The "body acid-base theory" has been falsified, so is it still meaningful to talk about the "acidity and alkalinity" of food?

Author: Cui Yihui, registered dietitian

Reviewer: Wang Junbo, Associate Professor and Doctoral Supervisor, Peking University Health Science Center

There is such a news that the San Diego court in California, USA, ruled that Robert O. Young, the founder of the "acid-base body theory", should compensate a cancer patient with 105 million US dollars. This time, the pseudoscience of the "acid-base body theory" was completely exposed and overturned. So, people are more or less confused! Since the body constitution is not divided into acid and alkaline, does the food we eat every day still have to be divided into acid and alkaline? Is there any meaning in classifying the acidity and alkalinity of food?

First of all, we need to clarify a concept. For any kind of food, after being metabolized by the human body, whether its final metabolite is acidic or alkaline has nothing to do with the sour, salty, or sweet taste we experience on the tip of the tongue. According to the acidity and alkalinity of the final metabolites of food in the human body, we divide food into two categories: acidic food and alkaline food. You may ask, "The theory of body acid-base has been proven to be pseudoscience, so it doesn't make much sense to classify food into acidity and alkalinity. Since the human body has a strong self-regulating ability, even if we eat a lot of fish and meat and almost no vegetables and fruits, it will not make our blood acidic, right?" Indeed, our body is very "smart". In order to maintain the stability of the internal environment of the body, especially the pH of the blood, it is stable at 7.35-7.45, which belongs to the weak alkaline range. Because once the internal environment of the body is destroyed and the pH of the blood changes, life will be directly threatened.

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Just like the theory of "acid-base constitution theory" that "eating acidic food will make the blood (constitution) acidic", it really underestimates our body's ability to regulate itself, and it is not true. However, we should not go to the other extreme just because the "acidity and alkalinity of constitution" is denied today - ignore the acidity and alkalinity of food, eat whatever we like and want at will, "heavy" fish and meat, fine staple food/processed food, and "light" on the intake of fruits and vegetables. This is an unhealthy eating pattern. Because if the proportion of acidic food in the three meals a day is large, the body will have to work hard to maintain the homeostasis of the internal environment and the acid-base balance of the blood. For the body, this is the so-called "acid load".

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In the short term, acid load will not cause the body's internal environment to become acidic, but in the long run, it will increase the body's regulatory burden. In order to neutralize the excessive acid ions produced by food metabolism, the body will mobilize calcium in the bones (the bones are the body's "calcium store") and excrete it with the acid ions in the urine. A deficit in the "calcium store" will promote the occurrence of osteoporosis. Of course, acid load not only affects the "calcium store" of the bones, but also affects the inventory of other micronutrient warehouses in the body, causing unnecessary "internal consumption", thereby bringing more health risks. Therefore, the acidity and alkalinity of the body does not exist, but the acidity and alkalinity of food cannot be ignored. The risk of "acid load" brought about by excessive selection of acidic foods should still be given enough attention. Yes, although the acid-base theory of the body has been denied, it is still very important to choose what food to eat.