Many argue that blood pH is “always constant” because it is tightly regulated by homeostatic mechanisms. But such claims often stop at the assumption without showing how exactly these mechanisms work, or under what conditions they might fail.

Let’s compare this with blood pressure. Our body works hard to keep blood pressure in a normal range. Yet, we know from data that diet (e.g., sodium intake), kidney function, and vascular flexibility all influence blood pressure. It is not always constant — otherwise, no one would suffer from hypertension or hypotension.

The same applies to blood pH. While mechanisms exist (buffer systems, kidney function, respiration), they are not perfect. Kidney performance, for example, naturally declines with age. Hydrogen ions (H⁺) and bicarbonate ions (HCO₃⁻) are key players. If the diet is low in bicarbonate-rich foods (natural fruits and raw vegetables), excess H⁺ cannot always be neutralized effectively.

This is why blood pH can shift. The normal range is about 7.35–7.45. Even small deviations outside this window — acidosis (lower) or alkalosis (higher) — have major consequences. The very existence of these medical terms proves that blood pH can change. Venous blood gas (VBG) analysis, a direct measurement, shows variations in humans from ~6.5 (fatal acidosis) to ~7.6 (fatal alkalosis), with moderate to high imbalances linked to disease risk.

So the question is:

• Do you believe diet has a measurable role in blood pH regulation?
• Could chronic dietary patterns — particularly acidogenic modern diets — contribute to subtle but clinically relevant shifts in blood pH over time?

I’d love to hear thoughts, data, or experiences from colleagues working in nutrition, physiology, or clinical medicine.