How fibre can help reduce the risk of Cardiovascular disease

Diabetes, Heart, Diets | August 29, 2019 | Author: Naturopath

diet, diabetes, cardiovascular

How fibre can help reduce the risk of Cardiovascular disease

Cardiovascular disease is related to obesity, high cholesterol, high blood pressure, high glucose and high levels of insulin. Increasing dietary fibre can have an impact on the reduction of these cardiovascular disease markers. 

Cardiovascular disease refers to conditions that involve a narrowing or blockage of the blood vessels that provide oxygen and blood to the heart and can lead to heart attack, angina or stroke. The main condition affectig people with cardiovascular disease is known as coronary artery disease (CAD).

Coronary Artery Disease (CAD) is impairment of the flow of blood through the coronary arteries and is most commonly caused by atheroma.

Atherosclerosis is characterised by atheroma’s which intrude on walls of medium and large arteries. They are made up of lipids, inflammatory cells, muscle cells and connective tissue.

Atheroma is a degeneration of the artery wall caused by a build-up of fatty plaques and scar tissue. 

How Fibre can HelpAs the plaque grows it causes a narrowing of the vessel wall (arterial lumen) which impedes the flow of blood and oxygen (ischemia). This can often cause pectordial discomfort such as pain or feeling of pressure (angina pectoris), especially on exertion or when stressed.

Ruptured or split coronary plaques can occur, exposing contents which activate platelet activity and a coagulation cascade (blood clot formation). 

This can result in acute thrombus, which aim is to seal off the damage to the artery wall, but instead can cause blockage to the flow of blood and oxygen to the heart (myocardial ischemia).

Risk Factors

One of the risk factors to the development of atherosclerosis is dyslipidaemia (one or more imbalances of fats in the blood). Other risks include diabetes, high blood pressure, smoking, family history, sedentary lifestyle and obesity.

Preventative measures

If you are at risk of developing cardiovascular disease it is important to make diet and lifestyle change.

  • Balance blood lipids
  • Diabetes control
  • Reduce salt intake
  • Healthy diet
  • Stop smoking
  • Get active
  • Weight loss

How Fibre can HelpHow Fibre can Help

Studies have shown that an intake of dietary fibre is associated with a decrease in cardiovascular disease. Dietary fibre is carbohydrate from plant food which is indigestible by humans, due to a lack of the specific digestive enzymes, and thus are not absorbed by the body.

Dietary fibres are classified depending on the water solubility properties they contain and are either soluble or insoluble.

  • Insoluble fibres cause rapid emptying time from the stomach, form bulk for the bowel and decrease intestinal transit time, helping with bowel regularity. They pass through the intestinal system intact. These are lignins, celluloses, and hemicelluloses obtained from whole-grain foods, bran, nuts, and seeds.
     
  • Soluble fibres are edible but not absorbed by the body. They are either partially or totally fermented by bacteria in the colon, producing short-chain fatty acids (SCFA, s) in the large intestine. Soluble fibres absorb water forming a gelwhich slows gastric emptying time and digestion and the absorption of nutrients. Soluble fibres  are pectin, gums, mucilages, beta glutens, fructans (oligofructose and inulin) and also some hemicellulose. These come from fruits, berries, legumes, oats and barley for example.

Dietary fibre may reduce the risk of developing cardiovascular disease through a variety of mechanisms, these include:

  • Improving serum lipid concentrations (fat in blood)
  • Lowering blood pressure
  • Reducing inflammation

Fibre for cholesterol lowering

Dietary fibres gather and absorb cholesterol during digestion. This decreases the absorption through the liver, increasing excretion through bile and bowel defecation.

Water-soluble fibre products include Beta-glucan, psyllium, pectin and guar gum, have been found to lower serum LDL cholesterol concentrations, without affecting HDL cholesterol or triacylglycerol concentrations.

Increasing the production of Short-chain fatty acids in the large intestine from the fermentation of soluble fibre leads to alterations in the microbiota (the community of commensal, symbiotic and pathogenic microorganisms) in the digestive system. The human microbiota is made up of trillions of cells including bacteria, fungi and viruses most of which are found in the gut (but also the genitals and skin).

  • SCFA’s such as propionic acid has been shown to decrease synthesis of cholesterol in the liver, reducing cholesterol in the blood.
  • SCFA’s increase the acidification of gastrointestinal tract which decreases the solubility of the free bile acids, and increases excretion of bile and removal through the bowel (bile contains mainly cholesterol).

Metabolic syndrome and hypertension

Hypertension is a major risk factor for coronary heart disease and elevated blood pressure is also a component of metabolic syndrome, a group of risk factors for atherosclerotic disease and diabetes mellitus.

Dietary fibre intake from whole foods or supplements may lower blood pressure, improve serum lipid levels, reduce inflammatory mediators,  lower serum glucose levels and support weight loss. 

Studies have shown a high fibre diet reduced blood pressure in people suffering from hypertension or high blood pressure, with beneficial result using beta-glucan (from oats).

Water soluble fibres such as psyllium, moderate high levels of glucose and insulin concentrations after eating in non-insulin dependent diabetics, if taken with meals, and also support weight reduction and blood pressure reduction.

Inflammation

Oxidative stress is associated with the pathogenesis of atherosclerosis. Diets high in added sugar leads to obesity, insulin resistance, increased gut permeability and low-grade inflammation.

Gut microbiota plays a significant role in the development of obesity, obesity-associated inflammation and insulin resistance. Modulating the digestive bacteria with the use of prebiotics (fibre) and probiotics promote a healthy digestive system.

Fibre has also been shown to reduce inflammation, possibly due to its ability to slow the absorption of glucose through digestion. This then down-regulates he inflammatory response mediated by gut microbiota.  

Functional fibres

Functional fibres are non-digestible carbohydrates which have been extracted and isolated through manufacturing. These include β-glucans, chitosan, psyllium, lignans, fructans, gums, pectin, polydextrose, resistant dextrins and starches.

  • Prebiotics. These are considered functional fibres as they support the growth of beneficial bacteria in the bowel, such as lactobacilli and bifidobacterial, and improve health. These include galacto-oligosaccharides, fructooligosaccharides (fructans) and lactulose.

Summary

Increasing dietary fibre intake can help reduce the risk of developing cardiovascular disease by - Increasing dietary fibre intake can help reduce the risk of developing cardiovascular disease by - 

  • Reducing the absorption of fatty acids and cholesterol (reduced LDL cholesterol)
     
  • Increase bile excretion through the bowel (bile contains cholesterol)
     
  • Increases fermentation to produce proprionic acid which inhibits HMG-Co reductase (the production of cholesterol by the liver)
     
  • Reduces glucose absorption and decreases insulin secretion (associated with high blood pressure and diabetes)
     
  • Supports the microbiome 
     
  • Reduce mediators for inflammation (associated with chronic heart disease)

The bottom line - consuming the high amounts of dietary fibre can significantly reduce their incidence and mortality from cardiovascular disease.

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References

https://www.merckmanuals.com/professional/cardiovascular-disorders/coronary-artery-disease/overview-of-coronary-artery-disease

https://www.merckmanuals.com/professional/cardiovascular-disorders/arteriosclerosis/atherosclerosis#v6616200

https://www.mayoclinic.org/diseases-conditions/heart-disease/symptoms-causes/syc-20353118

Dietary Fiber, Atherosclerosis, and Cardiovascular Disease https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6566984/

What are the gut microbiota and human microbiome? https://www.medicalnewstoday.com/articles/307998.php

https://www.heartfoundation.org.au/images/uploads/main/Eating_for_Heart_Health_-_Position_Statement.pdf

Dietary fiber, lipids and atherosclerosis. https://www.ncbi.nlm.nih.gov/pubmed/2823590

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