How the Alkaline Diet Works

The alkaline diet is an eating plan often used to enhance health. With an emphasis on fresh vegetables and fruits, it's based on the idea that after all foods are digested and absorbed, they reach the kidneys as either acid-forming or base-forming compounds.

Scientists have used various techniques to analyze foods and determine the acid or base load of each food on the body. Researchers Remer and Manz developed a measure called the potential renal acid load (PRAL). Foods such as cheese, meat, fish, shellfish, and grains produce acid after being consumed.

As the charts below indicate, some foods are more acid- or base-producing than others. For example, spinach is more base-forming than watermelon, while cheddar is more highly acid-forming than egg whites.

Proponents of the alkaline diet suggest that a diet high in acid-producing foods disrupts the blood's normal pH level and, in turn, triggers the loss of essential minerals (such as calcium) as the body attempts to restore equilibrium. This imbalance is said to increase susceptibility to illness.

Not only thought to improve health, the alkaline diet is said to preserve muscle mass, slow the aging process and protect against a variety of health problems, ranging from headaches and the common cold to diabetes, cardiovascular disease, kidney stones, and osteoporosis.

Proponents also claim that the alkaline diet can boost energy levels and help with weight loss.

The following foods are commonly recommended as part of the alkaline diet. The table is adapted from the Remer and Manz study. Foods that have a negative value have a base effect.

Foods that are acidic, like lemon juice, can be still base-forming. 

Proponents of the alkaline diet typically suggest avoiding the following foods, which have a positive value and an acid effect. The table is adapted from the Remer and Manz study. 

So far, there's little scientific support for claims that the alkaline diet can promote weight loss and fight disease. However, some research has shown that the diet may offer certain health benefits.

1) Muscle Mass

A study published in the American Journal of Clinical Nutrition in 2008, for instance, found that alkaline diet may help preserve muscle mass as you age (an important factor in preventing falls and fractures). In a three-year-long clinical trial involving 384 men and women (ages 65 and up), the study's authors determined that a high intake of potassium-rich foods (such as the fruits and vegetables recommended as the foundation of the alkaline diet) may help older adults maintain muscle mass as they get older.

In a more recent study (published in Osteoporosis International in 2013), researchers analyzed data on 2,689 women ages 18 to 79 and found a "small but significant" association between adherence to the alkaline diet and maintenance of muscle mass.

2) Diabetes

There's also some evidence that an alkaline diet may protect against diabetes. In a study published in the German journal Diabetologia in 2014, for example, 66,485 women were followed for 14 years. During that time, 1,372 new cases of diabetes had occurred. In their analysis of the participants' food intake, researchers determined that those with the most acid-forming diets had a significantly greater risk of developing diabetes.

The study's authors suggest that a high intake of acid-forming foods may be linked to insulin resistance, an issue closely linked to diabetes.

3) Chronic Kidney Disease

A higher dietary acid load is said to increase metabolic acidosis and increase the risk of kidney disease progression. For a study published in the American Journal of Nephrology in 2015, researchers followed 15,055 people without kidney disease over 21 years (who were part of the Atherosclerosis Risk in Communities study) and found that after adjusting for other factors (like risk factors, caloric intake, and demographics), a higher dietary acid load was associated with a higher risk of developing chronic kidney disease.

Of the individual dietary components, a higher magnesium intake and vegetable sources of protein had the strongest protective association with chronic kidney disease.

4) Cardiovascular Disease

A high acid load diet is associated with higher mortality rates, according to a study published in the Journal of Nutrition in 2016. For the study, researchers used data from the Swedish Mammography Cohort and the Cohort and Swedish Men, which included 36,740 women and 44,957 men at the start of a 15 year follow-up period. In both men and women, there were higher mortality rates in those who consumed either a high dietary or alkaline load diet compared to those who consumed an acid-base balanced diet.

A study published in Cardiovascular Diabetology in 2016 found that people with the highest PRAL had a significant increase in atherosclerotic cardiovascular disease and tended to belong to the high-risk group compared with those with the lowest PRAL scores.

5) Fracture Risk

Although some research suggests that an alkaline diet may decrease fracture risk, a 2015 study published in Osteoporosis International followed 861 70-year-old men and women and found that dietary acid load had no significant associations with bone mineral density or with the diagnosis of osteoporosis. 

If you have a health condition (such as kidney disease or cancer), be sure to consult your care provider before making any change to your diet. Additionally, people on medications that affect the body's levels of calcium, potassium, or other minerals should check with their doctor before trying the alkaline diet.

Following the alkaline food lists too strictly without considering other factors (like protein or overall caloric intake) can lead to health problems like protein or nutrient deficiency or excessive weight loss.

There are some products marketed as "alkaline water" or alkaline forming products. The safety of such products isn't known.

Although an alkaline diet shouldn't be used in place of standard treatment for any health condition, adopting a plant-based diet rich in fruits and vegetables may help you achieve overall wellness and protect against certain diseases.

There are plenty of foods on the acid-forming list (like grains, beans, nuts) that have positive attributes and there are foods on the base forming list (like coffee and wine) that should only be consumed in moderation. Rather than viewing the food lists as "foods to eat" and "foods to avoid" lists, think of the acid and base forming foods on a continuum and strive for a balanced diet.