Researchers at the German Cancer Research Center are advocating the systematic fortification of foods with vitamin D. Their model calculations show that the addition could prevent approximately 130,000 cancer-related deaths in Europe.
Vitamin D is considered a booster of the immune system. In a new study, researchers from the German Cancer Research Center (DKFZ) now show that the vitamin helps reduce cancer mortality. Researchers have found that foods in 34 European countries are fortified with vitamin D, preventing approximately 27,000 cancer deaths a year. According to model calculations, if all countries enriched food with sufficient vitamin D, about 130,000 of all cancer deaths in Europe could be prevented. That would be about nine percent. Cancer researchers are therefore calling for the systematic fortification of foods with vitamin D.
However, vitamin D supplementation alone would probably not prevent cancer, says Tobias Niedermaier, a member of the study, but only cancer deaths. In an interview, a cancer researcher explains what makes this difference.
What do we know about the relationship between vitamin D intake and cancer? How does vitamin D prevent this?
Niedermaier: Vitamin D does not reduce the risk of cancer, but it reduces the risk of dying from cancer. It has various effects on the immune system and essentially has an immunomodulatory effect. It suppresses carcinogenic factors, so-called oncogenes and chronic inflammatory reactions. It is assumed that the multiple effects of vitamin D on the entire immune system and especially on cancer cells increase the probability of cancer survival. Always in addition to established therapies, by no means as a substitute.
The immune system also plays a vital role in killing the cancer cells that occur in our body every day. Does vitamin D not support the immune system in this daily struggle and does it act preventively?
Niedermaier: This cannot be ruled out, but there are not enough data to suggest that vitamin D supplementation reduces the risk of cancer. However, there are plausible reasons to believe that a reduction in cancer risk, although it exists, has not been found in previous studies. This includes, for example, the fact that control groups often also took vitamin D or that vitamin D was administered in the wrong form, for example in insufficient doses or in very high monthly doses instead of daily small doses.
What was the basis of your investigation?
Niedermaier: The cornerstone was a meta-analysis of randomized trials, according to which the administration of vitamin D in the form of 400 international units per day reduces cancer mortality by eleven percent.
But certainly not all studies have reached these eleven percent?
Niedermaier: No. For example, it was 15 percent in the study of 800 units per day and 17 percent in the study of 2,000 units per day. Thus, cancer mortality tended to decline more sharply in studies with higher daily doses. 400 units is a size that could realistically be achieved by enriching food.
The products have been shown in studies, why do you advocate food fortification with vitamin D?
Niedermaier: I recently published a study with colleagues, for which we looked at the literature on accumulation and serum levels. The question was: how much will the level of vitamin D in the serum increase when consuming fortified foods? We found that the extent of the increase in serum was virtually identical to the increase in serum from studies that administered 400 units per day in tablet form. Our conclusion: If the food is adequately fortified with vitamin D, an increase in serum serum similar to that achieved with vitamin supplements can be achieved.
But is strengthening food the better way?
Niedermaier: Only a minority of the population takes vitamin D tablets. By enriching food, people would get out of vitamin D deficiency almost automatically. Like iodinated table salt, it has long been a common practice and has significantly reduced the previously widespread iodine deficiency and its consequences. It would be an easier, cheaper and more effective way to improve vitamin D levels in the population.
Adding something to the finished product is easy. But if I consciously eat it healthy, I don’t pour vitamin D into broccoli.
Niedermaier: That is right. But you can enrich a variety of foods that are the absolute basis that everyone consumes or should consume: orange juice, bread, milk, yogurt, oatmeal, cereals… It’s not that you can enrich everything, because also processing and preparation is vitamin D lost. But the supply of suitable food is large enough to reach everyone.
The press release cites the United States, Canada and Finland as examples of countries where this is already happening. Are the “you” three or how common is enrichment?
Niedermaier: It is not particularly widespread in Europe. The only countries that are significantly enriching are Finland and the United Kingdom, to a lesser extent Iceland and Sweden. In addition, there is no country that is systematically enriched.
What conclusions can you draw from where vitamin D was added to food?
Niedermaier: There is a study comparing serum levels in Finland between 2000 and 2011. Of the 6,000 Finns in the study, only 44 percent had sufficient vitamin D levels in 2000 with serum levels above 50 nanomolar per liter. Milk, dairy products, margarine, orange juice and cereals have been systematically enriched there with vitamin D since 2003. And in 2011, more than 90 percent were adequately supplied with vitamin D. This shows that even in a country with long dark winters, food fortification can D significantly reduce the spread of deficiency. It is well known that fortification is effective.
Do you also have corresponding values for Germany?
Niedermaier: There is a study by the Robert Koch Institute with a representative group of the population across the seasons. About 30 percent were poorly cared for and another 31 percent had suboptimal care. 38 percent was sufficiently supplied, in any case on an annual average. This, of course, fluctuates, with about 50 percent being insufficiently supplied in winter and less than 20 percent adequately supplied. Regarding vitamin D intake, there is still much room for improvement in Germany.
For humans, sunlight is the main source of vitamin D production, little of food …
Niedermaier: Exactly. The problem is that most of the population in Germany is deficient in vitamin D or at least a suboptimal supply during the year. The sun’s rays are not intense enough in winter and you should protect yourself from the sun in summer as well. The golden mean is right. If you are trying to expose yourself to the sun, as many parts of your body as possible should be exposed to the sun, but not for too long so that you do not get burned. The duration varies depending on the skin type and season, which is not generally the case.
They said that the more vitamin D you give, the better the results …
Niedermaier: I would assume that with 400 units a day, the potential is not yet exhausted. If someone takes 400 units a day through food, including systematically fortified ones, there is still the potential for a few percentage points to further reduce mortality if, for example, someone takes another 1000 units a day through pills.
Is there a risk of overdose?
Niedermaier: Of course, you should not exaggerate. Up to 4,000 units per day is considered safe. Sunlight cannot be overdosed, the body stops production in time when exposed to high levels. Overdose of dietary supplements is theoretically possible. In practice, this may happen several times a year. There are very highly enriched preparations, 20,000 units in a capsule. It is then recommended to take one of these capsules every 20 days. If you take one such capsule – or even several – a day, it is quite possible that problems will occur. 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 amount, there is no risk of overdose.