Adopting a diet with no refined sugars, no grains, and very low carbohydrates (under 50g per day) is expected to lead to significant improvements in gut health markers including tight junctions, inflammation, and SIBO, this is expected to contribute to a reduction in high blood pressure.
This type of dietary restriction (often resembling a strict ketogenic or very low-carb approach) directly addresses the root causes fuelled by high-carb diets.

1. Improvement in Gut Wall Tight Junctions and Reduced SIBO
Eliminating refined sugars, grains, and high-carb foods directly impacts the microbial environment:

Starving the Overgrowth (SIBO): Bacteria that cause SIBO primarily ferment carbohydrates to thrive and produce gas. By severely restricting their primary food source, you effectively “starve” the bacterial overgrowth. This can lead to a natural reduction in SIBO symptoms and colony count.
Reduced Bacterial Toxins: As the SIBO population declines and the consumption of inflammatory food triggers stops, the production of bacterial toxins like LPS (lipopolysaccharide) is reduced. Less LPS in the gut means less potential to damage the tight junctions of the intestinal wall.
Strengthening the Barrier: This environment helps reduce the physical and chemical stress on the intestinal lining, allowing the damaged tight junctions to heal and restore the integrity of the gut barrier.

2. Reduction in Chronic Low-Grade Inflammation
A severe carbohydrate restriction has a profound anti-inflammatory effect on the entire body:

Lower Insulin and Glucose Spikes: By removing refined sugars and quickly digestible carbohydrates, you eliminate the frequent high spikes in blood glucose and insulin. This shift reduces a major metabolic trigger for systemic inflammation.
Reduced Inflammatory Signalling: With fewer microbial toxins leaking into the bloodstream (due to a healed gut barrier) and lower metabolic stress, the body’s overall state shifts away from chronic pro-inflammatory signalling (cytokines), resulting in a measurable decrease in low-grade inflammation.

3. Potential Reduction in High Blood Pressure
Since emerging research links chronic low-grade inflammation and intestinal permeability to the development and severity of hypertension, correcting the gut issues is expected to yield cardiovascular benefits:

Interrupting the Inflammation-Hypertension Loop: By healing the gut and reducing the systemic inflammatory state, you remove a major underlying driver of vascular stiffness and endothelial dysfunction, which are key mechanisms in high blood pressure.
Metabolic Effects: Very low-carb diets often lead to significant weight loss and improved insulin sensitivity. Both of these metabolic improvements are independently powerful factors for lowering blood pressure.
Reduced Fluid Retention: Carbohydrate restriction often results in a rapid decrease in fluid retention (due to lower insulin levels and reduced glycogen storage), which can lead to an immediate, though sometimes temporary, drop in blood pressure.

In summary, this highly restricted diet creates a less hospitable environment for SIBO, reduces the burden of toxins and inflammation on the body, and thereby addresses several known risk factors and contributors to high blood pressure.

How The Integrity of The Gut Is Compromised By SIBO

Inflammation and Damage to the Mucosa (the lining of the gut): The overgrowth of some bacteria can lead to them becoming pathogenic can cause low-grade inflammation in the lining (mucosa) of the small intestine. This inflammation can damage the intestinal epithelial cells and lead to atrophy (wasting away) of the intestinal villi, compromising the physical barrier in the gut.

Disruption of Tight Junctions:
(The tight junctions are integral parts of the epithelial cells themselves, specifically acting as the seal that holds adjacent cells together)

The intestinal barrier’s integrity is largely maintained by tight junctions-that seal the spaces between adjacent epithelial cells. Bacterial products, toxins and the resulting inflammation can interfere with the expression, structure, and function of these tight junction proteins. When these junctions are compromised, the barrier becomes “leaky,” allowing larger molecules (like undigested food particles, dead bacterial fragments, and toxins- like pesticides) to pass from the small intestine lumen into the bloodstream.

In essence, SIBO creates an inflammatory environment and produces compounds that directly or indirectly weaken the physical seals (tight junctions) between the cells of the small intestine lining, resulting in increased intestinal permeability.