Of the 23 D vitamin supplements analysed, only eight were within 20 percent of the advertised content, as required by the Finnish Food Safety Authority Evira, according to Tarja Nurmi of the university’s Institute of Public Health and Clinical Nutrition.
Researchers also tested three vitamin D sprays, of which only one met Evira’s criteria. The research did not cover oil-based products.
”Initially I thought there might be one or two products that clearly diverged from the product description, but it was quite a surprise that nearly 50 percent of the products researched contained clearly less vitamin D than claimed on the packaging,” said Nurmi.
D vitamin tablets are a food supplement, and not inspected before they go on sale.
"It has earlier been the case that supplements should have been analysed before a license for sale could be granted, but then the practice of other EU countries was adopted, where just a notification would suffice,” explained Nurmi.
Researchers found that the retail outlet or price had no relationship to the product’s quality. Products purchased at pharmacies were no more reliable than those found at health food stores or supermarkets.
Evira announced on Thursday afternoon that it will investigate the claims, starting with inspecting the research results of the University of Eastern Finland.
A spokesperson for the Food Safety Authority also said that any responsible retailer would remove the products from sale until their content description or content itself is altered.
Sunshine is the best source of vitamin D, but in northern latitudes the sun's rays are not strong enough to produce it for a portion of the winter.
Finnish health officials recommend supplements for children, with larger doses for those with darker skin.
This chart shows in green the brands that were within 20 percent of the advertised vitamin D content.