In some countries, foods are fortified with vitamin D. It is estimated that this prevents around 27,000 cancer deaths per year. “According to our calculation models, if all countries fortified foods with adequate amounts of vitamin D, around 130,000 or around 9% of all cancer deaths in Europe could be prevented,” says Hermann Brenner, head of the study. . Tobias Niedermaier, researcher in the Department of Clinical Epidemiology and Aging Research at the German Cancer Research Center in Heidelberg, explains why.
What do we know about the connection between vitamin D intake and cancer? How does Vitamin D counteract this?
Vitamin D does not reduce the risk of cancer, but it does reduce the risk of dying from cancer. It has a variety of effects on the immune system and basically has an immunomodulatory effect. It suppresses the factors that favor cancer, the so-called oncogenes and chronic inflammatory reactions. The assumption is that the multiple effects of vitamin D on the entire immune system and especially on cancer cells increase the chances of cancer survival. Always in addition to established therapies, not in any way substitute.
The immune system also plays a crucial role when it comes to killing cancer cells that occur in our body every day. Does vitamin D not support the immune system in this daily struggle and in this sense does it have a preventive effect?
This cannot be ruled out, but there is insufficient data to suggest that vitamin D supplementation reduces the risk of cancer. However, there are plausible reasons to assume that a reduction in cancer risk, even if it exists, has not been found by previous studies. This includes, for example, that comparison groups often also took vitamin D or that vitamin D was given in the wrong form, for example in insufficient doses or in very high monthly doses instead of small daily doses.
What was the basis of your investigation?
The cornerstone was a meta-analysis of randomized trials, according to which administration of vitamin D tablets in a dosage of 400 international units per day reduces cancer mortality by 11%.
But surely not all studies have reached this eleven percent?
No For example, in the study with 800 units per day it was 15%, in the study with 2000 units per day it was 17%. Cancer mortality therefore tended to decline more markedly in studies with higher daily doses. 400 units is the size that could realistically be reached with the food fortification.
Preparations have been provided in the studies, why do you advocate fortifying foods with vitamin D?
I had recently published a study with colleagues for which we had reviewed the literature on accumulation and serum levels. The question was, when you eat fortified foods, how much does your serum vitamin D level increase? We found that the range of serum elevations was virtually identical to the serum elevations in studies administering 400 units per day in tablet form. Our conclusion: If food is adequately fortified with vitamin D, serum levels can be increased in a similar way to those obtained with the administration of vitamin supplements.
But is fortifying food then the best way?
Only a minority of the population takes vitamin D tablets. Fortifying foods would get people out of their vitamin D deficiency almost automatically. Just like iodized table salt has long been commonplace and has greatly curbed the previously widespread iodine deficiency and its consequences. It would be a simpler, cheaper and more effective way to improve vitamin D levels in the population.
Adding something to a finished product is easy. But if I consciously eat healthy, I don’t sprinkle vitamin D on my broccoli.
Right. But you can fortify a number of foods that are absolute essentials that everyone consumes or should consume: orange juice, bread, milk, yogurt, oat milk, cereals. It’s not like you can fortify everything, because even vitamin D is lost through processing and preparation. But the range of suitable foods is wide enough to reach everyone.
The press release cites the United States, Canada and Finland as example countries where this has already been done. Are they “the” three or how common is it to fortify?
It is not particularly widespread in Europe. The only countries that are significantly enriching are Finland and the United Kingdom and, to a lesser extent, Iceland and Sweden. Other than that, there is no country that would systematically get rich.
What conclusions could you draw from where vitamin D was added to food?
There is a study that compared serum levels in Finland in 2000 and 2011. Of the 6,000 Finns involved in the study, only 44% had an adequate intake of vitamin D with serum levels above 50 nanomoles per liter in 2000. Milk , dairy products, margarine, orange juice and cereals have been systematically enriched with vitamin D since 2003. And in 2011, more than 90 percent were sufficiently supplied with vitamin D. This shows that even in a country with long, dark winters, food Fortifying with vitamin D can greatly reduce the spread of a deficiency. It is well known that fortification is effective.
Do you also have corresponding values for Germany?
There is a study by the Robert Koch Institute with a representative group of the population through the seasons. About 30% were poorly cared for and another 31% had suboptimal care. 38 per cent were adequately supplied, in any case on an annual average. Of course, this varies, in the winter around 50 percent are inadequately supplied and less than 20 percent are adequately supplied. There is still a lot of room for improvement in Germany when it comes to vitamin D intake.
For humans, sunlight is the main source of vitamin D production, not so much from food …
Exactly. The problem is that most of the population in Germany has a vitamin D deficiency throughout the year or at least a suboptimal supply. Because the sun’s rays are not intense enough in the winter and you should protect yourself from the sun’s rays even in the summer. The golden mean is right. If you are attempting to expose yourself to the sun, as many parts of your body as possible should be exposed to the sun, but not too long to avoid sunburn. The duration varies according to the type of skin and the season, which cannot be said in general terms.
They say the more vitamin D is given, the better the results will be …
I assume that with 400 units per day the potential is not yet exhausted. If someone takes 400 units per day from food, including systematically fortified ones, there is still the potential for a few percentage points of further reduction in mortality if, for example, they take another 1000 units per day via pills.
Is there a risk of overdose?
Of course, you shouldn’t overdo it. Up to 4000 units per day are considered safe. You cannot overdose on sunlight, the body shuts down production in good time if exposed to high levels. An overdose from food supplements is theoretically possible. In practice, this happens perhaps a handful of times a year. There are very highly fortified preparations, 20,000 units in one capsule. The recommendation is therefore to take one of these capsules every 20 days. If you take one of these capsules – or even more – per day, it is entirely possible that you have problems. Too much vitamin D leads to high levels of calcium in the blood, which can also be very dangerous. It is important to note that if the food is fortified in the usual quantities, there is no risk of overdose.
Thomas Röbke spoke with Tobias Niedermaier.
Find out more: This article first appeared on helmholtz.de.