A Guide to Understanding Vitamin D Deficiency


Vitamin D is a fat-soluble vitamin that plays a crucial role in maintaining overall health and wellness. Unlike many other types of vitamins that can be obtained through the foods we consume, vitamin D is found in relatively few foods and is mainly attained through supplementation and our skin’s exposure to sunlight. 

If you don’t have enough vitamin D in your body, this is referred to as “vitamin D deficiency.” Vitamin D deficiencies are becoming increasingly common; research published in the National Institutes of Health database suggests that it affects approximately 42% of the U.S. population

It’s believed that the uptick in cases is due to more routine testing for vitamin D deficiencies combined with a greater number of people staying indoors. Although vitamin D deficiencies are seen across all age groups and demographics, adults over the age of 65 and people with dark skin tend to be at greater risk. 

Understanding the Role of Vitamin D in the Body

Vitamin D is an essential vitamin that helps the body absorb calcium and phosphorous, two minerals that are crucial for healthy bone development and maintenance. Receptors for vitamin D are present in numerous organs and tissues within the body; it’s been found to play a role in the immune and nervous systems, as well as mood regulation and mental health. Studies suggest vitamin D can reduce inflammation and the growth of cancer cells, as well as help control infections. 

Our skin has the remarkable ability to synthesize vitamin D through exposure to sunlight; although this is the primary natural source of vitamin D, many people now spend the majority of their time indoors and avoid sun exposure due to the risk of skin cancer. Only a handful of foods contain vitamin D naturally, which is why certain foods (like milk and orange juice) are fortified with it. However, it’s difficult to receive sufficient vitamin D through diet alone, so supplementation is often needed to ensure adequate intake. 

Factors That Contribute to Vitamin D Deficiency

Vitamin D deficiencies can be caused by both lifestyle-related and physiological factors:

  • Insufficient sun exposure: Modern lifestyles have shifted towards sedentary indoor activities and occupations, which has reduced the amount of sun exposure many people receive. Those who are homebound, live in locations with limited sunlight, or wear long clothing that covers the skin are more likely to develop a deficiency. Vitamin D deficiencies can also be more prevalent during the winter due to less sunlight during the day.  
  • Darker skin: Individuals with darker skin tones have higher melanin levels, which acts as a natural sunscreen. As a result, it’s more difficult for those with darker skin to synthesize vitamin D. 
  • Age: The skin’s capacity to synthesize vitamin D decreases with age, which makes older adults more prone to deficiency. As people age, their kidneys also have difficulty converting vitamin D to its active form.
  • Sunscreen use: Although sunscreen is essential to protect your skin from burns and skin cancer, it blocks the UVB rays needed to synthesize vitamin D. 
  • Diet: Diets lacking in vitamin D-rich foods like fatty fish, fortified dairy products, and egg yolks, can contribute to insufficient intake. Since many natural sources are animal-based, those who follow a strict vegan diet are more likely to develop vitamin D deficiencies. 
  • Certain medical conditions: Some medical conditions can prevent the body from absorbing vitamin D, such as cystic fibrosis, celiac disease, Crohn’s disease, and other gastrointestinal disorders. Kidney and liver disease can reduce the amount of enzymes needed to change vitamin D to a form the body can use. 
  • Certain medications: some medications can lower vitamin D levels in the body, including Rifampin, Orlistat, laxatives, steroids, seizure-preventive drugs, and cholesterol-lowering drugs. 
  • Obesity: Vitamin D is stored in adipose (fat) tissue; in those with higher amounts of body fat, vitamin D tends to “hide” in fat cells, leading to lower amounts of it circulating in the blood. 
  • Weight loss surgery: Weight loss surgeries that involve reducing the size of the stomach or bypassing part of the small intestines, like gastric bypass surgery, make it harder for the body to absorb certain nutrients, vitamins, and minerals, including vitamin D.

Since the causes of vitamin D are multifaceted, it’s important to take a holistic approach to maintain healthy levels. If you currently have a vitamin D deficiency, this means looking at your lifestyle, what you eat, and any health conditions you might have. 

Symptoms of Vitamin D Deficiency and Health Implications

Although many patients are asymptomatic, vitamin D can have noticeable symptoms, including:

  • Fatigue
  • Bone pain or achiness
  • Muscle weakness
  • Loss of appetite
  • Inability to sleep well
  • Hair loss 
  • Depression
  • A tendency to get sick more easily
  • Pale skin

Since it plays such a vital role in bone health, vitamin D deficiencies can lead to serious bone conditions, like osteoporosis, which causes a loss of bone density and makes bones more prone to breaking. In children, vitamin D deficiencies can cause rickets, a rare condition that affects bone development and growth. It can also lead to osteomalacia, a condition that weakens bones and causes bone pain and muscle weakness. 

Beyond issues with bone density and growth, low levels of vitamin D have been linked to a higher risk of heart attacks, congestive heart failure, strokes, diabetes, hypertension, and autoimmune disorders. Studies have also found links to mental health issues, like mood disorders, cognitive impairment in older adults, severe asthma in children, and certain cancers. 

Treatment for Vitamin D Deficiency

The two primary ways of treating vitamin D deficiency are getting more sun exposure and getting more vitamin D from either diet or supplementation. 

Despite skin cancer concerns, spending a moderate amount of time outdoors in the sun can help you maintain adequate vitamin D levels. Most experts recommend around 10 to 30 minutes of sun exposure on your face, arms, and legs a few times a week, depending on your skin tone, time of day, and geographical location. However, it’s still important to strike a balance between healthy sun exposure and protecting your skin from excessive UV radiation.

Incorporating more vitamin D-rich foods in your diet, like fatty fish, egg yolks, fortified dairy products, and mushrooms can also be very beneficial. In some cases, it may be necessary to take a vitamin D supplement. Vitamin D supplements come in two main forms: D2 and D3. While both can increase vitamin D levels, D3 is generally considered more effective in raising and maintaining optimal levels. 

Consult a healthcare professional before starting any supplementation regimen to determine the right dosage for you; when taken in excess, vitamin D supplements can cause vitamin D toxicity.

Effective Strategies for Preventing or Overcoming Vitamin D Deficiency

Healthy vitamin D levels place a crucial role in the journey toward optimal health and well-being. From maintaining strong bones and good mental health to preventing serious health conditions, this essential nutrient is a cornerstone for overall vitality.Whether you have vitamin D deficiency or risk factors for developing it, Dr. Jennifer Hubert can help you develop a personalized health plan tailored to your specific needs. With years of experience in internal medicine, Dr. Hubert takes a holistic approach that focuses on the whole person, not just the symptoms. She’ll actively listen to your concerns and work with you to find the best solutions to achieve your health goals and lead a healthier life. Schedule a consultation today at (707) 380-1838.