Josep A. Tur

Cohort Profile: Design and methods of the PREDIMED study

The Spanish Ministry of Health—Instituto de Salud Carlos III (ISCIII) funded the project for the period 2003–05 (RTIC G03/140). In 2006 a new funding modality was established by ISCIII through the CIBER (Centros de Investigacion Biomedica En Red). Fisiopatologia de la Obesidad y Nutricion (CIBERobn), which is providing funding for 7 of the original research groups, whereas the other 12 were funded by a new research network (RTIC RD 06/0045). Other official funds from Spanish government agencies have been obtained for subprojects related to intermediate outcomes (lipoproteins, inflammatory markers, vascular imaging, genomic and proteomic studies, etc.). Obviously, the donation by food companies of all the VOO and mixed nuts needed throughout the duration of the study is a substantial contribution.

Antioxidant response to oxidative stress induced by exhaustive exercise

The aim of this work was to demonstrate the occurrence of oxidative stress during exhaustive exercise and to determine the antioxidant response. Eight voluntary male subjects participated in this study. The exercise was a cycling mountain stage (171 km) and the cyclists took a mean+/-S.E.M. time of 270+/-12 min to complete it. Blood samples were taken before the cycling stage, immediately after the stage, 3 h after finishing the stage and on the morning of the following day. We determined the activities of erythrocyte antioxidant enzymes, blood levels of oxidised glutathione, plasma levels of antioxidant vitamins and carotenoids, and the serum lipid and cholesterol profile. The mountain cycling stage induced significant increases in catalase and glutathione reductase activities. Significant decreases in glutathione peroxidase activity, both determined with hydrogen peroxide and with cumene hydroperoxide as substrates, were observed. Blood oxidised glutathione and serum uric acid rose after the stage. Plasma vitamin E increased after the stage but dropped to below basal values after 3 h of recovery. Triglycerides and VLDL-cholesterol increased significantly after the stage and remained high 3 h after the cycling stage. The mountain cycling stage induced oxidative stress, as was evidenced by the increases in blood GSSG and in serum urate concentrations and by the pattern of change of erythrocyte antioxidant enzyme activities. A specific utilisation of alpha-tocopherol against oxidative stress during recovery was evidenced.

Relation between oxidative stress markers and antioxidant endogenous defences during exhaustive exercise

Hydrogen peroxide (H2O2) could induce oxidative damage at long distance from its generation site and it is also an important signalling molecule that induces some genes related to oxidative stress. Our objective was to study the plasma and blood cells capability to detoxify H2O2 after intense exercise and its correlation with oxidative damage. Blood samples were taken from nine professional cycling, participating in a mountain stage, under basal conditions and 3 h after the competition. Catalase and glutathione peroxidase activities decreased (40 and 50% respectively) in neutrophils after the cycling stage, while glutathione peroxidase increased (87%) in lymphocytes. Catalase protein levels and catalase specific activity maintained basal values after the stage in plasma. Catalase protein levels decreased (48%) in neutrophils and its specific activity increased up to plasma values after exercise. Myeloperoxidase (MPO) increased (39%) in neutrophils after the cycling stage. Exercise-induced hemolysis and lymphopenia inversely correlated with cellular markers of oxidative stress. Plasma malondialdehyde (MDA) directly correlated with neutrophil MPO activity and erythrocytes MDA. Intense exercise induces oxidative damage in blood cells as erythrocytes and lymphocytes, but not in neutrophils.

Dietary sources of omega 3 fatty acids: public health risks and benefits

Omega 3 fatty acids can be obtained from several sources, and should be added to the daily diet to enjoy a good health and to prevent many diseases. Worldwide, general population use omega-3 fatty acid supplements and enriched foods to get and maintain adequate amounts of these fatty acids. The aim of this paper was to review main scientific evidence regarding the public health risks and benefits of the dietary sources of omega-3 fatty acids. A systematic literature search was performed, and one hundred and forty-five articles were included in the results for their methodological quality. The literature described benefits and risks of algal, fish oil, plant, enriched dairy products, animal-derived food, krill oil, and seal oil omega-3 fatty acids.

The Effect of Nitric-Oxide-Related Supplements on Human Performance

Nitric oxide (NO) has led a revolution in physiology and pharmacology research during the last two decades. This labile molecule plays an important role in many functions in the body regulating vasodilatation, blood flow, mitochondrial respiration and platelet function. Currently, it is known that NO synthesis occurs via at least two physiological pathways: NO synthase (NOS) dependent and NOS independent. In the former, L-arginine is the main precursor. It is widely recognized that this amino acid is oxidized to NO by the action of the NOS enzymes. Additionally, L-citrulline has been indicated to be a secondary NO donor in the NOS-dependent pathway, since it can be converted to L-arginine. Nitrate and nitrite are the main substrates to produceNO via the NOS-independent pathway. These anions can be reduced in vivo to NO and other bioactive nitrogen oxides. Other molecules, such as the dietary supplement glycine propionyl-L-carnitine (GPLC), have also been suggested to increase levels of NO, although the physiological mechanisms remain to be elucidated. The interest in all these molecules has increased in many fields of research. In relation with exercise physiology, it has been suggested that an increase in NO production may enhance oxygen and nutrient delivery to active muscles, thus improving tolerance to physical exercise and recovery mechanisms. Several studies using NO donors have assessed this hypothesis in a healthy, trained population. However, the conclusions from these studies showed several discrepancies. While some reported that dietary supplementation with NO donors induced benefits in exercise performance, others did not find any positive effect. In this regard, training status of the subjects seems to be an important factor linked to the ergogenic effect of NO supplementation. Studies involving untrained or moderately trained healthy subjects showed that NO donors could improve tolerance to aerobic and anaerobic exercise. However, when highly trained subjects were supplemented, no positive effect on performance was indicated. In addition, all this evidence is mainly based on a young male population. Further research in elderly and female subjects is needed to determine whether NO supplements can induce benefit in exercise capacity when the NO metabolism is impaired by age and/or estrogen status.

Worldwide consumption of functional foods: a systematic review

The present systematic review was performed to assess differences in the worldwide consumption of functional foods. The Medline and Scopus databases were used to search the existing literature. A total of 23 studies that examined functional food consumption and included information on the country, gender, and age of participants were identified for inclusion. The studies investigated a variety of functional foods, and analysis of the findings indicates it is not possible to reach generalized conclusions about consumer choices regarding functional food consumption. Gender, age, level of education, and personal health status may each predict consumption of one or more functional foods. Further studies aimed at gaining a better understanding of the factors that influence consumption of functional foods are needed.

Impact of folic acid fortification of flour on neural tube defects: a systematic review

OBJECTIVE To review the impact of folic acid fortification of flour on the prevalence of neural tube defects (NTD). DESIGN Systematic review of the literature on MEDLINE via PubMed, Scopus, OvidSP and LILACS (Latin American and Caribbean Health Sciences Literature) reporting the impact of folic acid fortification of flour on the prevalence of NTD in 2000-2011. Focusing on Santiago of Chiles birth defects registry (1999-2009) and the monitoring of flour fortification, we analysed the prevalence (NTD cases/10 000 births) pre and post flour fortification and the percentile distribution of folic acid content in flour (2005-2009). We explored the potential association between median folic acid in flour (mg/kg) and the prevalence of NTD. SETTING Chile, Argentina, Brazil, Canada, Costa Rica, Iran, Jordan, South Africa and the USA. SUBJECTS Live births and stillbirths. RESULTS Twenty-seven studies that met inclusion criteria were evaluated. Costa Rica showed a significant reduction in NTD (∼60 %). Prevalence in Chile decreased from 18·6 to 7·3/10 000 births from 1999 to 2007 and showed a slight increase to 8·5 in 2008-2009, possibly due to changes in fortification limits. When we related the prevalence of NTD with levels of flour fortification, the lowest prevalence was observed at a folic acid level of 1·5 mg/kg. CONCLUSIONS Fortification of flour with folic acid has had a major impact on NTD in all countries where this has been reported. Chile showed a 55 % reduction in NTD prevalence between 1999 and 2009. There is a need to constantly monitor the levels of flour fortification to maximize benefits and prevent the potential risk of folic acid excess, moreover to be vigilant for any new adverse effects associated with excess.

Adherence to the Mediterranean dietary pattern among the population of the Balearic Islands

The aim of the present study was to assess the prevalence of the Mediterranean dietary pattern (MDP) in the population of the Balearic Islands and socio-demographic and lifestyle factors that might determine adherence to the MDP. A cross-sectional nutritional survey was carried out in the Balearic Islands between 1999 and 2000. A random sample (n 1200) of the adult population (16-65 years) was interviewed. Dietary questionnaires incorporating questions related to socio-economic status, education level, lifestyle factors and health status were utilised. Dietary habits were assessed by means of two 24 h recalls, and a quantitative food-frequency questionnaire. Adherence to the MDP was defined according to a score constructed considering the consumption of nine MDP characteristic components: high MUFA:saturated fatty acids ratio, moderate ethanol consumption, high legumes, cereals and roots, fruits, vegetables, and fish consumption, and low consumption of meat and milk. Then, socio-demographic, lifestyle and health status variables that could determine a higher or lower adherence were assessed. Adherence to the MDP among the population of the Balearic Islands was found to be 43.1 (sd 5.8)%, and was similar in all socio-demographic and lifestyle groups, with some differences according to age, sex and physical status. There was an increase in the percentage of adherence with age, which was greater in males than in females. A more physically active lifestyle was associated with a higher adherence to the MDP. The promotion of the Mediterranean lifestyle, including the MDP and greater physical activity, should be reinforced in the population of the Balearic Islands and especially in the younger generations.

Food Consumption Patterns in a Mediterranean Region: Does the Mediterranean Diet Still Exist?

Aims: To assess the food consumption patterns in the adult population of a Mediterranean region: the Balearic Islands (BI). Methods: A cross-sectional nutritional survey was carried out in the BI between 1999 and 2000. A random sample (n = 1,200) of the adult population (16–65 years) was interviewed. Dietary habits were assessed by means of 24-hour recall during 2 non-consecutive days, the first in the warm season and the second in the cold season, and a quantitative food frequency questionnaire. Anthropometric measurements were also obtained. Results: Current food patterns in the BI are characterized by a prominent consumption of dairy products, vegetables, fruit, bread, soft drinks and meat. According to the dietary guidelines for the Spanish population, only appropriate consumption of olive oil and other fats, dairy products, nuts, and soft drinks have been achieved. Intakes of fruit, vegetables, fish, eggs, pulses, cereals and potatoes are below desirable levels. On the other side, intakes of sugary products, sweets and cakes are higher than desirable. Alcohol intake, in the context of the Mediterranean diet, can be considered as acceptable. Conclusions: The dietary patterns observed among the BI population are in harmony with the actual dietary trends in Spain and other Mediterranean countries. Mediterranean dietary habits still exist, but a progressive departure from the traditional Mediterranean diet is being observed mainly in younger generations. It would be desirable to increase the consumption of fish, vegetables, fruit, cereals and pulses and decrease the intake of food sources containing saturated fat.

Sodium Nitrate Supplementation Does Not Enhance Performance of Endurance Athletes

PURPOSE Supplementation with inorganic nitrate has been suggested to be an ergogenic aid for athletes as nitric oxide donor. The purpose of this study was to determine whether ingestion of inorganic sodium nitrate benefits well-trained athletes performing a 40-min exercise test in laboratory conditions. In addition, we investigated the effect of this supplement on plasma levels of endothelin-1 (ET-1) and in nitrated proteins. METHODS Thirteen trained athletes participated in this randomized, double-blind, crossover study. They performed a 40-min cycle ergometer distance-trial test after two 3-d periods of dietary supplementation with sodium nitrate (10 mg·kg of body mass) or placebo. RESULTS Concentration of plasma nitrate (256 ± 35 μM) and nitrite (334 ± 86 nM) increased significantly (P < 0.05) after nitrate supplementation compared with placebo (nitrate: 44 ± 11 μM; nitrite: 187 ± 43 nM). In terms of exercise performance, there were no differences in either the mean distance (nitrate: 26.4 ± 1.1 km; placebo: 26.3 ± 1.2 km; P = 0.61) or mean power output (nitrate: 258 ± 28 W; placebo: 257 ± 28 W; P = 0.89) between treatments. Plasma ET-1 increased significantly (P < 0.05) just after exercise in nitrate (4.0 ± 0.8 pg·mL) and placebo (2.4 ± 0.4 pg·mL) conditions. This increase was significantly greater (P < 0.05) in the nitrate group. Levels of nitrated proteins did not differ between treatments (nitrate: preexercise, 91% ± 23%; postexercise, 81% ± 23%; placebo: preexercise, 95% ± 20%; postexercise, 99% ± 19%). CONCLUSION Sodium nitrate supplementation did not improve a 40-min distance-trial performance in endurance athletes. In addition, concentration of plasma ET-1 increased significantly after exercise after supplementation with sodium nitrate.