Vitamin D: Fat-Soluble Vitamin Deficiency & Toxicity Symptoms

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  • 0:44 Deficiency
  • 3:02 Sources
  • 4:11 Toxicity
  • 5:17 Lesson Summary
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Lesson Transcript
Instructor: Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

Vitamin D is a fat-soluble vitamin that is made by your body when your skin is exposed to the sun. It is also obtained through foods. Learn about conditions that result due to vitamin D deficiency, such as rickets and osteomalacia, as well as symptoms of toxicity.

Vitamin D

Are you looking for a reason to play hooky and spend the afternoon sunbathing on the beach? Why not tell your boss you need some time to work on strengthening your bones? You see, when your skin is exposed to ultraviolet light from the sun it makes vitamin D, which is a fat-soluble vitamin that is essential for strong bones. In fact, this clever interaction with the sun has earned vitamin D the nickname 'The Sunshine Vitamin.' Vitamin D keeps your bones strong because it helps your body absorb calcium. In this lesson you will learn what happens when your body does not have enough vitamin D and what to expect if too much is taken in.


I guess you could say that calcium has a true love for vitamin D. In fact, without adequate amounts of vitamin D in your body, calcium just wanders through your digestive system refusing to absorb into your body. This is a problem because your body needs to get this calcium to work to maintain the structure of your bones.

If a child has a vitamin D deficiency, meaning their body does not have enough of the vitamin, they can develop a condition called rickets. This is a vitamin D deficiency in children characterized by bowed legs. The bowed legs result because the leg bones are too weak to support the child's weight. The misshaped legs look unstable, as if the child is walking on rickety legs, which might help you recall this term.

Rickets does not happen in adults because their bones have stopped growing, but they can develop osteomalacia, which is a vitamin D deficiency in adults characterized by a softening of the bones. If the condition continues, it can develop into bone pain and muscle aches. You can recall this term by remembering that the prefix 'osteo' refers to bones and 'malacia' sounds a lot like malleable. We know that when something is malleable, it's soft and bendable, so thinking of the malleable bones of osteomalacia might help jog your memory.

With osteomalacia, the bones are depleted of calcium; this weakens the bones and increases the risk of the bones breaking. However, osteomalacia is not the same as osteoporosis, which we often hear about in relation to bone fractures. Osteoporosis is a loss of bone density after the bone is constructed, kind of like a house that is deteriorating, whereas osteomalacia is a problem with the building of the bone, as if the building materials were not sufficient to begin with. Osteoporosis is due to more than just a deficiency in vitamin D, and increasing the intake of vitamin D will not increase the bone density in a person with osteoporosis. However, additional vitamin D is thought to slow further bone loss.

Sources of Vitamin D

We learned that your body can make vitamin D when your skin is exposed to sunlight. This is good because there are only a few natural food sources that provide vitamin D, such as egg yolks and fatty fish, like salmon or tuna. We do see some foods fortified with vitamin D, such as breakfast cereals and dairy products, yet even with these fortified sources, many people need sun exposure to obtain sufficient amounts of the vitamin.

Now, if you think about it, anything that gets in the way of the sun's light penetrating your skin could diminish the amount of vitamin D your body is able to make. This is why certain groups have an increased risk of vitamin D deficiency. For example, people who live at high latitudes where there is insufficient ultraviolet radiation to make the vitamin; people who avoid the outdoors or keep the skin covered while outdoors, which includes covering the skin with sunscreen; people with dark skin; and people who wear concealing clothing for religious reasons all have to make sure they are getting adequate amounts of vitamin D.

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