Did you know that having adequate levels of vitamin D helps reduce the risk of cancer? We explain its function in the human body and what its relationship is with this disease.
Vitamins are a group of substances necessary for cellular functioning, growth and normal development of our body. In fact, there are 13 essential vitamins, each with different particularities and tasks; vitamin D is one of them.
In the healthy population it is generally considered that 25OH D3 should be at values of 20 ng/ml (50 nmol/L) to be considered sufficient, however to maintain bone health the limit would be 30 ng/ml (75 nmol/L).
Epidemiological studies have shown that in geographical areas with greater exposure to UVB rays there is a lower incidence and mortality in certain types of cancer, including breast, colon, ovarian and prostate cancer. Vitamin D has demonstrated activity through the Vit D receptor (VDR) pathway on tumor cells and indirectly by regulating their behavior through the microenvironment of stromal cells, adipose tissue and inflammatory cytokines. Specifically on breast cancer and cell growth the VDR receptor is very important for its progression to metastasis and low levels of Vit D would be a facilitator of metastasis.
There is evidence of a lower incidence of breast cancer in women with levels of 25(OH) D3 considered adequate compared to deficient levels. Values below 20 ng/ml could be considered a modifiable risk factor for breast cancer.
Observational studies have been published that have shown a significant relationship between sun exposure and cancer incidence. In the 9-year prospective American study conducted by the National Institutes of Health (NIH)-AARP Diet and Health Study, an increased risk of melanoma of up to 22% was demonstrated, while the risk of lymphomas, colon, prostate or kidney cancer decreased between 10% and 17% among other types of cancers.
Regarding studies that have related serum levels of 25(OH) D3 and cancer, it is relevant to highlight a meta-analysis in which a reduction of up to 50% in the risk of colorectal cancer was demonstrated when Vit D levels were above 33 ng/ml with respect to values of 12 ng/ml. Evidence of a lower incidence of breast cancer in women with 25(OH) D3 levels considered adequate compared to deficient levels has recently been demonstrated in the study by McDonell et al.
Based on data from two clinical trials with 3,325 patients and a prospective cohort of 1,713 patients receiving calcium and vitamin D supplements and having their Vit D values analyzed every 6 months, the authors have demonstrated up to 82 % lower incidence of breast cancer at prospective follow-up of up to 4 years in women with 25(OH) D3 values between 20 ng/ml and 60 ng/ml compared to < 20 ng/ml. In addition, the authors themselves have demonstrated a correlation in breast cancer incidence and different Vit D levels, assuming a dose-response curve and have therefore considered Vit D deficiency as a modifiable factor for breast cancer risk.
Data from clinical trials aimed directly at demonstrating the efficacy of Vit D supplementation on cancer incidence have been inconclusive and have generated controversy on the subject. Thus, the VITAL study and related meta-analyses have not shown a lower incidence of cancer with Vit D supplementation, although lower mortality in the meta-analysis.
Hypotheses have been published to explain this failure to demonstrate the efficacy of vitamin D supplementation. These include methodological problems of patient inclusion, differences in race and population residence, methodology of analysis of 25(OH) D3 levels, permissibility of vitamin supplement intake and sun exposure, and especially, problems in analyzing the obese population.
Thus, in the VITAL study, patients with body mass index (BMI) below 25kg/m2 showed a significant reduction in cancer, while in other BMI categories this did not occur. Vit D has a high affinity for fatty tissue, so when administering Vit D supplements, overweight people need more supplementation to reach adequate levels of 25(OH) D3.
We invite you to practice self-care! Healthy habits, prevention and regular check-ups are key factors for health. Together we can reduce the impact of this disease.
Astorga Oncology Clinic. Always with you.
Source: Santiago Escobar Gómez, mastólogo.
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