Our guts are the same as they were decades ago, but something has changed - more and more people eat enough, yet still lack nutrients. Nutritionist Fatima Hapon points out that the problem isn't digestion, but lifestyle, and breaks it down into four factors.

The first is the rise in diagnosed digestive problems - celiac disease, inflammatory bowel diseases, SIBO, gastritis - conditions that in some people really do reduce absorption. The second is the increased use of medications: so-called proton-pump inhibitors (omeprazole and similar) can interfere with the absorption of vitamin B12, iron, calcium and magnesium. A cure for one thing, a hole for another - the classic story of modern medicine.

The third factor is less sun. We spend more and more time indoors, and that leads to a widespread deficiency of vitamin D. The fourth - and perhaps the most important - is restrictive or unbalanced diets, plus more and more ultra-processed food that delivers calories but not vitamins, minerals and fiber.

"Many people have a diet rich in calories but poor in nutrients," says Hapon. A person who takes in 2,000 calories a day can still end up short on omega-3 if they don't eat enough oily fish. A simple but uncomfortable truth: a full plate doesn't mean a nourished body.

Experts note that the most common deficiencies are in vitamin D, magnesium, iron, zinc and omega-3. Supplements can help when tests show a deficiency - but they remain a supplement, not a substitute for a balanced diet and healthy habits. In other words, there's no pill that replaces what we've forgotten to eat.