Key facts about alkaline food

Our bodies are always working to regulate their acid-base balance. Is an alkaline diet an essential part of that process?


Lara Brunner

What are alkalising and acidifying foods?

Foods that are acidic are not necessarily acid-forming when digested. Lemon juice has a pH value of 2.4, for example. However, it puts a limited acid load on the kidney. Lemon juice therefore functions as alkaline-forming in the body. The acid load is calculated using the PRAL value – more about this later in the blog post.

The nutrition pyramid contains both alkaline and acid-forming foods. Cereals are acid-forming foods and protein-rich foods are particularly acidic. There is a direct correlation between the quantity of sulphur-containing amino acids and phosphorus and acidity. Green vegetables, fruit and salad are the main source of alkalines. Eating a balance diet as defined in the Swiss food pyramid enables your body's buffer systems to maintain a healthy acid-base balance.

How do acid and alkaline-forming foods affect the body?

All food that we consume is metabolised. Whether this forms acids or alkalis is calculated using the PRAL factor. PRAL stands for potential renal acid load and indicates the acid load that has to be processed by the kidneys. The higher the value, the greater the acid-forming effect of the food. If the value is negative, the food is alkaline-forming.

Certain parts of the body are alkaline when healthy (connective tissue, lymph nodes, small intestine) and others are acidic (vagina, stomach, large intestine). Our blood, for example, has a pH value of 7.36, which means it is slightly alkaline. The body's efficient buffer systems are constantly working to maintain this value. Even minor changes can be dangerous. Hyperacidity is identified by a blood gas test.

Alkalines are simply excreted once they have been metabolised. Acids have to be neutralised first. If the body doesn’t ingest sufficient alkaline minerals to neutralise the acids, it has to plunder its own deposits. Minerals are recruited from bones, teeth, hair roots and vital organs. If this process occurs over a longer period of time, it can cause damage such as tooth decay, hair loss and osteoporosis

Can an alkaline diet prevent hyperacidity?

The acid-base balance is not just influenced by diet – age, stress, alcohol, caffeine, nicotine and too little exercise can also upset the balance.

Experts are divided over whether an alkaline diet is really essential to maintaining a healthy acid-base balance. They do agree that healthy eating is important: lots of fresh fruit and vegetables, not too much meat. Anyone who eats a balanced and varied diet has no need to worry about hyperacidity. The Swiss food pyramid is a good point of reference.

Alkaline-forming foods (PRAL)


  • Dried figs (-18.1)
  • Apricots (-4.8)
  • Lemons (-2.6)


  • Spinach (-14.0)
  • Fennel (-7.9)
  • Rocket (-7.5)


  • Carrot juice (-4.8)
  • Unsweetened orange juice (-2.9)
  • Red wine (-2.4)


  • Parsley (-12.0)
  • Basil (-7.3)
  • Chives (-5.3)

Acid-forming foods (PRAL)

Fish and seafood

  • Shrimp (18.2)
  • Prawns (15.5)
  • Mussels (15.3)

Meats and sausages

  • Calf's liver (14.2)
  • Salami (11.6)
  • Turkey (9.9)

Bread and pasta

  • Wholemeal spaghetti (7.3)
  • Melba toast (5.9)
  • White bread (3.7)

Milk, dairy products and eggs

  • Parmesan (34.2)
  • Quark/fromage frais (11.1)
  • Hen's eggs (8.2)


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