One in eight Irish people has a vitamin D deficiency, according to research conducted by UCC scientists.
Across Europe, the prevalence of vitamin D deficiency is 13 per cent, the study published in the American Journal of Clinical Nutrition finds.
Up to 40 per cent of people in the countries surveyed have vitamin D levels which are not sufficient to support good bone health, according to Prof Kevin Cashman and Prof Mairead Kiely of UCC's centre for nutrition research.
The information provided in the study of almost 56,000 people in 18 countries is critically important for public health authorities across Europe, they say.
Severe vitamin D deficiency causes rickets in children and osteomalacia, or softening of the bones, in adults. It may also increase the risk of many other chronic non-bone related diseases.
The study shows up to a range of 18 to 65 per cent of dark-skinned people in the UK, Norway and Finland were vitamin D deficient - much higher than for the white populations in those three countries.
In Ireland, the authors estimate that 500,000 people, or 12 per cent of the population, have vitamin D deficiency.
The UCC team says it is developing food-based strategies to deal with the problem, including the provision of vitamin D-enhanced foods such as bread, mushrooms, cheese, fish, pork, beef and eggs.
“While sunlight is a key provider, it is not strong enough during winter months to allow skin to make vitamin D,” said Prof Cashman.
“Even in summer, public health advice suggests limiting unprotected sun exposure due to important concerns about skin damage and cancer. The alternative source of vitamin D is dietary supply, however the amount in the diet of many Europeans has been shown to be low. Thus, additional supplies are required in the diet.”