Dietary Acid Load and High Alkaline Diet: Connection to Kidney Disease

The human body strives for perfect balance. Think about it–too much stress, too much food, not enough sleep, working or playing too much can all create imbalances. In the same way, the body strives for internal balance: balance of electrolytes like sodium, potassium, phosphorus and calcium; fluid balance; and balance of acid and base–the blood pH.

The pH of blood is a measure of how much acid and how much alkaline are in the body fluids. If there is too much acid, a condition called metabolic acidosis occurs. On the other hand, if there is too much alkali, a condition called metabolic alkalosis occurs.

Why is this important for people with chronic kidney disease?

Because the kidneys help keep pH normal by neutralizing and removing acid from the blood through the urine. They also make bicarbonate to help with pH balance. As kidneys work less, more acid stays in the body. This acid has to be neutralized and stored in the body. In order to do this, the body breaks down muscles and bones. As a result, there is muscle wasting and weakened bones—two conditions often seen in later stages of kidney disease. Metabolic acidosis has been reported as early as stage 3 chronic kidney disease (CKD). However, it is most often seen in stages 4 and 5 CKD as glomerular filtration rate (GFR) drops below 30 mL/min. Dialysis patients are also at risk for metabolic acidosis. (1)

How is metabolic acidosis treated?

The treatment for metabolic acidosis is to make the blood more alkaline. Doctors often prescribe sodium bicarbonate, and monitor the blood pH level as well as gases like oxygen and carbon dioxide. The dialysis prescription may be adjusted.

Foods can also help manage pH balance. Some of the foods we eat produce acid, some produce alkali and some are neutral. Most fruits and vegetables produce alkali and most protein foods produce acid. Today’s Western diet, high in animal protein and low in fruits and vegetables, produces extra acid and lacks the buffering provided by produce. The acid produced by food is called the dietary acid load.

Which foods have a high dietary acid load?

• Meat, poultry, fish
• Cheese, egg yolk
• Peanuts
• Grains and grain products
• Carbonated drinks, especially colas

Which foods have a low acid load? (high alkaline foods)

• Most fruits and vegetables
• Legumes, textured soy protein, egg whites

Which foods are neutral?

• Fats and oils
• Sugar
• Milk and yogurt (close to neutral although high in protein)

Studies in people with CKD have shown that the combination of foods eaten can make the blood more or less acidic. (2, 3) The goal is to eat more alkali-producing foods and fewer acid-producing foods. In other words, a high alkaline, low acid diet.

What is the benefit of this diet?

This type of diet may help some people with CKD maintain a balanced pH level to prevent or decrease acidosis. By reducing the amount of acid the kidneys must manage, and by reducing ammonia build-up there is less kidney damage (1). Reducing certain animal proteins and increasing fruits and vegetables can make the body fluids less acidic. This in turn can help keep muscles and bones from breaking down to neutralize acids. The result is a slower decline in GFR and slower progression of CKD.

Is a high alkaline diet good for all kidney patients?

As always, each person should consult with their physician about their needs since each person has unique needs based on kidney function, potassium level, appetite, treatments, dietary intake and medications. Here is some information about a high alkaline diet to consider and discuss with your doctor or dietitian before making changes to your current diet:

• Lowering certain protein foods helps reduce acid. For a CKD non-dialysis diet this may already be a part of the diet plan. It’s important to get the right mix of high and low quality protein foods. Getting enough calories is also important.
• Dialysis patients need extra protein and are not advised to reduce protein foods. Instead, they are encouraged to eat more plant-based protein foods and egg whites to replace some animal proteins.
• Soy foods provide high quality protein and are high alkaline. Consider including soy as a replacement for some meats.
• The potassium in fruits and vegetables is partially responsible for producing more alkaline. Some people with CKD and many hemodialysis patients must limit their intake of potassium to keep from having high blood potassium. It is essential to work with the dietitian to determine the minimum and maximum number of daily fruit and vegetable servings to eat.
• CKD patients who do not need to limit potassium can enjoy a variety of fruits and vegetables, and are encouraged to include a serving of white or sweet potatoes. Keep track of potassium lab results because levels may go up with diet changes or as kidney function declines.
• People with diabetes may choose lower carbohydrate vegetables rather than increasing fruits to help manage blood sugar.
• Some medications used to treat blood pressure and fluid retention cause higher blood potassium levels. Ask your doctor about your medications.
• Fruits and vegetables such as rhubarb, spinach, beet greens and chard are unable to provide alkaline and should be avoided due to a high oxalate content.
• Carbonated drinks have a high acid load, especially colas which contain phosphoric acid. So stick to regular water instead.

Summary

We continue to research and study dietary and lifestyle changes to learn about what helps kidneys work longer. Today’s kidney diet focuses on whole foods, homemade meals and attention to health attributes of food. While a high alkaline diet may not be for all kidney patients, there are some who can benefit from this way of eating.

References

1. Alkaline Diet and Metabolic Acidosis: Practical Approaches to the Nutritional Management of Chronic Kidney Disease, Larissa Rodrigues Neto Angéloco, et al.,  Journal of Renal Nutrition; Published online: December 5, 2017

2. Reducing the Dietary Acid Load: How a More Alkaline Diet Benefits Patients with Chronic Kidney Disease, Passey, C. et al, Journal of Renal Nutrition, Vol. 27, Issue 3, p151–160; Published online: January 20, 2017

3. Vegetarianism: Advantages and Drawbacks in Patients with Chronic Kidney Diseases, Chauveau, Philippe et al., Journal of Renal Nutrition , Volume 23 , Issue 6 , 399 – 405, 2013.,