Summer heat prevention measures and recommended products

Japanese modern lifestyle

Don’t you feel tired? No appetite? Can not sleep??

If you have such a symptom, it may be “summer heat”. We call it “Natsu bate” in Japanese. “Natsu” means summer and “Bate(ru)” means being exhausted. Japanese summer is hot and humid, so many foreigners may find it harder than they imagined.

Today, I will introduce what you can do when you are in such a physical condition. Let’s get over the summer heat together and have a lively and enjoyable summer!

Causes of natsubate (summer heat)

Lack of vitamin

When it’s hot, our bodies sweat and evaporate, trying to lower their body temperature. Sweat contains not only water but also vitamins and minerals, which are taken out of the body together.

What happens if you are deficient in vitamins and minerals?

Vitamin deficiency causes fatigue, dizziness, headache, palpitation, shortness of breath, abnormal sweating, constipation, and diarrhea.

Mineral deficiency causes depression, hypothermia, anemia, rough skin and stiff neck mouth ulcers, weight gain and immunity. You may get tired easily, lose your concentration, or become frustrated.

In this way, if you do not supplement the nutrients that are lacking when you sweat, the nutritional balance will be lost and summer heat fatigue will appear.

Indoor / outdoor temperature difference

Next is the temperature difference.

When you move from a hot outside to an air conditioned room, your body will be cooled at once. The body temperature is regulated by sweating and constricting blood vessels by the action of autonomic nerves. Repeatedly going back and forth between indoors and outdoors where there is a large temperature difference puts a strain on the autonomic nerves and prevents them from functioning properly.

The balance between the sympathetic nerves that activate the state of the mind and body and the parasympathetic nerves that rest the mind and body is lost, and various symptoms such as dullness, anxiety, headaches and motives appear.

Temperature difference in the body

Another problem is the temperature difference inside the body.

If you sit and work in a cool room all the time, the blood vessels in your lower body will atrophy, and only your lower body and toes will tend to get cold. The temperature difference between the toes and the brain can be more than 10 degrees!

Even though the lower half of the body is cold, it becomes difficult to dissipate heat well with only the upper half of the body having heat. When that happens, you may feel dull, and have symptoms of heat fatigue.

Solutions for natsubate (summer heat)

So what can we do to solve such a health problems? Let’s check it out!

Eat a well-balanced diet

In the hot summer, be careful about the nutritional balance of your diet. Sweating is especially prone to vitamin b1 deficiency.

Foods rich in Vitamin B1
  • Eel
  • Pork
  • Yellowtail
  • Soybeans
  • Brown rice
  • Spinach
  • Sesame

Eating it with garlic, Chinese chive or green onions is recommended as it improves the absorption of vitamin B1.

In Japan, it is customary to eat eels on “Doyo no ushi no hi”. It refers to the turn of the season. Let’s eat nutritious eels when the season changes to get more energy!

It’s 28th Wednesday, July this year 2021!!

Foods rich in Mineral
  • Seaweed
  • Spinach
  • Melon
  • Peach
  • Grape

Within 5℃

As a guide, the temperature difference that does not burden our body is 5℃. Set the temperature of the air conditioner to about 26 to 28℃. If you cannot change the settings, for example at the office, adjust the direction of the wind so that the cool wind does not hit you directly, or prepare a pair of socks or something to put on, so that you do not get cold.

The temperature difference between the outside temperature and the room temperature should be about 5℃.


If only your lower body or toes are cold, exercising and sweating will help regulate your body temperature and eliminate the temperature difference in your body.

“Aerobic exercise” is an effective exercise. Start with what you can do comfortably, such as walking, squats, yoga, and stepping up and down.

If you sweat, don’t forget to rehydrate and replenish vitamins and minerals!

Convenient item to prevent heat fatigue

As mentioned above, thermoregulation becomes very important. Here are two useful items to help you avoid sudden changes in body temperature and heat buildup in your upper body.

Handy fan

In Japan, people has started carrying handy fans since around 2018. It’s a personal fan and it’s very small in size.

It has become a popular summer item with each passing year, and now there are various types such as manual, rechargeable, neck-hanging, and hand-held etc. There are many color choices too.

You can buy it at 100-yen shops, general stores, and online shopping.

Click here for Francfranc’s popular items that sparked handy fans. Their 2021 model.


We bought the one at Flying Tiger. It was reasonable, 550yen. It can fold on the bar so that we can use it by a hand also on a table.

Jacket with fans

Do you see someone wearing a jacket with small fans on it like this?

Originally, it was used as a savior for construction site workers who work under the strong sun. And gradually it is becoming more common for ordinary people to wear it as everyday wear.

This year, apparel makers and sporting goods makers are also participating, and cool designs are on sale. If you have a lot of work outside, why not check it out?

Goodbye to summer heat

Summer in Japan, it’s really hot and humid. If you don’t take care of yourself well, you will get natsubate. Let’s take proper measures and survive the summer energetically!


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