NUTRITION AND
THE IMMUNE SYSTEM

The immune system isconstantly working to protect
the body from infection,
injury, and disease.

OVERVIEW OF THE IMMUNE SYSTEM
The immune system consists of various organs,tissues, and cells located throughout the body.

tonsils
lymph nodes

WHITE BLOOD CELLS (WBCs)

thymus• The cells of the immune system• Made inside bone marrow• WBCs travel through the body inside lymph
vessels, which are in close contact with thebloodstream

spleenTHERE ARE SEVERAL TYPES OF WBCs

peyer’s patches
lymph vessels

NEUTROPHILSEngulf & destroybone marrow

BASOPHILS
Releasehistamine(MACROPHAGES)

Engulf & destroy

EOSINOPHILSFight parasiticinfections

LYMPHOCYTESAttack specificpathogens

PLASMA CELLS
Produceantibodies

MONOCYTESThe immune system provides three levels of defense
against disease-causing organisms:

1

3

2

BARRIERSINNATE IMMUNITYACQUIRED IMMUNITY• Skin and mucus membranes• Stomach acid and digestiveenzymes• Beneficial bacteria that live inthe colon (the gut microbiota)

WBCs called neutrophils andmacrophages engulf anddestroy foreign invaders anddamaged cells• WBCs called T lymphocytes(T cells) target and destroy
infected or cancerous cells• WBCs called B lymphocytes(B cells) and plasma cells
produce antibodies thattarget and destroy infected orcancerous cells

Prevent entry

Specific defense

General defense

KEY FEATURES OF THE IMMUNE RESPONSEOXIDATIVE BURSTO₂O₂O₂O₂O₂-• Certain immune cells produce a concentrated burst ofreactive oxygen species (ROS), damaging substancesthat help kill invading organisms

Important nutrients• Vitamin C• Vitamin E• Iron• Zinc• Copper• Selenium

Connection• Prolonged and continuous exposure to ROS can lead todamage and disease• The listed antioxidant nutrients protect immune cells
and keep the oxidative burst in check

PROLIFERATION• Refers to an increase in the number or amountof something• The immune system is constantly producing cells,
chemicals, and proteins to carry out its functions• When it encounters a foreign invader, it ramps up
production to respond as needed

Important nutrients• Vitamin A• Vitamin D• Folate• Vitamin B12• Vitamin B6

B CELL
PLASMA CELLSConnection• Iron
• ZincANTIBODIES• Proliferation requires energy, building blocks, andcofactors to produce the many cells and substances
needed to mount an effective immune response• The listed micronutrients have essential roles in theproduction and development of all new cells in the body,
including immune cells

INFLAMMATION• Isolates the injured or infected area
• Helps deliver immune cells, chemical messengers, andantibodies to sites of injury or infection

Important nutrients• EPA• DHAConnection• Inappropriate activation or the inability to turn off
inflammation can lead to tissue damage and chronic
disease• EPA and DHA have anti-inflammatory activity that canhelp keep inflammation in check

NUTRIENTS THAT SUPPORT IMMUNE FUNCTION
NUTRIENTRDA (adults)

EPA + DHA

No RDA
Advised to consume two servings ofoily fish/week

herring 3 oz, 1.8 g
salmon 3 oz, 1.5 gsardines 3 oz, 1.2 g

Vitamin A*

Men: 900 µg/day
Women: 700 µg/day

egg 1 large, 80 µg
carrot** 1/2 cup raw, 534 µg
sweet potato** 1/2 cup baked, 961 µg

Vitamin C*

Men: 90 mg/day
Women: 75 mg/day

sweet red pepper 1 medium, 152 mg
kiwifruit 1 medium, 91 mg
strawberries 1 cup whole, 85 mg

19-70 years: 600 IU/day
71 years and older: 800 IU/daypink salmon 3 oz, 370 IU
sardines 3 oz, 164 IU
fortified milk 1 serving, 120 IU
sunshine

15 mg/dayalmonds 1 oz, 7 mg
sunflower oil 1 T, 6 mg
avocado 1 whole, 2.7 mg

400 µg/day

lentils 1/2 cup cooked, 179 µg
spinach 1/2 cup cooked, 131 µgenriched bread*** 1 slice, 84 µg

Vitamin B12

2.4 µg/day

clams 3 oz, 84.1 µg
mackerel 3 oz, 16.1 µg
beef 3 oz, 6.9 µg

Vitamin B6

19–50 years: 1.3 mg/day
Men 51 years and older: 1.7 mg/day
Women 51 years and older:
1.5 mg/day

salmon 3 oz, 0.5 mg
turkey 3 oz, 0.7 mg
potato with skin 1 medium, 0.7 mg

Zinc

Men: 11 mg/day
Women: 8 mg/day

Oysters 6 medium, 27–50 mg
beef 3 oz, 4–6 mg
yogurt 1 cup, 1.8 mg

Iron*

Men and women 51 years and older:
8 mg/day
Women 19–50 years: 18 mg/day

beef 3 oz, 1.6 mg
tuna 3 oz, 1.3 mg
lentils 1/2 cup cooked, 3.3 mg

900 µg/day

oysters 6 medium, 2,397 µg
cashew nuts 1 oz, 622 µg
lentils 1 cup cooked, 497 µg

55 µg/daytuna 3 oz, 92 µg
pork 3 oz, 32.5 µg
whole-wheat bread 1 slice, 8.2 µg

Vitamin D*Vitamin E*

FolateCopperSelenium

GOOD SOURCESLOW FATMILK

YOGURT
Low Fat

RDA = Recommended Dietary Allowance | IU = International Units | g = grams | mg = milligrams | µg = microgramsoz = ounce(s) | T = tablespoon*Underconsumed by eating the typical American diet. Iron underconsumed by adolescent females andpregnant women only**A source of provitamin A carotenoids***A source of folic acid, the synthetic form of folate

For some nutrients, getting more than the RDA
might be of further benefit
VITAMIN C
Routine supplementation withvitamin C (0.25 to 2 g/day)
reduces the occurrence of thecommon cold inindividuals
undergoingheavy physicalstress (marathon
runners, skiers,
and soldiers insubarctic
conditions).

Routine supplementation withvitamin C slightly reduces theduration of the common cold.

The LPI recommends a daily
intake of at least 400 mg ofvitamin C for generally healthy
adults.

Vitamin C

400 mg/day

VITAMIN D
Low vitamin D status is linked
to a higher risk of upper
respiratory tract infections andsome autoimmune disorders.
Supplementation withvitamin D reduces the risk ofacute respiratory tract infection.

The LPI recommends 2,000 IU (50 µg) of
supplemental vitamin D daily for generally
healthy adults.

Vitamin D
2,000 IU

SOURCES• Micronutrient Information Center, lpi.oregonstate.edu/mic/micronutrients-health/immunity• Textbook of Medical Physiology, 9th edition. Guyton and Hall
• Dietary Guidelines for Americans 2015–2020, Eighth edition, health.gov/dietaryguidelines/2015/guidelines/© Linus Pauling Institute