Acidic Foods and Alkaline Foods
In nutrition, foods are generally classified into two categories: acidic foods and alkaline foods. The acidity or alkalinity of a food is not related to its own pH value, but is primarily determined by the substance it becomes in the human body after digestion, absorption, and metabolism. Foods that produce acidic substances are called acidic foods, such as animal organs, muscles, and plant seeds (grains). Foods that produce alkaline substances are called alkaline foods, such as vegetables, melons, beans, and tea.
What are acidic foods?
Animal organs, muscles, fat, protein, and grains contain relatively high levels of sulfur (S), phosphorus (P), and chlorine (Cl) elements. After metabolism in the human body, they produce substances like sulfuric acid, hydrochloric acid, phosphoric acid, and lactic acid, which are the sources of acidic substances in the body.
What are alkaline foods?
Most vegetables, fruits, seaweed, beans, and dairy products contain relatively high levels of calcium (Ca), potassium (K), sodium (Na), and magnesium (Mg) elements, which can become alkaline substances after metabolism in the body.
Fruits, though sour, are alkaline foods
Fruits contain various organic acids, making them taste sour, but after digestion, most are oxidized into alkaline foods. An exception is citric acid, which increases the acidity of body fluids and is considered an acidic food. The organic acids mainly found in vegetables are malic acid, citric acid, tartaric acid, and oxalic acid.
Special attention should be paid to oxalic acid here. Its organic compounds are not easily oxidized. The calcium oxalate formed with calcium salts is insoluble in water and accumulates in the kidneys, affecting calcium absorption. Vegetables such as tomatoes, potatoes, and spinach contain oxalic acid. Theoretically, alkalosis can also occur, but it is uncommon in humans because the large amount of gastric acid can neutralize it.
Excessive consumption of acidic foods leads to acidosis
If acidic foods are consumed excessively to the point that they cannot be neutralized, it leads to an acidic state, consuming alkaline elements such as calcium, potassium, magnesium, and sodium. This can cause the blood to darken, increase its viscosity and blood pressure, leading to acidosis.
What are the symptoms of acidosis?
In young people, it can induce skin diseases, neurasthenia, excessive stomach acid, constipation, and cavities. In middle-aged and elderly people, it is prone to cause hypertension, arteriosclerosis, cerebral hemorrhage, and stomach ulcers. Since acidosis is caused by excessive consumption of acidic foods, one should not be a picky eater. Instead, one should eat more vegetables and fruits to maintain the body's acid-base balance.