What Are Acidic Foods, and Do You Really Need to Avoid Them?

Over the years, there have been many claims about acidic foods and how they affect the body. But before we dig deeper into that, let’s start with the basics. 

The pH scale is a tool that measures how much acid or base is in something, like a food or your body. On a scale from 0 to 14: 

• 7 is neutral

• Less than 7 indicates an acid

• Greater than 7 indicates a base (more alkaline) 

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The average pH of the human body is 7.4. When foods are broken down in the body, they can make other compounds that are more or less acidic. 

People who promote the “alkaline diet” recommend limiting foods that create an acidic environment. They believe that acidic environments can harm your health. But is there evidence for this? Here’s what the science says about alkaline versus acidic foods and this dietary approach. 

What are acidic foods?

Here are two ways you can think about foods and acidity: 

• Some foods create an acidic environment in your body. Once certain foods get broken down and digested, they increase the “potential renal acid load,” or PRAL. This value measures acid removed through urine (pee), which helps determine your body’s acid-alkaline balance. Meat and fish are high-PRAL (acid-forming) foods because they are made of amino acids that create a more acidic environment in the body. Someone following an “alkaline diet” would focus on avoiding these types of acidic foods.

• The pH content of the food itself is acidic. Certain foods, like lemons and tomatoes, are acidic by nature and have a pH level below 7. People with gastroesophageal reflux disease (GERD) may want to avoid acidic foods because they can trigger GERD symptoms.

High acid-forming foods

High-acid foods, which create more acid when digested, include:

• Meat, including fresh and processed 

• Poultry, like chicken and turkey

• Fish, such as salmon, shrimp, scallops, and tuna

• Dairy products, including milk, cheese, and butter

• Eggs 

• Grains

Foods with a naturally high acid level

Some foods have a naturally high acid content (low pH levels). These are different from the acid-forming foods above. Foods with a high acid level include many fruits, such as: 

• Lemons

• Limes

• Plums

• Grapes

• Grapefruit

• Blueberries

• Pineapple 

• Oranges

• Tomatoes

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Keep in mind that the acidity of a specific food is only one piece of the puzzle when it comes to the pH level in your body. While some fruits and vegetables can have high acid levels, this doesn't necessarily mean that they increase acid levels in the body after they’re digested. In fact, most fruits and vegetables are actually alkaline-forming in your body. This helps the internal environment in your body become less acidic.

Other acidic items include fizzy or carbonated drinks and alcoholic beverages, such as:

• Soda

• Beer

• Cider

• Prosecco

• White wine

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Note that in addition to having a high acid level, alcohol is acid-forming as well, which means that it increases acid in the body. 

Alkaline vs. acidic foods

Alkaline-forming foods create less acid when they break down during digestion. Unlike acid-forming foods, they are considered low PRAL, so they don’t produce much acid for the kidney to filter out. The alkaline diet is based on limiting acid-promoting foods and adding more foods that should create a more alkaline environment. 

Foods that are considered alkaline-producing include:

• Fruits

• Vegetables 

• Nuts 

• Legumes

Should you replace acidic foods with alkaline foods?

Overall, more research is needed to better understand how effective alkaline diets might be in specific situations. Research shows that eating a diet with lots of high-PRAL foods, such as red meat, may increase the risk of cancer. And eating a diet rich in low-PRAL foods, such as fruits and vegetables, can help prevent cancer and improve overall health. 

However, this likely isn’t because fruits and vegetables are low PRAL but because they’re rich in essential nutrients. So eating a diet rich in alkaline foods can have health benefits, but it may not be related to their effect on the acid-base balance in the body.  

Rather than focusing on the acid-forming potential of a food, it’s best to focus on eating a variety of nutrient-dense foods. This can definitely include some high-PRAL foods, such as animal proteins and grains.

However, if you have kidney problems, there’s more evidence that a diet lower in acid-forming foods might have health benefits. Talk with your healthcare team to see whether increasing alkaline foods may be a good idea for you. 

Do acid-forming foods cause metabolic acidosis?

Acid-forming foods don’t cause metabolic acidosis (too much acid in the body) as long as you have healthy kidneys. 

Once food is broken down and absorbed into the bloodstream, the lungs and kidneys work together to keep your blood pH in a very narrow range. If the products of a food are more acidic, the kidneys start working to get rid of the extra acid in the urine. So your blood pH will not be affected in a significant way by the foods you eat. 

However, acid-forming foods can make your urine more acidic. If a food creates a more acidic product when broken down, the kidney will filter out more acid in the urine. This lowers the pH of the urine. But urine pH doesn’t have any impact on your health.

If you have chronic kidney disease (CKD), your kidneys have a tougher time filtering out acids. This can lead to a buildup of acid in the blood (metabolic acidosis). 

Can acid-forming foods cause kidney problems?

There’s a complex relationship between acid-forming foods and kidney problems.

One study looked at the dietary acid load of over 15,000 people and then followed them for 21 years. People who ate more acid-forming foods were more likely to develop kidney disease at some point. 

Even so, if you have healthy kidneys, acid-forming foods probably won’t cause kidney problems. But eating a diet high in acid-forming foods can lead to other health conditions, which in turn can cause kidney problems. 

For example, processed meat is an acid-forming food that has been linked to a number of other health problems, like cancer and high cholesterol. These health conditions can affect your kidneys, too. So people can develop kidney problems from eating processed meat, but it probably has less to do with the acidic nature of the meat and more to do with the overall health impact of eating this particular food. 

However, if you already have CKD, eating acid-forming foods will affect your kidney health. Studies have shown that people with CKD seem to have worsening kidney function if they eat a diet high in acid-forming foods. This can make it harder for the kidneys to keep your blood pressure in check. This is why a healthcare professional may recommend limiting how much animal protein you eat if you have CKD. 

A diet high in animal protein can also make you more likely to develop kidney stones. If you have kidney stones, your healthcare team may recommend that you eat fewer acidic foods, like red meat. 

Can acid-forming foods cause bone deterioration?

Proponents of the alkaline diet say that it can help prevent osteoporosis (bone loss). This is because if there’s too much acid in your blood, minerals from bones can be released into the bloodstream to help create a normal pH. 

But in otherwise healthy people, eating acidic foods doesn’t seem to lead to increased risk of fractures or bone mineral loss. Urine pH is also not associated with bone mineral density. 

However, it’s possible that people with poor kidney function might be more likely to develop bone deterioration if they eat a more acid-forming diet. More studies are needed to know for sure. 

Do acidic foods cause gastric upset?

Acidic foods can lead to stomach discomfort for people with heartburn (GERD). Some people are especially sensitive to the effects of acidic foods, which can irritate the lining of the stomach and esophagus. And this can lead to the classic symptoms of heartburn. 

This is why people with GERD may benefit from following a GERD diet, which involves avoiding acidic foods and: 

• Spicy foods

• Fatty foods

• Alcohol

• Caffeine

• Mint

Can acidic foods damage your teeth?

Yes, drinks and liquid products with high acid content can damage your teeth if you drink them in excess. These include:

• Soda

• Sports drinks

• Coffee

• Tea 

• Lemon juice 

• Apple cider vinegar 

These types of drinks can wear away your enamel — the layer that protects your teeth. In turn, this can lead to cavities, infection, and staining. You can help reduce these effects by brushing your teeth or rinsing your mouth with water after you eat.

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Written by:

Karen Hovav, MD, FAAP

Karen Hovav, MD, FAAP, has more than 15 years of experience as an attending pediatrician in a variety of clinical settings. She has worked in a large academic center in an urban city, a small community hospital, a private practice, and an urgent care clinic.

Edited by:

Alex Eastman, PhD, RN

Alex Eastman, PhD, RN, is a California-based registered nurse and staff medical editor at GoodRx, where he focuses on clinical updates and Latino health.

Reviewed by:

Farzon A. Nahvi, MD

Dr. Nahvi is an emergency medicine physician and author of “Code Gray: Death, Life, and Uncertainty in the ER.” He works clinically at Concord Hospital in Concord, New Hampshire, and is a clinical assistant professor of emergency medicine at the Geisel School of Medicine at Dartmouth. Prior to this, he worked as an ER physician and clinical assistant professor of emergency medicine at the Mount Sinai Health System, NYU Langone Health, NYC Health + Hospitals/Bellevue, and the Manhattan VA. He is a graduate of Cornell University and NYU School of Medicine.

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