Navigating the Microbiome: A Closer Look at Micronutrients
For many years, the idea that bacteria within the human gut could significantly contribute to our essential B vitamin intake has been dismissed by the medical community. This was seen to be a design flaw in the human body, with the majority of gut bacteria residing in the colon, far from the absorption sites in the small intestine. However, recent research has exposed this misconception, revealing a complex interplay between gut microbes and nutrient absorption that isn't all good.
New research demonstrates that bacterially produced B vitamins are absorbed by the body, with specialised transporters positioned in the colon to facilitate this process. While some bacterially produced B vitamins may serve the needs of colonocytes (cells lining the colon), others play vital roles in maintaining bowel health and regulating immune activity. For instance, severe B3 deficiency can lead to colitis-driven diarrhea, emphasizing the importance of B vitamins in preserving bowel integrity.
However, it's essential to recognise that gut bacteria produce B vitamins primarily for their own survival, relying on these nutrients for essential metabolic processes. This mutual relationship raises intriguing questions about nutrient exchange within the microbiome and who ultimately benefits from these interactions - us or them?
As a clinical nutritionist, this had me thinking about the use of supplements. High-dose supplements, while intended to address nutritional deficiencies, may inadvertently alter the composition of the gut microbiota by feeding them. Excess micronutrients left unabsorbed in the large bowel can act as food for microbial growth, influencing microbial diversity (or lack thereof) and potentially exacerbating dysbiosis. While supplements may address immediate nutritional needs, their long-term effects on the microbiome need careful consideration.
Furthermore, emerging research suggests that the microbiome plays a pivotal role in enhancing nutrient bioavailability, particularly for minerals. Short-chain fatty acids produced by gut bacteria contribute to maintaining optimal pH levels for mineral solubility, while mucin proteins aid in mineral binding and absorption. However, the microbiota's quest for essential minerals can lead to microbial competition and theft, with bacteria extracting minerals from our food, compromising our defenses and microbial balance. This is relevant for anyone with nutrient deficiencies, such as iron. It could be that you are consuming enough (through diet or supplements), but that your microbiome is sequestering it before you get to absorb it.
This new research highlights the challenges with supplementing for nutrient deficiencies, and the importance of ensuring you are aware of the dosages you are taking and if they are right for you (and your gut). This is especially important if you are experiencing challenging gut health symptoms. A qualified healthcare provider, such as clinical nutritionists, will be able to help you with this.
If you would like further information on this topic please reach out. I always love to dig deeper into the research!
Reference
Uebanso, T., Shimohata, T., Mawatari, K., Takahashi, A. (2020). Functional Roles of B‐Vitamins in the Gut and Gut Microbiome. Molecular Nutrition Food Research, 64. https://doi.org/10.1002/mnfr.202000426.