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3rd August 2021
Colorectal cancer is the third most common cancer worldwide, accounting for an estimated 1.8 million new cases and over 880,000 deaths in 2018. However, the incidence of early-onset colorectal cancer (EOCRC), defined as colorectal cancer in those under 50 years of age, is increasing by approximately 7.9% per year among those aged 20 – 29 years. Moreover, EOCRC is more often diagnosed at an advanced stage. While the reasons for this are uncertain, it could be linked to sedentary behaviour or obesity. A further compounding factor, is the delay in seeking advice with one study in 1089 patients with EOCRC, reporting that nearly two-thirds of patients waited 3 – 12 months before seeking medical advice, with many indicating that they were initially misdiagnosed.
One potential protective factor against colorectal cancer is vitamin D and there is evidence of a strong inverse relationship between vitamin D levels and the risk of colorectal cancer. Nevertheless, whether reduced plasma levels of vitamin D are also associated with the development of early-onset colorectal cancer is uncertain. In trying to ascertain the relationship between these two factors, a team from the Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, US, turned to the Nurses’ Health Study II which is a prospective cohort study of 116,429 female nurses aged between 25 and 42 years and which began in 1989. Study participants are followed every 2 years by self-administered questionnaires which captures information on demographics, lifestyle factors, the presence of co-morbidities etc and a food frequency questionnaire, every 4 years. For the present study, the researchers set the primary end point as the development of EOCRC, identified from medical records. In addition, the researchers collected data on the presence of adenomas and serrated polyps, which are pre-cancerous lesions. The plasma vitamin D levels were estimated based on factors such as dietary intake, age, race etc using a previously defined model.
A total of 94,205 women were included in the analysis and there were 111 documented cases of early-onset colorectal cancer detected between 1991 and 2015. The median vitamin D intake was 372 IU/day and vitamin D levels > 450 IU/day were associated with a reduced risk of developing EOCRC compared to intakes < 300 IU/day (hazard ratio, HR = 0.49, 95% CI 0.26–0.93). The HR per 400 IU/day increases was 0.46 (95% CI 0.26–0.83). Interestingly, the researchers also found that the HR for dietary vitamin D intake had a stronger inverse association with the development of EOCRC per 400 IU/day increase than among supplement users (0.34 vs 0.77, dietary vs supplements). There were 1439 newly diagnosed adenomas and 1878 serrated polyps in those aged less than 50 years and again, higher vitamin D intake was associated with a lower risk of developing either lesion.
The authors concluded that given the association between higher vitamin D intake and early-onset colorectal cancer, strategies to ensure adequate intake of the vitamin could serve as an important preventative measure in younger adults.
Kim H et al. Total Vitamin D Intake and Risks of Early-Onset Colorectal Cancer and Precursors. Gastroenterology. 2021
29th September 2020
Although in a recent review, NICE concluded that there was no evidence to support either a preventative or treatment role for vitamin D, new evidence from an analysis of a large patient cohort, suggests an inverse relationship between levels and positive COVID-19 status, implying that the vitamin has a protective role.
A team of US researchers retrospectively analysed a large, anonymous patient data set 50 US states and the District of Columbia between March and June 2020, for whom 25-hydroxyvitamin D (25(OH)D) levels were recorded in the previous 12 months. They limited their analysis to one COVID-19 test result per patient and included all available demographics including ethnicity and categorised 25(OH)D status as either low (<20ng/ml), adequate (30-34ng/ml) or higher ( >60ng/ml).
In total, 191,779 patients were included with a mean age was 54 years (68% female) and overall the COVID-19 positivity rate was 9.3%. When examining the relationship between 25(OH)D levels and COVID-19 positivity, the rate was highest among those with a low vitamin D status (12.5%) and decreased as it improved, being 8.1% for those with adequate levels and 5.9% among those with the highest levels.
In terms of ethnicity, COVID-19 positive rates were highest in black individuals (15.7%) compared to Hispanics (12.8%) and lowest in white, non-Hispanics (7.2%, p< 0.001 for both comparisons). Furthermore, the difference in positivity rates between ethnic groups was reflected in mean 25(OH)D levels, which were 33.0 vs 29.1 vs 28.8 ng/ml for white, blacks and Hispanic individuals (p< 0.001) respectively. In regression analysis, there was a strong association between vitamin D levels and lower COVID-19 after adjustment for all demographic factors (adjusted odds ratio = 0.98 per ng/ml increment).
The authors concluded that their findings provide a further rationale to explore the role of vitamin D supplementation to reduce the risk of COVID-19 infection.
Kaufman HW et al. SARS-CoV-2 positivity rates associated with circulating 25-hydroxyvitamin D levels. PLoS ONE 15(9): e0239252. https://doi.org/ 10.1371/journal.pone.0239252