Vitamin D and Fatigue

Do you find yourself waking up tired, even after a good night's rest? Though there are numerous causes for fatigue, a nutrient deficiency is not often considered. A frequent offender may be vitamin D. It's estimated that roughly 35% of adults in the U.S. are deficient in this vital nutrient.

A Vitamin D deficiency may cause fatigue

Vitamin D's importance in bone metabolism has long been recognized, but recent evidence suggests it might also have an impact on a number of other conditions, including fatigue. Although some individuals with low levels of vitamin D are asymptomatic, others struggle with fatigue and an overall feeling of low energy.

Vitamin D is believed to help with the generation of energy, increase muscular power, and level off a person's mood.

How Vitamin D Affects Energy and Fatigue

The exact mechanism by which vitamin D affects fatigue is not fully understood. Nevertheless, vitamin D participates in the process of producing energy. Vitamin D influences mitochondria which function as cellular energy producers.

Vitamin D helps absorb calcium which is vital for muscle contraction and strength. Muscle weakness and fatigue can result from low nutrient levels. Vitamin D plays a role in the regulation of serotonin and melatonin, which affect human mood and sleep patterns. Poor sleep causes people to experience reduced energy and fatigue.

Our immune system becomes vulnerable when vitamin D levels decrease. An increase in chronic inflammation, together with extended recovery time from sickness, results in heightened fatigue.

Signs of a Vitamin D Deficiency

• Fatigue and low energy

• Muscle weakness or cramps

• Bone or joint pain

• Getting sick more often

• Insomnia

Other complications of vitamin D deficiency in adults include low blood calcium levels (hypocalcemia), low blood phosphate levels (hypophosphatemia), and osteomalacia, which is a softening of bones in adults.

Risk Factors

Vitamin D deficiency can be caused by not enough exposure to sunlight or vitamin D in the diet. However, some people may have additional issues absorbing or effectively using vitamin D.

Certain medications, such as steroids and laxatives, may contribute to a vitamin D deficiency. Obesity may also reduce the availability of vitamin D.

Some gastrointestinal conditions can impact nutrient absorption. For example. Crohn’s disease and celiac disease can cause inflammation in the small intestine, where vitamin D is absorbed.

Other conditions that can impact vitamin D levels are gastric bypass surgery, kidney disease and liver disease. People over 65 and those with more pigment in their skin also have a greater risk of deficiency in the nutrient.

How to Improve Vitamin D Levels

1.Get Some Sunshine

Our bodies produce vitamin D when exposed to UVB rays from the sun. Try to get 10-30 minutes of sun exposure on your bare arms or legs a few times a week. Sunscreen may reduce the amount of sun exposure, so try exposing your skin without sunscreen for the first 10-15 minutes before applying.

Your body produces vitamin D when exposed to UVB rays

If you have darker skin, try to get 30-40 minutes of sun exposure 3-4 times a week. Your skin contains more melanin, which protects you from the sun's rays, but may also reduce your vitamin D exposure.

In the winter months, the sun's UVB rays can be too weak for proper vitamin D production. In the winter, you may need to obtain vitamin D from food and/or supplements.

2. Get Vitamin D from Food Sources

Salmon is a source of vitamin D

While sunlight is the best source of vitamin D, you can also get vitamin D in your diet. Here are some foods that contain vitamin D:

• Fatty fish, such as salmon or tuna

• Rainbow trout

• Egg yolks

• Fortified cow’s milk

• Fortified plant-based milks

• Fortified orange juice

  
  

Wild-caught fish contain more vitamin D than farmed fish.

3. Try Vitamin D3 Supplements

Unless you are getting sufficient vitamin D through sun exposure or diet, you will need to take supplements. Vitamin D3 (cholecalciferol) is far better at increasing your blood levels than D2.

The regular dose of vitamin D is 1,000–2,000 IU (25–50 mcg) per day. In case you lack vitamin D, the dose is 5,000-10,000 IU daily for 8-12 weeks under medical supervision. If your levels are sufficient, it is possible to continue with 2,000 IU daily, in case you are still unable to make sufficient amounts of vitamin D from sun exposure or diet.

Liquid or soft gel forms of the vitamin can be easier to absorb. Since vitamin D is fat-soluble, taking it with a meal that contains fat can further improve absorption.

A Few Nutrients That Work With Vitamin D

1. Magnesium

Fatigue can also be caused by a deficiency of magnesium. Vitamin D needs magnesium in order to be activated into its active form of calcitriol. If your level of magnesium is low, your body will utilize stored magnesium to activate the vitamin D. Try to get more magnesium from foods or supplements. Look for upcoming posts on magnesium.

Several nutrients work alongside vitamin D

2. Vitamin K2

Vitamin K2 is also a nutrient that works alongside vitamin D. Vitamin K2 can be found in egg yolks, butter, cheese, eel, chicken, fermented soybeans, and sauerkraut.

3. Calcium

Vitamin D helps your body absorb calcium.

4. Zinc

Zinc helps activate vitamin D and supports immune function alongside the nutrient.

Vitamin D Testing

Healthcare providers don't normally conduct regular vitamin D screenings, unless a patient shows risk factors for deficiency or has specific health issues. Functional medicine providers, including physicians and functional dietitians, frequently recommend vitamin D and other nutrient deficiency tests.

Your healthcare provider can order blood tests measuring vitamin D levels. A deficiency exists when a patient's level falls below 20 ng/mL.

Can you get too much vitamin D?

Sometimes you can get too much of a good thing, especially if you're taking high amounts of vitamin D3 supplements over a long duration of time. However, you can’t get too much vitamin D from sunlight! While relatively rare, toxicity can occur and may lead to hypercalcemia, which can leave you terribly fatigued, weak, hurt your bones, disturb your heartbeat, cause vomiting, and even lead to kidney stones.

If you have risk factors for developing vitamin D deficiency or are experiencing crushing fatigue, it is worth getting your vitamin D levels checked.

References:

Vitamin D Deficiency. Cleveland Clinic, 2022. https://my.clevelandclinic.org/health/diseases/15050-vitamin-d-vitamin-d-deficiency

Di Molfetta IV, Bordoni L, Gabbianelli R, Sagratini G, Alessandroni L. Vitamin D and Its Role on the Fatigue Mitigation: A Narrative Review. Nutrients. 2024 Jan 10;16(2):221. doi: 10.3390/nu16020221. PMID: 38257114; PMCID: PMC10818509.