and 51° N). Major differences in 25-hydroxyvitamin D (25(OH)D) concentration were found between regions, the lowest values being seen in the North and the greatest in the South, with a significant ‘sun’ effect (r = 0.72; p = 0.03) and latitude effect (r = -0.79; p = 0.01). In this healthy adult population, 14% of subjects exhibited 25(OH)D values ≤ 30 nmol/l (12 ng/ml), which represents the lower limit (< 2 SD) for a normal adult population measured in winter with the same method (RIA Incstar). A significant negative correlation was found between serum intact parathyroid hormone (iPTH) and serum 25(OH)D values (p < 0.01). Serum iPTH held a stable plateau level at 36 pg/ml as long as serum 25(OH)D values were higher than 78 nmol/l (31 ng/ml), but increased when the serum 25(OH)D value fell below this. When the 25(OH)D concentration became equal to or lower than 11.3 nmol/l (4.6 ng/ml), the PTH values reached the upper limit of normal values (55 pg/ml) found in vitamin D replete subjects. These results showed that in French normal adults living in an urban environment with a lack of direct exposure to sunshine, diet failed to provide an adequate amount of vitamin D. It is important to pay attention to this rather high prevalence of vitamin D insufficiency in the general adult population and to discuss the clinical utility of winter supplementation with low doses of vitamin D.

A Primary Prevention Trial Using Nutritional Doses of Antioxidant Vitamins and Minerals in Cardiovascular Diseases and Cancers in a General Population: The SU.VI.MAX Study—Design, Methods, and Participant Characteristics

The SUpplementation en VItamines et Minéraux AntioXydants (SU.VI.MAX) Study is a randomized, double-blind, placebo-controlled, primary-prevention trial designed to test the efficacy of daily supplementation with antioxidant vitamins (vitamin C, 120 mg; vitamin E, 30 mg; and beta-carotene, 6 mg) and minerals (selenium, 100 microg; and zinc, 20 mg) at nutrition-level doses (one to three times the daily recommended dietary allowances) in reducing several major health problems in industrialized countries, especially the main causes of premature death, cancers and cardiovascular diseases. The present report describes the design, implementation, and baseline characteristics of participants in this 8-year cohort study, which started in 1994 in France; 12,735 eligible subjects (women aged 35-60, and men aged 45-60) were included in 1994 and will be followed for 8 years. Participants undergo a yearly visit consisting, every other year, of either biological sampling or clinical examination. They also regularly provide information on health events and dietary intake by filling out computerized questionnaires using the Minitel Telematic Network. Data on baseline characteristics of the participants suggest that the present sample is close to the national population in terms of geographic density, socioeconomic status, and the distribution of various major risk factors for the diseases under study. The choice of the study population should allow the results of this trial to apply to adult populations of both sexes in France and other industrialized countries.

Dietary intakes and food sources of n−6 and n−3 PUFA in french adult men and women

The intake of individual n−6 and n−3 PUFA has been estimated in 4,884 adult subjects (2,099 men and 2,785 women), volunteers from the French SU.VI.MAX intervention trial. The food intakes of each subject were recorded in at least ten 24-h record questionnaires completed over a period of 2.5 yr, allowing the estimation of the daily intake of energy; total fat; and linoleic, α-linolenic, arachidonic, eicosapentaenoic (EPA), n−3 docosapentaenoic (DPA), and docosahexaenoic (DHA) acids. The mean total fat intake corresponded to 94.1 g/d (36.3% of total energy intake) in men and 73.4 g/d (38.1% of energy) in women. The intake of linoleic acid was 10.6 g/d in men and 8.1 g/d in women, representing 4.2% of energy intake; that of α-linolenic acid was 0.94 g/d in men and 0.74 g/d in women, representing 0.37% of energy intake, with a mean linoleic/α-linolenic acid ratio of 11.3. The mean intakes of long-chain PUFA were: arachidonic acid, 204 mg/d in men and 152 mg/d in women; EPA, 150 mg/d in men and 118 mg/d in women; DPA, 75 mg/d in men and 56 mg/d in women; DHA, 273 mg/d in men and 226 mg/d in women; long-chain n−3 PUFA, 497 mg/d in men and 400 mg/d in women. Ninety-five percent of the sample consumed less than 0.5% of energy as α-linolenic acid, which is well below the current French recommendation for adults (0.8% of energy). In contrast, the mean intakes of long-chain n−6 and n−3 PUFA appear fairly high and fit the current French recommendations (total long-chain PUFA: 500 mg/d in men and 400 mg/d in women; DHA: 120 mg/d in men and 100 mg/d in women). The intakes of α-linolenic acid, and to a lesser extent of linoleic acid, were highly correlated with that of lipids. Whereas the main source of linoleic acid was vegetable oils, all food types contributed to α-linolenic acid intake, the main ones being animal products (meat, poultry, and dairy products). The main source of EPA and DHA (and of total long-chain n−3 PUFA) was fish and seafood, but the major source of DPA was meat, poultry, and eggs. Fish and seafood consumption showed very large interindividual variations, the low consumers being at risk of insufficient n−3 PUFA intake.

Iron deficiency in Europe.

In Europe, iron deficiency is considered to be one of the main nutritional deficiency disorders affecting large fractions of the population, particularly such physiological groups as children, menstruating women and pregnant women. Some factors such as type of contraception in women, blood donation or minor pathological blood loss (haemorrhoids, gynaecological bleeding...) considerably increase the difficulty of covering iron needs. Moreover, women, especially adolescents consuming low-energy diets, vegetarians and vegans are at high risk of iron deficiency. Although there is no evidence that an absence of iron stores has any adverse consequences, it does indicate that iron nutrition is borderline, since any further reduction in body iron is associated with a decrease in the level of functional compounds such as haemoglobin. The prevalence of iron-deficient anaemia has slightly decreased in infants and menstruating women. Some positive factors may have contributed to reducing the prevalence of iron-deficiency anaemia in some groups of population: the use of iron-fortified formulas and iron-fortified cereals; the use of oral contraceptives and increased enrichment of iron in several countries; and the use of iron supplements during pregnancy in some European countries. It is possible to prevent and control iron deficiency by counseling individuals and families about sound iron nutrition during infancy and beyond, and about iron supplementation during pregnancy, by screening persons on the basis of their risk for iron deficiency, and by treating and following up persons with presumptive iron deficiency. This may help to reduce manifestations of iron deficiency and thus improve public health. Evidence linking iron status with risk of cardiovascular disease or cancer is unconvincing and does not justify changes in food fortification or medical practice, particularly because the benefits of assuring adequate iron intake during growth and development are well established. But stronger evidence is needed before rejecting the hypothesis that greater iron stores increase the incidence of CVD or cancer. At present, currently available data do not support radical changes in dietary recommendations. They include all means for increasing the content of dietary factors enhancing iron absorption or reducing the content of factors inhibiting iron absorption. Increased knowledge and increased information about factors may be important tools in the prevention of iron deficiency in Europe.

The potential role of antioxidant vitamins in preventing cardiovascular diseases and cancers

Cardiovascular diseases and cancers constitute major public health problems in all industrialized countries, where they are the main causes of premature mortality. There is a large body of evidence suggesting that free-radical production can directly or indirectly play a major role in cellular processes implicated in atherosclerosis and carcinogenesis. Here we present mechanistic data and results of epidemiologic studies on the relationship between antioxidant vitamin intake or biochemical status and the risk of cancer and cardiovascular diseases. Most epidemiologic data obtained on this topic were based on an observational approach, i.e., ecologic, case-control, or prospective studies. All these studies indicate that a high dietary intake or high blood concentrations of antioxidant vitamins are associated with a reduced risk of cardiovascular diseases and cancer at several common sites. Although the results of these studies are convergent, they merely suggest a relationship at the population and individual level but do not affirm a causality link. Only intervention studies (randomized trials), by specifically changing antioxidant vitamin intake, can provide conclusive answers. The apparent discrepancies between the results of four recently published trials may be explained by the type of population (general or high-risk subjects), the differing doses of supplementation (nutritional levels or higher), the number of antioxidants tested (one, two, or more), and the type of administration (alone or in balanced association). It thus appears that a low risk of pathologies may be related to multiple nutrients consumed at nutritional doses and in combination. Optimal effects may be expected with a combination of nutrients at levels similar to those found in a healthy diet. A single antioxidant vitamin given at high doses in subjects with high risk of pathologies (smokers, asbestos-exposed subjects) may not have substantial benefits and could even have negative consequences.

Breakfast type, daily nutrient intakes and vitamin and mineral status of French children, adolescents and adults

OBJECTIVEnTo examine associations between the consumption of different types of breakfasts, dietary intakes, and selected indices of nutritional status.nnnMETHODSnDietary intakes were obtained using the dietary history method, and serum bioassays were used to assess vitamin and mineral status in a representative community-based sample of 1108 French children (ages 2 to 10 years), adolescents (ages 10 to 18 years), and adults (ages 18 to 65 years). Breakfasts were divided into three categories: low-energy (<15% of the energy RDA), medium-energy (15-25%) and high-energy (>25%).nnnRESULTSnHigh-energy breakfasts were associated with the consumption of ready-to-eat (RTE) cereals. High-energy breakfasts and cereal consumption, both more common among children and adolescents than among adults, were also associated with a greater proportion of daily energy from carbohydrate and lower proportion of energy from fat. High-energy breakfasts and cereal consumption were further associated with higher intakes of vitamins and minerals as measured by percent RDAs. High-energy breakfasts and cereal consumption were associated with lower serum cholesterols and improved biochemical indices of nutritional status. Serum concentrations of vitamin B1 (in children and adolescents), vitamin B2 and beta-carotene (in adults) were significantly linked to the level of energy provided by breakfast.nnnCONCLUSIONnThe consumption of breakfast cereals appears to have a positive impact on nutritional status regardless of age.

Determinants of thyroid volume in healthy French adults participating in the SU.VI.MAX cohort

To study the relative importance of determinants of thyroid volume.

Obesity and other health determinants across Europe: the EURALIM project.

STUDY OBJECTIVE EURALIM (EURope ALIMentation), a European collaborative study, aimed to determine and describe the extent to which European data on risk factor distributions from different populations could be pooled and harmonised in a common database for international comparisons. SETTING Seven independent population-based surveys from six European countries (France, Italy, Northern Ireland/United Kingdom, Spain, Switzerland, the Netherlands). METHODS Data for 18u2009381 women and 12u2009908 men aged 40–59 were pooled in a common database. Central statistical analyses on major cardiovascular risk factors were conducted with careful consideration of methodological issues, including differences in study designs, data assessment tools, and analytic techniques used. MAIN RESULTS Because of the detected variability among methods used, direct comparisons of risk factor distributions and prevalences between studies were problematic. None the less, comparisons of within population contrasts by sex, age group, and other health determinants were considered to be meaningful and apt, as illustrated here for obesity. Results were targeted and disseminated to both the general public and public health professionals and framed in the context of a European information campaign. CONCLUSIONS International and national comparisons between existing locally run studies are feasible and useful, but harmonisation methods need improvement. Development of an international risk factor surveillance programme based on decentralised data collection is warranted. In the meantime, risk factor contrasts across populations can be used as a basis for targeting needed public health intervention programmes.

The immune response in iron-deficient young children: Effect of iron supplementation on cell-mediated immunity

The effects of iron deficiency on immunity remain controversial. This study was designed to assess the impact of iron supplementation on the immune status, in 81 children aged 6 months–3 years, at high risk for iron deficiency, using a longitudinal double blind randomised and placebo-controlled study. Lymphocytes of iron-deficient children produced less interleukin-2 in vitro. Iron supplementation for 2 months increased mean corpuscular volume, serum ferritin and serum transferrin, but had no effect on the parameters of T-cell mediated immunity. The lower interleukin-2 levels in iron-deficient suggest that cell-mediated immunity may be impaired in iron deficiency.

5,10-methylenetetrahydrofolate reductase common mutations, folate status and plasma homocysteine in healthy French adults of the Supplementation en Vitamines et Mineraux Antioxydants (SU.VI.MAX) cohort

The 677cytosine mutation identified in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene has been frequently associated with an elevated plasma homocysteine concentration. The aim of the present study was to determine the impact of this MTHFR common mutation on plasma and erythrocyte folate (RCF) and plasma total homocysteine (tHcy) concentrations in healthy French adults. A cohort of 291 subjects living in the Paris area and participating in the Supplementation en Vitamines et Mineraux Antioxydants (SU.VI.MAX) study were analysed to assess the impact of MTHFR polymorphism 677C-->T on folate status and plasma tHcy concentration. The frequency of the mutant homozygote for 677C-->T polymorphism (677TT genotype) in the present cohort was 16.8%. There were significant differences in plasma tHcy between 677CC, 677CT and 677TT genotype groups. The RCF concentrations were significantly different between each genotype, the lowest levels being associated with the 677TT genotype. When segregated by gender, no differences in tHcy between homozygous 677TT, heterozygous 677CT and wild-type 677CC genotype groups in women were observed. The fasting tHcy in women was unrelated to the 677C-->T mutation. However, tHcy was significantly increased in men with the homozygous 677TT genotype. We also analysed the possible implication of a second new MTHFR polymorphism (1298A-->C) in subjects with mild hyperhomocysteinaemia (4th quartile of homocysteinaemia; tHcy >11.1 micromol/l). The polymorphism 1298A-->C did not have a notable effect on tHcy or on the RCF levels. Our observations confirm a relatively high frequency of the 677TT genotype in the French population. Women with this genotype did not show the same increase in tHcy observed in men. In the present study dietary folate intake was not measured. Thus, the interaction of dietary folate with the MTHFR genotype in the French population needs further study.