Immune Health
How Vitamin D Affects Your Immune Health
Author

Fact Checked By Jill Armijo, PTA, CHC

What Vitamin D Does for Your Body

Ever heard ‘moderation in all things,’ or ‘too much of a good thing isn’t better?’

That’s how you need to look at vitamin D. Your body wants just the right amount of it to function optimally. Not enough or too much, and things get rough (1).

Vitamin D helps with various functions, including:

  • Keeping bones strong and muscles moving fluidly (2).
  • Absorbing calcium to support bone, muscle, and heart tissue (3).
  • Reducing inflammation, modulating cell growth, neuromuscular and immune function, and glucose metabolism (4).
  • Working with parathyroid glands to balance calcium in the blood (5).

Having healthy bones protects children from rickets and adults from osteomalacia.

These conditions cause bone pain, poor growth, soft, weak bones, and deformities (6).

The parathyroid glands balance calcium in the blood through communication with the kidneys, gut, and skeleton.

With insufficient vitamin D, your parathyroid glands will ‘borrow’ calcium from your bone tissue to keep blood calcium in the normal range to ensure fluid muscle contraction (7).

Immunity and Vitamin D

Vitamin D affects cells in the immune system and protects against infection and autoimmune disorders.

It supports immunity by inhibiting B cell proliferation, blocking B cell differentiation, and immunoglobulin secretion (8).

During the recent viral outbreak, researchers noted that U.S. patients with low levels of vitamin D were more likely to be hospitalized (9).

A higher incidence of autoimmune disease is linked with insufficient vitamin D in the body (10).

Vitamin D Deficiency

Symptoms of vitamin D deficiency can include:

  • Muscle weakness
  • Poor coordination
  • Bone and muscle pain
  • Fatigue
  • Mood disorders like depression (11).

Weak bones can lead to osteoporosis (bone density loss), which can cause bones to break easily, sometimes without falling (12).

Vitamin D deficiency can be caused by lack of sunlight, nutrition, and other factors, along with certain medical conditions that don’t allow the intestines to absorb vitamin D through supplements:

  • Cystic fibrosis (13).
  • Crohn’s disease (14).
  • Celiac disease (gluten intolerance) (15).
  • Kidney disease (16).
  • Liver disease (17).
  • Obesity (18)

Weight loss surgeries may make it difficult for the intestines to absorb certain nutrients, including vitamin D, despite varying supplementation doses (19).

A body mass index greater than 30 is associated with lower vitamin D levels since the nutrient becomes isolated in fat cells and is unusable (20).

Kidney and liver diseases reduce the amount of an enzyme needed to change vitamin D to a form the body can use (21).

Other factors that can lead to vitamin D deficiency are:

  • Age: The skin’s ability to make vitamin D lessens with age (22).
  • Skin color: Dark-colored skin is less able to make vitamin D than fair-colored skin (23).
  • Breast milk contains no vitamin D, and infant formula contains only tiny amounts of vitamin D (24).
  • Laxative use can deplete vitamins and minerals because they speed food through the digestive tract before it can absorb the nutrients.
  • Intestinal motility disorders, constipation, and inflammatory bowel disease (IBS) (25).
  • Anxiety and depression (26).
  • Steroids and medications (27), (28).

Getting Enough Vitamin D

Before antibiotics, doctors advised patients with tuberculosis to go to sanatoriums where they got plenty of time in the sunshine. They thought sunlight directly killed the disease (29).

Nannies were notorious for administering cod liver oil, a source of abundant vitamin D, to unhappy children to treat tuberculosis and protect them from infections (30).

Your skin produces vitamin D by using ultraviolet B radiation the sun emits, and it promotes optimal absorption of calcium from your diet (31).

The three best ways to get vitamin D are:

  • Sun
  • Food
  • Supplements

Sunlight - Melanin is a pigment in the eyes, hair, and skin. Fair-skinned and younger people convert sunshine into vitamin D more readily than darker-skinned individuals and those over age 50 (32).

Ten to thirty minutes several days a week in sunlight is usually sufficient and typically isn’t enough exposure to cause skin cancer (33).

Getting the radiation you need depends on where you live and the time of day and year due to the ozone layer and the sun’s zenith. Areas near the equator have higher ultraviolet light.

The sun’s rays are most powerful between 10 a.m. and 3 p.m. but vary depending on cloud cover and air pollution (34).

Diet - Vitamin D doesn’t occur naturally in many foods. That’s why we fortify foods like milk.

It may be difficult, especially for vegans or people who are lactose intolerant, to get enough vitamin D from their diets, which is why some people take supplements. Some excellent sources of vitamin D are:

  • Eel
  • Trout
  • Swordfish
  • Salmon
  • Tuna
  • Fortified dairy (orange juice, milk, yogurt)
  • Fortified cereals
  • Sardines
  • Beef liver
  • Egg yolk
  • Shitake mushrooms (35).

Supplements - You can’t get too much vitamin D from the sun, although too much UV rays cause other problems like sunburns, wrinkles, leathery skin, liver spots, cancer, eye damage, and actinic keratosis (scaly patches) (36), (37).

Recommended amounts of vitamin D vary, depending on:

  • Age
  • Skin color
  • Climate

You may need to supplement orally if you’re older, have dark skin, or live in a northern climate. If you use sunscreen or stand behind a window, you won’t get the UV rays from the sun needed for your skin to create vitamin D (38).

Vitamin D Toxicity

While rare, vitamin D toxicity can be a severe problem. It builds up calcium in your blood (hypercalcemia), which can cause:

  • Nausea and vomiting
  • Increased thirst and urination.
  • Poor appetite.
  • Constipation.
  • Weakness.
  • Confusion.
  • Pain.
  • Kidney problems (stones)
  • Ataxia (loss of muscle control and stumbling)
  • Dysarthria (slurred speech due to lack of muscle control) (39), (40).

This is why it is important to take Vitamin D with K. The K2 part of the supplement ensures calcium deposit in the right places.

Conclusion

Vitamin D is essential for the proper functioning of your body and its immune system, but too much can wreak havoc.

Discuss dosing and other medications you’re taking with your health provider before adding extra fish or supplements to your diet.

She should check your blood levels and adjust vitamin A and D doses since vitamin A is abundant in some fish oils and is also toxic at high levels.

Author

Fact Checked By Jill Armijo, PTA, CHC

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