What is the "alkaline diet" and why is it so popular?
The alkaline diet (or "pH diet") claims that certain foods make your body "acidic," supposedly promoting diseases like cancer, osteoporosis, or chronic fatigue. According to its proponents, consuming "alkaline" foods (vegetables, fruits, nuts) and avoiding "acidic" ones (meat, dairy, grains) would alkalize your blood and prevent or even cure cancer.
This theory is extremely popular on social media and has been promoted by celebrities, wellness influencers, and supplement sellers. The problem: it has no real scientific basis.
⚠️ Why This Myth Is Dangerous
Believing you can "alkalize your body" to prevent cancer can lead to:
- Rejecting validated medical treatments
- Spending money on useless products (alkaline water, pH supplements)
- Restrictive diets with no real benefit
- False sense of security against a serious disease
Blood pH: How It Really Works
Blood pH is a critical parameter that the body maintains in an extremely narrow range: 7.35 to 7.45 (slightly alkaline). This control is so important that deviating from that range is a medical emergency called acidosis or alkalosis.
Three systems regulate blood pH:
- Chemical buffers (bicarbonate, phosphates, proteins) neutralize acids or bases instantly.
- Respiration: the CO₂ you exhale regulates pH by forming carbonic acid in blood.
- Kidneys: excrete acids or reabsorb bicarbonate as needed (slower but very powerful process).
Key conclusion: Diet cannot significantly change your blood pH. If it did, you'd be in the ER, not feeling "more energized."
Important fact: What foods can change is urine pH. A diet rich in animal protein can make your urine more acidic (pH 5-6), and one rich in vegetables more alkaline (pH 7-8). But urine pH does not reflect blood pH nor affect cancer risk.
Do Cancer Cells Thrive in Acidic Environments?
This is the core of the myth. The truth has nuances:
Yes, cancer cells create an acidic microenvironment around them. This is due to their altered metabolism (Warburg effect): even in the presence of oxygen, they prefer to ferment glucose to lactate, acidifying the extracellular space.
But: