Sweet potatoes are rich in nutrients. According to measurements, every kilogram of sweet potato contains 290 grams of sugar, 23 grams of protein, 5 grams of crude fiber, and 2 grams of fat. They also contain a variety of vitamins and minerals. The vitamin content is comparable to that of citrus fruits, especially yellow-fleshed sweet potatoes, which contain 52 milligrams of carotene per 100 grams. Sweet potatoes can supply the body with a large amount of energy; 1 kilogram of sweet potato can produce 5317 kilojoules of heat, while 1 kilogram of white flour or rice produces only 14779 kilojoules. More remarkably, the protein in sweet potatoes complements the protein in rice and flour, significantly supplementing the lack of vitamin C in flour, calcium in rice, and the deficiency of carotene in both. Eating sweet potatoes mixed with rice and white flour can improve the nutritional value of staple foods and help people live longer.
Li Shizhen, a physician of the Ming Dynasty, said: "People in the sea live long, and it is because they eat sweet potatoes."
Substances in sweet potatoes effectively prevent cancer
As is well known, sweet potatoes are very nutritious. However, more valuable is that 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 come 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 virus activity, block the production of nitrosamines in the gastrointestinal tract, eliminate the toxic effects caused by mercury, cadmium, arsenic, etc., in food or the environment, and block the carcinogenic process of toxic metals. Sweet potatoes are called by experts the most balanced health food.
And the unique dehydroepiandrosterone in sweet potatoes—a steroid hormone similar to androgen, secreted by the adrenal gland—can both prevent cancer and prolong life.
Note! There are many considerations for eating sweet potatoes in winter
Don't eat sweet potato skins
The hot roasted sweet potatoes of the moment are sweet and delicious, some even roasted until "sugar oil" drips out. The charred skin of the sweet potato is also very popular, and many people eat it along with the skin.
Experts say it's best not to eat the skin of roasted sweet potatoes because the skin contains more alkaloids, and eating too much can cause gastrointestinal discomfort. Especially the skin of sweet potatoes with black spots should not be eaten, as it can cause poisoning.
Eating sweet potatoes must pay attention to time and method
1. Sweet potatoes should not be eaten raw
Because the cell membranes of the starch in raw sweet potatoes are not destroyed by high temperature, it is difficult to digest in the human body. At the same time, when cooking sweet potatoes, the steaming time should be appropriately extended to destroy the "gasification enzyme" contained in the sweet potatoes, so that you will not experience discomfort such as bloating, heartburn, belching, nausea, and gas after eating.
2. It's good to eat sweet potatoes with other foods
If you eat sweet potatoes with rice and flour, it can also play a complementary role in protein; if you also eat them with some pickles or fresh radishes, you can reduce the production of stomach acid.
3. It's 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 human body, and the sunlight in the afternoon can promote the absorption of calcium. 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.
To eat sweet potatoes, 3 conditions must be met
1. Try not to eat sweet potatoes 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, increasing the possibility of reflux.
2. It's best not to eat more than three taels (150 grams) of sweet potatoes a day
Moreover, if you have acid reflux, you can split the three taels into several meals.
3. Don't eat sweet potatoes with overly sweet things
Sweet potatoes are sweet themselves. If you eat them with other sweet foods at the same time, the possibility of reflux doubles. Therefore, try not to eat sweet potatoes 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.
Middle-aged and elderly people can eat sweet potato buns in moderation
Everyone has eaten buns, but you may not have eaten sweet potato buns made from sweet potatoes. This kind of bun is much more delicious than a white flour bun and is especially suitable for middle-aged and elderly people.
The method for making sweet potato buns is very simple. First, wash the sweet potatoes you bought, peel them, and steam (or boil) them until cooked. Then, mash them thoroughly, add an equal amount of flour and a certain amount of water, and mix well. In summer and autumn, the mixed dough will naturally ferment in about half a day. At this point, you can steam it according to the usual method for making steamed buns. When the temperature is low, you can add yeast or fermented dough to the dough to help it ferment.
A notable feature of sweet potato buns is that they have a slight sweetness without adding sugar, making them delicious. Sweet potato buns are good for digestion and absorption and have a laxative effect. From a nutritional point of view, every 100 grams of sweet potato contains 0.9 grams of protein, 0.5 grams of crude fiber, 77 milligrams of calcium, and various amino acids such as valine, leucine, isoleucine, threonine, phenylalanine, lysine, and tryptophan. These nutrients are exactly what middle-aged and elderly people need.
Tip 1: What to do if you feel nauseous after eating sweet potatoes?
Sweet potatoes contain a substance called "gasification enzyme," which produces a large amount of stomach acid in the human stomach and intestines, causing heartburn, nausea, and vomiting of acid water after eating. Therefore, it is important to master the correct way to eat sweet potatoes, such as eating them with rice and flour, and controlling the amount eaten at one time; eating them with pickles or salty soup; cooking them thoroughly to steam and destroy most of the gasification enzyme; or soaking raw sweet potatoes in a small amount of alkali, alum, or salt water solution before cooking them into a finished dish.
Tip 2: How to choose good sweet potatoes?
Sweet potatoes with a dark brown skin or black spots are contaminated with black spot bacteria. The toxicity of black spot bacteria can make sweet potatoes hard and bitter, and are highly toxic to the human body. Moreover, this toxin is not easily destroyed by boiling or roasting, so it must never be eaten, otherwise the consequences could be unthinkable.