Nutrition usually makes a small but potentially valuable contribution to successful performance in elite athletes, and dietary supplements can make a minor contribution to this nutrition programme. Nonetheless, supplement use is widespread at all levels of sport. Products described as supplements target different issues, including (1) the management of micronutrient deficiencies, (2) supply of convenient forms of energy and macronutrients, and (3) provision of direct benefits to performance or (4) indirect benefits such as supporting intense training regimens. The appropriate use of some supplements can benefit the athlete, but others may harm the athlete’s health, performance, and/or livelihood and reputation (if an antidoping rule violation results). A complete nutritional assessment should be undertaken before decisions regarding supplement use are made. Supplements claiming to directly or indirectly enhance performance are typically the largest group of products marketed to athletes, but only a few (including caffeine, creatine, specific buffering agents and nitrate) have good evidence of benefits. However, responses are affected by the scenario of use and may vary widely between individuals because of factors that include genetics, the microbiome and habitual diet. Supplements intended to enhance performance should be thoroughly trialled in training or simulated competition before being used in competition. Inadvertent ingestion of substances prohibited under the antidoping codes that govern elite sport is a known risk of taking some supplements. Protection of the athlete’s health and awareness of the potential for harm must be paramount; expert professional opinion and assistance is strongly advised before an athlete embarks on supplement use.
- Journal of the International Society of Sports Nutrition
- Published about 8 years ago
Nutrient timing is a popular nutritional strategy involves the consumption of combinations of nutrients–primarily protein and carbohydrate–in and around an exercise session. Some have claimed that this approach can produce dramatic improvements in body composition. It has even been postulated that the timing of nutritional consumption may be more important than the absolute daily intake of nutrients. The post-exercise period is widely considered the most critical part of nutrient timing. Theoretically, consuming the proper ratio of nutrients during this time not only initiates the rebuilding of damaged muscle tissue and restoration of energy reserves, but it does so in a supercompensated fashion that enhances both body composition and exercise performance. Several researchers have made reference to an anabolic “window of opportunity” whereby a limited time exists after training to optimize training-related muscular adaptations. However, the importance - and even the existence - of a post-exercise ‘window’ can vary according to a number of factors. Not only is nutrient timing research open to question in terms of applicability, but recent evidence has directly challenged the classical view of the relevance of post-exercise nutritional intake with respect to anabolism. Therefore, the purpose of this paper will be twofold: 1) to review the existing literature on the effects of nutrient timing with respect to post-exercise muscular adaptations, and; 2) to draw relevant conclusions that allow practical, evidence-based nutritional recommendations to be made for maximizing the anabolic response to exercise.
BACKGROUND: Avocados contain monounsaturated fatty acids (MUFA) dietary fiber, essential nutrients and phytochemicals. However, no epidemiologic data exist on their effects on diet quality, weight management and other metabolic disease risk factors. The objective of this research was to investigate the relationships between avocado consumption and overall diet quality, energy and nutrient intakes, physiological indicators of health, and risk of metabolic syndrome. METHODS: Avocado consumption and nutrition data were based on 24-hour dietary recalls collected by trained NHANES interviewers using the USDA Automated Multiple Pass Method (AMPM). Physiological data were collected from physical examinations conducted in NHANES Mobile Examination Centers. Diet quality was calculated using the USDA’s Healthy Eating Index-2005. Subjects included 17,567 US adults >19 years of age (49% female), including 347 avocado consumers (50% female), examined in NHANES 2001–2008. Least square means, standard errors, and ANOVA were determined using appropriate sample weights, with adjustments for age, gender, ethnicity, and other covariates depending on dependent variable of interest. RESULTS: Avocado consumers had significantly higher intakes of vegetables (p < 0.05); fruit, diet quality, total fat, monounsaturated and polyunsaturated fats, dietary fiber, vitamins E, K, magnesium, and potassium (p < 0.0001); vitamin K (p = 0.0013); and lower intakes of added sugars (p < 0.0001). No significant differences were seen in calorie or sodium intakes. Body weight, BMI, and waist circumference were significantly lower (p < 0.01), and HDL-C was higher (p < 0.01) in avocado consumers. The odds ratio for metabolic syndrome was 50% (95th CI: 0.32-0.72) lower in avocado consumers vs. non-consumers. CONCLUSIONS: Avocado consumption is associated with improved overall diet quality, nutrient intake, and reduced risk of metabolic syndrome. Dietitians should be aware of the beneficial associations between avocado intake, diet and health when making dietary recommendations.
Vegetables are important sources of dietary fiber, vitamins and minerals in the diets of children. The United States Department of Agriculture (USDA) National School Lunch Program has new requirements for weekly servings of vegetable subgroups as well as beans and peas. This study estimated the cost impact of meeting the USDA requirements using 2008 national prices for 98 vegetables, fresh, frozen, and canned. Food costs were calculated per 100 grams, per 100 calories, and per edible cup. Rank 6 score, a nutrient density measure was based on six nutrients: dietary fiber; potassium; magnesium; and vitamins A, C, and K. Individual nutrient costs were measured as the monetary cost of 10% daily value of each nutrient per cup equivalent. ANOVAs with post hoc tests showed that beans and starchy vegetables, including white potatoes, were cheaper per 100 calories than were dark-green and deep-yellow vegetables. Fresh, frozen, and canned vegetables had similar nutrient profiles and provided comparable nutritional value. However, less than half (n = 46) of the 98 vegetables listed by the USDA were were consumed >5 times by children and adolescents in the 2003-4 National Health and Nutrition Examination Survey database. For the more frequently consumed vegetables, potatoes and beans were the lowest-cost sources of potassium and fiber. These new metrics of affordable nutrition can help food service and health professionals identify those vegetable subgroups in the school lunch that provide the best nutritional value per penny.
The B-vitamins comprise a group of eight water soluble vitamins that perform essential, closely inter-related roles in cellular functioning, acting as co-enzymes in a vast array of catabolic and anabolic enzymatic reactions. Their collective effects are particularly prevalent to numerous aspects of brain function, including energy production, DNA/RNA synthesis/repair, genomic and non-genomic methylation, and the synthesis of numerous neurochemicals and signaling molecules. However, human epidemiological and controlled trial investigations, and the resultant scientific commentary, have focused almost exclusively on the small sub-set of vitamins (B₉/B12/B₆) that are the most prominent (but not the exclusive) B-vitamins involved in homocysteine metabolism. Scant regard has been paid to the other B vitamins. This review describes the closely inter-related functions of the eight B-vitamins and marshals evidence suggesting that adequate levels of all members of this group of micronutrients are essential for optimal physiological and neurological functioning. Furthermore, evidence from human research clearly shows both that a significant proportion of the populations of developed countries suffer from deficiencies or insufficiencies in one or more of this group of vitamins, and that, in the absence of an optimal diet, administration of the entire B-vitamin group, rather than a small sub-set, at doses greatly in excess of the current governmental recommendations, would be a rational approach for preserving brain health.
BACKGROUND: Vitamin K2 contributes to bone and cardiovascular health. Therefore, two vitamin K2 homologues, menaquinone-4 (MK-4) and menaquinone-7 (MK-7), have been used as nutrients by the food industry and as nutritional supplements to support bone and cardiovascular health. However, little is known about the bioavailability of nutritional MK-4. To investigate MK-4 and MK-7 bioavailability, nutritional doses were administered to healthy Japanese women. FINDINGS: Single dose administration of MK-4 (420 mug; 945 nmol) or MK-7 (420 mug; 647 nmol) was given in the morning together with standardized breakfast. MK-7 was well absorbed and reached maximal serum level at 6 h after intake and was detected up to 48 h after intake. MK-4 was not detectable in the serum of all subjects at any time point. Consecutive administration of MK-4 (60 mug; 135 nmol) or MK-7 (60 mug; 92 nmol) for 7 days demonstrated that MK-4 supplementation did not increase serum MK-4 levels. However, consecutive administration of MK-7 increased serum MK-7 levels significantly in all subjects. CONCLUSIONS: We conclude that MK-4 present in food does not contribute to the vitamin K status as measured by serum vitamin K levels. MK-7, however significantly increases serum MK-7 levels and therefore may be of particular importance for extrahepatic tissues.
Vitamin B12 is one of the essential vitamins affecting various systems of the body. Reports of psychiatric disorders due to its deficiency mostly focus on middle aged and elderly patients. Here we report a case of vitamin B 12 deficiency in a 16-year old, male adolescent who presented with mixed mood disorder symptoms with psychotic features. Chief complaints were “irritability, regressive behavior, apathy, crying and truancy” which lasted for a year. Premorbid personality was unremarkable with no substance use/exposure or infections. No stressors were present. The patient was not vegetarian. Past medical history and family history was normal. Neurological examination revealed glossitis, ataxia, rigidity in both shoulders, cog-wheel rigidity in the left elbow, bilateral problems of coordination in cerebellar examination, reduced swinging of the arms and masked face. Romberg’s sign was present. Laboratory evaluations were normal. Endoscopy and biopsy revealed atrophy of the gastric mucosa with Helicobacter Pylori colonization. Schilling test was suggestive of malabsorbtion. He was diagnosed with Mood disorder with Mixed, Psychotic Features due to Vitamin B12 Deficiency and risperidone 0.5 mg/day and intramuscular vitamin B12 500 mcg/day were started along with referral for treatment of Helicobacter pylori. A visit on the second week revealed no psychotic features. Romberg’s sign was negative and cerebellar tests were normal. Extrapyramidal symptoms were reduced while Vitamin B12 levels were elevated. Risperidone was stopped and parenteral Vitamin B12 treatment was continued with monthly injections for 3 months. Follow-up endoscopy and biopsy at the first month demonstrated eradication of H. pylori. He was followed monthly for another 6 months and psychiatric symptoms did not recur at the time of last evaluation. Despite limitations, this case may underline the observation that mood disorders with psychotic features especially with accompanying extrapyramidal symptoms lacking a clear etiology may be rare manifestation of vitamin B12 and/or folate deficiency in children and adolescents and be potentially amenable to treatment.
OBJECTIVE: To identify reasons why eligible families are not accessing free ‘Healthy Start’ vitamin supplementation (providing vitamins A, C and D) in England. DESIGN: Qualitative study using in-depth interviews. SETTING: 13 primary care trusts in England. PARTICIPANTS: Purposive sample of 15 Healthy Start coordinators, 50 frontline health and children’s professionals and 107 parents. RESULTS: Vitamin take-up was low across all research sites, reported as below 10% of eligible beneficiaries for free vitamins. Reasons identified by both parents and professionals included (1) poor accessibility of vitamins, (2) low promotion of the scheme by health professionals, (3) a lack of awareness among eligible families, and (4) low motivation among mothers to take vitamins for themselves during pregnancy or for children under 4 years old. CONCLUSIONS: Low uptake rates can be explained by poor accessibility of vitamins and lack of awareness and motivation to take vitamin supplements among eligible families. Universal provision (at least for pregnant women) and better training for health professionals are identified as potential solutions worthy of further research and evaluation.
Considering that hyperhomocysteinemia is an independent risk factor for cardiovascular disease, the purpose of this study was to determine the kinetics of serum homocysteine (tHcy) and the vitamins involved in its metabolism (folates, B(12), and B(6)) in response to acute exercise at different intensities. Eight sedentary males (18-27 yr) took part in the study. Subjects were required to complete two isocaloric (400 kcal) acute exercise trials on separate occasions at 40% (low intensity, LI) and 80% VO(2peak) (high intensity, HI). Blood samples were drawn at different points before (pre4 and pre0 h), during (exer10, exer20, exer30, exer45, and exer60 min), and after exercise (post0, post3, and post19 h). Dietary, genetic, and lifestyle factors were controlled. Maximum tHcy occurred during exercise, both at LI (8.6 (8.0-10.1) µmol/L, 9.3% increase from pre0) and HI (9.4 (8.2-10.6) µmol/L, 25.7% increase from pre0), coinciding with an accumulated energy expenditure independent of the exercise intensity. From this point onwards tHcy declined until the cessation of exercise and continued descending. At post19, tHcy was not different from pre-exercise values. No values of hyperhomocysteinemia were observed at any sampling point and intensity. In conclusion, acute exercise in sedentary individuals, even at HI, shows no negative effect on tHcy when at least 400 kcal are spent during exercise and the nutritional status for folate, B(12), and B(6) is adequate, since no hyperhomocysteinemia has been observed and basal concentrations were recovered in less than 24 h. This could be relevant for further informing healthy exercise recommendations.
Over the past few decades, food fortification and infant formula supplementation with high levels of vitamins have led to a sharp increase in vitamin intake among infants, children and adults. This is followed by a sharp increase in the prevalence of obesity and related diseases, with significant disparities among countries and different groups within a country. It has long been known that B vitamins at doses below their toxicity threshold strongly promote body fat gain. Studies have demonstrated that formulas, which have very high levels of vitamins, significantly promote infant weight gain, especially fat mass gain, a known risk factor for children developing obesity. Furthermore, ecological studies have shown that increased B vitamin consumption is strongly correlated with the prevalence of obesity and diabetes. We therefore hypothesize that excess vitamins may play a causal role in the increased prevalence of obesity. This review will discuss: (1) the causes of increased vitamin intake; (2) the non-monotonic effect of excess vitamin intake on weight and fat gain; and (3) the role of vitamin fortification in obesity disparities among countries and different groups within a country.