What Are the Side Effects of the Alkaline Diet?

December 21, 2025 •

4 min read

The human body’s intricate regulatory system makes altering blood pH with food nearly impossible, a reality that debunks the core premise of this eating plan. Consequently, the side effects of the alkaline diet are primarily linked to its restrictive nature rather than its stated purpose.

Quick Summary

The alkaline diet's strict restrictions can lead to serious nutritional deficiencies, financial costs, and an unhealthy relationship with food, all while failing to alter blood pH effectively.

Key Points

Nutrient Deficiencies: Restricting food groups like meat, dairy, and certain grains can lead to inadequate intake of protein, calcium, iron, and vitamin B12.
Blood pH is Unaffected: The core scientific claim is false; the body's pH is tightly regulated by internal mechanisms and is not altered by dietary choices.
Psychological Strain: The diet's restrictive rules and 'good vs. bad' food mentality can lead to stress, anxiety around food, and potentially disordered eating.
Financial and Social Costs: Sourcing specific, fresh foods can be expensive and time-consuming, while the diet's limitations can hinder social dining experiences.
Not for Everyone: Individuals with pre-existing conditions like kidney disease or heart problems, and vulnerable groups like children and pregnant women, should avoid this diet unless supervised by a doctor.

The Unproven Science Behind the Alkaline Diet

At its core, the alkaline diet operates on the scientifically unproven theory that consuming specific 'alkaline-forming' foods can alter the body's pH balance to improve health and prevent disease. In reality, the body's pH is tightly regulated by the kidneys and lungs, maintaining a narrow, slightly alkaline range (pH 7.35–7.45) in the blood. If this delicate balance were to shift significantly, it would indicate a serious, life-threatening medical condition, not a dietary issue. While diet can influence urine pH, this is simply the body's natural waste-filtering process and has no bearing on the blood's pH. The side effects of the alkaline diet, therefore, do not come from a dangerous shift in body chemistry, but from the flawed and restrictive nature of the diet itself.

Significant Risks of Nutritional Deficiencies

Perhaps the most significant side effect of a restrictive alkaline diet is the potential for nutritional deficiencies. Because the diet categorizes many protein-rich foods, dairy, and whole grains as 'acidic' and restricts or eliminates them, followers can miss out on critical nutrients.

Protein Deficiency

Causes: Strict adherence to the diet can lead to inadequate protein intake, as meat, dairy, and often legumes and soy are limited or forbidden.
Effects: Insufficient protein can lead to a loss of muscle mass, decreased immune function, and a reduced capacity for tissue repair.

Calcium Insufficiency

Causes: Dairy products like milk and cheese are a primary source of easily absorbed calcium but are often restricted. Some plant sources of calcium, like spinach, contain compounds that hinder absorption.
Effects: Low calcium intake is a significant risk factor for bone health issues, particularly for older adults, and can increase the risk of osteoporosis over time.

Vitamin and Mineral Deficiencies

Causes: Eliminating entire food groups can also result in deficiencies in other essential nutrients.
Effects: A shortage of Vitamin B12, found predominantly in animal products, can lead to nerve damage and anemia. Restricting certain foods can also cause inadequate intake of iron, zinc, and other vital minerals.

Psychological and Lifestyle Challenges

Beyond nutritional concerns, following the alkaline diet can have considerable mental, emotional, and social side effects.

Mental and Emotional Strain: Categorizing foods as 'good' or 'bad' based on an unfounded premise can lead to stress, fear around food, and contribute to or trigger disordered eating patterns.
Social and Financial Barriers: The diet’s restrictive nature can be socially limiting, making it difficult to eat at restaurants or with friends. Following it often requires careful meal prep and sourcing specialized ingredients, which can be both time-consuming and expensive.
The Yo-Yo Effect: The diet is notoriously difficult to maintain long-term due to its strictness. When individuals return to their regular eating patterns, they are susceptible to regaining lost weight and potentially more, leading to a frustrating yo-yo cycle.

Contraindications and Health Risks

For certain individuals, the alkaline diet poses significant health risks and should be avoided.

Kidney Disease: While some adaptations may be prescribed for patients with existing kidney disease, the general restrictive nature of the diet, particularly concerning protein, can be dangerous without strict medical supervision. The kidneys are responsible for regulating the body's pH, and altering a patient's diet without expert guidance is unwise.
Heart Conditions: Individuals with certain heart conditions or those on medications affecting potassium levels should approach the diet with extreme caution. Excessive fluctuations in electrolyte intake can be dangerous.
Children and Pregnant Women: The elimination of nutrient-dense food groups like dairy and meat makes the diet inappropriate and unsafe for children and pregnant women, whose nutritional needs are critical for growth and development.

Alkaline Diet Claims vs. Scientific Reality

To better understand the true nature of the alkaline diet's side effects, consider this comparison between its claims and the scientific facts:


Alkaline Diet Claims	Scientific Reality
Changes blood pH to fight disease.	Blood pH is tightly regulated by the kidneys and lungs and cannot be altered by food intake.
Boosts bone health by preventing calcium loss.	Restricting dairy and protein can actually lead to calcium and protein deficiencies, which may harm bone health over time.
Improves overall health by alkalizing the body.	Any health benefits observed are likely due to the diet's emphasis on unprocessed, whole foods, not the mythical pH balancing effect.
Is easy to follow for improved wellness.	It is highly restrictive, difficult to maintain, and can cause nutritional deficiencies and stress about food.

Conclusion: A Balanced Perspective

The alkaline diet is an eating plan built on a flawed scientific premise, and its primary side effects are linked to its highly restrictive nature rather than its intended purpose. While its emphasis on fruits and vegetables can be a healthy aspect, the severe limitation of nutritious protein, dairy, and whole grains creates significant risks for nutritional deficiencies. For most people, a well-balanced diet containing a variety of whole foods, rather than a restrictive, pH-focused regimen, provides the most substantial and sustainable health benefits. Those considering the alkaline diet, especially those with pre-existing health conditions like kidney or heart disease, should consult a healthcare professional or registered dietitian to ensure their nutritional needs are met safely. For further evidence-based guidance on healthy eating, resources like the Cleveland Clinic offer expert nutritional advice. What Is the Alkaline Diet, and Is It Safe?

Frequently Asked Questions

No, this is a central myth of the diet. Your body has a robust internal system involving the kidneys and lungs that keeps your blood pH within a very narrow, slightly alkaline range. Diet has no significant or lasting effect on this process.

Common deficiencies can include protein, calcium, vitamin B12, and iron, due to the diet's restriction or elimination of nutrient-dense foods like meat, dairy, and some grains.

People with existing kidney disease, heart conditions, or those taking certain medications should avoid this diet. It is also considered unsafe for children and pregnant women due to the risk of nutritional gaps.

While it may initially lead to weight loss due to reduced calories, its restrictive nature makes it difficult to sustain. Many people experience a yo-yo effect, regaining weight after stopping the diet.

Any reported benefits are more likely linked to the diet’s emphasis on fruits and vegetables, not its supposed pH effects. In fact, restricting dairy can increase the risk of poor bone health due to calcium deficiency.

No. The claims about the benefits of alkaline water are not supported by science. The body naturally regulates its own pH, and consuming expensive alkaline water offers no proven advantage over regular filtered water.

Feeling better often results from simply eating more whole foods like fruits and vegetables while cutting out processed foods, sugar, and alcohol. This is a general benefit of healthy eating, not a result of alkalizing the body.