Taking Vitamin D but it's not improving your levels?
Perhaps you’ve been taking a good dose of quality vitamin D for months, years even. But your blood test barely budges.
Here’s why that happens — and why 'just take more' isn’t always the answer.
Absorption problems – If you have gut issues like coeliac, Crohn’s, bile acid insufficiency, or even just take your vitamin D without enough dietary fat, you might not absorb it well.
Genetic factors – Some people have genetic variants that affect vitamin D transport or conversion — meaning you need more personalised dosing and cofactors.
Stored in fat tissue – Vitamin D is fat-soluble, so in higher body fat it can get “trapped” instead of circulating.
Chronic illness or inflammation – Autoimmune conditions, infections, and inflammatory states can change how your body uses and converts vitamin D, keeping blood levels low.
Low magnesium – Magnesium is essential for activating vitamin D. Without it, your levels can stall no matter how much you take.
Medications – Certain drugs (anticonvulsants, steroids, cholesterol-lowering meds) can interfere with vitamin D absorption or speed up breakdown.
Liver or kidney function issues – Both organs are needed to convert vitamin D into its active forms. If they’re under-functioning, levels can stay low.
If your vitamin D levels aren’t improving, you need to uncover why, which means looking at gut health, cofactors like magnesium, genetics, medications, and inflammation.