A critical review of studies on vitamin D in relation to colorectal cancer

Published on Friday, 01 December 2017

Abstract

Vitamin D intake has been hypothesized to reduce the risk of several types of cancer.

Vitamin D and its analogues have demonstrated anticancer activity in vitro and in animal models. However, the risk of colorectal cancer in relation to dietary vitamin D remains controversial.

A literature search was performed for articles on epidemiologic studies of vitamin D and colorectal cancer and the mechanisms involved.

Studies that combine multiple sources of vitamin D or examine serum 25(OH)D3 usually find that above-average vitamin D intake and serum metabolite concentrations are associated with significantly reduced incidence of colorectal cancer.

A number of mechanisms have been identified through which vitamin D may reduce the risk of colorectal and several other types of cancer.

Although studies that include vitamin D from all sources or serum 25(OH)D3 usually show significantly reduced incidence of colorectal cancer in association with vitamin D, analyses limited to dietary vitamin D tend to have mixed results.

The likely reason that dietary vitamin D is not a significant risk reduction factor for colorectal cancer in many studies is that dietary sources provide only a portion of total vitamin D, with supplements and synthesis of vitamin D in the skin in association with solar UV-B radiation providing the balance.

There is strong evidence from several different lines of investigation supporting the hypothesis that vitamin D may reduce the risk of colorectal cancer.

Further study is required to elucidate the mechanisms and develop guidelines for optimal vitamin D sources and serum levels of vitamin D metabolites.

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