THE digestive system can cause problems for many in summer. Some lose their appetite while others suffer bouts of diarrhea. Traditional Chinese medicine recommends foods to benefit the digestive system in summer, letting you avoid the problems and giving you a stronger spleen and stomach.

TCM has a lot to say about this zhu xia, or "summer sickness," which arrives in warm weather and departs when it cools down. The main symptom is loss of appetite - and TCM stresses the importance of regular meals.

Prevailing pathogenic dampness in summer is the main external cause of digestive problems, according to TCM. When pathogenic dampness invades, the stomach (digestive system) and spleen (converts food into energy) are usually the first to be attacked and begin to function poorly.

Apart from a poor appetite and indigestion, inflammation in the digestive system can happen easily with a weak spleen. Some foods such as lotus roots, purple haricots (beans) and crucian carp are recommended as they help dispel pathogenic heat and strengthen the spleen and stomach.

There are many other yin ("cold" energy) foods that can help, including tomatoes, apples, pears, watermelon, fungus, cucumber, chrysanthemum, yam, sweet potatoes, pearl barley, millet, mung beans, seaweed and white gourd.

Lisa Chen, a 23-year-old student, says her stomach went "on strike" recently. She doesn't feel like lifting her chopsticks, not even for her favorite fried chicken wings. It happens every summer.

"Whenever the weather gets hot, I started to lose my appetite, and sometimes tire easily," says Chen. "I don't push myself to eat when I have no appetite. My mom says it's no big deal, just zhu xia, which she suffered from for a couple of years.

She's glad to lose weight in the easy, no-will power way, but TCM doctors warn that irregular eating habits undermine the digestion and aggravate existing problems. Lack of nourishment can cause dizziness and fatigue.

Zhu xia is common in warm weather, especially in southern China that has a hot and damp climate, says Dr Zhang Zhenxian, chief physician of the Special Needs Department of Yueyang Hospital.

"Summer sickness is more likely to affect vulnerable people, especially the elderly and children," he says. The most common symptom is loss of appetite; some people feel dizzy, weak, get headaches and feel chest pains. Women are more likely to suffer than men.

Summer sickness does not manifest itself with particular organ problems. It just comes in summer, disappears in fall and may recur in the next summer.

Generally speaking, the main cause is pathogenic heat and damp, which are strong in summer. These pathogenic energies easily "invade" weak people who feel ill when their body cannot adjust to the new hot and damp internal environment.

The spleen and stomach are usually the first to be attacked. Iced or cold drinks aggravate the problem, though they make people feel cool temporarily.

"Sweating is the major way for the human body to dispel internal heat," says Zhang.

"Iced drinks prevent people from sweating, usually leading to accumulation of pathogenic internal heat. "Foods that are 'cold' and reinforce yin energy are not cold in temperature, and are recommended for summer sickness."

Crucian carp

Milky crucian carp soup is one of Chinese's favorite dishes as it is not only delicious but also greatly fortifying. It is a good choice for the weak, the elderly, pregnant women and patients convalescing.

Apart from giving energy to the weak, crucian carp is also effective in improving the digestion. Crucian carp and water shield (a water plant) soup was recommended indigestion and poor appetites in "Tang Bencao" ("Tang Materia Medica"), a pharmacopoeia of the Tang Dynasty (618-907 AD).

TCM believes that "neutral" energy crucian carp can help dispel pathogenic dampness, benefit the spleen, improve appetite, reinforce and activate blood circulation.

Eating it often can help strengthen the digestive system, relieve vomiting and diarrhea, nourish blood and energy, and relieve edema. As well, it is a popular therapy to promote lactation in pregnant women.

There are various ways to cook crucian carp including steaming, frying or cooking with soy sauce. Yet fried crucian carp is the most popular as the nutrition is best absorbed this way.

It is a good choice for most people but not for anyone with a fever. It is best not to eat crucian carp with leaf mustard, honey and mai dong (ophiopogon root).

Purple haricot

Purple haricot is a nutritious food recommended in summer as it also helps relieve various digestive problems. It can help warm the stomach and spleen, dispel pathogenic dampness and heat, relieve diarrhea and thirst as well as summer-sickness, as recorded in "Bencao Gangmu" ("The Compendium of Materia Medica") by the famous herbalist Li Shizhen in the Ming Dynasty (1368-1644).

TCM believes that "neutral" purple haricots can help reinforce energy, dispel pathogenic dampness, benefit the spleen, and relieve summer sickness. They are especially recommended for those with weak digestive systems, or who suffer indigestion, vomiting, poor appetite or acute inflammation in their digestive systems.

Purple haricots are suitable for most people with digestion problems. They can also help relieve pathogenic dampness related to problems like colds, headaches, dizziness, irritation and thirst. They are also recommended for cancer patients as modern research has found them rich in hemaglutinin, which helps fight cancer.

Always remember to cook purple haricots well before eating as raw purple haricots are said to be poisonous. Choose only tender purple haricots as the poisonous matter tends to gather in older haricots. Remember to boil them in water for at least 10 minutes so that the poisonous elements can be naturally neutralized.

Lotus root

Lotus root is high in nutrition yet low in fat. It can be eaten uncooked, steamed, fried or made into soup. The choicest lotus roots are usually available in summer and autumn.

The best have white skins, short yet fat joints and a faint aroma.

The section of the plant next to the top tastes excellent and is the choice for raw servings.

The sections beside it can be good for steamed or fried dishes, while the other parts are best used in soup.

Lotus root has a high medical value whether cooked or not.

According to TCM, uncooked lotus root is a "cold" food that helps dispel pathogenic heat, improves the appetite, promotes fluid, relieves blood stagnation, thirstiness and hang-overs.

Cooked lotus root is "warm" and helps nourish the stomach and spleen, reinforces the heart and blood, soothes nerves and relieves diarrhea.

Lotus root starch is especially recommended for people with digestive problems as it is nutritious and easy to digest.

It can also help improve the appetite by boosting the stomach.

Lotus rhizome node (lotus root's joints) is a "neutral" herb that is widely used to stop bleeding.

The ancient Chinese used to cook brown sugar with six mashed lotus rhizome nodes and drink the soup to cure various bleeding problems.

Uncooked lotus roots with a dressing made of vinegar and sugar are one of the most popular dishes for many Chinese in summer.

The sour and sweet taste helps stimulate the appetite while uncooked lotus root helps activate the digestive system and improve the appetite as well.

It is not necessary to peel the skin before cooking, but avoid using iron or aluminum saucepans to cook lotus roots for a long time lest they cause too much oxidation.

Lotus root juice

Ingredients: Lotus root (500g), pear (500g), chufa (500g), cane (500g) and sheng di (rhizome of rehmannia, 250g)

Preparation: 1. Wash the ingredients.

2. Juice them in a juice machine.

Benefits: Helps nourish the stomach, promotes fluids, and relieves irritation and thirstiness.

Lotus root and celery congee

Ingredients: Lotus roots (250g), celery (50g), rice (500g) and a few ginger slices

Preparation: 1. Wash and slice the ingredients.

2. Make congee.

Benefits: Benefits the spleen, improves the appetite, reinforces the blood and relieves high blood pressure.

Purple haricot, jujube and corn congee

Ingredients: 50 purple haricot beans, corn (150g), 15 jujubes and some brown sugar as needed

Preparation: 1. Cook beans for about 30 minutes.

2. Add other ingredients and make congee.

Benefits: Benefits the spleen, nourishes the blood, dispels pathogenic dampness, and relieves summer sickness.

Turnip crucian carp soup

Ingredients: 1 crucian carp, turnip (200g) and ginger slices

Preparation: 1. Fry the crucian carp slightly, slice turnip.

2. Cook the fish on a medium heat for 10 minutes, then add turnip slices.

3. Cook for another 10-20 minutes until the soup turns milky.

4. Season with salt.

Benefits: Helps warm the stomach and spleen, dispels pathogenic dampness, and improves the appetite.