Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance

Exercise Nutrition for Adults Older Than 40 Years

In general, nutrient needs do not change much for older individuals who exercise regularly yet moderately for the purposes of chronic disease risk reduction. Overall diets should reflect those recommended by such authorities as the American Dietetic, Heart, and Diabetes Associations, with special attention to ensuring ample protein and antioxidant intakes. Proper timing and amounts of nutrients consumed before physical activity should be practiced, to ensure adequate fueling while minimizing gastrointestinal discomfort. Consuming energy during activities lasting less than 90 minutes is unnecessary if the individual is well fueled before starting. After exercise, consuming a blend of carbohydrate and protein is often advocated for glycogen resynthesis and muscle protein repair, but the importance of this for those not engaging in regular vigorous activity remains to be clarified. Adequate hydration is critical to physical performance and health during exercise, particularly in the heat. Because thirst might not sufficiently reflect fluid needs of older individuals, this matter deserves special attention. Sports drinks are generally not necessary for events lasting less than 60 minutes and may provide unwanted calories, sugars, and sodium for older exercisers. Naturally occurring sources of electrolytes may be preferable.

Pediatric obesity: parallels with addiction and treatment recommendations

Rates of pediatric obesity have increased dramatically over the past decade. This trend is especially alarming because obesity is associated with significant medical and psychosocial consequences. It may contribute to cardiovascular, metabolic, and hepatic complications, as well as to psychiatric difficulties. The development of obesity appears to be influenced by a complex array of genetic, metabolic, and neural frameworks, along with behavior, eating habits, and physical activity. Numerous parallels exist between obesity and addictive behaviors, including genetic predisposition, personality, environmental risk factors, and common neurobiological pathways in the brain. Typical treatments for pediatric obesity include behavioral interventions targeting diet or exercise. These treatments have yielded mixed results and typically have been examined in specialty clinic populations, limiting their generalizability. There are limited medication options for overweight children and adolescents, and no approved medical intervention in children younger than 16 years old. Bariatric surgery may be an option for some adolescents, but due to the risks of surgery, it is often seen as a last resort. The parallels between addiction and obesity aid in developing novel interventions for pediatric obesity. Motivational enhancement and cognitive-behavioral strategies used in addiction treatment may prove to be beneficial.

Nutrient supplementation post ambulation in persons with incomplete spinal cord injuries: a randomized, double-blinded, placebo-controlled case series

OBJECTIVE

To examine effects of protein-carbohydrate intake on ambulation performance in persons with incomplete spinal cord injury (SCI).

DESIGN

Double-blinded treatment with washout and placebo crossover.

SETTING

Academic medical center.

PARTICIPANTS

Three subjects aged 34 to 43 years with incomplete SCI at C5-T4.

INTERVENTIONS

Subjects walked to fatigue on 5 consecutive days. On fatigue, participants consumed 48g of vanilla-flavored whey and 1g/kg of body weight of carbohydrate (CH(2)O). Weekend rest followed, and the process was repeated. A 2-week washout was interposed and the process repeated using 48g of vanilla-flavored soy.

MAIN OUTCOME MEASURES

Oxygen consumed (Vo(2); in L/min), carbon dioxide evolved (Vco(2)), respiratory exchange ratio (RER: Vco(2)/Vo(2)), time (in minutes), and distance walked (in meters) were recorded. Caloric expenditure was computed as Vo(2) by time by 21kJ/L (5kcal/L) of oxygen consumed. Data were averaged across the final 2 ambulation sessions for each testing condition.

RESULTS

Despite slow ambulation velocities (range, .11-.34m/s), RERs near or above unity reflected reliance on CH(2)O fuel substrates. Average ambulation time to fatigue was 17.8% longer; distance walked 37.9% longer, and energy expenditure 12.2% greater with the whey and CH(2)O supplement than with the soy drink.

CONCLUSIONS

Whey and CH(2)O ingestion after fatiguing ambulation enhanced ensuing ambulation by increasing ambulation distance, time, and caloric expenditure in persons with incomplete SCI.

Special populations: the female player and the youth player

Females and youth are frequently described as "special" populations in football literature, but together these two populations outnumber male players. What makes females "special" is that they tend to eat less when training and competing than their male counterparts, leading to lower intakes of energy, carbohydrate, and some nutrients. Youth football players are special in regard to energy and nutrient requirements to promote growth and development, as well as to fuel sport. There is limited research on the dietary habits of these two populations, but the available literature suggests that many female and youth players need to increase carbohydrate intake, increase fluid intake, and develop dietary habits to sustain the demands of training and competition.

Nutritional profile of the Brazilian Amputee Soccer Team during the precompetition period for the world championship

OBJECTIVE

The purpose of this study was to determine the dietary and anthropometric profiles of the Brazilian amputee soccer players during the training period before the world soccer amputee championship, according to their positional roles in the game.

METHODS

Fifteen male athletes participated in the study. Data on height, weight, skinfold thickness, and circumferences were collected to assess nutritional status. Dietary intake was obtained by using 6-d dietary records, analyzed by a Nutrition Support Program for total energy intake, carbohydrates, proteins, lipids, vitamins, and minerals. One-way analysis of variance was used to identify differences in groups (P < 0.05).

RESULTS

Midfield players were heavier than the others, and this difference may have been caused by a large quantity of subcutaneous fat. Dietary data showed a low carbohydrate intake and high protein and fat intakes. No athlete met the recommendations for vitamin E, and forward players did not meet recommendations for calcium.

CONCLUSION

Amputee athletes need an individualized nutritional orientation and the lack of information about disabled sports and athletes highlights the need for more studies in this area.

Energy balance in weight stable athletes with and without menstrual disorders

The energy balance and nutritional adequacy was assessed in a group of runners with irregular menstrual function (IR, n = 10) and in a comparable group of runners with normal menstrual function (R, n = 10). Based on computerized records of 3 days food intake, the mean content of energy and macronutrients were estimated. Excess energy expenditure (EEE) during training hours was estimated using HF monitoring and individual HF/VO2 nomograms. For the rest of a daily 24 h cycle, estimated values for basal metabolic rate (BMR) and sedentary metabolic rate were applied. Daily training-related excess energy expenditure (2.1 +/- 0.3 vs 2.2 +/- 0.4) MJ (Mean +/- SEM) and total energy expenditure (TEE) (11.0 +/- 0.3 vs 11.2 +/- 0.4) MJ in R vs IR were not different in the two groups. Calculated daily energy intake (EI) was, however, significantly lower in IR (9.7 +/- 0.5 MJ) than in R (12.3 +/- 0.7 MJ), (P = 0.007). Calculated EI and TEE were in balance in R athletes. When the same calculations were applied on IR athletes, a moderate but statistically significant negative energy balance was found (-1.5 +/- 0.6 MJ, P = 0.03). The calculated energy deficit was supported by significantly lower levels of free thyroxine in IR athletes, and may indicate an adaptive lower BMR in IR athletes. Mean intakes of carbohydrates (7.0 g/kg in R and 5.7 g/kg in IR) and protein (1.71 g/kg in R and 1.49 g/kg in IR) were close to guidelines. Intakes were not significantly different in the two groups. The most important difference in macronutrient intake was found in dietary fat (1.70 g/kg in R and 1.04 g/kg in IR) that was significantly lower in the IR group than in the R group (P = 0.007). The weight stable IR and R athletes seemed to meet the recommended intake of carbohydrates, protein and fat in their diet fairly well. However, according to the present calculations, a small energy deficit was observed in IR athletes but not in R athletes. Compared with the intake of the R athletes, this energy deficit seems primarily to be related to a lower intake of dietary fat in IR athletes.

Nutritional aspects of women strength athletes

Strength training elicits sports related and health benefits for both men and women. Although sexual dimorphism is observed in exercise metabolism, there is little information outlining the specific nutritional needs of women strength athletes. Many women athletes restrict energy intake, specifically fat consumption, in order to modify body composition, but this nutritional practice is often counter-productive. Compared to men, women appear to be less reliant on glycogen during exercise and less responsive to carbohydrate mediated glycogen synthesis during recovery. Female strength athletes may require more protein than their sedentary and endurance training counterparts to attain positive nitrogen balance and promote protein synthesis. Therefore, women strength athletes should put less emphasis on a very high carbohydrate intake and more emphasis on quality protein and fat consumption in the context of energy balance to enhance adaptations to training and improve general health. Attention to timing of nutrient ingestion, macronutrient quality, and dietary supplementation (for example, creatine) are briefly discussed as important components of a nutritionally adequate and effective strength training diet for women.

Perfil antropométrico e ingestão de macronutrientes em atletas profissionais brasileiros de futebol, de acordo com suas posições

O objetivo do presente estudo foi avaliar o perfil antropométrico, o valor energético total da dieta (VET) e a ingestão de macronutrientes em atletas profissionais de futebol, assim como verificar se existem diferenças entre as posições: goleiros (n = 12), zagueiros (n = 20), meio-campistas (n = 41), laterais (n = 21) e atacantes (n = 24) dentre as variáveis estudadas. A amostra foi composta por 118 futebolistas (23 anos ± 5 anos), profissionais da elite do Estado de São Paulo. Todas as avaliações foram realizadas durante o período competitivo. A composição corporal foi determinada através da medida das dobras cutâneas e os dados nutricionais obtidos por inquérito alimentar. Os goleiros e zagueiros mostraram-se mais altos, pesados e com maior quantidade de massa magra do que os demais atletas, porém sem diferenças significativas em relação à percentagem de gordura. Em relação aos hábitos alimentares destes atletas, verificou-se que os mesmos apresentaram dieta com baixa ingestão de carboidratos, hiperprotéica e tendência à hiperlipídica. Assim, pode-se concluir que existem diferenças antropométricas entre as posições estudadas e inadequações nutricionais. Os resultados do presente estudo sugerem que sejam realizadas intervenções nutricionais em futebolistas de elite, visando melhorar o desempenho.

Dietary Reference Intakes for the macronutrients and energy: considerations for physical activity

The Dietary Reference Intakes (DRIs) are the North American reference standards for nutrients in the diets of healthy individuals. The macronutrient DRI report includes the standards for energy, fat and fatty acids, carbohydrate and fiber, and protein and amino acids. Equations used to identify the Estimated Energy Requirement (EER) were also developed based on individual characteristics including levels of physical activity. The DRIs for the macronutrients are presented as Recommended Dietary Allowances (RDAs) or Adequate Intakes (AIs), as well as Acceptable Macronutrient Distribution Ranges (AMDRs), and were arrived at by considering both nutrient inadequacies and excesses. In addition, recommendations are made that would reduce the risk of chronic diseases, such as setting intake limits for added sugar; reducing cholesterol, saturated, and trans fatty acids consumption; and increasing levels of physical activity. As healthy individuals include those engaged in various levels of physical activity, the DRIs should apply to the athlete and address their macronutrient and energy needs. This paper summarizes the macronutrient DRI report as applied to the adult, with discussion of the dietary needs of those engaged in various levels of physical activity, including the athlete.Key words: nutrition, requirements, guidelines, performance, human.

Dietary supplements and sports performance: amino acids

This is the third in a series of six articles to discuss the major classes of dietary supplements (vitamins; minerals; amino acids; herbs or botanicals; metabolites, constituents/extracts, or combinations). The major focus is on efficacy of such dietary supplements to enhance exercise or sport performance.

Exercise and the Institute of Medicine Recommendations for Nutrition

The Food and Nutrition Board of the Institutes of Medicine (IOM) recently released energy, macronutrient, and fluid recommendations, which acknowledged for the first time that active individuals have unique nutritional needs. The IOM calculated an acceptable macronutrient distribution range for carbohydrate (45%-65% of energy), protein (10%-35% of energy), and fat (20%-35% of energy; limit saturated and trans fats). These proportions provide a range broad enough to cover the macronutrient needs of most active individuals, but specific carbohydrate and protein recommendations are also typically made based on a g/kg body weight formula. These ranges are 5 to 12 g of carbohydrate/kg body weight and 1.2 to 1.8 g/kg body weight for protein depending on the level of physical activity. The IOM report also gives recommendations for the two essential fatty acids: linoleic acid (men, 14-17 g/d; women, 11-12 g/d) and linolenic acid (men, 1.6 g/d; women, 1.1 g/d). Baseline adequate intakes for fluid (water + other beverages) were set at 3.0 L and 2.2 L for sedentary men and women, respectively, with higher intakes needed to account for physical activity and exposure to extreme environments.

Micronutrient requirements of physically active women: what can we learn from iron?

The health benefits of physical activity are well established and there is increasing recognition of the importance of fitness as a key modulator of chronic disease. The impact of physical activity on micronutrient requirements is a topic of tremendous interest to the lay public, but the interest is in sharp contrast to data from well-designed studies. Research in this area is poorly controlled for nutritional status of the participants, standardized exercise protocols, markers and cutoff points for measurement of micronutrient status, and variability in subject characteristics. The micronutrient status of women in the general population is of concern, but it is not clear that physical activity increases the requirement of most micronutrients. When dietary intake is adequate, the results of most studies are either equivocal or show no benefit to performance of supplementation. In the few instances where exercise does appear to increase an individual's requirement, the increase can be obtained within the additional calories required for energy balance. In the absence of consistent data, micronutrient supplementation is often indiscriminate without regard to nutrient status. Because iron is such a key nutrient for physical activity, and the status in women is often compromised, it serves as a useful example of how current research limits the ability to make recommendations regarding the impact of exercise on micronutrients requirements in women. With the recent recognition of the importance of physical activity to the prevention and treatment of chronic diseases through the life span, more attention should be focused on the impact of exercise on micronutrient requirements, especially in the context of weight loss regimens.

Protein Needs of Older Adults Engaged in Resistance Training: A Review

Protein recommendations by some professional organizations for young adults engaged in resistance training (RT) are higher than the recommended dietary allowance (RDA), but recommendations for resistance-training older adults (>50 years old) are not well characterized. Some argue that the current RDA is adequate, but others indicate increased protein needs. Although concerns have been raised about the consequences of high protein intake, protein intake above the RDA in older adults is associated with increased bone-mineral density when calcium intake is adequate and does not appear to compromise renal health in older individuals with normal renal function. Individual protein needs for older adults in RT are likely highly variable according to health and training regimen, but an intake of 1.0–1.3 g · kg−1· day−1should adequately and safely meet the needs of older adults engaged in RT, provided that their energy needs are met.

Nutritional concerns for the child and adolescent competitor

With exercise for sports competition in children and adolescents, acute nutrient needs will change. Fluid intake to ensure the replacement of water and minerals (electrolytes) lost in sweat is important. Energy needs also increase because of the elevated energy expenditure with physical activity. Arguably carbohydrate is the recommended source of training needs, although research has yet to be done to show performance benefits in young athletes on a high-carbohydrate diet. In the majority of sports, an increased intake of food naturally occurs to accommodate the day-to-day nutrient needs of young athletes, and unlike non-athlete, young competitors typically come closer to meeting their requirements for micronutrients. Nonetheless, certain athletic groups may be at risk for shortfalls in their diet. Compared to athletes in team sports, participants in weight-control sports may be at greater risk of failing to meet requirements for energy, protein, and some micronutrients. Endurance athletes, particularly female distance runners, may have intake deficits for the minerals iron and calcium. Acute issues such as heat illness and chronic concerns that include impaired growth and development, and the risk of injuries that include stress fractures may be an outcome of inadequate nutrition during physical training.

Effects of exogenous leptin on satiety and satiation in patients with lipodystrophy and leptin insufficiency

To examine leptin's role in human appetite regulation, we studied recombinant methionyl human leptin's effects on satiation and satiety in a model of leptin insufficiency, lipodystrophy. Eight females with hypoleptinemia and lipodystrophy were given sc injections of A-100 (maximal dose, 200% of that predicted to normalize serum leptin) for 4 months. Satiation and satiety were determined before and again during leptin treatment. Satiation was measured as the time to voluntary cessation of eating from a standardized food array after a 12-h fast. Satiety was determined as the time to hunger sufficient to consume a full meal after consumption of a standardized preload. During leptin treatment, satiation time decreased (41.2 +/- 18.2 to 19.5 +/- 10.6 min; P = 0.01), satiety time increased (62.9 +/- 64.8 to 137.8 +/- 91.6 min; P = 0.04), energy consumed to produce satiation decreased (2034 +/- 405 to 1135 +/- 432 kcal or 8.5 +/- 1.7 to 4.7 +/- 1.8 MJ; P < 0.01), and the amount of food desired in the postabsorptive state decreased (P < 0.02). Ghrelin concentrations also decreased during leptin administration (284.3 +/- 127.9 to 140.6 +/- 104.5 pmol/liter; P < 0.002). We conclude that increased leptin in patients with lipodystrophy results in less caloric, shorter, more satiating meals and longer-lived satiety. These data support the hypothesis that leptin plays an important, permissive role in human appetite regulation.

Vitamin and mineral status: effects on physical performance

Public health recommendations encourage the selection of a balanced diet and increasing physical activity to foster health and well-being. Whereas the adverse effects of restricted intakes of protein, fat, and carbohydrate on physical performance are well known, there is limited information about the impact of low intakes of vitamins and minerals on the exercise capacity and performance of humans. Physically active people generally consume amounts of vitamins and minerals consistent with the recommendations for the general public. However, when intakes are less than recommendations, some noticeable functional impairments occur. Acute or short-term marginal deficiencies, identified by blood biochemical measures of vitamin B status, had no impacts on performance measures. Severe deprivation of folate and vitamin B12 result in anemia and reduce endurance work performance. Evidence of vitamin A and E deficiencies in athletic individuals is lacking apparently because body storage is appreciable. In contrast to vitamins, marginal mineral deficiencies impair performance. Iron deficiency, with or without anemia, impairs muscle function and limits work capacity. Magnesium deprivation increases oxygen requirements to complete submaximal exercise and reduces endurance performance. Use of vitamin and mineral supplements does not improve measures of performance in people consuming adequate diets. Young girls and individuals participating in activities with weight classifications or aesthetic components are prone to nutrient deficiencies because they restrict food intake and specific micronutrient-rich foods. This information will be useful to professionals who counsel physically active people and scientific groups who make dietary recommendations to improve health and optimize genetic potential.

Nutritional considerations for vegetarian athletes

With the growing interest in the potential health benefits of plant-based diets, it is relevant to consider whether vegetarian dietary practices could influence athletic performance. Accordingly, this review examines whether nutrients that may differ between vegetarian and omnivorous diets could affect physical performance. We also describe recent studies that attempt to assess the effects of a vegetarian diet on performance and comment on other nutritional aspects of vegetarianism of relevance to athletes. Although well-controlled long-term studies assessing the effects of vegetarian diets on athletes have not been conducted, the following observations can be made: 1) well-planned, appropriately supplemented vegetarian diets appear to effectively support athletic performance; 2) provided protein intakes are adequate to meet needs for total nitrogen and the essential amino acids, plant and animal protein sources appear to provide equivalent support to athletic training and performance; 3) vegetarians (particularly women) are at increased risk for non-anemic iron deficiency, which may limit endurance performance; and 4) as a group, vegetarians have lower mean muscle creatine concentrations than do omnivores, and this may affect supramaximal exercise performance. Because their initial muscle creatine concentrations are lower, vegetarians are likely to experience greater performance increments after creatine loading in activities that rely on the adenosine triphosphate/phosphocreatine system. 5) Coaches and trainers should be aware that some athletes may adopt a vegetarian diet as a strategy for weight control. Accordingly, the possibility of a disordered eating pattern should be investigated if a vegetarian diet is accompanied by unwarranted weight loss.

Intercollegiate student athlete use of nutritional supplements and the role of athletic trainers and dietitians in nutrition counseling

A survey of university student athletes was conducted to determine supplement use, perceived efficacy of supplements, availability and use of nutrition services, and perceived nutrition knowledge of athletic trainers. Results from 236 athletes showed that 88% used one or more nutritional supplements, yet perceived efficacy was moderate (2.9 or less; 5-point scale). Classes (69.4%), brochures (75%), and individual counseling (47%) were available and were used by 29.9%, 33.2%, and 17.9% of athletes, respectively. Primary sources of nutrition information were athletic trainers (39.8%), strength and conditioning coaches (23.7%), and dietitians (14.4%). Athletes perceived athletic trainers to have strong nutrition knowledge (mean=3.8+/-0.9; 5-point scale). Many (23.5%) did not know whether a dietitian was available. Dietitians must accelerate their marketing efforts to student athletes, work closely with athletic trainers to provide sound nutrition information, and provide services that meet the needs of a diverse population of student athletes.

Influence of prolonged endurance cycling and recovery diet on intramuscular triglyceride content in trained males

Intramuscular triglycerides (IMTG) are assumed to form an important substrate source during prolonged endurance exercise in trained males. This study investigated the effects of endurance exercise and recovery diet on IMTG content in vastus lateralis muscle. Nine male cyclists were provided with a standardized diet for 3 days, after which they performed a 3-h exercise trial at a 55% maximum workload. Before and immediately after exercise and after 24 and 48 h of recovery, magnetic resonance spectroscopy (MRS) was performed to quantitate IMTG content. Muscle biopsies were taken after 48 h of recovery to determine IMTG content by using quantitative fluorescence microscopy. The entire procedure was performed two times; in one trial, a normal diet containing 39% energy (En%) as fat was provided (NF) and in the other a typical carbohydrate-rich athlete's diet (LF: 24 En% fat) was provided. During exercise, IMTG content decreased by 21.4 +/- 3.1%. During recovery, IMTG content increased significantly in the NF trial only, reaching preexercise levels within 48 h. In accord with MRS, fluorescence microscopy showed significantly higher IMTG content in the NF compared with the LF trial, with differences restricted to the type I muscle fibers (2.1 +/- 0.2 vs. 1.4 +/- 0.2% area lipid staining, respectively). In conclusion, IMTG content in the vastus lateralis muscle declines significantly during prolonged endurance exercise in male cyclists. When a normal diet is used, IMTG contents are subsequently repleted within 48 h of postexercise recovery. In contrast, IMTG repletion is impaired substantially when a typical, carbohydrate-rich athlete's diet is used. Data obtained by quantitative fluorescence microscopy correspond well with MRS results, implying that both are valid methods to quantify IMTG content.

Position of the American Dietetic Association and Dietitians of Canada: vegetarian diets

It is the position of the American Dietetic Association and Dietitians of Canada that appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases. Approximately 2.5% of adults in the United States and 4% of adults in Canada follow vegetarian diets. A vegetarian diet is defined as one that does not include meat, fish, or fowl. Interest in vegetarianism appears to be increasing, with many restaurants and college foodservices offering vegetarian meals routinely. Substantial growth in sales of foods attractive to vegetarians has occurred and these foods appear in many supermarkets. This position paper reviews the current scientific data related to key nutrients for vegetarians including protein, iron, zinc, calcium, vitamin D, riboflavin, vitamin B-12, vitamin A, n-3 fatty acids, and iodine. A vegetarian, including vegan, diet can meet current recommendations for all of these nutrients. In some cases, use of fortified foods or supplements can be helpful in meeting recommendations for individual nutrients. Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life-cycle including during pregnancy, lactation, infancy, childhood, and adolescence. Vegetarian diets offer a number of nutritional benefits including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fibre, magnesium, potassium, folate, antioxidants such as vitamins C and E, and phytochemicals. Vegetarians have been reported to have lower body mass indices than non-vegetarians, as well as lower rates of death from ischemic heart disease, lower blood cholesterol levels, lower blood pressure, and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer. While a number of federally funded and institutional feeding programs can accommodate vegetarians, few have foods suitable for vegans at this time. Because of the variability of dietary practices among vegetarians, individual assessment of dietary intakes of vegetarians is required. Dietetics professionals have a responsibility to support and encourage those who express an interest in consuming a vegetarian diet. They can play key roles in educating vegetarian clients about food sources of specific nutrients, food purchase and preparation, and any dietary modifications that may be necessary to meet individual needs. Menu planning for vegetarians can be simplified by use of a food guide that specifies food groups and serving sizes.

Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets

It is the position of the American Dietetic Association and Dietitians of Canada that appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases. Approximately 2.5% of adults in the United States and 4% of adults in Canada follow vegetarian diets. A vegetarian diet is defined as one that does not include meat, fish, or fowl. Interest in vegetarianism appears to be increasing, with many restaurants and college foodservices offering vegetarian meals routinely. Substantial growth in sales of foods attractive to vegetarians has occurred, and these foods appear in many supermarkets. This position paper reviews the current scientific data related to key nutrients for vegetarians, including protein, iron, zinc, calcium, vitamin D, riboflavin, vitamin B-12, vitamin A, n-3 fatty acids, and iodine. A vegetarian, including vegan, diet can meet current recommendations for all of these nutrients. In some cases, use of fortified foods or supplements can be helpful in meeting recommendations for individual nutrients. Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood, and adolescence. Vegetarian diets offer a number of nutritional benefits, including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fiber, magnesium, potassium, folate, and antioxidants such as vitamins C and E and phytochemicals. Vegetarians have been reported to have lower body mass indices than nonvegetarians, as well as lower rates of death from ischemic heart disease; vegetarians also show lower blood cholesterol levels; lower blood pressure; and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer. Although a number of federally funded and institutional feeding programs can accommodate vegetarians, few have foods suitable for vegans at this time. Because of the variability of dietary practices among vegetarians, individual assessment of dietary intakes of vegetarians is required. Dietetics professionals have a responsibility to support and encourage those who express an interest in consuming a vegetarian diet. They can play key roles in educating vegetarian clients about food sources of specific nutrients, food purchase and preparation, and any dietary modifications that may be necessary to meet individual needs. Menu planning for vegetarians can be simplified by use of a food guide that specifies food groups and serving sizes.

Dietary recommendations and athletic menstrual dysfunction

Exercise-induced or athletic menstrual dysfunction (amenorrhoea, oligomenorrhoea, anovulation, luteal phase deficiency, delayed menarche) is more common in active women and can significantly affect health and sport performance. Although athletic amenorrhoea represents the most extreme form of menstrual dysfunction, other forms can also result in suppressed estrogen levels and affect bone health and fertility. A number of factors, such as energy balance, exercise intensity and training practices, bodyweight and composition, disordered eating behaviours, and physical and emotional stress levels, may contribute to the development of athletic menstrual dysfunction. There also appears to be a high degree of individual variation with respect to the susceptibility of the reproductive axis to exercise and diet-related stresses. The dietary issues of the female athlete with athletic menstrual dysfunction are similar to those of her eumenorrhoeic counterpart. The most common nutrition issues in active women are poor energy intake and/or poor food selection, which can lead to poor intakes of protein, carbohydrate and essential fatty acids. The most common micronutrients to be low are the bone-building nutrients, especially calcium, the B vitamins, iron and zinc. If energy drain is the primary contributing factor to athletic menstrual dysfunction, improved energy balance will improve overall nutritional status and may reverse the menstrual dysfunction, thus returning the athlete to normal reproductive function. Because bone health can be compromised in female athletes with menstrual dysfunction, intakes of bone-building nutrients are especially important. Iron and zinc are typically low in the diets of female athletes if meat products are avoided. Adequate intake of the B vitamins is also important to ensure adequate energy production and the building and repair of muscle tissue. This review briefly discusses the various factors that may affect athletic menstrual dysfunction and two of the proposed mechanisms: the energy-drain and exercise-intensity hypotheses. Because energy drain can be a primary contributor to athletic menstrual dysfunction, recommendations for energy and the macro- and micronutrients are reviewed. Methods for helping the female athlete to reverse athletic menstrual dysfunction are discussed. The health consequences of trying to restrict energy intake too dramatically while training are also reviewed, as is the importance of screening athletes for disordered eating. Vitamins and minerals of greatest concern for the female athlete are addressed and recommendations for intake are given.

The nutrient and anthropometric status of physically active and inactive older adults

OBJECTIVE

To assess nutrient intake, anthropometrics, and biochemical indicators in physically active and inactive older adults.

DESIGN

A cross-sectional sample of older adults who participated in the Third National Health and Nutrition Examination Survey, 1988-94, was divided into two groups based on activity level.

PARTICIPANTS/SETTING

A national sample of men (n = 1876) and women (n = 2009) 65 years of age and older who reported diet and exercise information and were medically examined.

MAIN OUTCOME MEASURES

Association of activity level with nutrients, anthropometrics, and biochemistries.

ANALYSIS

Means were calculated for each of the variables observed by activity category. T tests were used to determine if the differences in the means were statistically significant at P <.05.

RESULTS

Older adults reported intakes of food energy, calcium, magnesium, and zinc below recommendation. Nutrient intakes and anthropometrics for active and inactive women were similar; those for active and inactive men differed significantly for many nutrients and for anthropometrics associated with activity. CONCLUSIONS ANS IMPLICATIONS: Inadequate intakes of food energy and micronutrients are of concern because of the metabolic stresses associated with activity. Future research is needed to determine the impact of increased physical activity on nutrient needs and body composition in the elderly.

Effects of habitual physical activity on the resting metabolic rates and body compositions of women aged 35 to 50 years

OBJECTIVE

To examine the effect habitual physical activity has on resting metabolic rate (RMR) and body composition (fat-free mass[FFM], fat mass, and percent body fat) in active compared to sedentary adult women.

DESIGN

RMR was measured (by indirect calorimetry) twice after a 12-hour fast at the same point of the menstrual cycle and 48 hours after exercise. FFM, fat mass and percent body fat were measured using whole body air displacement plethysmography. Energy intake and expenditure were determined using 7-day weighed-food records and activity logs.

SUBJECTS

Healthy, weight-stable premenopausal women aged 35 to 50 years classified as either active (approximately 9 hours per week of physical activity for 10 or more years) (n= 18) or sedentary (approximately 1 hour per week of physical activity) (n= 14).

STATISTICAL ANALYSES

Analysis of covariance was used to investigate differences in mean RMR (kcal/day) between the groups adjusted for FFM, and independent t tests were used to determine differences in demographic, energy expenditure, and diet variables.

RESULTS

Percent body fat and fat mass were lower (P<.0005) and RMR (adjusted for FFM) was significantly higher in the active women (P=.045) compared with sedentary controls. In the active and sedentary groups respectively, mean adjusted RMR was 1,510 kcal/day and 1,443 kcal/day, body fat was 18.9% and 28.8%, and fat mass was 11.1 kg and 18.8 kg. Groups were similar in body mass, FFM, body mass index, and age. Mean energy balance appeared to be more negative in the active group (P=.0059) due to significantly higher mean self-reported energy expenditures (P=.0001) and similar mean self-reported energy intakes (P=.52) compared with sedentary controls. These data indicate that active women who participate in habitual physical activity can maintain lower body fat and a higher RMR than sedentary controls with similar body mass, FFM, and body mass index.

APPLICATIONS/CONCLUSIONS

This research supports and emphasizes the benefits of habitual physical activity in maintaining RMR and lower body fat levels in middle-aged women.

Updates in pediatric nutrition

Ongoing research in several areas of pediatric nutrition has new practical applications for community-based pediatricians. For example, a fresh understanding of risk factors for rickets persuades pediatricians to recognize and treat this disease, which was thought to be nearly extinct in the modern industrialized world. Similarly, an expanded awareness of the antibacterial components of breast milk encourages a more complete dialogue between pediatricians and new mothers about the potential benefits of breast-feeding. For those infants with feeding intolerance, new data help to refine the indications for hypoallergenic formulas, which are increasingly recommended for children with a variety of symptoms. The past year also has seen breakthroughs in our understanding of supplemental nutrition for children. Vitamin A may provide direct benefits for the most vulnerable of children, namely premature infants at high risk for lung disease. At the other end of the pediatric spectrum, adolescent athletes seeking to enhance their performance are consuming poorly studied sports supplements that may not be beneficial and may even be toxic. Finally, a greater appreciation for the epidemic of obesity that is sweeping the United States and other countries suggests that children at high risk may represent a far more diverse population than had been recognized previously.