The immune system is in a constant state of surveillance. When a pathogen is presented, it
stimulates the immune response, which requires the availability of substrates for energy
production (to fight infection), synthesis of proteins (such as antibodies and cytokines), and the
proliferation of immune cells. Many nutrients are required for a sufficient immune response.
Good nutrition forms an atmosphere in which the immune system is capable of an adequate
response when challenged. Poor nutrition, on the other hand, prevents a proper immune
system reaction.
Impairments of the immune system and susceptibility to infection caused by nutrient
deficiencies can be reversed when adequate nutrient supply is reinstated. This demonstrates a
causal relationship between nutrient availability and the immune system’s ability to defend
against pathogens and respond to challenges.
The nutrients that are essential for the optimization of the immune system are many but the
most relevant are vitamins A, B-6, B-12, C, D, E, folate (B-9), and the trace elements zinc,
selenium, iron, and copper.
Nutrients and the foods to focus on this season:
Vitamin A
● Recommended Dietary Allowance (RDA): Adult females 700 mcg RAE and Adult males
900 mcg RAE
Foods to include:
● Dark orange or green vegetables (carrots, sweet potatoes, pumpkin, squash, kale,
spinach, broccoli)
● Orange fruits (apricots, peaches, papaya, mango, cantaloupe)
● Tomatoes
Vitamin B-6
● Recommended Dietary Allowance (RDA): Adults 1.3 mg per day
Foods to include:
● Chickpeas
● Starchy vegetables
● Onions
● Whole grain cereals
● Green leafy vegetables
● Fruits (other than citrus)
● Soybeans
● Tofu
Vitamin B-9 or Folate
● Recommended Dietary Allowance (RDA): Adults 400 mcg DFE per day
Foods to include:
● Broccoli, Brussels sprouts, green leafy vegetables, spinach, kale, cabbage, peas, chickpeas
Vitamin B-12
● Recommended Dietary Allowance (RDA): Adults 2.4 mcg per day
Foods to include:
Fortified foods such as plant milks and breakfast cereals
Supplementation is recommended for everyone eating a strictly plant-based diet as B-12 is only formed by bacteria found in soil, water, and animal products. A daily 250-500 mcg B-12 supplement should be sufficient for most adults to meet their needs.
Vitamin C
● Recommended Dietary Allowance (RDA): Adult females 75 mg and Adult males 90 mg
per day
Foods to include:
● Oranges, red and green peppers, strawberries, black currants, kiwi, broccoli, Brussels
sprouts, potatoes
Vitamin D
● Recommended Dietary Allowance (RDA): Adults 600 IU or 15 mcg per day, increasing to
800 IU or 20 mcg per day for those over 70 years old.
Foods to include:
A ½ cup of portabella mushrooms has 0.1 mg or 4 IU per serving which is 1% of
the daily value.
Fortified foods such as plant milks and cereals.
Supplementation with vitamin D3 600-800 IU/15-20 mcg daily. However, testing
is recommended as some individuals may require more to reach adequate levels.
Vitamin E
● Recommended Dietary Allowance (RDA): Adults 15 mg daily
Foods to include:
Nuts and seeds
kiwifruit
Mango
Tomato
Spinach
Copper
● Recommended Dietary Allowance (RDA): Adults 900 mcg per day
Foods to include:
Nuts and seeds
Potatoes
Mushrooms
Tofu
Iron
● Recommended Dietary Allowance (RDA): Adults females 18 mg per day, Adult males 8 mg per day
Foods to include:
● Beans, nuts, dried fruit, whole grains, dark green leafy vegetables
Selenium
● Recommended Dietary Allowance (RDA): Adults 55 mcg per day
Foods to include:
● Brazil nuts and grains
Zinc
● Recommended Dietary Allowance (RDA): Adult females 8 mg and Adult males 11 mg per day
Foods to include:
● Grains, nuts and seeds
9 Essential Amino Acids
Essential amino acids must be supplied from the diet because humans lack the ability to synthesize these amino acids. If you eat a wide variety of plant-based foods, including beans, whole grains, fruits, vegetables, nuts, and seeds, you will consume all the essential amino acids in abundance. There is no need to combine certain foods because your body will break down the proteins that come from your food and recycle the amino acids as needed.
● Phenylalanine
● Valine
● Tryptophan
● Threonine
● Isoleucine
● Methionine
● Histidine
● Leucine
● Lysine
Foods to include daily:
● Beans, whole grains, fruits, vegetables, nuts, and seeds.
Essential Fatty Acids
Omega-3 and omega-6 fatty acids are polyunsaturated fatty acids or PUFAs.
Types of omega-3 fatty acids:
● Alpha-linolenic acid (ALA)
● Eicosapentaenoic acid (EPA)
● Docosahexaenoic acid (DHA)
Foods to include:
● Nuts and seeds
● Supplementation with algae omega-3s, DHA, and EPA, if needed.
