What Prevents Vitamin D Absorption

Vitamin D is an important nutrient that the body uses to support critical health functions, including boosting immune function, supporting proper bone formation, and promoting tissue and colon health. However, what prevents vitamin D absorption can prove difficult for your health. You can develop a deficiency of this vitamin if you don’t absorb it properly in your small intestine, and it even causes some side effects. 

How Does The Body Absorb Vitamin D?

Vitamin D SoftGel

Vitamin D is a fat-soluble vitamin, which means this type of vitamin needs dietary fat to be broken down and absorbed into the body. Most people get their vitamin D from internal chemical reactions caused by direct exposure to ultraviolet rays in sunlight. 

Few natural foods can be considered sources of vitamin D, such as fatty fish, egg yolks, cheese, beef liver, fish liver oil, and certain mushroom species, but artificially fortified foods like milk, fortified fruit juices, cereals, and other dietary sources of the vitamin are also sought after. 

Taking vitamin D supplements is also a great way to fill in the body’s need for vitamins. Most often, supplementation can also deliver other important nutrients that work well with vitamin D and make absorption faster and easier.

what prevents vitamin D absorption
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Factors That Prevent Vitamin D Absorption

There are a few factors behind the trouble in absorbing vitamin D. Some factors that may reduce or block its absorption include:

  • Age
  • Gastrointestinal diseases
  • Obesity
  • Liver disease
  • Kidney diseases
  • Radiation treatment
  • Taking certain medications

Since one can’t properly absorb vitamin D into their system without a healthy intake of fat, any condition that hinders the ability to absorb fat can also prevent the body from absorbing it properly. Not only that, it can leave your body prone to various conditions. 


As a person ages, the risk for vitamin D deficiency significantly increases. In the United States, the percentage of older adults suffering from vitamin D deficiency ranges from 20 to 100%

Gastrointestinal diseases

Conditions that affect the intestines, such as celiac disease, chronic pancreatitis, Crohn’s disease, and cystic fibrosis, can all prevent the body from properly absorbing vitamin D found in food.

The average Crohn’s patient absorbs roughly only 30 percent less of the vitamin D present in their diet when compared to people who don’t have Crohn’s or any other similar gastrointestinal condition. 

Patients who have been officially diagnosed with celiac disease are at an elevated risk of developing vitamin D deficiency. Studies reveal that vitamin D deficiency occurs in 64% of men and 71% of women with celiac disease. This is further exacerbated by the fact that a gluten-free food diet is not fortified with enough vitamins and minerals to meet their health needs.

Low levels of vitamin D are usually associated with chronic pancreatitis. However, one study shows that excessive amounts of vitamin D can also trigger recurrent episodes.


Having a body mass index (BMI) higher than 30 can cause a deficiency in vitamin D. since subcutaneous body fat can trap it, making it an important health concern for those who are obese.  

On the other hand, people who are obese and don’t undergo gastric bypass can hold abnormally high amounts of vitamin D in their fatty tissues. While this is not a problem of fat absorption, it can still lower nutrient availability in other areas of your body.

Gastric bypass surgery

When a person undergoes gastric bypass surgery, the procedure makes a portion of the stomach nonfunctional and reroutes the small intestine, and since vitamin D is absorbed in the small intestine, this rerouting can reduce your chances of properly extracting the vitamin from your diet, which ends in vitamin D deficiency. 

Supplementation is usually recommended for gastric bypass patients. Not doing so would result in them consuming only about 50% of the recommended daily requirements of vitamin D. This decreased intake of vitamin D leads to a decrease in the absorption of calcium from the intestinal lumen.

Liver diseases 

Vitamin D deficiency is extremely common in liver disease patients since it negatively impacts how the body absorbs vitamin D. Up to 93% of liver patients have some degree of vitamin insufficiency, with liver cirrhosis patients suffering most from the severe deficiency.

Kidney diseases

The kidneys convert vitamin D absorbed by the body to the active form of vitamin D, calcitriol, needed by the body. With chronic kidney disease, vitamin D levels begin to drop because affected kidneys are less able to convert vitamin D into its active form.

At the same time, those deficient in vitamin D have an increased risk of developing albuminuria (a type of protein in the urine) over five years. It is considered an early sign of kidney damage.

Radiation treatment

Vitamin D deficiency is fairly common among cancer patients undergoing radiation therapy. Radiotherapy affects vitamin D metabolism and distribution in the body, which affects its outcomes as there are vitamin D receptor polymorphisms that are sensitive to radiation.

Taking certain medications

Some medications can also lower the body’s vitamin D levels and even inhibit its absorption; these include oral steroids, laxatives (prednisone), and cholesterol-lowering drugs (cholestyramine and colestipol), seizure-control drugs (phenobarbital and phenytoin), statins, and diuretics. These medications, especially diuretics and steroids, can interact with vitamin D supplements.

Symptoms Of Vitamin D Deficiency

Vitamin D deficiency symptoms can be difficult to detect because symptoms may not be apparent for several months or years. Sometimes, no symptoms appear at all.

Some of these symptoms include

  • Frequent illnesses (colds, flu, etc.)
  • Fatigue
  • Back pains
  • Muscle pains
  • Impaired wound healing
  • Bone pain and bone loss
  • Weight gain
  • Hair loss
  • Depression and anxiety

Final Take

Vitamin D deficiency is a significant health concern that not many people take seriously. Its effects are often subtle, nonspecific, and easy to dismiss. so it may be hard to tell at times. 

If you think you may have a vitamin D deficiency, consult your healthcare professional for a blood test. Addressing it early on is wise and can reduce your risk of other more serious health conditions. 

Adding vitamin D-rich foods and beverages and regular exposure to healthy sunlight (8 AM) can also help meet the body’s nutrient requirements. To maximize the efficacy of your supplementation, be aware of the points listed in this article in regards to what prevents vitamin D absorption.

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.

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