Modern heart advice usually focuses on cholesterol, quitting smoking, and getting more exercise. But as World Heart Day arrives on September 29, emerging research points to an unexpected regulator of cardiovascular risk: the human digestive system.
While scientists work to fully map the "gut-heart axis", local experts warn that chronic inflammation from a compromised gut wall could be quietly threatening your heart health long before traditional warning signs appear.
According to data from the World Health Organization (WHO), cardiovascular diseases (CVDs) are the leading cause of death globally, with 1 in 3 deaths occurring prematurely in people under the age of 70.
While these figures are concerning, a growing body of evidence suggests that our gut health plays a surprising role in lowering that risk.
To break down this emerging frontier in medicine, "The National" spoke to Leane Keizer, registered dietitian and head of public affairs at Danone Southern Africa.
Discovering the gut-heart axis
While the "gut-brain axis" has become a popular topic in the wellness industry, the concept of a "gut-heart axis" is a relatively new term in medical science.
“We know that the gut plays a role in our digestive well-being, immunity, and mental health,” says Keizer.
“But more and more, we are seeing evidence of the gut influencing our chronic disease risk as well, including type 2 diabetes, long-term chronic cancers, and even heart disease. Scientists are trying to investigate exactly what interaction is happening in the gut that decreases our risk for heart disease.”
According to Keizer, the process begins with managing systemic inflammation. She suggests imagining the gut as a continuous, hollow pathway.
“From your mouth to your bottom, your gut is basically a long tube going through your body. That tube is exposed to elements from the outside world, food, liquids, bacteria and pathogens.
"Inside your large and small intestines, that tube is filled with trillions of microbes that we call the gut microbiome. The make-up of that bacteria is what influences our long-term health.”
The critical biological link to the heart lies within the structural strength of the gut wall.
“If that gut wall is not strong, if its barrier gets compromised or permeated in any way, it allows harmful bacteria and pathogens to pass through the gut into the actual body system,” Keizer explains.
“That inflammation, on a micro level, triggers an inflammatory response throughout the whole body, including the cardiovascular system. The pro-inflammatory reaction of a compromised gut wall has a long-term inflammatory impact on the heart. It is not the only cause of heart health concerns, but it is a major one.”
Telltale signs of an unhealthy gut
The quality, abundance, and diversity of your gut microbiome act as a direct predictor of major health outcomes, including obesity, type 2 diabetes, and depression.
Keizer notes that cutting-edge global research (particularly in the UK and the Americas) is currently using large-scale stool sampling to map gut characteristics against chronic conditions to build predictive health models.
But how can an individual tell if their gut microbiome is compromised and silently threatening their heart?
Keizer points to two major indicators:
- Digestive comfort: Experiencing abnormal, chronic levels of bloating, aches, pains, or severe flatulence are clinical signs that the digestive system needs support.
- The Bristol Stool Chart: Clinicians use this visual scale to judge gut health based on stool consistency.
Keizer translates this into relatable South African terms:
- The "Chuckles": If your stool consistently resembles small, hard round pellets (like the popular chocolate snack), it is an indication of chronic constipation.
- The "Hot Chocolate": The polar opposite consistency indicates short-burst or chronic diarrhoea.
“If you find that more than 80% of your stools are behaving on one of those two polarised consistencies, it is a sign that your gut needs additional support, and you should probably consult a specialist,” Keizer advises.
The "protein craze" vs the "state of the plate"
When looking at the "state of the plate" and food inequalities in South Africa, Keizer expresses professional concern over modern diet trends, specifically, the commercial obsession with protein at the expense of fibre.
“South Africa has never had a public health risk when it comes to protein. As a nation, we are a good protein-eating nation,” she says.
“It is a bit worrying for me as a healthcare professional that we are putting so much emphasis on one nutrient. Protein is essential for muscle integrity, but only about 20% of your dietary intake should come from protein.”
Keizer breaks down the ideal macronutrient split for a healthy body:
- Carbohydrate-based foods: 50% to 55%.
- Fats and oils: 25% to 30% (ideally naturally occurring in foods, rather than added).
- Protein: 20% (Maximum of 1 gram per kilogram of body weight per day, unless you are an extreme sportsman).
“The nutrients I am more concerned about are micronutrients,” Keizer stresses. “In South Africa, vitamin A, zinc, and iron are severely lacking in our diet to the point of harm. 10% of children are not getting enough iron, which we need for immunity and cognitive development.
"Furthermore, the vital message about fibre is being completely lost in the protein craze.”
A practical guide to heart protection
To feed your microbiome, keep your gut wall intact, lower systemic inflammation, and protect your heart, Keizer offers a highly actionable daily checklist:
The balanced plate rule
Draw a line down the centre of your plate and split it into three functional zones:
(50%) Must be filled with whole vegetables and fruit (e.g., a large salad or cooked vegetables) to feed your gut bacteria.
(25%) A source of clean protein (chicken, fish, meat, eggs). Keizer highly recommends beans, legumes, and lentils because they double as an immense source of fibre.
(25%) High-fibre, unrefined starches.
Keizer suggests easy cultural swaps:
- Upgrade your pap: Stir cooked lentils directly into your pap to add hidden fibre.
- Keep skins on: Eat potatoes with the skin on instead of peeling them.
- Swap grains: Choose whole-wheat bread over white bread, and brown rice over white.
“Drink at least eight glasses of water a day to cleanse the gut, ensure smooth mobility, and lubricate the digestive tract for easy passage.”
"Precision biotics"
To clear up common linguistic confusion in the wellness sphere, she provides two simple definitions:
- Prebiotics: A type of dietary fibre that passes through your gut undigested, serving as food or fuel for your existing gut bacteria.
- Probiotics: The live bacterial organisms themselves (found in yoghurt and amasi) that actively enter and colonise your gut.
While a combination of fibre (prebiotics) and live cultures (probiotics) is the best way to build a healthy gut shield today, the future holds promise for highly specific medical interventions.
“Do we know of one precision probiotic you can take today that will decrease heart disease? No, unfortunately, that is not how it works yet, but research is underway,” says Keizer.
“Danone globally cares immensely about gut health research and fermentation. At our research facility in Paris, scientists have actually developed an AI gut and are testing the impact of different biotics.
"The goal is to see if we can identify 'precision biotics' that will target specific conditions, whether that is decreasing IBS, depression, or cardiovascular risk.
"The dream is that if you have a family history of heart disease, you will be able to walk into a shop and choose a specific yoghurt designed to lower your risk.
"While we aren’t there yet, the best thing you can do today is use fibre and fermented dairy to support a diverse, abundant gut, because a protected gut means a protected heart.”
vuyile.madwantsi@national.mg.co.za