What Is the Alkaline Diet?
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Medically reviewed by Simone Harounian, MS
The alkaline diet is an eating pattern that minimizes acid-forming foods, like animal proteins and cheeses, and emphasizes alkaline-producing foods, like fresh fruits and vegetables. Proponents of the alkaline diet say that eating foods with alkaline properties can lower the risk of chronic conditions like cancer, osteoporosis, kidney disease, and high blood pressure.
However, this diet may have a few downsides, and there isn't much research to support its benefits.
How the Alkaline Diet Works
The main goal of the alkaline diet—which is sometimes called the acid-ash diet—is to optimize the body’s pH. PH measures how acidic or alkaline (basic) a substance is. Here’s how the pH scale works:
pH values range from 0 to 14
pH values up to 7 are considered acidic
A pH value of 7 is considered neutral, meaning it’s neither alkaline nor acidic
pH values greater than 7 are considered alkaline
Proponents of the alkaline diet argue that increasing the body’s pH can lower your risk of chronic conditions. While clinical evidence supporting the health benefits of the alkaline diet is lacking, there are a few reasons why it might work.
Eating large amounts of acid-producing foods may lead to low-grade metabolic acidosis over time. Mild acidosis refers to an elevated amount of acid in the body that still falls within the normal range.
Chronic acidosis has been associated with a greater risk of illnesses like cancer, osteoporosis, high blood pressure, and diabetes. Fans of the alkaline diet reason that eating alkaline, or non-acidic, foods can help lower the risk of these conditions.
While an association between elevated levels of acid in the body and negative health outcomes may exist, there’s little data to support that one causes the other.
So far, only animal studies have shown that cancer cells may thrive in acidic environments.
One human-based study reported an association between eating alkaline foods and a lower risk of breast cancer. However, the researchers were uncertain whether the finding was due to the fruits and vegetables being alkaline or other properties, like their high antioxidant and fiber contents. It's also possible that people who ate more fruits and vegetables were less likely to be diagnosed with breast cancer because they also ate less fatty meats and cheeses.
When it comes to the alkaline diet and cancer, there is little to no research to show that alkaline diets can (or cannot) help prevent or treat cancer.
Another gap in the alkaline diet’s logic is that it's nearly impossible to markedly shift the pH of certain parts of the body with diet.
Various parts of the body have different pHs. The stomach’s juices are naturally acidic, with a very low pH of about 1.5 to 2.0 which assists in digestion and protects the body from disease, leading to the production of microbes.
The blood has a higher pH, between 7.35 and 7.45, a range that’s tightly controlled by the kidneys and lungs and remains unchanged by the diet. If the pH of the blood veers outside of this narrow window, it can be fatal.
Urine is the only bodily fluid with a pH that’s readily affected by the diet, but these fluctuations tend to be well controlled by healthy kidneys.
In other words, your food choices can’t markedly shift the overall pH of the body. Still, proponents of the alkaline diet argue that even if the eating pattern doesn’t materially shift the body’s pH, it spares vital organs—like the kidneys—from having to work harder to keep the body’s pH in balance.
While there are several scientifically sound reasons to add more alkaline foods like fruits and vegetables to your diet, little research currently supports following a full alkaline diet for optimal health.
The Alkaline Diet's Questionable Origins
One of the biggest champions of the alkaline diet was Robert Young, author of the 2002 book The pH Miracle: Balance Your Diet, Reclaim Your Health. Young was convicted for practicing without a medical license in 2016.
Guidelines of Alkaline Diet
The alkaline diet doesn’t categorize foods based on how acidic or basic they are but instead on how those foods function in the body. This is measured by a food’s potential renal acid load, or PRAL. The PRAL quantifies a food’s ability to produce acid in the body.
For example, citrus fruits like oranges are naturally acidic but because they have a negative PRAL, they’re considered basic on the alkaline diet. In contrast, a protein-rich food like salmon may not taste acidic but because it is acid-forming, it’s discouraged on the alkaline diet.
What to Eat and Drink on the Alkaline Diet
The alkaline diet emphasizes fruits and vegetables above all. The goal is to emphasize foods with negative PRALs and eliminate foods with positive PRALs to prevent acid buildup in the body.
Food groups and beverages that are encouraged on the alkaline diet include:
Fruits: Especially apples and unsweetened apple juice, dried apricots, bananas, figs, raisins, prunes, dates, unsweetened grape and orange juices
Vegetables: Especially beets, beet greens, Swiss chard, dandelion greens, kale, leeks, mustard greens, spinach, turnip greens
Herbs and spices: Especially fresh dill, dried basil, coriander, curry powder, oregano, parsley
Sweeteners: Honey, marmalade
Beverages: Water, mineral soda water, tea, some types coffee
Fats: Olive oil and margarine are considered neutral
Foods and Drinks Not In the Alkaline Diet
Acid-forming foods are limited on the alkaline diet. Food groups and beverages with potentially positive PRAL values that should be avoided on the alkaline diet include:
Animal proteins: Including dairy, eggs, fish and shellfish, poultry, red meat
Nuts and seeds: Especially peanuts, walnuts, pumpkin seeds, sesame seeds, sunflower seeds
Starches: Brown rice, oats, pasta, breakfast cereals, rice, whole wheat bread, bran, rye
Legumes: Lentils, peas
Sweets: Gelatin-based desserts and puddings
Beverages: Colas, pale beers
Meal Ideas for the Alkaline Diet
A strict alkaline diet is primarily made of fruits and vegetables. Here’s an example of a day of alkaline meals:
Breakfast: Vegetable hash with a banana on the side
Lunch: Kale salad with avocado, blueberries, tomatoes, red onion, and dressing made from lemon juice and olive oil
Snack: Apple with herbal tea
Dinner: Vegetable stir fry over cauliflower rice
Benefits of the Alkaline Diet
The alkaline diet includes nutrient-dense ingredients thanks to its focus on fruits and vegetables. Here are a few health benefits of eating more alkaline foods.
May Improve Heart Health
Adopting an alkaline diet can support cardiovascular health by minimizing fatty animal foods (like red meat and cheeses) and emphasizing fiber-rich plant foods.
With its emphasis on fruits and vegetables, the alkaline diet is bound to boost dietary fiber intake. Eating more fiber helps lower LDL-cholesterol levels in the blood, a key risk factor for cardiovascular disease.
A recent study found that people eating lower PRAL (i.e. more alkaline diets) were more likely to meet national dietary guidelines for heart-healthy nutrients like potassium and fiber compared to people eating higher PRAL (i.e. more acid-producing) diets. People eating lower PRAL diets also ate less saturated fat, the type of dietary fat that raises LDL-cholesterol levels in the blood.
Also, alkaline foods like fresh fruits and vegetables are rich in potassium and low in sodium, which can help lower blood pressure levels.
May Prevent Kidney Stones
Eating a diet high in animal protein can also increase the amount of acid that’s excreted in the urine. A lower pH in the urine can raise the risk of kidney stones over time.
Conversely, diets low in meat, fish, and poultry and high in potassium-rich fruits and vegetables make the urine more alkaline, which lowers the likelihood of kidney stone development or recurrence.
Is the Alkaline Diet Safe?
While the alkaline diet emphasizes nutrient-dense whole foods, the meal plan is generally not recommended for optimal health. Here's why the alkaline diet may not be safe for everyone.
It Lacks Protein
The alkaline diet excludes animal proteins and limits plant-based proteins, making it nearly impossible to eat enough protein on the meal plan. Eating enough protein is critical for maintaining lean muscle and bone mass, supporting growth and development, and strengthening the immune system.
A strict alkaline diet is not recommended for overall health, particularly for people who may need more dietary protein, such as children, people who are pregnant or breastfeeding, and older people.
It Eliminates Entire Food Groups
While eliminating certain foods can be necessary in some health conditions (like gluten in the case of celiac disease), cutting out entire food groups without a medical reason to do so is not advised.
Eating an alkaline diet that excludes animal proteins and dairy products could lead to deficiencies in important nutrients like calcium, iron, zinc, and vitamin B12 over time. Such a restrictive diet can also create a disordered mindset around eating, as entire, healthy food groups are eliminated without reason.
Following a strict alkaline diet also means meals are made almost entirely from fruits and vegetables. While fresh produce is full of nutrition, it’s impossible to meet your caloric needs with fruits and vegetables alone.
In summary, eating an alkaline diet can make it difficult to meet your nutrient needs. Following such a restrictive meal plan can have both physical and emotional consequences over time.
A Quick Review
The alkaline diet encourages eating alkaline, or low-acid, foods like fruits and vegetables to supposedly optimize pH levels in the body and lower the risk of chronic diseases.
Adding more fruits and vegetables to your plate can lower your risk of chronic conditions, but research doesn’t support a direct link between eating alkaline foods and better health. Eating a strict alkaline diet that eliminates proteins, dairy, and grains is neither necessary nor encouraged in order to eat a nourishing, well-balanced diet.
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