Vitamin D is one of the most studied and researched for several years in relation to people's health. There are studies showing that normal blood levels of this vitamin have positive effects on tuberculosis, AIDS, COVID-19, flu, sepsis, viral hepatitis, dengue and cancer, reflecting a better response to treatment, fewer complications and fewer deaths. Although several vitamins and micronutrients have been studied in cancer patients, none have shown such promising results as vitamin D.
Vitamin D, considered a pre-hormone by many researchers, acts in the regulation of calcium and bone metabolism, along with the parathormone. It is present in food sources such as fish, eggs, mushrooms, among others, being converted in the skin by the action of UVB rays in the form of ergocalciferol (D2) into cholecalciferol (D3). Therefore, its absorption depends on a healthy diet and adequate sun exposure. In Brazil, we have a high incidence of skin cancer, so sun exposure requires care such as the use of sunscreen, whose action reduces the conversion of vitamin D, but it should be used as an important prevention factor in this type of cancer.
It is present in food sources such as fish, eggs, mushrooms, among others, being converted in the skin by the action of UVB rays in the form of ergocalciferol (D2) into cholecalciferol (D3). Therefore, its absorption depends on a healthy diet and adequate sun exposure. In Brazil, we have a high incidence of skin cancer, so sun exposure requires care such as the use of sunscreen, whose action reduces the conversion of vitamin D, but it should be used as an important prevention factor in this type of cancer.
Vitamin D deficiency is present worldwide, reaching 90% of the population in some places. The main risk groups for this deficiency are the elderly, people over 60 years old, whose skin capacity to convert is reduced; the obese, people with a body mass index > 30 kg/m2, because it is sequestered by the fatty tissue; and black people, because the greater amount of melanin in their skin makes it difficult to convert this vitamin.
In Brazil, despite having sun all year round, there are more and more people with vitamin D deficiency. This may be associated with the increase in the number of obese and elderly people, respectively, approximately 41 million and 38 million Brazilians, as well as to use of sunscreen and less daily sun exposure. According to the Brazilian Society of Endocrinology and Metabolism, the diagnosis of vitamin D deficiency varies according to the group of people and occurs as follows:
1. ≥ 20 ng/ml is desirable for the healthy general population;
2. 30 - 60 ng/ml is recommended for risk groups, such as the elderly, pregnant women, patients with osteomalacia, rickets, osteoporosis, secondary hyperparathyroidism, inflammatory diseases, autoimmune diseases, chronic renal and pre-bariatric diseases;
3. 10 - 20 ng/ml is considered low, with a risk of increased bone remodeling and, therefore, loss of bone mass, in addition to the risk of osteoporosis and fractures;
4. ≤ 10 ng/ml is very low and at risk of evolving with defects in bone mineralization such as osteomalacia and rickets.
In people with cancer, chemotherapy reduces the absorption of vitamin D by the digestive system, this also occurs when there is surgery in the gastrointestinal tract where part of it is removed because of the tumor. In addition, these people are instructed to have less exposure to the sun and find it difficult to eat properly, so they have less absorption of the vitamin. Although there are studies saying that serum levels of vitamin D ≥ 40 ng/ml prevent some types of cancer, this is not a consensus, because it does not occur in all scientific studies.
Most studies show that it is involved in increasing tumor sensitivity to chemotherapy and radiotherapy, contributing to a greater response to treatment and increased survival. This positive action of vitamin D in cancer patients occurs because it inhibits carcinogenesis, delays tumor progression, promotes cell differentiation, inhibits the proliferation of cancer cells, has anti-inflammatory, immunomodulatory, pro-apoptotic and anti-angiogenic effects, it decreases the invasiveness of the tumor and the propensity for metastasis.
In terms of vitamin D supplementation in cancer patients, 2 surveys stood out in the American Congress of Clinical Oncology, one of the most respected in the world. The first study showed that patients with metastatic colon cancer who were supplemented with vitamin D had longer survival than those who did not take the vitamin. The second, a study of 79,000 cancer patients followed up for four years, found an increase in survival in patients who received vitamin D supplementation. the study, the lead researcher advises oncologists to supplement vitamin D for their patients.
Another problem associated with the treatment and cancer itself is the loss of bone mass, a study with women with breast cancer supplemented with vitamin D showed less bone loss. This is because vitamin D plays an important role in bone metabolism.
Although vitamin D shows very interesting results for cancer patients, its supplementation should be guided by the physician and the oncology team. For both cancer and COVID-19, many people started taking very high amounts of this vitamin on their own, having problems with intoxication, which could lead to kidney failure and hospitalization. Therefore, the first step is its dosage in blood tests in the diagnosis of cancer, based on this result the doctor will decide on the need to prescribe or not vitamin D. In addition, the use of vitamin D does not exclude the usual treatment of cancer, it can be a tool of help, not a cure.
In conclusion, vitamin D can be used in cancer patients, with positive results in survival, response to treatment and loss of bone mass. However, your supplementation should always be monitored by the doctor, because it depends on your blood levels and diagnosis of deficiency. Always talk to your doctor before taking any vitamins.
References:
1. Maeda S et al. Recomendações da Sociedade Brasileira de Endocrinologia e Metabologia (SBEM) para o diagnóstico e tratamento da hipovitaminose DArq Bras Endocrinol Metab. 2014;58/5
2. Vaughan-Shaw VG et al. The effect of vitamin D supplementation on survival in patients with colorectal cancer: systematic review and meta-analysis of randomized controlled trials. Brit J Cancer 2020; 123:1705–1712
3. Chandler PD et al. Effect of Vitamin D3 Supplements on Development of Advanced Cancer. JAMA Network Open. 2020;3(11):e2025850
4. Akutsu T et al. Vitamin D and Cancer Survival: Does Vitamin D Supplementation Improve the Survival of Patients with Cancer. Curr Oncol Reports 2020: 22:62
Article published in FolhaMed on September 8, 2021
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