Acid or alkaline, how does it work?

Lemon juice is said to be a healthy drink with possible beneficial properties. It is particularly popular in the alternative health community due to its purported alkalizing effects. However, lemon juice has an unequivocally low pH and should therefore be considered acidic, not alkaline. This article examines why some people find lemon juice to be alkalizing, despite its acidic pH, and what this means for your body.

What is pH?

When talking about acidic or alkalizing foods, it is important to understand the concept of pH. Simply put, pH is a measure of the acidity or alkalinity of a solution on a scale of 0 to 14. A pH of 7 is considered neutral. Any pH value below 7 is considered acidic, and any pH value above 7 is considered alkaline. On the pH scale, the difference between two adjacent numbers represents a tenfold difference in acidity. For example, a pH of 5 is 10 times more acidic than a pH of 6 and 100 times more acidic than a pH of 7.

Because they contain a large amount of citric acid, lemons have an acidic pH. Lemon juice has a pH between 2 and 3, which means that it is 10,000 to 100,000 times more acidic than water.

The purported benefits of alkalizing foods

The alkaline diet has gained popularity in recent years. It is based on the principle that the foods you eat can alter the pH of your body. To set the record straight, there is no evidence to support the alkaline diet. According to research, the foods you eat have very little effect on the pH of your blood.

However, the alkaline diet classifies foods into three groups:

Acidifying foods: meat, poultry, fish, dairy products, eggs and alcohol.
Neutral foods: natural fats, starches and sugars.
Alkalizing foods: fruits, nuts, legumes and vegetables.
Proponents of this diet believe that eating large amounts of acid-forming foods can make your body’s pH more acidic, increasing your susceptibility to disease.

For example, many believe that your body steals alkaline calcium from your bones to offset the acidifying effects of the foods you eat. Some also believe that cancer only develops in acidic environments and that you can prevent or even cure it by following an alkaline diet. Followers of this diet therefore try to improve their health and reduce their risk of disease by limiting acidifying foods and favoring alkalizing foods.

Why is lemon juice considered alkalizing despite its acidic pH?

Whether a food has an acidic or alkaline effect on the body has little to do with the pH of that food before it is digested. Rather, it depends on whether acidic or alkaline byproducts are created after your body digests and processes food. One method of estimating what type of by-product a food will produce is the “ash analysis” technique. In this method, food is burned in the laboratory to simulate digestion. The pH of its ashes is used to classify foods as acidic or alkaline. Ash analysis is the reason foods are sometimes said to produce acid or alkaline “ash.” However, because ash analysis is an imprecise estimate, scientists now prefer to use a different formula that classifies foods based on their potential renal acid load (PRAL). The PRAL of a particular food is the amount of acid expected to reach the kidneys after the body has metabolized that food.

In general, the kidneys keep the pH of the blood constant by removing excess acid or alkali through the urine. Acidic nutrients like protein, phosphorus, and sulfur increase the amount of acid the kidneys have to filter. Meats and grains, which tend to contain these nutrients, receive a positive PRAL score. On the contrary, fruits and vegetables are rich in alkaline nutrients such as potassium, calcium and magnesium. These reduce the amount of acid the kidneys have to filter and therefore give you a negative PRAL score.

Like other fruits, lemon juice produces alkaline byproducts once it has been metabolized. Therefore, it has a negative PRAL score. This is why some people consider lemon juice to be alkaline, even though it has an acidic pH before being digested.

Lemon juice can alkalinize urine but not blood.

Many advocates of the alkaline diet use pH test strips to check the alkalinity of urine. They think it helps them determine how alkaline your body really is.
What they don’t realize is that while lemon juice can make urine pH more alkaline, it doesn’t have the same effect on blood pH.

According to research reviews published in 2013 and 2012, the foods you eat have a very limited effect on your blood pH. Some much older studies have estimated that you would need to eat the equivalent of 8kg of oranges, which have alkalizing potential similar to lemons, in one sitting to raise your blood pH by just 0.2.

Foods have such limited effects on your blood pH because your body needs to maintain pH levels between 7.35 and 7.45 for your cells to function properly. If your blood pH values ​​are outside this range, you have a condition called metabolic acidosis or alkalosis, which can be very dangerous if left untreated. However, this rarely happens because your body is very good at keeping your blood pH values ​​from falling outside the normal range. One of the ways to keep levels constant is to use the kidneys to filter out excess acids in the urine.

This is why your urine may become more acidic a few hours after eating a large steak, or less acidic after eating a diet high in alkalizing foods. However, while the acidity of your urine can vary depending on the foods you eat, the pH of your blood remains constant. So while drinking lemon juice can make urine more alkaline, it’s unlikely to have an effect on blood pH.

Does the pH of food matter?

Proponents of the alkaline diet seem to believe that the foods you eat can affect your health by influencing the pH of your blood. They generally claim that alkalizing foods prevent bone loss and may prevent cancer. However, as discussed above, this theory completely ignores the role the kidneys play in regulating the pH of the blood, among other methods the body uses to maintain pH.

Also, contrary to popular belief, many major reviews have concluded that acid-forming diets have no impact on calcium levels in the body. In fact, several studies link diets rich in protein, which is thought to be acidifying, with healthier bones.

As for the effects that some people believe acidifying foods have on cancer, studies show that there is no direct relationship between the amount of acidifying foods you eat and your risk of developing the disease. However, an alkaline diet may have health benefits for some people. For example, people with kidney disease generally need to limit their protein intake. Eating an alkaline diet may slightly reduce this need.

It can also reduce the risk of kidney stones in people who are prone to developing them. However, more research is needed on these purported benefits before strong conclusions can be drawn.

Other benefits of lemon juice

Although it has very little alkalizing effect on the blood, regular consumption of lemon juice can have a number of other beneficial health effects. For example, lemon juice is rich in vitamin C, a powerful antioxidant that helps keep the immune system strong and helps prevent and fight disease. 30 ml of lemon juice covers around 13% of the daily needs of vitamin C.

Also, drinking a beverage rich in vitamin C, such as lemon water, with meals can help increase the absorption of certain minerals, including iron. Lemon juice also contains small amounts of antioxidants that can help reduce the risk of heart disease by strengthening blood vessels, reducing inflammation, and preventing plaque buildup. Additionally, some research suggests that regular consumption of lemon juice may help prevent the formation of certain types of kidney stones.

In summary

Lemon juice has an acidic pH before being digested. However, once metabolized by the body, it produces alkaline by-products. These alkaline byproducts can make the urine more alkaline, but they have little effect on the pH of the blood. Therefore, it is unlikely that any health benefits lemon juice may offer come from its purported alkalizing effect.

* Presse Santé strives to transmit health knowledge in a language accessible to all. In NO CASE, the information provided can not replace the advice of a health professional.

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