Editor's note

The ancient Chinese created an agricultural solar system - still in use today - that is based upon their observation of crops, climate, astrology, and the study of animal and plant life cycles. The system guided farmers as to when to sow seeds and when to harvest them, and this system has now been in place for more than 2,000 years.

Today, with advances in science and technology, agriculture depends less on this ancient wisdom. But this seasonal calendar still operates as a reference guide for gourmands to seek out the best times for seasonal delicacies and for health experts to plan nutritious diets.

In a single year, the system features 24 "solar terms" - each lasting one day and occurring every two weeks. Each has its own name and characteristics. The Global Times is presenting a weekly series examining which foods and delicacies are best enjoyed during these periods, as well as tips on preserving general health.

Since the solar calendar period of xiaoshu (lesser heat) which fell on July 7, residents in Shanghai have been experiencing extreme summer heat, with temperatures skyrocketing to 35 C or even higher almost every day.

So how to deal with this almost unbearable heat, while staying fit and healthy at the same time? The Global Times has consulted a number of traditional Chinese medicine (TCM) doctors in the city to get some practical advice about this matter.

Three principles of diet

"Summer is the season in which many digestive disorders prevail, so the basic principle for a summer diet is to make sure that your food is properly cooked and that you don't eat any leftovers. Hygiene is very important in hot weather," said Xiong Anling, a TCM doctor from the Tong Han Chun Tang Pharmacy (20 Yuyuanxin Road).

Xiong said that when people don't eat enough of the right food, the source of their energy is weakened, thus meaning people are in danger of becoming tired and losing weight. There is also the increased danger of contracting diseases due to a weakened immune system. However, he also warned that overeating in summer can impose an unnecessary burden on your digestive functions, which may lead to abdominal distension, vomiting or diarrhea.

To secure the cleanliness of your food means not only washing fruit and vegetables, but also making sure that your food has not gone bad because of the high temperatures. Xiong suggests that people should not eat day-old leftovers because it is likely the food has been infected with harmful bacteria.

He also points out that many people are passionate about a particular flavor in their everyday diet, such as cold food, spicy food, or sour food. However, according to TCM, the over consumption of a particular flavor, sourness or spice over a long period, may also cause problems. For example, too much salty food can slow down your blood circulation and lead to a pasty complexion; too much bitter food can make the skin dry and cause your hair to fall out; and excessive absorption of spicy food can result in dull, unhealthy-looking fingernails. "I always suggest to my patients that they maintain a balanced diet, which will help their bodies to absorb all the nutrients they need to stay healthy," said Xiong.

Skin scraping

As a traditional treatment in China, skin scraping is known for its efficacy in promoting blood circulation. In summer, skin scraping is extremely popular as it can relieve the discomfort and consequent ailments, caused by heatstroke.

With a piece of ox horn, or sandalwood, you can practice skin scraping at home. The basic steps are: first, to apply essential oil (a pharmacist will advise which) for skin scraping onto your back to lubricate the skin; second, hold the ox horn or sandalwood at a 45-degree angle to the skin, and scrape your back from the backbone to both sides until the scraped skin turns red; the final step is to remove the oil and apply another essential oil, balm, onto the skin (which may look bruised and red), and leave it there for a couple of minutes before washing off.

Normally the redness or bruising will appear after about 20 scraping movements on the same area of skin, and people may feel some pain during this process. The skin scraping should be carried out in a warm room, that doesn't have any draughts. It is also suggested to drink a cup of warm water after the skin scraping, and not to have a cold shower for at least 30 minutes.