The Ming Dynasty physician Li Shizhen said: "People who live by the sea are long-lived because they eat sweet potatoes." Sweet potatoes are rich in nutrition, and the protein they contain complements the protein in rice and flour. They can significantly supplement the lack of vitamin C in flour, calcium in rice, and the deficiency of carotene in both. Mixing sweet potatoes with rice and white flour can improve the nutritional value of staple foods, helping people to live longer.
Substances in sweet potatoes effectively prevent cancer
As is well known, sweet potatoes are very nutritious. However, more remarkably, in the recent "ranking" of 20 anti-cancer vegetables released by the Japanese National Cancer Research Center, sweet potatoes took the top spot.
Cancer cells originate from human epithelial cells, and sweet potatoes are rich in starch, carotene, and more than 10 trace elements such as potassium and iron. These can protect the structural integrity of human epithelial cells, inhibit viral activity, block the production of nitrosamines in the gastrointestinal tract, eliminate toxic effects caused by mercury, cadmium, arsenic, etc., in food or the environment, and interrupt the carcinogenic process of toxic metals. Sweet potatoes are called by experts the most nutritionally balanced health food.
Moreover, sweet potatoes contain a unique dehydroepiandrosterone—a steroid hormone similar to androgen, secreted by the adrenal gland, which can both prevent cancer and prolong life.
In winter, do not eat roasted sweet potatoes with their skin
The hot roasted sweet potatoes of the season are sweet and delicious, some even roasted until "sugar oil" leaks out. The charred skin of the sweet potato is especially popular, and many people eat it along with the skin.
Experts say that it is best not to eat roasted sweet potatoes with their skin, because the skin contains more alkaloids, and excessive consumption can cause gastrointestinal discomfort. Especially the skin of sweet potatoes with black spots should not be eaten, as it can cause poisoning.
When eating sweet potatoes, you must pay attention to the time and method
1. Sweet potatoes should not be eaten raw
Because the cell membranes of the starch in raw sweet potatoes are not broken down by high temperature, it is difficult to digest in the human body. At the same time, when boiling sweet potatoes, the steaming time should be appropriately extended to destroy the "gasifying enzyme" contained in the sweet potatoes, so that you will not experience discomfort such as bloating, heartburn, belching, nausea, or flatulence after eating.
2. It is good to eat sweet potatoes with other foods
If sweet potatoes are eaten with rice and flour, it can also play a complementary role in protein; if you also pair them with pickles or fresh radishes, you can reduce the production of stomach acid.
3. It is best to eat sweet potatoes at noon
This is because the calcium contained in sweet potatoes needs 4 to 5 hours to be absorbed by the body after eating, and the sunlight in the afternoon can promote calcium absorption. In this case, eating sweet potatoes at lunch allows the calcium to be fully absorbed before dinner, without affecting the absorption of calcium from other foods at dinner.
Three conditions must be met for eating sweet potatoes in winter
The first condition is to try not to eat them on an empty stomach. Eating sweet potatoes on an empty stomach increases the chance of acid reflux and heartburn, because sweet potatoes themselves contain relatively high carbohydrates and are somewhat sweet, which increases the possibility of reflux.
The second is that you should not eat more than three *liang* (about 150 grams) of sweet potatoes in a day. And if you have acid reflux, you can split the three *liang* into smaller portions.
The third is not to eat sweet potatoes with overly sweet things. Sweet potatoes are sweet themselves, and if you eat them with other sweet foods, the possibility of reflux doubles. Therefore, sweet potatoes should generally not be eaten with overly sweet foods at the same time.
Which groups of people should not eat sweet potatoes?
Patients with diarrhea and diabetics should not eat sweet potatoes. People with stomach problems should not eat too much to avoid bloating.
What to do if you feel nauseous after eating sweet potatoes?
Sweet potatoes contain a substance called "gasifying enzyme," which produces a large amount of stomach acid in the human stomach and intestines, causing heartburn, nausea, and vomiting of sour water after consumption. Therefore, it is important to master the correct way to eat sweet potatoes, such as eating them with rice and flour, and controlling the portion size at one time; eating sweet potatoes with some pickles or salty soup; cooking them thoroughly to use the steam to destroy most of the gasifying enzyme; or soaking raw sweet potatoes in a solution of a small amount of alkali, alum, or salt water before cooking them.
How to choose good sweet potatoes?
Sweet potatoes with a blackish-brown skin or black spots are contaminated by black spot bacteria. The toxicity of the black spot bacteria can make the sweet potato hard and bitter, and it is highly toxic to the human body. Moreover, this toxin is not easily destroyed by its biological activity whether boiled or roasted, so it must absolutely not be eaten, otherwise the consequences could be disastrous.