Eating Greens and How It Affects Immune Health

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Eating Greens and How It Affects Immune Health

My mother always used to tell me “eat your greens, they’re good for you!” It turns out, mother was more right than she could possibly know.

Eating one’s greens may be even more crucial for immune health than we previously thought, according to recent research which has discovered that an immune cell population essential for intestinal health may be controlled by leafy greens in the diet.

The immune cells, termed innate lymphoid cells (“ILCs”), are located in the lining of the digestive tract. They were discovered in 2013 by researchers at the Walter and Eliza Hall Institute of Molecular Research in Australia. [1]

Let me back-track a bit. Science has, for many years, divided the immune system into two types: innate and adaptive. Innate immunity is present at birth and does not require prior exposure to protect you against pathogens. Adaptive immunity only develops when you have been exposed to a pathogen, for instance chickenpox. Once exposed to a pathogen, your immune cells are able to recognize the invader and mount a defense against it. Adaptive immunity provides the SWAT team that identifies an invading enemy and makes the specific weapons (known as antibodies) needed to destroy it. The fascinating thing about ILCs is that they are neither innate nor adaptive, they sort of straddle the two.

ILCs include cells that have been known for decades, such as natural killer (NK) cells and lymphoid tissue-inducer (LTi) cells. NK cells are key in protecting us from cancer as they recognize a huge array of tumor cells and cancer stem cells and help to eliminate them through cytotoxicity and the production of cytokines. Other ILCs are found mainly in the mucosal lining of the gut and in other mucosal-associated lymphoid tissues, where they work hard to protect us from pathogens.

The 2013 research [2] discovered that a gene called T-bet is essential for producing these all-important ILCs. Going back to the subject of eating greens, they found that the gene responds to signals in the food we eat. They discovered that T-bet is the key gene that tells precursor cells to develop into ILCs. It does this in response to signals from the food we eat and to the presence of bacteria in the gut.

Here’s how it works. Apparently proteins in green leafy and cruciferous vegetables interact with a cell surface receptor that switches on T-bet. Researchers think that the proteins in leafy greens may be part of the same signaling pathway used by T-bet to produce ILCs.

These researchers were excited about the discovery because it has been exceedingly difficult to isolate or produce ILCs. So finding out that something as simple as leafy greens and cruciferous vegetables in the diet can turn on the gene responsible for making ILCs is noteworthy. Without eating greens and without T-bet, the body becomes more susceptible to bacterial infections and other diseases.

Beyond their role in immunity, ILCs are also found in adipose (fat) tissue where they regulate thermogenesis and prevent inflammation that may lead to metabolic syndrome, obesity-related asthma and insulin resistance. [3]

Interestingly, while reading all the research as I prepared to write this article, I came across any number of web articles that boldly denied that diet had any role to play in bolstering immunity – despite the vast amount of research that’s being published to the contrary. Some people live in an interesting land called DENIAL.

For more information on which foods help with immunity and fighting cancer, see my page Diet and Cancer.

References:

[1] Gene Discovery Reveals Importance of Eating Your Greens –

https://www.wehi.edu.au/news/gene-discovery-reveals-importance-eating-your-greens

[2] T-bet is essential for NKp46+ innate lymphocyte development through the Notch pathway –

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4076532/

[3] Innate lymphoid cells: A new paradigm in immunology – http://science.sciencemag.org/content/348/6237/aaa6566

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