Nutrient deficiency: Why healthy eating alone isn't always enough

Dr. Charalampos Romanos · April 14, 2026 · 5 min read

A paradox I see repeatedly in my Zurich practice: patients who eat very consciously, healthy salads, whole grains, fish — and yet have nutrient deficiencies. It's not just a matter of diet. It's a matter of absorption, storage capacity, gene expression, and lifestyle factors. Simply "eating better" is often not enough.

Why the soils are the problem

Modern agriculture has depleted the soils. Vegetables and fruits grown today often have 50-75% fewer minerals than 50 years ago. This is not your fault as a patient — this is a global soil problem. An apple today has less magnesium, zinc, selenium than your grandmother's apple.

Malabsorption — The underestimated problem

Low stomach acid is common, especially with ageing. Many older patients take proton pump inhibitors, which restrict the absorption of B12, calcium, iron. Gut bacterial dysbiosis — an increasingly common problem — also impairs nutrient absorption. Nice vegetables are useless if the gut can't absorb them.

Genetic polymorphisms and nutrient metabolism

Some people have genetic variants (MTHFR polymorphisms, for example) that affect how efficiently they metabolise folate. Some people have variants in vitamin D receptors. This means: the same amount of nutrient is absorbed and used differently by different people. Diet alone cannot compensate for this.

Endurance athletes and increased consumption

People with high physical activity consume more nutrients. Training programmes increase the need for magnesium, zinc, iron, B vitamins. A runner who runs 80 km per week and eats normally will probably develop deficiencies. This requires targeted supplementation.

Stress and magnesium depletion

Chronic stress depletes magnesium. This is biochemically established. Many of my patients with stress and poor sleep are simply magnesium-depleted. Supplementation can work wonders. Cortisol and stress create an environment that promotes nutrient depletion.

Smart supplementation — You don't need everything

I am not an advocate of arbitrary mega-supplementation. That's a waste of money and can even be harmful (e.g., too much iron). But targeted supplementation based on tests makes sense. Vitamin D in winter, B12 for vegetarians, magnesium for stress patients — this is rational, individualised functional medicine.