Vitamin D deficiency during winter

Winter is a time of year when the days are shorter and the temperatures are colder, making it difficult to get out and enjoy the sunshine. Unfortunately, this can result in vitamin D deficiency during the winter months, as vitamin D is primarily obtained through exposure to the sun. Vitamin D is essential for healthy bones, immune system, and overall health, so it’s important to get the right amount each day. Fortunately, there are some simple ways to make sure you don’t become deficient in vitamin D during the winter months. Here are some tips on how to avoid vitamin D deficiency during cold winter months.

What is the role of vitamin D in the body?

Vitamin D is primarily responsible for the absorption and maintenance of adequate levels of calcium and phosphorus in the body. Both minerals can be found mostly in the skeleton.

  • Calcium is the most abundant mineral in the body and is necessary to build and maintain strong bones. It also serves to carry out other functions such as muscle contraction, blood clotting and nerve impulses.
  • Phosphorus is the second most abundant mineral in the body. It can mostly be found in the teeth and bones. Phosphorus is present in every cell of the body and makes up approximately 1% of a person’s total body weight [1] It also has metabolic functions such as energy storage and enzyme regulation.

What are the causes of vitamin D deficiency?

  • Lack of sun exposure: It’s very common during winter as people spend more time indoors and the skin has limited exposure to sunlight. Likewise, people living in northern latitudes or highly polluted areas may have difficulty with sun exposure.
  • Skin color: Pigmentation in the skin reduces the body’s ability to absorb the sun’s ultraviolet B (UVB) rays.
  • Older adults: With age, the body’s ability to synthesize vitamin D deteriorates. It is also common for older people to spend more time indoors.
  • Obesity: People with a high percentage of body fat may have difficulty synthesizing vitamin D through the skin. [2]

What are the symptoms of Vitamin D deficiency?

For the most part, people with vitamin D deficiency have no symptoms. However, chronic deficiency can cause hypocalcemia, a calcium deficiency disease, and hyperparathyroidism, in which the parathyroid glands create a hormonal imbalance that raises blood calcium levels. [3]

These conditions can cause secondary symptoms such as:

  • Bone fragility
  • Bone pain
  • Fatigue
  • Muscle weakness
  • Muscle pain
  • Arthralgias or joint stiffness

What are the health implications of Vitamin D deficiency?

Prolonged deficiency of vitamin D, can result in complications such as:

  • Cardiovascular conditions
  • Autoimmune problems
  • Neurological diseases
  • Infections
  • Pregnancy complications
  • Certain types of cancer, such as breast, prostate and colon cancer.

health implications of Vitamin D deficiency

What are the best sources of Vitamin D?

Very few foods contain this vitamin in natural form. Foods fortified with vitamin D provide most of the vitamin D in the diets of people in the United States [4]. Vitamin D can be found naturally in foods such as:

  • Sun exposure
  • Fortified foods
  • Fatty fish such as salmon or trout
  • Fish liver oil
  • Egg yolk
  • Avocado
  • Mushrooms
  • Beef liver

How can I avoid vitamin D deficiency during the winter?

Ironically, it is during autumn and winter that we need vitamin D the most to combat the viruses typical of the season. For this reason, it is vitally important to take appropriate measures against seasonal vitamin D deficiency.

Increase your intake of D-rich foods.
Take a vitamin D supplement (consult your doctor about the correct dosage).
Try to sunbathe for 15 minutes a day.

Genetic predisposition to Vitamin D deficiency

Several studies have identified genetic variations in various genes that contribute to vitamin D deficiency, for example. The group-specific component (GC) gene, also known as the vitamin D-binding protein (DBP), encodes a protein that belongs to the albumin gene family that binds to vitamin D and transports it to target tissues. Genetic mutations of these genes have been associated with vitamin D deficiency in numerous studies as well.

The CrossDNA genetic test analyzes this and other genes related to predisposition to vitamin D deficiency. Find out how you can take care of your health by making informed, personalized decisions based on your DNA.


[1] Fósforo en la dieta. (s. f.). MedlinePlus en español. Recuperado 28 de diciembre de 2022, de

[2] [3] Ware, M., RDN, & L.D. (2022, febrero 23). Vitamin D: Benefits, deficiency, sources, and dosage.

[4] Romaní de Gabriel, J. (2010). Vitamina D. Actas dermo-sifiliograficas, 101(9), 739–741.

[5]  Slater, N. A., Rager, M. L., Havrda, D. E., & Harralson, A. F. (2017). Genetic variation in CYP2R1 and GC genes associated with vitamin D deficiency status. Journal of Pharmacy Practice, 30(1), 31–36.

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