Lemon juice is considered a healthy drink that boosts immunity and helps fight certain diseases. It is especially popular in alternative medicine because of its supposed alkalizing effect .
What is pH?
pH is a measure of the acidity of a food that takes a value on a scale from 0 to 14. At a value of 7, pH is considered neutral . Any pH below 7 is considered acidic and any value above 7 is considered alkaline .
The pH values show a tenfold difference in acidity . A food that has a pH = 5 is ten times more acidic than a food with a pH = 6 and 100 times more acidic than a food with a pH = 7. Lemon juice has a pH between 2 and 3 , which makes it 10,000 to 100,000 times more acidic than water.
Why is lemon juice considered alkalizing?
Whether food has an acidic or alkaline effect on the body has little to do with its pH before it is digested . Instead, it depends on whether acidic or alkaline by-products are created , after the food is absorbed and processed by the body.
One of the methods for evaluating food by-products is known as ‘ash analysis’. In it, food is burned in a laboratory to simulate what happens during digestion . The p H of the ash is then used to classify foods as acidic or alkaline .
However, this method gives an inaccurate estimate and scientists prefer to use a formula that classifies foods based on the amount of kidney acid that is excreted after the body metabolizes that food.
The kidneys maintain a constant pH of the blood by excreting excess acid or alkali in the urine . Protein, phosphorus and sulfur contained in food increase the amount of acid that the kidneys need to filter . Therefore, meat and cereals , which usually contain these nutrients in the largest quantities, have a positive result for the amount of kidney acid .
Fruits and vegetables are high in alkaline nutrients such as potassium, calcium and magnesium . They eventually reduce the amount of acid that the kidneys will have to filter, and thus get a negative result for the amount of kidney acid.
Like other fruits, lemons produce alkaline by-products after being metabolized. This is why lemon juice is considered alkaline , even though it has an acidic pH before it is absorbed.
Lemon juice alkalizes urine, but not blood
Lemon juice can make the pH of urine more alkaline, but it does not have the same effect on the pH of the blood . In fact, studies show that, in general, the foods we eat have a very limited effect on blood pH.
Researchers estimate that we should eat 8 kg of oranges at a time – which have a similar alkalizing effect to lemons – to increase the pH of our blood by only 0.2 .
Food has a limited effect on the pH of the blood because our body maintains pH levels between 7.35-7.45 for our cells to function properly. When the pH of the blood goes beyond this range , a condition called metabolic acidosis or metabolic alkalosis develops , which can be dangerous and even fatal.
However, this rarely happens because the body has different mechanisms by which it keeps blood pH within normal limits . One of them is to filter the excess acid in the urine through the kidneys.
Other benefits of lemon juice
Although it has a weak alkalizing effect on the blood, regular drinking of lemon juice can help boost immunity .
Lemon juice is high in vitamin C, a powerful antioxidant that helps keep the immune system strong. 30 ml of lemon juice provide 23% of daily needs for vitamin C.
Drinking lemon water during meals helps to better absorb certain minerals , including iron.
Lemon juice can prevent the formation of certain types of kidney stones and contains antioxidants that reduce the risk of heart disease.