Every year, during this season when we are approaching the height of summer, many schools hold a sports day. Thus, this is also the time of the year when the risk of children’s heatstroke becomes a concern. While many schools have called off their sports events due to COVID-19, there are rising concerns that, as the temperature and humidity continue to rise toward mid-summer, the almost compulsory use of masks will increase the risk of heatstroke.

One of the preventive measures that can be taken at home to protect the health and lives of children is adopting a healthy diet. What foods help prevent a heatstroke? As the ‘stay at home’ self-restriction continues, increasing burden is placed on parents to prepare all the meals for their children. Is there a way to ease this burden while at the same time giving due consideration to nutrition? We asked Dr. Chikako Yasui, Associate Professor of the College of Gastronomy Management, Ritsumeikan University and also a national registered dietician and certified health exercise instructor.

Heatstroke refers to various physical disorders caused when the body water and salt go out of balance leading to dysfunction of physiological thermoregulation. Its symptoms are wide ranging, including dizziness, headache, nausea, and impaired consciousness. Associate Professor Yasui stresses the importance of not only taking sufficient water, but also regularly taking three meals a day to ensure sufficient intake of carbohydrate which provides energy to keep the body moving. Intake of water and meals are the grand principle for preventing heatstroke diet-wise. “Skipping breakfast is a particularly high risk factor. When you don’t take breakfast, and even though you’re in a good condition at the beginning of exercise, you might fall sick without noticing it as the temperature and humidity rise,. Never be overconfident that you’ll be okay just because you’re not feeling sick at the moment. Actually, in early spring or autumn, when the temperature is not that high, people sometimes start exercising in heavy clothing and get heatstroke. This is because our bodies are not yet used to the heat in spring and therefore often fail to regulate body temperature” says Associate Professor Yasui.

Mind the body water and salt balance

Assuming that we take all three meals as a premise, one of the important heatstroke factors that we should also mind is “imbalance of body water and salt.” According to Associate Professor Yasui, the two main roles that meals have from a nutrition perspective are:
(1) To store energy and nutrients necessary to keep the body active
(2) To supplement the energy and nutrients consumed by physical activity
To prevent heatstroke, it is essential that we supply water and salt lost by perspiration, both before and after exercising. As for meals, what kinds of food are effective for preventing heatstroke?

“When you want to supply water from beverages, try to avoid coffee, tea and green tea because they include caffeine which acts as a diuretic and promotes excretion of water from the body as urine. This may in some cases lead to dehydration. Mugicha (roasted barley tea) is recommendable as it does not contain caffeine. When children ask for sweet beverages, giving them 100% orange juice is advisable rather than artificial soft drinks, because it contains abundant vitamin C. Athletes often take orange juice for this reason. If you want to take in water from your meals, soups with vegetable are ideal because you can take not only water but also salt and potassium.”

Perspiration takes away iron, potassium and other minerals in addition to water and salt. The key to wisely supplementing these minerals is to choose highly nutritious foodstuff.　“Vegetables with deep green or yellow color are richer in minerals and vitamins than lighter colored vegetables. Try to include them in your diet. To give some examples, spinach, komatsuna (Japanese mustard spinach) and broccoli are more nutritious than cucumber.”

The vitamin B family plays a vital role in converting food nutrients into energy, but .it is difficult to intake the required amounts of vitamin Bs only from vegetables. Lack of vitamin B1 or B2 will hinder energy production making it difficult to recover from fatigue caused by heat exposure or exercise, and thus the risk of heatstroke is increased. Representative foods rich in vitamin B are:
・Pork
・Soybean and soy products (tofu, natto (fermented soybeans), etc.)
・Eggs
Associate Professor Yasui particularly recommends tonjiru (miso soup with pork and vegetables) as a great dish for the vitamin B intake because it allows you to take abundant water, protein and minerals, let alone vitamin B1 rich in pork.

Children who usually play outside a lot are likely to be affected by stay-at-home restrictions Children’s diet for coexisting with COVID-19

With the extended school closures and restrictions on going out since the COVID-19 outbreak, there are rising concerns about the health and nutritional status of children. Since most children are now hanging around at home, it is assumed that opportunities for children to consume snacks and sweetened soft drinks have increased, whereas their energy consumption has reduced. Children’s bodies grow day by day and obviously they need energy to grow, but you wouldn’t want too much weight gain that doesn’t involve increase in muscle mass.

“hildren who used to play outside and get a lot of exercise. If the amount of food intake remains unchanged, the unused energy will be stored as body fat. I assume most kids wouldn’t like the idea of reducing the number of side dishes, so perhaps their parents might want to reduce the amount of each dish they eat. Another thing is to agree on a limit of snacks they can eat, as it would also be difficult to completely forbid children from eating any snacks and sweetened beverages.

The frequency of cooking at home is increasing and many parents are worn out from the burden of having to prepare every meal for their children. The burden of preparing hearty meals is heavy, but we need to consider the nutritional aspects. What are the tips for balancing workload and nutrition? “Needless to say, it would be best if you could prepare a well-balanced meal complete with rice (or other staple food), a main dish and side dishes. In reality, however, it’s too much work to prepare so many dishes for every meal. You don’t have to prepare a perfectly balanced meal every time. Instead, try balancing your nutritional intake for each day. For instance, if you had a donburi (large bowl of rice often topped with meat and eggs) with hardly any vegetables for lunch, try to take lots of vegetables for dinner. Try to maintain nutritional balance for the day by supplementing the nutrients that were not enough in the previous meal. That would make things easier.”

The most important thing is to incorporate various nutrients into your diet, by combining rice, bread or other sources of carbohydrates, meat, fish and other sources of protein, as well as vegetables to ensure the intake of minerals and vitamins.