Research on Nutrition for Children
Science-Based Policy Statement on Optimal Nutrition for Children Playing Soccer
Soccer is a high intensity sport that requires a combination of power, speed, and endurance that can be sustained throughout a game. In order to fuel their muscles and perform sustained exercise at high level, children must consume adequate calories from carbohydrates, proteins and fats. In order to help meet their nutrient needs, parents and coaches need to guide children to consume lean animal and vegetable protein, whole grain carbohydrates, fruits and vegetables, and low fat dairy 1. Not only is it important to encourage the consumption of these food groups to meet energy needs, but these healthy food choices also provide the vitamins and minerals that are essential in regulating children’s energy, growth, and repair processes. Finally, it is critical that young players stay hydrated so that performance and heat regulation are not compromised. This paper provides parents and coaches with an overview of the current research on the nutritional needs of youth soccer players and provides practical recommendations for sustained energy and performance.
CALORIC (ENERGY) NEEDS
At this time there is a lack of research on the amount of energy a child expends in various sports The number of calories required over a 24-hour day depends on the age of the child and their activity level. We do know that children expend more energy per pound of body mass compared with adults – from 10-25% more. The younger the child the more this is true. This is due to children having less muscular coordination and economy of movement compared to adults. Young soccer players may require anywhere from 200-600 calories more per day, depending on the intensity and duration of play. Importantly, children playing soccer need to stay in “energy balance” – that means consuming ample calories for proper growth, development, and activity. As in adults, consuming more than they burn will lead to excess weight gain. According to the 2005 Dietary Guidelines from the U.S. Department of Agriculture (USDA) and the Department of Health and Human Services (USDHHS), ALL children 2 years and older should get 60 minutes of moderate to vigorous exercise on most, preferably all, days of the week. Caregivers of young soccer players need to recognize that if a child is only playing soccer on a daily basis and not engaged in additional physical activity, he or she might only just be meeting these recommendations. Therefore, some youth soccer players may not necessarily need more calories on a daily basis, but may need to pay more attention to the composition and timing of snacks and meals.
Carbohydrates – Energy for exercising muscles
Carbohydrates are essential for intense physical activity in sports such as soccer. They are the most readily available source of food energy for exercising muscles. When a child is training or competing, the muscles need energy to perform. The major source of energy for working muscles is glycogen. Glycogen is stored in muscles and the liver and is a starch produced by the body primarily from the glucose found in carbohydrates. Muscle glycogen provides the primary energy source for high intensity, maximal-outburst activity, and is also a significant fuel source for endurance exercise 7. Consuming adequate amounts of carbohydrate maintains usual training intensity and promotes rapid recovery. A regular soccer match has been shown to deplete muscle glycogen stores in children by approximately 35% and this gradual depletion parallels time to exhaustion8. Carbohydrate consumption pre-exercise stimulates muscle glycogen storage and may help delay fatigue during exercise. Carbohydrate consumption during exercise that lasts more than 60 minutes helps the body maintain blood glucose availability late in exercise 7. Post-exercise carbohydrates help improve muscle glycogen storage, especially within 30-60 minutes after the activity 9. (See meal timing section below.)
Children should consume 46-65% of their energy as carbohydrates10. If they are exercising for long durations and at high intensities, it may be beneficial for them to consume amounts at the upper end of this range. Children should eat carbohydrates at each meal with an emphasis on whole grains, fruits and vegetables.
At least half of the grains a child consumes should be whole grains which are full of nutrients and fiber 1. Children 4-8 years of age should have a daily dietary fiber intake of 25 g and 9-13 year olds should consume 31 g and 26 g, respectively 10. Unfortunately, the Average Dietary Fiber intake for children 2-5 years old is 11.4 g/day and for children 6-11 years old is 13.1 g/day 11. These low fiber intakes may reflect low intakes of whole grains, fruits, and vegetables and further emphasize a need to focus on these food groups.
Fruits and Vegetables.
Many people may think of carbohydrates as bread and rice, however, some of the most important carbohydrates in our diet come from colorful fruits and vegetables. Not only do fruits and vegetables fuel the body for exercise, they are also excellent sources of vitamins A and C, phytochemicals, and fiber. Children should consume at least 5 fruits and vegetables per day 1, 6. However, 63% of children 2 to 9 years of age are not consuming the recommended number of servings of fruits, and 78% are not consuming the recommended number of servings for vegetables. Children, on average, are only consuming 2.0 fruits and 2.2 vegetables per day 12. These low intakes are associated with inadequate intakes of vitamin A, vitamin C, and dietary fiber, in addition to high intakes of total fat and saturated fat 13. Children should strive to consume a variety of vegetables and the majority of servings of fruit should come from whole fruit (fresh, frozen, canned, dried) rather than fruit juice 6 14. Increased fruit juice intake is associated with excess adiposity (body fat) gains, whereas increased consumption of whole fruits is associated with reduced adiposity gains 15. Reasons for this may include that fruit juice is high in calories and not as filling as whole fruit which can lead to over consumption. The American Academy of Pediatrics recommends that for children ages 1 to 6, intake of fruit juice should be limited to four to six ounces per day. Children between the ages of 7 and 18 should consume no more than between eight and twelve ounces of juice a day 6, 14. If 100% fruit juice is provided in these appropriate amounts, it can be a healthy part of a child’s diet. 3
High glycemic index foods. The glycemic index or load of an individual food or a meal is a measure of how quickly it causes blood sugar levels to rise and fall. A food, snack or a meal that has a relatively high glycemic index or load WILL NOT provide lasting energy. The fiber, protein, fat, and simple sugar content all impact the glycemic index of a food, snack, or meal. Examples of high glycemic index foods include simple and refined sugars such as candy, white bread, and white rice. Children should be consuming snacks and meals that contain a relatively low glycemic load right before activity/training. For example, a breakfast that includes whole grain cereal and milk is likely to help sustain blood sugar and will help children better maintain blood sugar levels throughout the morning. Studies have shown that this maintains cognitive performance, reduces excess calorie intakes at lunch, and helps with exercise performance later in the day 16, 17. Table 2 lists some ideal foods for children to consume prior to activity
High fructose corn syrup.
High fructose corn syrup is a form of corn syrup which has undergone enzymatic processing that increases its fructose content. It is comparable to table sugar (sucrose) in sweetness and is used by food manufacturers as a useful alternative to sucrose in soft drinks and other processed foods. Beverages with high fructose corn syrup, sweets, and other sweetened foods that provide little or no nutrients should be avoided. Consumption of these foods is negatively associated with diet quality in children and can contribute to excessive energy intakes 6, 14. In addition, most of these products have a high glycemic index, which would cause children’s blood sugar to spike and then fall during a soccer game and lead to fatigue.