Antibiotic resistance makes pathogens more deadly: there are increasing reports of bacteria resistant to every known antibiotic, and multi-drug-resistant strains of diseases such as tuberculosis mean they are incredibly hard to treat. The WHO has called antibiotic resistance one of the biggest threats to global health and development. It is clear that we must reduce our use of antibiotics in order to help save them for when they are truly needed. But how can we achieve this worthy goal?
There are several reasons why antibiotic resistance is increasing. The process of resistance is natural - bacteria are always evolving to counter threats - but widespread use of antibiotics means that more bacteria and pathogens are exposed to a greater number of antibiotics, increasing the likelihood that a given pathogen will develop resistance. Responsibility for overuse lies with individuals, industry and healthcare regulators. For example, many people demand antibiotic treatments for viral infections such as colds or flu, even though using antibiotics is useless in these cases and increases the risk of antibiotic resistance. Equally, many sectors of the agriculture industry overuse antibiotics in animals in order to preemptively prevent illness. Though less of a problem in the UK, regulators should be much more restrictive in order to stringently prevent overuse. However, a fourth plank of response could come in the form of building healthier bodies in the first place. People with healthier immune systems fight disease much more effectively, eliminating pathogens before they become entrenched and helping prevent opportunistic secondary infections.
One way in which the immune system can be strengthened is through diet. Eating a wide range of nutritious foods is the best way to give the body the nutrients it needs. Fermented foods, mainly derived from fresh produce (especially in the case of fermented vegetables), increases the nutritional range of any diet - more nutrients are almost always a good thing. But the fermentation process also enhances the bioavailability of some nutrients by displacing anti-nutrients (substances that bind to nutrients and make them more difficult to absorb). In other words, fermentation enhances the nutritional potential of already-nutritious foods, making them an ideal addition to the diet. This is especially relevant to more vulnerable people such as the elderly who may, for various reasons, struggle to maintain a varied diet. Given that many fermented foods can be added as side-dishes to meals, there is a case for including fermented foods as an easy way to widen nutritional intake.
But there is also strong and promising scientific evidence for the role of fermented foods could play in enhancing immunity. Fermented foods contain probiotics (sometimes termed ‘good bacteria’) which, when ingested, have effects on the microbiome (community of bacteria) in the gut. Gut microbiota (microbes in the gut) are known to modulate gene expression in the intestinal tract, and this expression has knock-on effects for a host of body functions, including the immune system. The mechanisms through which microbiota exert influence the body’s immune response are extremely complex, with scientists still working to understand their effects in the gut. One pathway thought to be at work is the stimulation by probiotic bacteria of intracellular signalling pathways in epithelial cells. Epithelial cells line the intestines and the epithelial layer is the body’s first line of defence against pathogens. By stimulating intracellular signalling, probiotics are thought to help induce responses in the epithelial cells, helping to enhance their function as a barrier against infection.
Another line of enquiry comes from a recent discovery about HCA (hydroxycarboxylic acid) receptors. These receptors are found on the surface of fat tissue and immune cells, and are thought to have a role in stimulating the immune system. When lactic acid bacteria (found in many fermented foods) moves through the human gut, it produces D-phenyllactic acid, which binds strongly to the 3rd HCA receptor, inducing, researchers think, an immune response. While more investigation is needed into the complex science, the researchers theorise that this mechanism may be one of the reasons why eating fermented foods is associated with a boosted immune system, a correlation which has been found in previous research.
The case for fermented food and its role in immunity is therefore complex but clear. Current evidence suggests that eating fermented foods has a range of benefits, including for immunity. Eating fermented foods can increase the range of nutrients in a diet, and may have direct benefits in terms of nutrient absorption. Further, while the mechanisms are still being explored, fermented foods thought to also directly stimulate the immune system. Although much more research is needed to enhance our understanding of the benefits, it is reasonable to conclude that fermented foods can be safely included in the diets of healthy adults to help boost immunity. In addition, promoting healthy immune systems in adults may help reduce the need to overall antibiotic use, and help to preserve antibiotics for when they’re truly needed. Fermented foods aren’t a cure-all, but they are an incredibly interesting - and tasty - area of science we are only beginning to understand.
Article by Seb Fagan
Picture: Rob Oo/Fickr