In infants and very young children, the thymus is central to immunity, but for reasons not well understood, this gland shrinks and becomes inactive with age. Our spleens and bone marrow can create fresh new immune cells for us, but specialized tissues in our intestines play a starring role in most people’s immune function. These intensively active communities of immune cells sample everything that passes through your digestive tract.
In your gut, variety is the spice of immune vitality for at least two closely-related reasons:
- Variety in what you eat trains your immunity and gives your immune system a clearer picture of the challenges it faces from your environment and lifestyle.
- Variety in what you eat — and especially in plant-based foods — lends core strength to your intestinal microbial community. These gut microbes are gifted chemists that interact with your gut immune cells to create an amazing array of substances that impact health.
Together, what you eat, the microbes in your gut, and the chemistry between these microbes and your immune system create your own personal garden of life, your gut microbiome. The balance and diversity of microbes in your gut microbiome is pivotal, and altered gut microbiome makeup has been associated with obesity, cognitive problems, poor immunity, accelerated biological aging, and other health concerns.
Grow a Better Garden
Medical science increasingly appreciates the importance of the gut microbiome, because improving it is one of the easier ways to improve an individual’s overall health. So how does one go about growing a healthier internal garden of life?
Variety, variety, variety. Variety in veggies and fruit, in spices and herbs and teas. Rotating the kinds of grains (best: whole grains) you eat so that it’s not just wheat or rice or corn. Eating plants from the entire color spectrum. (Click the image to magnify and discover a rainbow of new foods to diversify your diet!)
Certain food types are especially good at boosting healthy gut bugs and a happy gut environment. Prebiotics are ideal foods for growing beneficial “friendly flora,” while probiotic foods contain microbes that promote healthy chemistry in the intestines to aid digestive and immune function. Examples of prebiotic foods include buckwheat, beans, peas, lentils, mushrooms, berries, nuts, seeds, green tea, apples, pears, cruciferous veggies (cabbage, etc.), onions, nutritional yeast, whole grains, tapioca, cassava, yucca, seaweed, root veggies, endives, chicory, dairy products, citrus fruits, squash, pumpkin, plantains, cocoa powder, whey, and soluble fiber supplements.
Probiotic foods include fermented dairy products like yogurt and kefir, unpasteurized cheeses, tempeh, natto, and unpasteurized pickled foods like kimchi, miso, sauerkraut, and probiotic supplements.
Meat is not always included in healthy food lists, because heavy consumption of it is linked to considerable health risk, especially for the heart and blood vessels. However, some evidence suggests that, in modest amounts — more like a spice for all the plant-based foods you’re going to enjoy — fish, meat, and other animal-based foods can contribute to diversity in the gut microbiome. If you do eat a lot of meat, though, cutting back could be an effective way of improving your own and your planet’s health.