A recent clinical trial indicates that magnesium supplements could enhance gut bacteria that play a role in reducing the risk of colon cancer, although the benefits appear to vary based on individual genetics and sex. Conducted by researchers at Vanderbilt University Medical Center, this study highlights the complex interplay between nutrition, genetics, and cancer prevention.
Colorectal cancer remains a major health concern, being the third most commonly diagnosed cancer worldwide and the second leading cause of cancer-related deaths. While the increased use of colonoscopies has led to a decline in incidence rates, new strategies for prevention are still urgently needed.
Dr. Qi Dai, a professor of medicine at VUMC and the study’s corresponding author, noted, “Our previous study showed magnesium supplementation increased blood levels of vitamin D when vitamin D levels were low. The current study reveals that magnesium supplementation also increases the gut microbes which have been shown to synthesize vitamin D in the gut without sunlight and locally inhibit colorectal cancer development.” This is significant, as vitamin D is crucial for bone health and overall well-being.
Study Design and Findings
In this double-blind, randomized controlled trial, researchers enlisted 240 participants with a history of colorectal polyps, a known risk factor for colorectal cancer. Participants were assigned to receive either personalized magnesium supplements or a placebo over a 12-week period. The dosage of magnesium glycinate was tailored based on individual calcium-to-magnesium intake ratios—generally around 2:1.
The research team collected various biological samples, including stool, rectal swabs, and blood, to assess changes in gut bacteria, specifically focusing on Carnobacterium maltaromaticum and Faecalibacterium prausnitzii. These two bacteria have been previously linked to vitamin D production in the gut and reduced cancer development in animal studies.
Additionally, the researchers examined the influence of genetic variations in the TRPM7 gene, which is critical for magnesium regulation in the body. The study specifically looked for a “missense variant” in which a single amino acid change might affect the function of the TRPM7 protein.
The results showed that individuals without the TRPM7 missense variant responded positively to magnesium supplementation, leading to increased levels of C. maltaromaticum and, to a lesser extent, F. prausnitzii. Notably, the response was more pronounced in women, suggesting potential hormonal influences.
Conversely, participants with the TRPM7 missense variant exhibited a reduction in these beneficial bacteria when taking magnesium. This indicates that the efficacy of magnesium supplementation might be influenced by individual genetic makeup.
Broader Implications and Limitations
Follow-up colonoscopies indicated a potential link between gut bacteria and polyp development. Participants with elevated levels of F. prausnitzii had a nearly 2.8-fold increased risk of developing new polyps compared to those with lower levels. In contrast, higher levels of C. maltaromaticum were associated with approximately an 85% reduction in the risk of developing serrated polyps, which are linked to a higher likelihood of progressing to colorectal cancer. Although these findings are intriguing, the results concerning C. maltaromaticum were described as “marginally significant,” warranting caution in interpretation.
The study does have limitations. The increase in F. prausnitzii was not statistically significant after adjusting for multiple comparisons, and the specific strains of bacteria responsible for the observed effects were not identified. Additionally, the trial predominantly involved older, White participants from Tennessee, limiting the generalizability of the findings. The short duration of the study (12 weeks) also means that long-term effects remain unknown.
Despite these limitations, the research opens the door for further exploration into how magnesium supplementation might serve as a preventative measure against colorectal cancer. The findings suggest a potential approach to “precision nutrition,” where genetic testing could help determine who stands to benefit most from magnesium intake.
Published in The American Journal of Clinical Nutrition, this study underscores the need for ongoing research into dietary supplements and their role in cancer prevention. More extensive investigations will be crucial in translating these findings into practical clinical recommendations.
