Does eating raw vegetables hinder digestion?
Many people are confused about the issue of eating raw versus cooked food. According to Western concepts, when vegetables and fruits are eaten raw, one can make use of the large amount of active enzymes they contain, such as amylase and proteases, which can break down starch and protein, thus aiding digestion. Not eating raw food can easily lead to indigestion. But what about according to traditional Chinese concepts? The advice is the exact opposite: food must be eaten hot, as raw and cold vegetables can harm the stomach and gradually weaken its digestive capacity... Indeed, Chinese people are accustomed to drinking hot water, and many places have the custom of eating hot food, even accompanied by hot soup to aid digestion. So, who is right?
Is it necessary to eat vegetables raw to digest them properly?
Let's first talk about these enzymes. Are the enzymes in raw vegetables really that important for us, and is it necessary to eat them raw to digest properly?
First, vegetables and fruits contain a wide variety of enzymes, not just those that help human digestion. There are also enzymes that are not conducive to the preservation and utilization of nutrients, such as oxidases that cause vitamin C and polyphenols to oxidize. Keeping all of them "alive" may not be ideal.
Secondly, one of the characteristics of enzymes is their strict requirement for reaction conditions, including temperature, pH, and ionic strength. The enzymes in raw vegetables are most active under the vegetable's own acid-base conditions, but this may not be the case in the human body. For example, the pH of a healthy person's stomach after a meal is between 2 and 3.5, a condition that is completely unsuitable for the various enzymes in vegetables, as the general pH of vegetables is between 4 and 6.
Therefore, for people with normal digestive capabilities, the enzymes in vegetables and fruits have very low activity at a pH below 3 and play little role in aiding digestion. Only for those with insufficient gastric juice and poor digestion might the enzymes in fruits and vegetables play a role to a certain extent. For example, patients with atrophic gastritis may have a pH value as high as 5 or more in the stomach due to a lack of gastric acid secretion, at which point the enzymes in fruits and vegetables can remain active.
What are the foods that truly aid digestion?
The foods that are truly effective for aiding digestion are, more than raw vegetables and fruits, fermented foods. For example, unheated yogurt, fermented tofu, sweet fermented rice, and douchi. This is because during the fermentation process, enzymes from microorganisms have already done the work of "pre-digestion" for the human body, breaking down proteins into small pieces and partially hydrolyzing starch.
Thus, for people with poor digestion, fermented foods can indeed be of great help. Moreover, the proteases, amylases, etc., secreted by microorganisms are often more heat-resistant, acid-resistant, and more active than those in vegetables and fruits, making them more effective.
Therefore, while eating raw vegetables may reduce the loss of vitamins and anti-cancer components and increase satiety through thorough chewing, it may not play a significant role in promoting digestion, except for a few vegetable varieties with exceptionally high enzyme activity.
Is it better to eat vegetables cooked?
On the other hand, let's discuss whether the human body necessarily needs to eat hot food.
Eating a small amount of raw vegetables may not have a significant impact on digestion and absorption. However, eating a large amount might have a different effect. This is because the body's own digestive enzymes are most active at body temperature of 37°C. If a large amount of cold vegetables and fruits are eaten, and the food cannot be "warmed up" to body temperature in time, the temperature in the stomach will drop significantly, blood circulation in the stomach will decrease, and the motility will slow down. Consequently, the activity of digestive enzymes will also be reduced. In other words, it may hinder the function of digestion and absorption. In a sense, this might be the very reason behind the traditional health advice.
However, this advice also varies from person to person. If a person is strong, has good blood circulation, and a strong ability to generate heat, they can increase enzyme activity by accelerating blood circulation in the stomach. If a person is naturally weak, cold-intolerant, with poor blood circulation and a weak ability to generate heat, eating a lot of raw and cold food can easily cause discomfort like bloating and abdominal distension. The reason why postpartum women should not eat raw and cold food is precisely this.
Who is suitable for eating raw vegetables?
Raw vegetables contain a lot of unsoftened fiber, which can be irritating to the digestive tract. Therefore, people prone to constipation are suitable for eating more raw vegetables, while those who are prone to diarrhea should avoid eating large amounts of them. Therefore, whether eating raw vegetables is detrimental to digestion and absorption, or even whether one should eat them at all, does not require a one-size-fits-all conclusion. Everyone should act according to their own capacity and let their own body be the guide.
If you feel refreshed and comfortable after eating raw vegetables, then by all means, eat more of them. If, on the contrary, you experience gastrointestinal discomfort, there is no need to force yourself. In fact, this is true for many nutritional claims.
Is eating raw eggplant healthy or toxic?
Removing oil? The idea that eating raw eggplant removes oil is not very scientifically accurate. Eggplant absorbs oil when cooked at high temperatures. If you place eggplant at 37°C, even if you soak it in oil, it cannot absorb nearly as much as it does when fried—and our gastrointestinal temperature is 37°C, not 180°C for stir-frying.
Controlling blood pressure? Eggplant does contain substances that help control blood pressure and inhibit cancer, mainly solanine. This toxin can be used medicinally for its antibacterial, blood pressure-lowering, heart-strengthening, and cancer cell apoptosis-promoting properties. For a stronger effect, green and sprouting potatoes might be better. However, please note that this is a toxin and should not be consumed indiscriminately.
Someone asked: If eggplant is heated and steamed, is the solanine still there? Will it affect its efficacy? There's no need to worry. Solanine is extracted using a method of heating under reflux, which shows that it is quite stable at 100°C.
In fact, the key is not whether it is eaten raw, but to use less oil and avoid high-temperature frying during cooking. Steaming or boiling at 100°C does not destroy too many antioxidant substances; some studies even suggest that pressure cooking at 108°C can better preserve certain antioxidant components in food. However, stir-frying temperatures reach over 160°C, and cooking temperatures in many homes that produce a lot of smoke can be as high as 200°C or more. A study in Japan once confirmed that vegetables cooked at excessively high temperatures not only lose their anti-cancer properties but can even promote the action of carcinogens.
Is it best to eat eggs "half-cooked"?
The best way to eat an egg is when the white is set and the yolk is semi-set or runny. This ensures good digestibility and absorption while minimizing nutrient loss.
The main reason for advocating cooked eggs is the fear of contamination. Considering that Salmonella contamination is not generally severe, and most people wash their eggs before cracking them, and many supermarket eggs have been surface-sterilized, solving the Salmonella problem, the safety of eggs is not a cause for concern. If you are still worried about Salmonella and avian influenza viruses, it is recommended to cook the eggs to above 85°C until the yolk is completely set, and then you can eat them without worry.
In summary, eating cooked eggs is harmless and does not result in significant nutrient loss. However, it is very unwise to fry eggs until they are dry and burnt, or to take the cooked yolk and stir-fry it again with other ingredients over high heat.
Is it good to eat cooked fruit?
Some might say: Isn't cooking apples a loss of nutrition? What's the point of eating them then? This sounds reasonable, but it's not actually the case. Common fruits like apples, pears, peaches, bananas, and pineapples contain very little vitamin C and even less of the B vitamins. The only heat-sensitive nutrients are these; fat-soluble substances like carotene and lycopene are not destroyed by heating at 100°C, and minerals and dietary fiber are not lost due to heating. Most of the polyphenolic antioxidant substances can also be retained under boiling conditions. As for health benefits like moisturizing, promoting bowel movements, and aiding digestion, eating them cooked is no hindrance at all. If boiling were to completely deactivate the compounds in plants, it would be impossible to explain why traditional Chinese medicine uses boiling to decoct medicinal herbs.
Fruits that are exceptionally rich in vitamin C, such as kiwis, oranges, grapefruits, and strawberries, do not need to be eaten cooked. However, for fruits that are not too high in vitamin C and are relatively heat-tolerant, eating them cooked is a viable option.