How much vitamin D should we take? - new Irish study gives clear guidance

We are all aware that we can benefit from taking Vitamin D supplements, particularly over the winter months. 

But with so many different brands and strength levels on the market, it can be difficult to know which one is best. 

And there are other factors to take into consideration, including skin tone, age and pregnancy.

Now for the first time, Vitamin D nutrition has been examined in terms of how people in Ireland aged 5 to 65 can achieve optimal intakes for long-term health.

A report on this research and guidance has been published by the Food Safety Authority of Ireland (FSAI).

Professor Kevin Cashman, Chair of the Public Health Nutrition Subcommittee that prepared the report explains why Vitamin D is so important.

“Vitamin D is involved in calcium metabolism and sufficient intake is essential for good bone health throughout the lives of children and adults,” he said. 

“It also contributes to the normal function of the immune system and maintenance of normal muscle function. 

“In certain life stages, it is important to ensure that we are not deficient in vitamin D. For example, during the teenage years when vitamin D facilitates the important gains in bone mineral mass, and during pregnancy where vitamin D is needed for the skeletal development of the foetus and to protect the mother’s bone health. 

“At all ages, people of darker-skinned ethnicity have higher vitamin D requirements because the increased content of melanin in darker skin reduces the body’s ability to make vitamin D from UVB rays from sunlight.”

Dr Pamela Byrne, CEO, FSAI welcomed the report clarifying optimal daily doses, current dietary intake and how Ireland can resolve this common nutrient deficiency.

“The weaker sunlight available from October to March in Ireland is not a source of vitamin D,” said Dr Byrne.

“People may be unaware that even on sunny days in winter, the sun’s rays are the wrong type for the production of vitamin D. As a result, we depend on our diets to supply this key vitamin, but levels of vitamin D are limited in our food supply. 

“This results in vitamin D deficiency being common among children and adults in Ireland. 

“We consider the prevention of vitamin D deficiency to be a public health nutrition priority and this report outlines how we can combat this deficiency through using both natural food sources of vitamin D and fortified foods along with appropriate doses of vitamin D supplements.”

Dr Byrne is calling on people to be mindful of the daily recommended dose and not to exceed this unless advised by a medical professional. 

“The tolerable upper limit intake level is 50 µg daily for children and 100 µg daily for adults, as declared by the European Food Safety Authority (EFSA),” she said.

“The recommended daily dose of 10 µg or 15 µg for children and adults, respectively, is overall a safe level of supplemental vitamin D, even when combined with vitamin D intake from diet and fortified foods.”

The report will now inform the Department of Health’s national guidelines on how to achieve optimal vitamin D nutrition in people aged 5 to 65 years. The report complements three previous FSAI reports which focussed on vitamin D nutrition for infants (first year of life), young children (aged 1 to 5 years) and older adults (aged 65 and older).

Optimum Dosage

- For healthy children (5 to 11 years) a daily vitamin D supplement containing 10 µg (400 IU) should be taken during extended winter (end of October to March) for those of fair-skinned ethnicity, and throughout the full year for those of darker-skinned ethnicity.

- For healthy teenagers and adults (12 to 65 years) a daily vitamin D supplement containing 15 µg (600 IU) should be taken during extended winter (end of October to March) for those of fair-skinned ethnicity, throughout the full year for those of darker-skinned ethnicity, throughout the full year for those who are pregnant, regardless of ethnicity.