Debating Diets: What is the alkaline diet?


Thinking about starting a new diet? While the amount of information available can be overwhelming, it’s possible to find a diet that is safe, suitable and effective for your lifestyle.

Erika Zoellner, senior registered dietitian at Baylor College of Medicine, discusses what you need to know about the alkaline diet.

How does the alkaline diet work?

The alkaline diet is a group of diets based on a discredited notion that the body pH balance can be affected by food, which is not the case physiologically. The food you consume does not affect the pH level of your blood.

This diet looks at the avoidance of acidic foods. Proponents of the alkaline diet believe acidic foods may cause low bone density, cancer, increased inflammation or different disease states in the body, none of which has been proven.

It was first established to change the acidity of the urine in the early 1900s by different researchers to treat kidney stones and urinary tract infections, but the alkaline diet for treatment of these conditions was superseded by drug therapies and because of the high variability of the effect of food on urinary pH.

What are recommended foods? Discouraged foods?

Alkaline foods include different fruits, vegetables and legumes, including soy, tofu, leafy greens and sea vegetables. This eating pattern eliminates acidic foods such as meat, fish, dairy, alcohol, eggs, wheat and yeast. Some acidic foods include:

  • Lentils
  • Nuts
  • Grain products
  • Beverages like coffee and alcohol
  • Ultra-processed foods

People who follow the alkaline diet tend to be lower in calcium (which helps prevent osteoporosis and maintains bone health), Omega−3s, protein and different vitamins like riboflavin.

A specific alkaline diet does not exist, which can be confusing to people interested in trying it. There is no specific ratio set for alkaline to acidic food intake. You can see a variation of alkaline diets that recommend 80/20 (alkaline:acid) or 60/40. Also, some may be short-term, like a cleanse, or long-term like the 80/20 or 60/40.

Who should avoid this diet?

An athlete or someone who exercises frequently at a moderate or high intensity should avoid this diet because their carbohydrate consumption may be too low with the avoidance of grains. Athletes have such high carbohydrate needs and that can be difficult while following the alkaline diet. The low-acid diet aspect, resulting in lower protein intake from meats and dairy sources, is often not enough to maintain athletic performance and muscle structure for athletes.

Patients with cancer should consult their physician and a dietitian about their nutrition needs before starting any kind of diet. We see people in alternative and functional medicine recommending this diet for people with cancer, but there is no correlation.

People prone to UTIs, kidney stones or other conditions that have been proposed to benefit from the alkaline diet may be taking medication for those conditions, so they should not stop taking those to participate in the diet.

People with osteoporosis or arthritis should not follow this diet as it is not inconclusive of calcium-containing foods with high bioavailability. Some arthritis medications suppress bone formation and promote resorption, so these individuals may need calcium supplements.

Studies have looked at the amount of calcium intake someone on the alkaline diet gets on average. They’ve shown it’s in the 550mg range, which is around 50 percent of the daily needs. Women who are postmenopausal and are producing less estrogen are at higher risk of decreased bone density.

What are the nutritional benefits of this diet? Can it help with weight management?

There are some nutritional benefits to the diet because it focuses on more of a healthy eating pattern in terms of incorporating more fruits, vegetables and legumes. It is not necessarily a bad diet, but it may be low in certain nutrients and long-term use of the alkaline diet can put people at risk of nutritional deficiencies.

What kind of physiological changes or side effects should be expected?

People are not going to see the intended physiological change of their blood pH changing. Our acid-based homeostasis is controlled by our respiratory and urinary systems, neither of which diet controls.

You may see some physical change with weight loss at first because people tend to eat a lower-calorie diet while consuming more fruits and vegetables rather than higher fat meat, processed foods and higher carbohydrate sources.

The diet also recommends a decrease in alcohol consumption. If you drink alcohol frequently before starting the alkaline diet, you are bound to see some weight loss.

What else should people know before considering this diet?

Any time you plan to try out a diet, it is important to investigate what is behind its claims and evaluate whether the diet suggestions align with our physiology. In terms of the alkaline diet, their claims do not align with our physiology. The alkaline diet proposes:

  • Change in blood pH levels
  • Strong bone density
  • Decreases cancer and cardiovascular events

You can lower your risk of certain health scares, but not from pH changes proposed by this diet.

The alkaline diet is not harmful because it reinforces healthy eating by consuming more fruits and vegetables, drinking lots of water and cutting back on added sugars, alcohol, meat and processed food – all of which improves overall health but are unrelated to alkalinity or pH of blood.

Additional Resources

Check out more from the Debating Diets series.

See dietitian-approved recipes.

Learn about the Medical Weight Management Clinic at Baylor.

-By Homa Shalchi

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