What Is the Alkaline Diet?

Alkaline diet

Verywell / Debbie Burkhoff

At Verywell, we believe there is no one-size-fits-all approach to a healthy lifestyle. Successful eating plans need to be individualized and sustainable, taking the whole person and their lifestyle into consideration. Prior to starting a new diet plan, consult with your healthcare provider or a registered dietitian, especially if you have an underlying health condition.

The alkaline diet is an eating plan that emphasizes fresh vegetables and fruits with the aim of maintaining an optimal pH level in the body. It's based on the premise that the food we eat alters the body's pH to be either acidic or alkaline.

This concept was developed during the mid-1800s as the dietary ash hypothesis. It proposed that once metabolized, foods leave an acid or alkaline "ash" (metabolic waste) in the body. According to proponents, the leftover ash directly affects the body's acidity or alkalinity.

The alkaline diet has been used in medical settings to prevent kidney stones and urinary tract infections. However, it is important to note that there is not a lot of science to support many of the purported health benefit claims of this eating plan. The body has many mechanisms to maintain a strict pH, including processes controlled by the lungs and kidneys.

The 2021 U.S. News and World Report Best Diets ranks the alkaline diet number 29 in Best Diets Overall and gives it an overall score of 2.5/5. Its ranking is based on the lack of quality research to support the diet, the many rules that make it difficult to follow, and its ineffectiveness for weight loss.

What Experts Say

"There’s little to no evidence supporting the premise of the alkaline diet. Our bodies do a good enough job on their own keeping our pH in check. There are a lot of rules and many foods that are 'hands-off' are actually healthy, like eggs and whole grains."

Kelly Plowe, MS, RD

What Can You Eat?

The alkaline diet categorizes food groups as either alkaline, neutral, or acidic. People following the diet are instructed to focus on eating lots of alkaline foods and fewer acidic foods.

  • Alkaline: Fruits and vegetables
  • Neutral: Natural fats, starches, and sugars
  • Acidic: Meat, poultry, fish, dairy, eggs, nuts, legumes, grains, and alcohol

Acid levels are measured by pH on a scale of 0 to 14 where the lower numbers represent more acidic compounds, higher numbers are more alkaline (or basic), and 7 is neutral.

What You Need to Know

The alkaline diet does not restrict foods to certain times of the day or require periods of fasting. The idea behind the alkaline diet is to eat more alkaline foods and fewer acidic foods.

Rather than viewing the food lists as "foods to eat" and "foods to avoid," the diet encourages followers to think of the foods on a continuum and strive for a balanced diet.

Some proponents of the diet recommend monitoring your urinary pH by testing the first urine of the day with at-home test strips to know how nutritional changes are affecting your body. Normal urine pH is slightly acidic, with usual values of 6.0 to 7.5, but the normal range is 4.5 to 8.0. 

What to Eat
  • Fruits

  • Vegetables

  • Coffee

  • Red and white wine

  • Lemon and lime juice

What Not to Eat
  • Meat

  • Poultry

  • Fish

  • Dairy

  • Eggs

  • Grains

  • Legumes

The goal of the alkaline diet is simply to eat more alkaline foods and less acidic foods by:

  • Eating more fruits and vegetables
  • Drinking less soda or eliminating it altogether
  • Drinking 64 ounces of mineral water a day 
  • Adding fresh lemon or lime to water (even though citrus fruits are acidic, they have an alkalizing effect within the body)
  • Limiting animal protein to one serving a day 
  • Replacing refined carbohydrates with vegetables; for example, choosing spiralized zucchini or carrots instead of spaghetti or finely chopped cauliflower instead of white rice
  • Drinking alkaline broth (Alkaline broth is an easy-to-make vegetable broth that's packed with vitamins and minerals including potassium.)

Potential Renal Acid Load

Scientists have used various techniques to analyze foods and determine the acid or base load of each food on the body.

On the alkaline diet, foods are measured by their potential renal acid load (PRAL) which was developed by researchers Thomas Remer and Friedrich Manz. On the PRAL scale, 0 is neutral while negative numbers are basic and positive numbers are acidic.

The following PRAL tables are adapted from the study by Remer and Manz and include PRAL levels for many alkaline and acidic foods.

Alkaline Foods
Food Potential Renal Acid Load (PRAL) mEq/100g
Fruit  
Apples -2.2
Apricots -4.8
Black currants -6.5
Lemon juice -2.5
Oranges -2.7
Peaches -2.4
Pears -2.9
Raisins -2.1
Strawberries -2.2
Watermelon -1.9
   
Vegetables  
Asparagus -0.4
Broccoli -1.2
Carrots -4.9
Celery -5.2
Cucumber -0.8
Green beans -3.1
Lettuce -2.5
Potatoes -4.0
Spinach -14.0
Tomatoes -3.1
   
Beverages  
Coffee -1.4
Red wine -2.4
White wine -1.2
Apple juice, unsweetened -2.2
Orange juice, unsweetened -2.9
Lemon juice, unsweetened -2.5
   
Condiments and Sweets  
Honey -0.3

Vegetables and fruits, by comparison, have negative PRAL numbers. Spinach (-14.0 PRAL), for example, is more base-forming than watermelon (-1.9 PRAL).

Acidic Foods
Food Potential Renal Acid Load mEq/100g
Meat  
Beef 7.8
Chicken 8.7
Pork 7.9
Salami 11.6
Turkey 9.9
   
Fish and Seafood  
Cod 7.1
Trout 10.8
   
Milk, Dairy, and Eggs  
Cheddar cheese, reduced fat 26.4
Cottage cheese, plain 8.7
Eggs 8.2
Egg white 1.1
Ice cream, vanilla 0.6
Milk, whole 0.7
Yogurt, plain 1.5
   
Beans and Legumes  
Lentils 3.5
   
Grain Products  
Bread, whole wheat 1.8
Bread, white 3.7
Rice, brown 12.5
Spaghetti 6.5
White flour 8.2
   
Nuts  
Peanuts 8.3
Walnuts 6.8

Foods such as cheese, meat, fish, shellfish, and grains produce acid after being consumed and have higher PRAL numbers. Cheddar cheese (26.4 PRAL), for example, is more acid-forming than egg whites (1.1 PRAL).

Pros and Cons

Pros
  • Can be satisfying and filling

  • Encourages plenty of fresh healthy produce

Cons
  • Lots of rules to remember

  • Limited research to support claims

The alkaline diet promotes an increased intake of fruits and vegetables while discouraging heavily processed foods that are high in sodium and saturated fat.

Increasing fruit and vegetable intake while decreasing processed foods would be beneficial for anyone as the typical Western diet is low in fruits and vegetables and has much more sodium and fat than is necessary. However, the alkaline diet has several drawbacks.

Pros

A fruit-and-vegetable-rich diet is very filling, making it easier to stick with. While there is no doubt that eating fewer processed foods is a good thing, there is little scientific evidence to support the claim that the alkaline diet can materially affect blood pH for the purpose of treating diseases.

It's important to note, however, that pH levels of specific areas of the body vary greatly while whole-body pH is kept within a tight range, thanks to the functions of our kidneys and lungs. 

Cons

There is no scientific evidence to support the premise that following an alkaline diet can improve health or that eating certain foods can change the pH of the body. For example, proponents of the diet claim that a highly acidic diet increases the risk of osteoporosis and fractures in older adults.

The theory is the body leeches calcium—an alkaline substance—from bones to balance out the acidity. However, the research does not support this.

In a 2015 study, researchers followed 861 men and women age 70 and found that dietary acid load had no significant associations with bone mineral density or with the diagnosis of osteoporosis.

Although the diet promotes an increase in healthy foods, it also restricts some nutritious foods such as milk and dairy products, which are excellent sources of dietary protein and calcium.

The diet's claims about restricting these foods are unfounded, as research studies indicate consuming these foods doesn't have an acidifying effect on the body, nor does it interfere with calcium metabolism. Similarly, eating meat doesn't change the pH of your body either.

Blood is naturally slightly alkaline with a pH between 7.36 and 7.44. If it falls outside those ranges, it can be fatal. One example is metabolic ketoacidosis, which is caused by diabetes, starvation, or alcohol intake and has little to do with diet. However, in healthy individuals, the body uses many mechanisms to control this tight range, ultimately ensuring our pH stays consistent. 

Is the Alkaline Diet a Healthy Choice for You?

The alkaline diet emphasizes eating fresh whole foods with a variety of fruits and vegetables and limited processed food. It allows for small amounts of animal protein and dairy while reducing refined grains, providing a wide array of nutrients.

The U.S. Department of Agriculture (USDA) dietary guidelines include calorie recommendations and tips for a healthy, balanced diet. The following nutrient-dense foods are recommended by the USDA.

  • Vegetables and dark, leafy greens (e.g., kale, spinach, broccoli, Swiss chard, green beans) 
  • Fruits (e.g., apples, berries, melon)
  • Grains (e.g., quinoa, brown rice, oats)
  • Lean meats (e.g., chicken breast, fish, turkey breast)
  • Beans and legumes (e.g., all beans, lentils, peas)
  • Nuts and seeds (e.g., walnuts, almonds, sunflower seeds)
  • Dairy (e.g., reduced-fat milk, cheese, yogurt
  • Oils (e.g., olive oil, avocado oil

Adopting a plant-based diet rich in fruits and vegetables may help you achieve overall wellness and protect against certain diseases.

However, the alkaline diet has plenty of healthy foods on the acid-forming list that are high in fiber, vitamins, and minerals and which are essential to overall health including grains, beans, nuts. Meanwhile, the base list includes coffee and wine, which nutrition experts agree should only be consumed in moderation.

The USDA's guidelines indicate that the number of calories a person needs to meet their nutritional minimums and achieve a healthy weight varies based on age, sex, and physical activity level. Use this calculator to determine your personal calorie needs.

The alkaline diet allows all of the foods recommended by the USDA to be consumed, although it restricts certain amounts of grains, legumes, animal protein, and dairy, and therefore is not necessarily considered healthy as it may lack varied nutrients and balance.

Health Benefits

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

Preserves Muscle Mass

Following an alkaline diet may help preserve muscle mass as you age—an important factor in preventing falls and fractures.

A three-year clinical trial of 384 men and women (ages 65 and up) published in the 2008 American Journal of Clinical Nutrition 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 2013 study published in Osteoporosis International, 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.

May Help Prevent 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, 66,485 women were followed for 14 years. During that time, 1,372 new cases of diabetes 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.

May Help Protect Against Kidney Disease

A higher dietary acid load is said to increase metabolic acidosis and increase the risk of kidney disease progression.

In a 2015 study, 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, higher magnesium intake and vegetable sources of protein had the strongest protective association with chronic kidney disease.

May Help Prevent Cardiovascular Disease

A high acid load diet may be associated with higher mortality rates, although the research is conflicting. A 2016 study 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.

In a second study published in the Journal of Nutrition in 2016, researchers used data from the Swedish Mammography Cohort and the Cohort of 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, researchers found 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.

Health Risks

While there are no common risks associated with the alkaline diet, it's evident that more research is still needed to determine its effectiveness for the many health claims it makes.

Additionally, 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.

Additionally, people with chronic diseases or on medications that affect the body's levels of calcium, potassium, or other minerals should check with their doctor before trying the alkaline diet.

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.

A Word From Verywell

For the average healthy individual, your body does a good job of regulating its various pH levels on its own and does not require specific dietary pH considerations.

While some health conditions such as kidney disease and diabetes may alter pH regulation, there's no scientific evidence to support the concept that certain foods will make your whole body more acidic and therefore more susceptible to disease.

Remember, following a long-term or short-term diet may not be necessary for you and many diets out there simply don’t work, especially long-term. While we do not endorse fad diet trends or unsustainable weight loss methods, we present the facts so you can make an informed decision that works best for your nutritional needs, genetic blueprint, budget, and goals.

If your goal is weight loss, remember that losing weight isn’t necessarily the same as being your healthiest self, and there are many other ways to pursue health. Exercise, sleep, and other lifestyle factors also play a major role in your overall health. The best diet is always the one that is balanced, sustainable, and fits your lifestyle.

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