The alkaline diet claims to boost the pH level of fluids in the body and reduce acidity, thereby improving your health. But, what is the real benefit of having a more alkaline system?
The theory is that by eating more alkaline foods — fruits, vegetables, nuts and legumes — your blood's pH level achieves a more desirable, less inflammatory state. When you're blood is more acid, you're at a greater risk of chronic disease, such as cancer and bone loss. An alkaline level is said to improve health outcomes.
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Increasing alkalinity in your body is said to boost your overall health and reduce your risk of chronic disease. By eating more plant-based foods, you reap health benefits, but not a lot of concrete science supports the need for creating an alkaline state in the body.
What Is pH?
The pH scale measures the two extremes of chemical properties that exist in compounds. If a substance has a pH level of 7, it's considered neutral. Therefore, a pH greater than 7 is basic and a level below 7 is acidic.
Maintaining the pH level around cells and tissues preserves life, including human life. Your blood has a carefully calibrated pH of about 7.4 — consistently hovering between 7.35 and 7.45.
The human diet's acid-base content has shifted over the past 10,000 years, and particularly in the last 200 years, from one of a hunter-gatherer to a farming, industrialized and processed one. The typical diet today is far more acidic than in early times.
Read more: What to Eat if You Have an Acidic Stomach
While the modern diet doesn't seem to have a huge impact on blood chemistry and pH levels, which the body carefully calibrates, it does change urinary chemistry, explains a paper published online in October 2011 in the Journal of Environmental and Public Health.
Promoting an Alkaline State
Proponents of an alkaline diet claim that the diseases of modern civilization, including cancer and osteoporosis, result from eating a diet with too high an acid load. Acidic foods are meats, poultry, dairy, fish, eggs, grains and alcohol. If you eat too much of these foods, according to some claims, your blood and bodily fluids become more acidic too.
But, if you consume alkaline foods, including fresh produce and nuts, your blood becomes more alkaline, which in turn, prevents major health risks — or so say the proponents of the diet.
But a steady pH level is not normal for your entire body. Your blood level hovers around 7.4, but other pH levels in your body vary greatly. The Journal of Environmental and Public Health article notes that the stomach has a pH of 1.35 to 3.5 — quite acidic — and the skin has a pH of 4 to 6.5. Your diet won't change these tightly regulated levels that exist for a reason; higher acidity levels protect the skin from infection, for example, and allow the stomach to digest food. Some acidity has a purpose.
Effects of Alkalinity on Disease
Many proponents of increasing the alkalinity of your blood claim it will prevent chronic disease, including cancer. As pointed out in a systematic review published in a June 2016 issue of BMJ Open, no actual research supports (or disproves) the association between diet acid load and the development or treatment of cancer.
A paper published in the Journal of Renal Nutrition in May 2017 suggests that, for people who already have kidney disease, an alkaline diet may slow progression of the disease or may improve renal function. Your kidneys filter waste, including excess acidity, to maintain your blood pH level at around 7.4. A low-acid diet that replaces much animal protein with plant-based options may have value because your kidneys don't have to work as hard to excrete the excess acid in meats, poultry, fish and dairy.
Osteoporosis and rapid bone loss is sometimes attributed to a high acid diet. You're better off maintaining alkalinity, advocates of a low-acid diet say, to preserve bone mass. PEN Nutrition and the Dietitians of Canada presented a position paper in 2019 confirming a lack of evidence to support the belief that high-protein (or high-acid) diets lead to increased dietary acid load and the resulting decreased bone cell growth and increased bone loss.
Research published in Nutrients in April 2018 concluded that, for most people, a typical Western diet with relatively high acid loads is not going to alter bone mineral density in any statistically notable way. Most people have normal renal function and acid excreting abilities. Bone loss is more likely due to age, gender, sedentary living and race.
However, older adults with diminished renal function may benefit from a diet that focuses on more alkaline foods. The alkaline diet reduces the stress on already compromised kidneys.
Possible Benefits of Alkaline
An alkaline diet is rich in healthy foods and discourages foods such as meats and full-fat dairy that are high in saturated fats. Reducing your intake of saturated fats and replacing them with unsaturated fats, found in avocados, olive oil and nuts, can lower blood pressure and cholesterol levels and improve lipid profiles. Basically, lower saturated fat intake is a plus for heart health.
Read more: Monounsaturated vs. Polyunsaturated Fats
The alkaline diet also boosts your intake of fruits and vegetables, which ups your nutritional intake. The consumption of fruits and vegetables by most Americans is woefully low. A press release from the Centers for Disease Control and Prevention in November 2017 detailed that just 9 percent of adults meet the recommended intake for vegetables, which is 2 to 3 cups per day, and that only 12 percent meet the recommendations for fruit, which is 1.5 to 2 cups per day.
This low intake of produce means the general nutrition profile of American adults is low in potassium and high in sodium. Eating a more plant-based diet can improve this ratio, which may benefit bone health, lessen hypertension and reduce muscle wasting, explains the 2011 Journal of Environmental and Public Health paper.
Increased intake of plant-based foods can also boost your intake of magnesium, which is generally poor for most adults, according to the Journal of Environmental and Public Health article. Magnesium is essential for many enzyme systems, and deficiency can cause weakness and fatigue, frequent cramping and abnormal heart rhythms. Magnesium is plentiful in green, leafy vegetables, legumes, nuts, seeds and whole grains, explains the National Institutes of Health Office of Dietary supplements.
- Nutrients: "Acid Balance, Dietary Acid Load and Bone Effects—A Controversial Subject"
- Journal of Renal Nutrition: "Reducing the Dietary Acid Load: How a More Alkaline Diet Benefits Patients With Chronic Kidney Disease"
- BMJ Open: "Systematic Review of the Association Between Dietary Acid Load, Alkaline Water and Cancer"
- Elmhurst College: "pH Scale"
- Journal of Environmental and Public Health: "The Alkaline Diet: Is There Evidence That an Alkaline pH Diet Benefits Health?"
- American Heart Association: "Saturated Fat"
- Centers for Disease Control and Prevention: "Only 1 in 10 Adults Get Enough Fruits or Vegetables"
- PEN Nutrition: "Diet Composition - Alkaline Diet"
- National Institutes of Health: "Magnesium"