Food Health：Getting Alkaline Foods Right

　　Food is divided into acid and alkaline, and generally speaking, plant-based foods are alkaline foods. Human body fluids also have different levels of acidity and alkalinity, but the human body has a sophisticated regulatory system and generally does not change much. The acidity or alkalinity of food has a minimal effect on the pH of human body fluids. Therefore, alkaline foods are not necessarily healthier. A healthy diet should include a variety of foods and balanced nutrition.

　　Do alkaline foods really exist? Foods do have acidity and alkalinity. In the ashes left after burning food, if they contain more phosphorus, sulphur and chlorine elements, they can produce an acidic solution when dissolved in water; if the ashes contain more potassium, sodium, calcium and magnesium elements, they can produce an alkaline solution when dissolved in water, which is the claim of the origin of food acidity and alkalinity.

　　Generally speaking, high-protein foods such as meat and eggs and high-starch foods such as rice and noodles contain more elements such as sulphur and phosphorus, which produce acidic substances after metabolism; while foods such as vegetables, fruits and milk contain more minerals such as potassium and calcium, and the metabolites are more alkaline. Therefore, most vegetables and fruits are alkaline foods, while most meats are acidic.

　　Is the human body acidic or alkaline? The human body has many body fluids, including intracellular fluid, blood, lymphatic fluid, digestive fluid (saliva, gastric fluid, intestinal fluid and bile, etc.), urine or sweat. These fluids do have different pH levels, for example, gastric fluid is acidic (pH 1.0-2.0); urine is weakly acidic (pH 5.0-7.0); and intestinal fluid is alkaline (pH 7.55-8.55). In contrast, the pH of human blood is generally 7.35-7.45.

　　There is no such thing as an "acidic" or "alkaline" body in medicine. Moreover, the human body has a stable system to maintain the acid-base balance - the acid-base buffer system - which automatically regulates the pH level in the body and usually maintains it within a stable range. For example, in human blood, if the pH of a person's blood falls below 7.35, acidosis may be occurring.

　　Does the acidity of food affect the acidity of the body? The body's pH level does not change significantly depending on the food you eat. The body will automatically adjust and repair itself whether you eat acidic or alkaline foods. Moreover, whether it is acidic or alkaline food, a little bit of acidity or alkalinity may have very little effect compared to the human body.

　　Therefore, for a healthy adult, the effect of the "acidity" of food on the body is almost negligible.

　　Are alkaline foods healthier? Many businesses claim that alkaline foods are healthier and can fight cancer. In fact, there is no scientific basis for these claims.

　　The effect of dietary intake on the body's acidity and alkalinity is actually very small. Although all kinds of fruits and vegetables are generally alkaline, eating more fruits and vegetables is healthy because of the nutrients they contain, such as vitamins, minerals and dietary fibre, but it does not mean that alkaline foods are healthier than other foods.