HEALTH has become such a trendy topic that it’s no surprise rumors about what we should and shouldn’t eat are rife on social media. Is it true, for instance, that leftovers stored overnight in the refrigerator can cause cancer?

A list of the 10 “most popular” health-related rumors in 2015, released earlier this month by the Beijing Internet Information Office and the Beijing Association of Science and Technology, shows the public’s preoccupation and misconceptions about daily diet.

The list includes some concepts that have come to be generally accepted facts and some that have their roots in traditional Chinese medicine. The list was compiled based on research on topics on the platform “Baidu Knows.”

Heading the list is the concept that some foods shouldn’t be paired with others, or the combination will create health problems and even poison the body. For example, in traditional Chinese medicine, eating crab and persimmon together is said to cause serious diarrhea, and eating watermelon right after eating mutton will damage the yang energy in the human body. Eating snails with beef, mutton or corn is a no-no said to cause hair loss, while eating pig’s liver with tofu or fish supposedly harms the heart.

Another of the top 10 rumors holds that people who want to lose weight should skip all eating after lunch.

About 80 percent of the online followers of such rumors are aged 25-36 ­­— the generation most reliant on information gleaned from the Internet. Some 40 percent of them have university degrees, the report said.

It is not that surprising to see so many well-educated young people hooked on rumors since these sorts of health issues are so well-presented online, said Jiang Zaifeng, a registered traditional Chinese medicine doctor based in Hong Kong.

“We can’t unequivocally state that each rumor is completely true or false,” he said. “There are sometimes grains of truth wildly exaggerated.”

“Since childhood, I was always been warned not to eat persimmon together with hairy crab,” said Kathy Qiao, 31. “My mother could never explain the reason but she insisted on following the rules because she said they were common sense known by everybody. So I believed it.”

David Jiang, 29, said he’s not persuaded that some foods make bad bedfellows. He said he has often broken the “rules” and had no adverse effects.

“Online, there are long lists of what you shouldn’t eat with what,” he said. “I remember one warning that eating duck and chestnuts together would poison the body. Yet my mother often added chestnuts to stewed duck with soybean sauce in winter. We never had any problems. I am not saying these lists are complete nonsense, but you need to take them with a grain of salt.”

Separating fact from fiction is indeed difficult because there are so many variables that affect how individual bodies react to different foods. In some cases, even the scientific community cannot agree on dietary issues.

To try to provide some clarity, Dr Jiang offered the following comments on the 10 most popular rumors.

Rumor No. 1:

People will poison themselves if they eat foods that have conflicting effects on the body.

7.8 million online followers

Comment: The rumor is based on the theory that certain traditional Chinese medicinal herbs cannot be prescribed together because they counteract one another. The rumor gained traction after the Chinese movie “Deadly Delicious” featured a wife killing her husband by feeding him foods that weren’t supposed to be eaten together.

In fact, the chemical compositions of certain foods can interact adversely when taken together, but those cases are rare and aren’t significant enough to cause public concern.

Rumor No. 2:

You will lose weight in a healthy manner if you stop eating all foods after lunch.

5.8 million followers

Comment: This is a concept rooted in ancient China, when people rose with the sun, went to bed at sunset and often had meager food rations. It is not good medical advice for modern-day people who are active into the late evening.

On an empty stomach for long periods, two hormones that hold the key to appetite and weight loss will become out-of-whack. Ghrelin, which is responsible for increasing appetite, gastric acid secretion and digestion, will increase quickly, while leptin, which helps control appetite and restrains formation of fat cells, will largely decline. The combination of these factors is likely to cause weight gain, not loss.

Rumor No. 3:

A normal person will have 3-6 kilograms of fecal matter in their intestines, while fat people suffering constipation will have 7-11 kilograms.

3.89 million followers

Comment: It is impossible for anyone to have as much as 6 kilograms of stool in the intestines, even if all foods eaten within one day are not absorbed. The intestines report to the brain when a certain volume of stool has accumulated in the bowels and should be evacuated.

It is healthy and normal for people to have bowel movements at least once every three days. Unnecessary laxative use can cause imbalance of beneficial intestinal flora.

Rumor No. 4:

Eating dishes that were refrigerated overnight can cause cancer because of a buildup of nitrites.

2.76 million followers

Comment: Research shows that nitrite content will increase only between 3-7 milligrams per kilogram when a dish is stored in a refrigerator overnight, which is far beneath national standards banning more than 30-70 milligrams of nitrite in processed meat products.

The causes of cancer are complicated. It is irrational to directly link limited amounts of nitrite in food to cancer.

Rumor No. 5:

Eating processed meat products causes cancer.

1.95 million followers

Comment: It is true that processed meat products are listed as Class A carcinogens by the World Health Organization, but it still depends on the intake quantity.

Rumor No. 6:

Milk sterilized at very high temperatures can be preserved longer but is far less nutritious than standard milk.

1.74 million followers

Comment: It is true that some vitamin content in milk is damaged under high temperatures, but highly nutritious calcium and protein aren’t affected.

Rumor No. 7:

Residue of acetochlor in market strawberries causes cancer.

1.33 million followers

Comment: The herbicide acetochlor is not commonly used in strawberry cultivation. The national standard for acetochlor residue in food is strict. Only very limited amounts of the residue are permitted in crops like rice, corn, soybeans, peanuts and rapeseed. Acetochlor has never been officially listed as a suspected carcinogen.

Rumor No. 8:

Eating alkaline foods helps prevent and fight cancer.

1.22 million followers

Comment: Alkaline foods, or those with low acidity, include such common commodities as vegetables, fruits and beans, while those on the acidity list include meat, fish, cheese and eggs.

Alkaline foods are beneficial to health, but the body needs nutritional balance also provided by acidic foods. Again, the causes of cancer are complicated. There is no concrete evidence that acidity or alkalinity in foods leads to cancer.

Rumor No. 9:

Food additives are detrimental to health.

1.1 million followers

Comment: Standard additives used to preserve or flavor foods won’t damage health as long as they are used in legally permitted quantities. Many food safety scandals have been caused by illegal practices involving dangerous additives or additives used in the wrong quantities.

Rumor No. 10:

Eating lychee sterilized with formalin causes hand, foot and mouth disease.

590,000 followers

Comment: Formalin is a water solution of the gas formaldehyde. According to national agricultural standards, lychee can be soaked in certain antiseptic solutions, but formalin is not one of them. Hand, foot and mouth disease is an infectious disease caused by virus in the intestines. It is spread through bodily secretions but not by formalin or any antiseptics.