Vital Nutrients for Healthy Immune System Function

Our food is our medicine! And this is especially true when we’re trying to defend ourselves against cold and flu season. Below is a list of essential nutrients the immune system needs to properly function. I’ve also included foods that contain the highest amount of that particular nutrient.

Vitamin A:

  • Fat soluble vitamin
  • Essential for the immune system and healthy skin
  • Helps T-cell (immune cell) function which helps destroy incoming pathogens (bacteria and viruses)
  • Foods rich in Vitamin A: carrots, spinach, kale, broccoli, winter squash

Vitamin D:

  • Fat soluble vitamin
  • Vitamin D is synthesized by the skin but in countries where sun exposure is limited (Canada) Vitamin D has become an essential nutrient
  • Whole body sunlight exposure results in a 10,000IU/day of vitamin D
  • Vitamin D helps increase macrophage production, which engulf and destroy harmful bacteria
  • Foods rich in Vitamin D: cod liver oil, oily fish (sardines, salmon, mackerel) and vitamin D fortified foods


  • Beneficial bacteria in the digestive system
  • They compete with harmful microorganisms for binding sites on mucosal surfaces which include your lungs and digestive system
  • Some probiotics are grown on milk protein, so patients who are lactose intolerant or have milk allergies need to check to make sure they are dairy-free
  • Food sources of natural probiotics: yogurt, kefir, sauerkraut, kimchi


  • Trace mineral – inorganic so isn’t water soluble or stored in fat.
  • Anti-viral activity against some viruses – rhinovirus and herpes simplex virus
  • Zinc also supports phagocytosis (engulfing foreign invaders like bacteria and viruses)
  • Foods rich in Zinc: oysters (seafood), pumpkin and squash seeds, cashews

Vitamin C:

  • Water soluble
  • Humans are unable to synthesize vitamin C, that’s why sailors got scurvy on long sea voyages
  • Phagocytes and T-cells of the immune system need vitamin C to function, therefore a decrease in this vitamin decreases the body’s immune response
  • Recommended Daily Allowance (RDA): 60mg. This is incredibly low as we all need more than 46mg/day to prevent scurvy
  • Food sources: guava (377mg), black currant, red peppers, kiwi, orange (82mg)

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