Gains in life years from vitamin D supplementation in cancer?

Vitamin D:

As is already known, you can produce vitamin D in your own body with the help of sunlight (i.e. UV light). Also various foods, e.g. fatty fish, avocados or porcini mushrooms, offer a higher content of vitamin D. As an alternative, the vitamin is now also marketed in concentrated form as tablets, drops, etc., e.g. Divisun, Oleovit D3 drops.

Effect of vitamin D shown in tabular form:

In this, vitamin D is studied and used in various fields. Especially the prevention of cancer is controversially discussed. The DGE (i.e. German Society for Nutrition) published in 2015 an overview table in which preventive effects of vitamin D for certain diseases were evaluated. According to the DGE, the evidence for preventive vitamin D effects on cancer was generally insufficient.

According to the table, for colorectal cancer, any risk reduction by biologically active vitamin D intake or its precursor (i.e., calcidiol) was noted.

Other cancers showed:

However, previous meta-analyses of randomized controlled trials of vitamin D intake in relation to cancer incidence and mortality incidence (total) yielded inconsistent results. Most studies showed generally lower doses of vitamin D with less than 1100 international units per day (1 IU corresponds to 0.025 µg).
Die vom Deutschen Krebsforschungszentrum analysierten Meta-Analysen haben dabei neuere randomisierte, kontrollierte Studien einbezogen, die auch höhere Dosen von Vitamin D-Einnahmen getestet haben. 

Meta-analyses:

Meta-analyses focus on inflammatory diseases, diabetes mellitus, respiratory diseases and cancer.

Note: The meta-analysis of the German Cancer Research Center (DKFZ for short) does not deal with the prevention of cancer, but with the prognosis of a disease course. According to the DKFZ, the meta-analyses used high-quality randomized trials from around the world. However, the biological cause of the positive effect of vitamin D has not yet been investigated in detail.

studies specifically investigated:

According to the DKFZ, the results of the meta-studies are as follows:

1. vitamin D supplementation and total cancer incidence and mortality: a meta-analysis of randomized controlled trials.

• METHODS: The researchers examined the PubMed and Embase trial portals from inception to November 2018, and the results were summarized and calculated using a random-effects model based on relative risks and confidence intervals. For overall cancer incidence, 10 studies (6537 cases, 3-10 years follow-up, 54-135 nmol/l of achieved serum calcidiol) were used and for overall cancer mortality, five studies (1591 cases, 3-10 years follow-up, 54-135 nmol/l of achieved serum calcidiol) were used.
• Conclusion: According to the analysis, only all-cause cancer mortality (not cancer incidence) was significantly reduced by vitamin D intake in the randomized controlled trials.

2 The role of vitamin D supplementation for primary prevention of cancer: meta-analysis of randomized controlled trials

• Methods: Database searches were used to analyse whether vitamin D supplementation for at least three years is effective compared with placebo for the prevention of any disease. For individual data, those reporting cancer incidence or mortality were used. Primary outcome was cancer incidence and cancer-related mortality.
• CONCLUSION: According to researchers, without the primary goal of cancer prevention, the use of vitamin D could be recommended for the prevention of cancer mortality because it may reduce mortality after cancer is diagnosed - but supplementation has no effect on cancer-related incidence.

3 Vitamin D supplementation and total cancer incidence and mortality: a meta-analysis of randomized controlled trials

• Methods: here the researchers also examined the PubMedand Embasetrial portals from inception to November 2018. the result was calculated using a random effects model based on relative risks and confidence intervals. For overall cancer incidence, 10 studies (6537 cases, 3-10 years follow-up, 54-135 nmol/l of achieved serum calcidiol) were used, and for overall cancer mortality, five studies (1591 cases, 3-10 years follow-up, 54-135 nmol/l of achieved serum calcidiol) were used.
• CONCLUSION: According to researchers, the results of this meta-analysis showed that vitamin D supplementation would have reduced all-cancer mortality with significance, but not overall cancer incidence.

In these analyses, vitamin D intake showed a 13% reduction in cancer mortality over the follow-up period.

Conclusion:

In all meta-analyses, vitamin D supplementation showed significant results related to overall cancer mortality (13% reduction) but not cancer incidence. The randomized, controlled, and methodologically high-quality studies were conducted globally around the world. The DKFZ used the results of the meta-analyses and made a calculation for the effect in Germany. According to this calculation, vitamin D supplementation of all Germans over 50 years of age could potentially prevent up to 30,000 cancer-related deaths per year and add more than 300,000 years of life. However, the biological processes that are the reason for this reduction have not yet been precisely elucidated.

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