Health · Healthcare & Policy · 3 hrs ago
Watchdog warns at-home vitamin D tests may give unreliable results
Which?
found that five rapid home vitamin D tests gave varying results when compared with a laboratory blood test.
The tests cost around £8 each and were used by the same person on the same day as the lab test.
The laboratory result showed sufficient vitamin D, while the rapid tests produced results ranging from deficient to sufficient.
In the UK, vitamin D deficiency is common, and levels can be affected by limited winter sunlight, diet and age.
Conflicting results could cause worry or false reassurance, lead people to buy high-dose supplements they do not need, or leave a genuine deficiency untreated.
Taking too much vitamin D over time can raise calcium levels in the blood, while deficiency can affect calcium absorption and increase osteoporosis risk.
The MHRA is reviewing rules for self-tests; Which?
advises people concerned about their levels to consult a qualified health professional rather than rely on a rapid home test alone.
Which? found significant variation between five at-home vitamin D tests and a laboratory blood test.
The tests gave results ranging from sufficient to deficient, while the laboratory test showed a sufficient level.
Which? warned that unreliable results could cause unnecessary worry, false reassurance or inappropriate use of high-dose supplements.
The Medicines and Healthcare products Regulatory Agency said it was reviewing regulations for self-tests.
Which? advised people concerned about their vitamin D levels to consult a qualified healthcare professional.
- Who
- Which? tested the kits, and the Medicines and Healthcare products Regulatory Agency is reviewing regulations.
- What
- An investigation found significant variation between rapid at-home vitamin D test results and a laboratory test.
- When
- The tests were taken on the same day; the article was published on 30 October 2026.
- Where
- The tests were widely available in the UK.
- Why
- Which? said unreliable results could worry or falsely reassure consumers, or lead them to take unnecessary high-dose supplements.
This story does not have two clearly opposing sides.
A researcher’s results from five rapid tests were compared with a laboratory blood test.
Which? shared its findings with the Medicines and Healthcare products Regulatory Agency.
The regulator confirmed it was reviewing existing regulations, with proposed changes intended to raise standards for self-tests.
- Number of rapid tests
- Five
- Cost
- Around £8 each
- Laboratory result
- Vitamin D levels within a sufficient range
- Sufficiency threshold
- Above 50 nmol/L is generally considered sufficient
- Rapid test threshold
- 75 nmol/L for a sufficient level
- Regulator
- Medicines and Healthcare products Regulatory Agency
What people are saying
People turn to at-home health checks for peace of mind and as a way of managing their own health so it is deeply concerning that tests sold by major high street brands and online gave completely contradictory results.
An inaccurate result risks driving people to spend money on potentially harmful high-dose supplements, or leaving a genuine deficiency untreated.