Eat Well: Eat for Defense

Heather Lutz, MS, RD, CSO, Medical Nutritional Therapist
Heather Lutz, Medical Nutritional Therapist

Boost your immune system by eating foods that increase the good bacteria in your gut. Fifty percent of the body’s immune system is located in the intestines. A significant focus of nutrition research today is on the amount, type, and variety of good bacteria in the digestive system.

Researchers are finding that there are many benefits to a healthy gut, including:
  • Reduced risk of colon cancer
  • Improved digestion and absorption of nutrients
  • Controlled appetite and reduced risk for obesity
  • Improved ability to fight upper respiratory infections

Good vs. Bad Bacteria:

Good bacteria are also known as beneficial bacteria, or any bacteria that enhances health. Some of the good bacteria are called L.acidophilius, L.casei, and S.boulardii. Bad bacteria are harmful and can cause illnesses such as pneumonia, strep throat, diarrhea, and food poisoning.

Foods that alter the balance of gut bacteria include convenience foods, refined sugars, and artificial sweeteners because they promote a less diverse presence of good bacteria. Other factors that inhibit good bacteria include antibiotics, stress, and advanced age. In people who consume healthy diets high in soluble fiber and fermented foods, the good bacteria can replenish. 

How to Increase Your Good Bacteria:

Start by increasing your intake of whole grains, fresh fruits, vegetables, plant proteins, cultured dairy, and fermented foods.

Grains and other plant foods provide a significant source of soluble fiber. Specific foods high in soluble fiber include: oats and oat bran, beans, peas, carrots, barley, citrus fruits, strawberries and apples. Plant proteins are also good sources of soluble fiber. Plant proteins include beans, peas, nuts, seeds, soy, and lentils. Substituting plant proteins for animal proteins several times a week can benefit your health.

How does fiber help the immune system?

As fiber is digested and fermented, it produces Butyrate. Butyrate boosts the production of interleukin-4, which stimulates the body’s infection fighting T-cells.

Fermented foods date back to ancient civilizations. Fermentation is a process of preserving food by introducing lactobacilli bacteria that converts the sugars and starches into lactic acid. Common fermented foods include: Sauerkraut, Kimchi, Miso, Tempeh, Kefir, Kombucha drinks, Sour dough bread, Buttermilk, Fish Sauce, Sour Cream, Crème Fraiche, Tobasco Sauce, Worcestershire Sauce, Yakult, and Yogurt.

Yogurt and Kefir

Walk into any grocery store today and see foods identified as good sources of probiotics or “live cultures”. The yogurt aisle has increased in size and variety for good reason. Cultured dairy foods, such as yogurt and kefir, are excellent sources of good bacteria, protein, and calcium. Interestingly, kefir is more diverse and rich in probiotic organisms and thus can more effectively colonize the intestinal tract with the good bacteria. Therefore, kefir is a much more potent source of probiotics than yogurt.

When shopping for yogurt, look for the phrase “live & active cultures.” Some brands will include the number of Colony Forming Units or CFU; quality brands will have 100 million CFU per gram. Look for products without added sugars, artificial flavors, or added color.

Dairy foods contain a natural sugar called lactose. Many people are unable to digest lactose. Fermented dairy foods contain lactic acid bacteria which break down the lactose into lactic acid. Thus, both yogurt and kefir are often tolerated by people who cannot consume milk. 

Probiotic supplements

If you decide to purchase a probiotic supplement, look for products that include a quality certification mark on the label; common organizations include, NSF International, and USP. The certification mark means that the product contains the ingredients on the label in the stated amounts, and that it has been tested to meet the acceptable limits of known contaminants and/or toxins. Let your physician know if you are taking a probiotic supplement.

There is no recommended daily intake level for probiotics at this time. It is recommended to increase plant foods and yogurt or kefir over taking a probiotic dietary supplement. Remember that too much of a good thing is not always better, however, adding a probiotic food or beverage will not make an unhealthy diet healthy.