Key points
- Synbiotic supplements are combinations of pre-, pro-, and postbiotics
- They are available as encapsulated, powdered, or ‘live’ fermented beverages
- Synbiotic supplementation has been demonstrated to reduce inflammatory markers and increase endogenous antioxidants and total antioxidant capacity
- Supplementation has also been shown to improve measures of cardiometabolic health
Synbiotics are foods or supplements that combine probiotics and prebiotics (and sometimes post-biotics). The term derives from the synergy of these components, i.e., synergistic biotics. In common usage, the term synbiotic refers to products that include isolated probiotics in combination with prebiotics and also to ‘live’ foods and beverages that contain pre-, pro-, and postbiotics in an ‘ecosystem’ in which there is fuel substrate (prebiotics) for live organisms (probiotics) which in turn produce organic acids and short-chain fatty acids that are beneficial to the health of the microbiome and the host animal (post-biotics).
Why are synbiotics (and gut health) important?
The gut is the gateway to the body that allows us to take in nutrients from food while keeping out pathogens and harmful chemicals that can cause disease and ill-health. The impact of gut health on immunity, inflammation, and neural and overall health is now becoming very well known. Disturbances to the balance of ‘good’ and ‘bad’ microbes in the gut (dysbiosis) can affect both nourishment and growth and conditions ranging from metabolic states like obesity and type 2 diabetes,1 functional gut disorders,2 inflammatory conditions,3-7 cardiovascular disease, and mental health challenges.8-17 The gut microbiome also has a specific, bidirectional relationship with hunger, satiety, inflammation and immunity, all of which interplay with the spectrum of health conditions including the metabolic disorders of obesity, metabolic syndrome, and diabetes.1, 3, 18, 19 The gut microbiome also has an interplay with sleep and stress, cofactors for the development of diabetes, obesity, mental health challenges, and other health conditions.
Check out all the articles on gut health: https://cliffharvey.com/?s=gut+health
Synbiotic = synergistic biotics
What is the microbiome?
Before looking into what the various biotics are, it’s important to understand common terms like microbiome and microbiota.
The microbiome is the community of microbes found in the body. Technically, the microbiome refers to collective genomes of these microbes with microbiotaused to describe the communities of microbes, but these terms are often used interchangeably. In common usage, microbiome refers to the community of bacteria in the gut, but it also includes other microbes like fungi, protozoa, and viruses and there is also distinct microbiota of the skin, oral cavity, and other surfaces.
What are prebiotics?
Prebiotics feed (beneficial) microbes in the gut. Usually, these are various sugars, fibres and resistant starches that feed particular varieties of bacteria (or in some cases beneficial yeasts).
What are probiotics?
Probiotics are microbes (usually bacteria but also some yeasts) that can be taken as a supplement and are purported to improve the balance of the microbiome.
What are postbiotics?
Postbiotics are chemicals that are produced by bacteria (i.e., probiotics) that have additional benefits to microbiota and systemic health. They are also known as organic acids and include short-chain fatty acids which feed cells of the digestive wall, other bacteria, and can be absorbed by the body for use as fuel (i.e., acetic acid, butyric acid, and lactic acid). These and other chemicals produced by bacteria in the gut also act as messengers that provide a ‘metabolic interaction’ between the host (you) and the microbiota and digestive environment.20
Short-chain fatty acids
Short-chain fatty acids have carbon chains between two and five in length. These fatty acids include acetic acid (C:2), propionic acid (C:3), butyric acid (C:4), and valeric acid (C:5). Short-chain fatty acids, especially butyric acid, are used extensively as fuel by intestinal epithelial cells.21 Fatty-acid chain length also affects the absorption of fats. Shorter chain fats do not require ‘bundling’ with micelles and chylomicrons for absorption and transport and so escape the usual route of absorption into the lymph, and later deposition into the bloodstream (via the subclavian vein) and instead, are far more likely to be absorbed into the hepatic portal vein and transported to the liver where they can be easily converted to ketone bodies,22-27 also a source of fuel for most tissue in the body.
Acetic acid
Acetic acid is a two-carbon short-chain fatty acid. It comprises 4-20% of vinegar, which has been demonstrated to improve postprandial insulin sensitivity in healthy and diabetic people and improve glycaemic responses to meals.28-30
Butyric acid
Butyric acid (butyrate) is a four-carbon, short-chain fatty acid found in the milk of ruminants and is present in small amounts in many dairy foods (the term butyrate comes from the same root as ‘butter’). Butyrate in humans is primarily produced by microbial intestinal fermentation of dietary fibre and resistant starches. Much of this is absorbed and used directly by colonocytes, with most of the remainder absorbed into the hepatic portal vein, and transported to the liver and converted into ketone bodies.26, 27 A small amount is absorbed directly from the large colon and enters systemic circulation, to be used directly by peripheral tissue.26
Butyrate inhibits inflammation and intestinal cancers, decreases oxidative stress, and promotes satiety.31, 32 Thus, it serves an important role in preserving the health of the colon, microbiota, and general and systemic health.
General Health Effects of Synbiotics
Synbiotics significantly increase gut levels of Bifidobacteria.34 Their use decreases inflammatory markers, especially Tumour necrosis factor-α (TNF-α) and c-reactive protein (CRP) in both healthy and disease states,35, 36 malondialdehyde (MDA),37, 38 and also reduces liver enzymes in non-alcoholic fatty-liver disease (NAFLD),39 with the greatest improvements in inflammatory markers seen in inflammatory bowel diseases (IBDs), arthritis, and NAFLD.35 Synbiotic supplementation may also increase total antioxidant capacity,37, 38 the antioxidants superoxide dismutase and nitric oxide,38 and have been clearly demonstrated to increase the key endogenous antioxidant glutathione.37, 38, 40 Supplementation also significantly reduces levels of gut-derived endotoxins41 which are implicated in cardiovascular and other diseases.
Synbiotic supplementation may also reduce body mass42 cholesterol, triglycerides, LDL-cholesterol, and increase HDL-cholesterol compared to placebo.43 These effects are most pronounced when synbiotics are supplemented for more than 8 weeks.43 A moderate reduction in fasting blood glucose (of around 0.2 mmol/L) has been observed in trials, however, this effect is greater with supplements containing multiple bacterial strains (~0.3 mmol/L reduction), and in people with blood glucose levels higher than 7 mmol/L, for which there is a significant and clinically meaningful reduction of around 0.7 mmol/L.44
Summary
Synbiotics can support gut-health and the microbiota and help to reduce inflammation and improve total antioxidant capacity. This has flow-on effects to systemic health with improvements in various cardiometabolic markers having been observed in randomised trials.
Part 2 on the Condition-Specific Benefits of Synbiotics coming soon!
Our favourite Synbiotic is Vita Biosa, get it via this link and save 10% (discount applied automatically)
www.nutritionstore.online/cliff-harvey
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