Sport Nutrigenomics: Personalized Nutrition for Athletic Performance

An individual's dietary and supplement strategies can influence markedly their physical performance. Personalized nutrition in athletic populations aims to optimize health, body composition, and exercise performance by targeting dietary recommendations to an individual's genetic profile. Sport dietitians and nutritionists have long been adept at placing additional scrutiny on the one-size-fits-all general population dietary guidelines to accommodate various sporting populations. However, generic “one-size-fits-all” recommendations still remain. Genetic differences are known to impact absorption, metabolism, uptake, utilization and excretion of nutrients and food bioactives, which ultimately affects a number of metabolic pathways. Nutrigenomics and nutrigenetics are experimental approaches that use genomic information and genetic testing technologies to examine the role of individual genetic differences in modifying an athlete's response to nutrients and other food components. Although there have been few randomized, controlled trials examining the effects of genetic variation on performance in response to an ergogenic aid, there is a growing foundation of research linking gene-diet interactions on biomarkers of nutritional status, which impact exercise and sport performance. This foundation forms the basis from which the field of sport nutrigenomics continues to develop. We review the science of genetic modifiers of various dietary factors that impact an athlete's nutritional status, body composition and, ultimately athletic performance

Vegetarian dietary patterns and cardiovascular risk factors and disease prevention: An umbrella review of systematic reviews.

BACKGROUND: Diet significantly influences the risk of developing cardiovascular disease (CVD), the leading cause of death in the United States. As vegetarian dietary patterns are increasingly being included within clinical practice guidelines, there is a need to review the most recent evidence regarding if and how these dietary patterns mitigate CVD risk. OBJECTIVE: This umbrella review of systematic reviews compared the relationships between vegetarian, vegan and non-vegetarian dietary patterns and CVD health outcomes and risk factors among presumably healthy adults (≥18 years) in the general population. METHODS: MEDLINE, CINAHL, Cochrane Databases of Systematic Reviews, Food Science Source and SportsDiscus databases were searched for systematic reviews (SRs) published from 2018 until March 2024. Eligible SRs and meta-analyses examined relationships between vegetarian or vegan diets and CVD risk factors and disease outcomes compared to non-vegetarian diets. SRs were screened in duplicate, and SR quality was assessed with AMSTAR2. The overall certainty of evidence (COE) was evaluated using the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) method. RESULTS: There were 758 articles identified in the databases search and 21 SRs met inclusion criteria. SRs targeting the general population had primarily observational evidence. Vegetarian, including vegan, dietary patterns were associated with reduced risk for CVD incidence [Relative Risk: 0.85 (0.79, 0.92)] and CVD mortality [Hazard Ratio: 0.92 (0.85, 0.99)] compared to non-vegetarian diets. Vegan dietary patterns were associated with reductions in CVD risk factors including blood pressure [systolic mean difference (95 % CI): -2.56 mmHg (-4.66, -0.445)], low-density lipoprotein cholesterol [-0.49 mmol/l (-0.62, -0.36)], and body mass index [-1.72 kg/m2 (-2.30, -1.16)] compared to non-vegetarian dietary patterns, as well as c-reactive protein concentrations in a novel meta-analysis [-0.55 mg/l (-1.07, -0.03)]. CONCLUSION: Practitioners can consider recommending vegetarian dietary patterns to reduce cardiometabolic risk factors and risk of CVD incidence and mortality

Vegetarian and Vegan Dietary Patterns to Treat Adult Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Plant-based dietary patterns, including vegetarian and vegan dietary patterns, may help to manage type 2 diabetes (T2DM) by contributing to maintenance of a healthy body weight, improved glycemic control, and reduced risk of diabetes complications. Several diabetes clinical practice guidelines support the use of vegetarian dietary patterns, but there has not been a recently updated systematic review (SR) of evidence from randomized controlled trials (RCTs) to examine efficacy. The primary objective of this SR was to examine the effect of vegetarian dietary patterns compared with nonvegetarian dietary patterns in adults with T2DM. MEDLINE, CINAHL, Cochrane CENTRAL Database of Controlled Trials, Food Science Source, and SportsDiscus databases were searched for RCTs published from 1998 to May 2023. Two independent reviewers extracted data and assessed risk of bias using the Cochrane RoB 2 tool. Data were pooled using a DerSimonian-Laird random-effects model and expressed as mean differences (MDs) with 95% confidence intervals (CIs). Heterogeneity was assessed using the I2 statistic, and certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation approach. Full texts of 66 articles were reviewed, and 7 RCTs (n = 770 participants) were included in this SR. Vegetarian dietary patterns likely reduce hemoglobin A1c [MD (95% CI): -0.40% (-0.59, -0.21)] and body mass index [MD (95% CI): -0.96 kg/m2 (-1.58, -0.34)] (moderate certainty evidence); may allow for reduced diabetes medication (in 2 of 3 included studies) (low certainty); and may improve metabolic clearance of glucose (insulin sensitivity) [MD (95% CI): 10% (1.86, 18.14)] (very low certainty), compared with nonvegetarian dietary patterns. There were no effects of vegetarian dietary patterns on fasting blood glucose, fasting insulin, or low-density lipoprotein cholesterol concentrations. These findings support the inclusion of vegetarian or vegan dietary patterns as options in nutrition care plans for adults with T2DM. PROSPERO REGISTRATION: CRD42023396453

International society of sports nutrition position stand: caffeine and exercise performance

Following critical evaluation of the available literature to date, The International Society of Sports Nutrition (ISSN) position regarding caffeine intake is as follows: 1. Supplementation with caffeine has been shown to acutely enhance various aspects of exercise performance in many but not all studies. Small to moderate benefits of caffeine use include, but are not limited to: muscular endurance, movement velocity and muscular strength, sprinting, jumping, and throwing performance, as well as a wide range of aerobic and anaerobic sport-specific actions. 2. Aerobic endurance appears to be the form of exercise with the most consistent moderate-to-large benefits from caffeine use, although the magnitude of its effects differs between individuals. 3. Caffeine has consistently been shown to improve exercise performance when consumed in doses of 3–6 mg/ kg body mass. Minimal effective doses of caffeine currently remain unclear but they may be as low as 2 mg/kg body mass. Very high doses of caffeine (e.g. 9 mg/kg) are associated with a high incidence of side-effects and do not seem to be required to elicit an ergogenic effect. 4. The most commonly used timing of caffeine supplementation is 60 min pre-exercise. Optimal timing of caffeine ingestion likely depends on the source of caffeine. For example, as compared to caffeine capsules, caffeine chewing gums may require a shorter waiting time from consumption to the start of the exercise session. 5. Caffeine appears to improve physical performance in both trained and untrained individuals. 6. Inter-individual differences in sport and exercise performance as well as adverse effects on sleep or feelings of anxiety following caffeine ingestion may be attributed to genetic variation associated with caffeine metabolism, and physical and psychological response. Other factors such as habitual caffeine intake also may play a role in between-individual response variation. 7. Caffeine has been shown to be ergogenic for cognitive function, including attention and vigilance, in most individuals. 8. Caffeine may improve cognitive and physical performance in some individuals under conditions of sleep deprivation. 9. The use of caffeine in conjunction with endurance exercise in the heat and at altitude is well supported when dosages range from 3 to 6 mg/kg and 4–6 mg/kg, respectively. 10. Alternative sources of caffeine such as caffeinated chewing gum, mouth rinses, energy gels and chews have been shown to improve performance, primarily in aerobic exercise. 11. Energy drinks and pre-workout supplements containing caffeine have been demonstrated to enhance both anaerobic and aerobic performance

High levels of cognitive dietary restraint are associated with stress fractures in women runners

Societal emphasis on body image and the 'ideal' body weight drives many women to make conscious efforts to limit their food intake in order to achieve or maintain a desired body weight. This attitude and eating behaviour is characterized by a preoccupation with food-related issues, and is referred to as dietary restraint or cognitive dietary restraint (CDR). The most commonly used instrument to measure and assess this dietary restraint is the restraint scale of the Three-Factor Eating Questionnaire (TFEQ). Female athletes are faced with body image challenges, as well as trying to achieve a body weight that is optimal for their performance. Many female athletes could therefore be experiencing these restrained eating patterns, to meet the combined pressures of an 'ideal body1 and enhanced performance. Most previous studies have generally found similar physical characteristics and energy intakes among women with differing restraint scores. However, CDR has been associated with subclinical menstrual cycle irregularities (MCI) and increased Cortisol levels, both of which can affect bone mineral density (BMD). Preliminary evidence has also reported an association between CDR and BMD or bone mineral content (BMC). Low BMD has been implicated in stress fracture risk, and runners are particularly at risk for lower extremity stress fractures. The purpose of this investigation was to assess CDR in female runners with a recent stress fracture (SF) and without a history of stress fracture (NSF). We recruited nulliparous normal-weight runners (running >20 km/wk) who were non-smokers, had regular menstrual cycles, were not currently dieting and had no history of an eating disorder. A sample of 79 runners (n = 38 SF, 29±5 yr; n = 41 NSF, 29±6 yr) completed a 3-day food record and questionnaire assessing physical activity, menstrual cycle history and perceived stress. The TFEQ was used to assess eating attitudes and behaviours, including CDR. SF and NSF runners had similar body mass index (21.2±1.8 vs 22.0±2.5 kg/m²), physical activity (35.7±13.5 vs 33.4±1.34 km/wk), perceived stress, and energy and macronutrient intakes. However, CDR was significantly higher in SF runners (11±5.4 vs 8.4±4.3, p<0.05). We conclude that women runners with a history of recent SF have higher levels of CDR. Subclinical MCI and increased Cortisol levels associated with high CDR may contribute to lowered BMD and increased risk for stress fracture. Prospective studies that include measurements of menstrual cycle characteristics, Cortisol levels and BMD are needed to determine if CDR is an independent risk factor for stress fractures, mediated by subclinical MCI and elevated Cortisol with subsequent bone loss.Land and Food Systems, Faculty ofGraduat

Genetic Modifiers of Caffeine and Endurance Performance in Athletes

Background: Caffeine is used as an ergogenic aid by athletes to improve performance. However, the effects of caffeine differ between athletes. This may be due to genetic differences affecting caffeine metabolism and caffeine response during exercise. Objective: The aim was to determine whether variation in the CYP1A2 gene, which affects caffeine metabolism, and the HTR2A gene, which encodes serotonin receptors and may affect caffeine response, modify the ergogenic effects of caffeine during a 10-km cycling time trial. Methods: Competitive male athletes (n=101; age: 25 ± 4 years) completed the time trial under three conditions: 0, 2 or 4 mg of caffeine per kg body mass, using a split-plot randomized, double-blinded, placebo-controlled design. DNA was isolated from saliva and genotyped for polymorphisms in CYP1A2 (rs762551) and HTR2A (rs6313). Results: Overall, 4 mg/kg caffeine decreased cycling time by 3% versus placebo. A significant (pPh.D

Genetic Modifiers of Caffeine and Endurance Performance in Athletes

Background: Caffeine is used as an ergogenic aid by athletes to improve performance. However, the effects of caffeine differ between athletes. This may be due to genetic differences affecting caffeine metabolism and caffeine response during exercise. Objective: The aim was to determine whether variation in the CYP1A2 gene, which affects caffeine metabolism, and the HTR2A gene, which encodes serotonin receptors and may affect caffeine response, modify the ergogenic effects of caffeine during a 10-km cycling time trial. Methods: Competitive male athletes (n=101; age: 25 ± 4 years) completed the time trial under three conditions: 0, 2 or 4 mg of caffeine per kg body mass, using a split-plot randomized, double-blinded, placebo-controlled design. DNA was isolated from saliva and genotyped for polymorphisms in CYP1A2 (rs762551) and HTR2A (rs6313). Results: Overall, 4 mg/kg caffeine decreased cycling time by 3% versus placebo. A significant (pPh.D

Cognitive dietary restraint is associated with stress fractures in women runners.

High levels of cognitive dietary restraint (CDR) have been associated with subclinical menstrual cycle irregularities and increased cortisol levels, both of which can affect bone mineral density (BMD). Low BMD has been implicated in stress fracture risk. We assessed CDR in female runners (≥ 20 km/wk) with a recent stress fracture (SF) and with no stress fracture history (NSF). A sample of 79 runners (n = 38 SF, 29 ± 5 y; n = 41 NSF, 29 ± 6 y) completed a 3-d food record and questionnaire assessing physical activity, menstrual cycle history, and perceived stress. SF and NSF runners had similar body mass index (21.2 ± 1.8 vs. 22.0 ± 2.5 kg/m2), physical activity (35.7 ± 13.5 vs. 33.4 ± 1.34 km/wk), perceived stress, and dietary intakes. CDR, however, was higher in SF runners (11.0 ± 5.4 vs. 8.4 ± 4.3, P &lt; 0.05). Subclinical menstrual cycle disturbances and increased cortisol levels that are associated with high CDR, might in turn contribute to lowered BMD and increased stress fracture risk.</jats:p