Vitamin-B12 is an essential nutrient for making DNA and keeping the nerve and blood cells healthy. However, different studies suggest that long term use of high dose Vitamin-B12 can be harmful and can increase the risk of certain cancers like lung/colorectal cancer.
Vitamin B12, also known as cobalamin, is a water-soluble vitamin commonly found in fish, animal products like milk, meat and eggs, and in some plants and plant products like fermented soy products and seaweeds. Vitamin B12 helps in keeping the nerve and blood cells healthy and is necessary for making DNA. Deficiency of Vitamin B12 is known to cause anemia, weakness and fatigue and hence we try to include foods containing Vitamin B12 in our daily diet or alternatively use Vitamin B12 supplements. However, there are rising concerns on long term use of high dose Vitamin B12 and its association with the risk of cancer. Different studies and analysis were carried out to investigate the impact of Vitamin B12 intake on cancer risk.
Studies on Vitamin B12 & Cancer Risk
In a clinical trial study, named the B-PROOF (B Vitamins for the Prevention of Osteoporotic Fractures) trial, done in Netherlands, the researchers assessed the effect of daily supplementation with vitamin B12 (500 μg) and folic acid (400 μg), for 2 to 3 years, on fracture incidence. Data from this clinical trial was used by researchers to further investigate the impact of long term supplementation of Vitamin B12 on cancer risk. The analysis included data from 2524 participants of the B-PROOF trial and was found that long term folic acid and vitamin-B12 supplementation was associated with a high risk of overall cancer and a significantly higher risk of colorectal cancer. However, the researchers suggest confirming this finding in larger studies, in order to decide whether Vitamin B12 supplementation should be restricted to only those with a known B12 deficiency (Oliai Araghi S et al, Cancer Epidemiol Biomarkers Prev., 2019).
In another international study published recently, the researchers analyzed the results from 20 population based studies and data from 5,183 lung cancer cases and their matched 5,183 controls, to evaluate the impact of high vitamin B12 concentration on cancer risk via direct measurements of circulating vitamin B12 in pre-diagnostic blood samples. Basically, the idea was to check whether high Vitamin B12 status was an indication of increased risk of lung cancer. Based on their analysis, they concluded that higher vitamin B12 concentrations are associated with increased risk of lung cancer and for every doubling levels of Vitamin B12, the risk increased by ~15% (Fanidi A et al, Int J Cancer., 2019).
Vitamin B12 as part of natural foods in our diet is needed for our health and well being. Key findings from all these studies suggest a positive association of long term use of high dose Vitamin B12 and the increased risk of cancers like colorectal cancer and lung cancer. While this does not mean we completely remove Vitamin B12 from our diets, one needs to be educated on taking the right amounts of Vitamin B12 as part of normal diet or while having a deficiency, to avoid the negative impacts that unwanted or extra vitamin-B12 supplementation (beyond the adequate level) can have on us, such as increasing the risk of different cancers such as lung/colorectal cancer.
Cancer patients often have to deal with different chemotherapy side effects which affect their quality of life and look out for alternative therapies for cancer. Taking the right nutrition and supplements based on scientific considerations (avoiding guesswork and random selection) is the best natural remedy for cancer and treatment related side-effects.