Although we are likely all hunkering down with wine and canned goods during this health crisis, it’s integral that we are getting foods into our diet that are specifically beneficial for the immune system… just in case. Whilst studying nutrition and specifically the immune system, there was one ingredient I found surprising to boost immunity. Yes most of us know garlic, lemon, ginger are pretty impressive when we aren’t well… but this one was new to me.
Mushrooms, specifically shiitake, oyster and reishi are POWERHOUSES! They contain vitamin D, some fibre, protein and also these things called polysaccharides. I won’t go into too much detail here but when these compounds pass through the digestive system, they trigger an immune response and tonnes of white blood cells flow through the body scouting out and destroying anything dangerous (viruses, bacteria, foreign bodies). MAGIC!
So, if you can find mushrooms anywhere at the moment…dried, fresh, shiitake, reishi, oyster, even chestnut and button… buy them! Below are three recipes that I would whooollly recommend…
If you are a wee health nut like me and want to understand more about the biological processes - scroll to the bottom and see a part of my latest assignment about them.
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Take care xx
Along with a handful of other fungi, shiitake mushrooms are powerhouses for the immune system. They contain Vitamin D, some fiber and protein and also contain glucose polysaccharides (Mercola, 2019).
They contain a chemical compound called polysaccharide lentinan and according to a large body of literature, these act as an immune modulator. Polysaccharides are large molecules made up of lots of chains of sugar and lentinan is a beta glucan polysaccharide. Although beta glucans go straight through the digestive tract and come out in the stool, they still stimulate a chain reaction at a certain place in the gut. Whilst in the gut, the immune cells recognise beta glucan as a foreign body and thinking it’s under attack, it stimulates the immune system to respond in a number of ways.
Kawata et al (2015) suggested that beta glucan polysaccharides in shiitake mushrooms were able to stimulate and activate macrophages, an essential cell in our immune system, spending their time in phagocytosis, engulfing waste and pathogens. When they make contact with a foreign body, they secrete cytokines, which are small proteins that act as chemical messengers. Cytokines carry vital information and stimulate cells to get to a site of injury and get to work. These specific cytokines are integral to the efficacy of the immune system.
Another way our body is stimulated to respond to mushrooms is with the help of an area in the digestive system called Peyer’s patches. Peyer’s patches is a grouping of tissue in the lower part of the intestine called gut associated lymphoid tissue (GALT). They form a very important part of the immune system and act as a surveillance system, monitoring foreign particles that pass through and relaying this information via chemical messengers back to the immune system to determine what is good or bad. It communicates with the flora in your gut and together they decide the bacteria’s fate, destroying or activating them. We want beneficial bacteria in our gut but not pathogenic antigens that cause harm. Peyer’s patches plays an integral role here and work symbiotically with the body to stimulate this immune response. They encourage the production of pathogen-specific antibodies and move them through the lymph system to hunt out pathogens (Guggenheim, 2014).
Shiitake mushrooms also contain vitamin D, which helps to protect the innate and adaptive immune systems. Your innate immune system is made up of white blood cells such as neutrophils and macrophages as well as dendric cells, natural killer cells and a few more. You are born with your innate immune system and these cells act naturally and quickly in response to an injury or infection. The adaptive immune system is antibody mediated and it kicks into action when the innate system fails. At first it is slower but is more specialised, so it can tailor itself to the various pathogens it encounters, learning the correct way to respond in the future. It is made up of lymphocytes, B and T cells, antibodies as well as microflora in the digestive system. Research indicates that Vitamin D has the ability to regulate T helper cells, helping the body determine what is an outside invader and what is self.
Although the research is recent, there is a strong correlation between Vitamin D deficiency and autoimmune responses. Autoimmune diseases stem from the body confusing external pathogens with self. T-helper cells help with cytokine production including interleukin-2, a cytokine-signaling molecule that assists with the activation of T-regulatory cells and cytotoxic T cells. Research has found that Vitamin D helps to balance out T-helper cell 1 (Th1) and T-helper cell 2 (Th2). Although this is a somewhat generalised understanding; the former tends to promote pro-inflammatory responses to intracellular viruses and is linked to autoimmunity, whilst the latter is linked more so with allergic immune responses and stimulates the production of antibodies to fight extracellular parasites. Autoimmune diseases such as rheumatoid arthritis, multiple sclerosis and Crohn’s disease are linked with dominance in Th1, whilst diseases such as lupus, athsma and ulcerative colitis have links with Th2 dominance (van Eden, 2002). A balance between both is important and vitamin D helps with this by promoting T-helper cells, essentially making your adaptive immune system smarter.
Whilst it’s known that we absorb Vitamin D from exposure to sunlight, unfortunately we tend not to spend as much time outside as we should and when we do, we wear sun protection inhibiting the amount we can absorb. Obtaining Vitamin D through dietary sources is highly recommended and mushrooms (especially when left out in the sunlight before consumption) can deliver substantial amounts (Cardwell, 2018).
As mentioned earlier, Vitamin D encourages the activation of cytotoxic T cells. These are more aggressive than T-helper lymphocytes and can destroy problematic cells that might be cancerous. They need help from interleukin-2 to activate, so a sufficient amount of T-helper cells need to be secreted in order for the cytotoxic cells to become cytolitic (cell destroyers) (Aranow, 2012). Efficient production and activation of all T cells is integral to promote immunity.