Vitamin D products should be controlled by pharmacies

The debate around vitamin D runs wild. According to research, too large amounts of vitamin D have more detrimental than beneficial effects, says Pentti Tuohimaa, Professor Emeritus of Anatomy at the University of Tampere.

Pentti Tuohimaa, Professor Emeritus of Anatomy at the University of Tampere, says that vitamin D should not be sold freely as a food supplement.

He would not make vitamin D a prescription drug, but it should be sold in pharmacies so that pharmacists could instruct their customers about the right dosage.

”It is astonishing that vitamin D is still classified as a food supplement. It works like a medicine and too large doses are harmful,” Tuohimaa says.

A vitamin D supplement is a prohormone which transforms into a hormone inside the body. As any other hormone, vitamin D has a specific optimal level. Both too small and too large amounts have a detrimental effect.

For this reason, Tuohimaa looks at the uproar caused by the analyses conducted at the University of Eastern Finland from another perspective. He is happy that the vitamin D content of the tested products was smaller, not larger than indicated by the product description.

“It surprised me that the vitamin level of one product was zero. On the other hand, this product was supposed to have the highest level of vitamin D, 125 micrograms, so it was quite lucky that the analysis showed no vitamin content. Unfortunately, in an analysis conducted by another laboratory, this product had the amount of vitamin D indicated by the package.”

Convincing results

According to Tuohimaa, the results from the University of Eastern Finland look convincing. The problem is that the laboratory they used is not accredited so the results are cast in a suspicious light.

“From the point of view of the manufacturers, the results are embarrassing, of course,” Tuohimaa says.

“I think it’s great that the University of Eastern Finland conducted this study because Evira, the Finnish Food Safety Authority, says it’s not their duty to conduct such analyses. It’s good to create pressure for the manufacturers of vitamin supplements.”

According to Tuohimaa, the officially recommended daily intake of vitamin D for adults in Finland is all right.

Instead, Tuohimaa is uneasy about the fact that the recommended daily dosage for children is 10 micrograms. He thinks this is too close to the dangerous amount, which for children is only 25 micrograms. For adults, the daily dose of vitamin D can be dangerous when it exceeds one hundred micrograms.

Too much vitamin D can cause poisoning.

Vitamin D raises the levels of calcium in the blood which can affect the muscles. If a person is constantly exposed to too high levels of vitamin D, the body can develop hypercalcemia which in extreme cases can lead to the serious malfunctioning of the cardiac muscles.

The controversy in the US divides opinions

The debate around vitamin D is heated in the United States . The Vitamin D Council supports ‘the more the merrier’ stance and bases its views mostly on the research result that older women have a smaller risk of bone fracture only with very high doses of vitamin D.

The Institute of Medicine (IOM) warns about the detrimental effect of excessive amounts of vitamin D. Tuohimaa agrees with IOM which has even based their opinion on Tuohimaa’s research results among others.

Not too much or too little

In 2005, Tuohimaa’s research group got the result that the risk of prostatic cancer was higher both among those men who got too little vitamin D and among those with high levels of vitamin D. This result has since been confirmed by nearly twenty other studies.

”What is most alarming is that total mortality from any kind of reason follows the same kind of a u-curve, so mortality increases with both low and high levels of vitamin D,” Tuohimaa says.

”The effect confirmed in cardiovascular diseases, cancer mortality and overall mortality are reason enough to take seriously the warning of not to take too much vitamin D.”

The beneficial effect of the proper amount of vitamin D has been proved in the most common types of cancer. Too much or too little of the vitamin increases the risk of cancer, a suitable level minimises the risk.

From the point of view of the individual, the effect is unfortunately marginal. Cancer cannot be completely prevented by taking vitamin D supplements. However, the effect of the vitamin becomes evident when large populations are studied.

More healthy years

Vitamin D is a key factor in regulating the human ageing process. In 2009, Pentti Tuohimaa’s research group published a result attesting to how sufficient dosages of vitamin D can postpone the occurrence of illnesses that come with ageing and increase the number of healthy years.

“If you can keep your levels of vitamin D on the optimal level your whole life, illnesses that come with ageing occur 2—7 years later than they would normally.”

Tuohimaa thinks that the sun is the best source of vitamin D and recommends that people in the Nordic countries should travel south for a week every winter.

“However, you definitely also need vitamin supplements in Finland. People seldom consume so much milk or dairy products that they would get a sufficient amount of vitamin D.”

Original text: Tiina Lankinen
Photograph: Teemu Launis
Translation: Laura Tohka

This story was originally published in Finnish in Aikalainen 16/2012