What Is the Alkaline Diet?

Fresh leaf vegetables
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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.

Followers of an alkaline diet believe eating a diet rich in alkaline-forming foods have unique health benefits, while a diet high in acid-producing foods disrupts the blood's normal pH level. This, 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.

The diet has been used medically to prevent kidney stones and urinary tract infections, however, there is not a lot of science to support many of the purported health benefits of the alkaline diet.

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

Background

The concept of alkaline and acidic foods was developed during the mid-1800s as the dietary ash hypothesis. It proposed that foods, once metabolized, leave an acid or alkaline "ash" in the body.

According to proponents of the alkaline diet, the metabolic waste—or ash—left from the burning of foods directly affect the acidity or alkalinity of the body. Choosing more alkaline foods, in theory, should alkalize your body and improve health.

Food groups can be alkaline, neutral, or acidic. 

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

Acid levels are measured by pH, 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. 

On the alkaline diet, it is suggested to monitor the pH of your urine to ensure it is alkaline (over 7) and not acidic (below 7).

It's important to note that pH levels in the body vary greatly. The stomach, for example, is filled with hydrochloric acid with a pH of 2 to 3.5, which is necessary to break up food during digestion. 

Blood, on the other hand, is 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 nothing to do with diet. 

As long as you're healthy, your body regulates the various pH levels of your body nicely. 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.

How It Works

To follow the alkaline diet, simply focus on eating lots of alkaline foods and fewer acidic foods. 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). On the PRAL scale, 0 is neutral, while negative numbers are basic and positive numbers are acidic.

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).

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

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 has shown that the diet may offer certain health benefits.

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-long 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 another 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.

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 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.

Chronic Kidney Disease

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

In 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.

Cardiovascular Disease

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

In a study published in Cardiovascular Diabetology in 2016, researchers 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.

However, a second study found both highly acidic and highly alkaline diets have high mortality rates, while those with a more neutral diet had greater longevity.

In a study published in the Journal of Nutrition in 2016, 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, 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.

Fracture Risk

It is believed 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 published in Osteoporosis International, 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. 

What to Eat

The idea behind the alkaline diet is to eat more alkaline foods and fewer acidic foods.

Alkaline Foods

  • Fruits

  • Vegetables

  • Coffee

  • Red and white wine

  • Lemon and lime juice

Acidic Foods

  • Meat

  • Poultry

  • Fish

  • Dairy

  • Eggs

  • Grains

  • Legumes

On the alkaline diet, foods are measured by their potential renal acid load. A negative number is more alkaline and a positive number is more acidic. These tables are adapted from the study by Remer and Manz.

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
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

Recommended Timing

The alkaline diet does not restrict foods to certain times of the day or require periods of fasting.

Resources and Tips

Following an alkaline diet isn’t complicated. The goal is simply to eat more alkaline and less acidic foods. Here are some tips to get started: 

  • Eat more fruits and vegetables.
  • Drink less soda or eliminate it altogether. 
  • Aim to drink 64 ounces of mineral water a day. 
  • Add fresh lemon or lime to water. Even though citrus fruits are acidic, they have an alkalizing effect in the body. 
  • Limit animal protein to one serving a day. 
  • Replace refined carbohydrates with vegetables. For example, choose spiralized zucchini or carrots instead of spaghetti or finely chopped cauliflower instead of white rice.
  • Drink alkaline broth. Alkaline broth is an easy-to-make vegetable broth that's packed with vitamins and minerals including potassium.

In addition, when following the alkaline diet, it is helpful to monitor your urinary pH to know how nutritional changes affect your body. You can buy urine pH strips online or at your local health-food store.

It is recommended that you use your first urine of the day. A number between 6.5 and 7.5 is ideal. 

Pros and Cons

While the alkaline diet can be a healthy way to eat, there are some concerns over its basic premise and its effectiveness.

Pros

  • Filling

  • Lots of fresh produce

Cons

  • Lots of rules to remember

  • Limited research

Pros

The alkaline diet promotes an increased intake of fruits and vegetables and avoids heavily processed foods that are high in sodium and saturated fat. That's beneficial because the typical Western diet is low in fruits and vegetables and has much more sodium and fat than is necessary.

A diet rich in fruits and vegetables is also very filling, which makes it easier to stick with.

However, 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.

Cons

As far as fad diets go, this one doesn't seem to be too risky, but it does restrict some nutritious foods such as milk and dairy products, which are excellent sources of dietary protein and calcium. That's unfortunate (and unfounded) because research studies indicate consuming these foods doesn't have an acidifying effect on the body, nor does it interfere with calcium metabolism. Eating meat doesn't change the pH of your body either.

While there is little evidence that an alkaline diet can render the benefits claimed by its supporters (especially that the diet can materially affect blood pH for the purpose of treating diseases), there is no doubt that eating fewer processed foods is a good thing.

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.

How It Compares

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 2019 U.S. News and World Report Best Diets ranks the alkaline diet number 32 in Best Diets Overall and gives it an overall score of 2.5/5.

Its low ranking is based on questionable research, many rules that make it difficult to follow, and ineffectiveness for weight loss.

USDA Recommendations

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 as part of a healthy diet:

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

The alkaline diet allows all of these foods to be consumed, although it restricts the amounts of grains, legumes, animal protein, and dairy.

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.

The USDA recommends consuming roughly 1,500 calories per day for weight loss, but this number varies based on age, sex, weight, and activity level. Use this calculator to determine your personal calorie needs.

Similar Diets

The alkaline diet shares some features with many healthy eating plans. Similar diets include:

  • Whole-food, plant-based diet: A vegetarian diet, this plan includes lots of vegetables and fruits, along with grains and legumes, while avoiding processed foods.
  • Mediterranean diet: This diet emphasizes plant-based eating but encourages consumption of fish and allows for small amounts of chicken, dairy products, eggs, and red meat.
  • Flexitarian diet: Also known as a "flexible vegetarian" diet, this eating plan emphasizes plant-based foods but allows for occasional allowances of foods that are not typically considered vegetarian.
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