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How to Recognize the Symptoms of Vitamin D Deficiency

Cod liver oil capsules contain a large amount of vitamin D
Cod liver oil capsules contain a large amount of vitamin D | Source


Prohormone: the precursor to hormones; they actually increase the efficacy of existing hormones and are eventually converted into hormones themselves.

Sterol: a steroid alcohol, which is a subgroup of steroids. Cholesterol is a sterol.

Vitamin D has been getting quite a bit of attention recently. It’s even been nicknamed “the sunshine vitamin” because our skin produces it when exposed to sunlight. Women know it as the vitamin that needs to be taken with calcium in order for it to be absorbed properly. But what exactly is Vitamin D?

Vitamin D is a prohormone sterol. It has several different forms, but we know it as vitamin D3, or cholecalciferol, which is made from cholesterol. Another form is vitamin D2, and is also called ergocalciferol, which is made from ergosterol.


An x-ray of a child with rickets.
An x-ray of a child with rickets. | Source

The History of Vitamin D

In 1913, vitamin A was discovered in cod liver oil by American researchers Elmer McCollum and Marguerite Davis. A British doctor named Edward Mellanby began giving cod liver oil to dogs and noticed that it prevented them from developing rickets.

In 1921, McCollum modified cod liver oil by destroying the vitamin A, and repeated Mellanby’s experiment. He found that the dogs still did not develop rickets and concluded that there was another compound in the oil that prevented the disease, which he named vitamin D.

In 1923, Harry Steenbock, an American biochemist at the University of Wisconsin, found that irradiating foods and other organic material with ultraviolet light increased the vitamin D content.

Steenbock used his irradiation technique on food given to rats and found that it cured them of rickets. After patenting the invention, Steenbock’s technique was used to irradiate foods, especially dairy products like milk, which increased their vitamin D content and essentially eradicated rickets.

It wasn’t until 1936 that the chemical structure of vitamin D was actually isolated by Robert Benedict Bourdillon, Otto Rosenheim, Harold King and Kenneth Callow, all of whom collaborated on the discovery.

What Does Vitamin D Do?

Vitamin D has a number of benefits. It prevents the onset of osteoporosis, cancer and even depression. In depressed patients, it actually works as an antidepressant, alleviating their symptoms. It has also been used as a treatment for multiple sclerosis, and even asthma.

It is most well-known as the cure for rickets, which is a disease of childhood that causes the bones to soften. This softening can lead to bone fractures and even permanent deformity. The disease is caused by the body’s inability to metabolize calcium, or phosphorus, which occurs when the body is vitamin D deficient. Osteomalacia is the adult form of rickets.

In the liver, vitamin D is converted into the prohormone calcidiol. As calcidiol travels through the bloodstream, the kidneys or monocyte-macrophages in the immune system convert calcidiol into calcitriol, which is the biologically active form of vitamin D.

Once converted, it is absorbed by target cells, specifically the intestines among others. Vitamin D enhances the absorption of calcium by the intestines, which allows more calcium to be absorbed and utilized. It also allows the parathyroid gland, which maintains blood serum calcium levels, to function properly.

This image shows how calcium is regulated in the body. How vitamin D affects this regulation is shown in orange.
This image shows how calcium is regulated in the body. How vitamin D affects this regulation is shown in orange. | Source

How Vitamin D Deficiency Affects the Body

Vitamin D deficiency can cause a number of different problems. Among the most common are osteoporosis, hypertension (high blood pressure), depression, heart disease, and rickets. A vitamin D deficiency can also increase the risk for:

  • Multiple sclerosis
  • Diabetes
  • Breast and ovarian cancer
  • Prostate cancer
  • Skin cancer
  • Colon cancer

One of the main reasons vitamin D is important is because it prevents osteoporosis. For decades we have been told that we need more calcium (especially women). To satisfy this requirement we are told to consume more dairy products, like milk. However, dairy products may actually be causing osteoporosis.

When we consume dairy products, whether it is cheese, milk, yogurt, or any other dairy product, we cause our body’s pH to become acidic. In an effort to fix this, the body uses the most abundant antacid it has: calcium. Where does it get the calcium? It’s stripped from the bones, which weakens them considerably.

Add to that the fact that most of us are at least somewhat deficient in vitamin D, and you have a recipe for osteoporosis. So, not only are we stripping the calcium our body does have, but we’re making it difficult for the body to absorb more of it.

Table of Recommended Dietary Allowances of Vitamin D

RDA of Vitamin D
Tolerable Upper Intake Levels
Infants 0 – 12 months old
400 IU
1,000 IU
Children 1 – 3 years old
600 IU
2,500 IU
Children 4 – 8 years old
600 IU
3,000 IU
Males and Females age 9 – 70
600 IU
4,000 IU
Males and Females age 71 +
800 IU
4,000 IU
Pregnant or Lactating
600 IU
4,000 IU

A Note About Breast Milk and Vitamin D

It should be noted that breast milk does not contain enough vitamin D to meet the daily requirement for newborns and infants. It is a good idea to supplement breast milk with vitamin D fortified formula to prevent the possibility of rickets in newborns and infants.

Vitamin D Supplementation

The human body uses vitamin D3 much more efficiently than D2, which is why most supplements are made from D3.

The two main sources of this vitamin are fish liver oil, and oil that has been extracted from wool. You can tell which source your supplement comes from by looking at the label on the back of the bottle.

If the label reads “fish oil” in parentheses then it’s obviously made from fish oil; however, if the label reads “Vitamin D3 (cholecalciferol),” then it’s made from wool oil, which is preferred by vegetarians. Interestingly, animals can obtain vitamin D by licking their fur.

Vitamin D supplementation is highly recommended for those who are not exposed to sunlight frequently, those who are overweight, or those who have dark skin (darker skin blocks 95 percent of ultraviolet light from reaching the deeper tissue, which makes manufacture of vitamin D all but impossible).

Our diet alone cannot give us the amount of D3 we need on a daily basis. Our skin typically manufactures about 10,000 to 20,000 IU of D3 when exposed to sunlight during the day. This is much more than the U.S RDA (recommended dietary allowance).

Tuna is a good source of vitamin D
Tuna is a good source of vitamin D | Source

There are some foods that contain vitamin D and can be eaten to augment exposure to sunlight. These foods include:

  • Catfish
  • Mackerel
  • Salmon
  • Sardines
  • Tuna
  • Eel
  • Eggs
  • Beef liver
  • Fish liver oil

Possible Side Effects of Vitamin D Supplementation

While side effects are possible, many experts in the medical community have exaggerated their findings. Many reports have warned that taking vitamin D supplements in higher dosages can cause calcification of soft tissue such as the lungs, kidneys and heart, which is called hypercalcemia. However, the length of time this takes to occur would be such that other symptoms of toxicity would show before any serious damage would be done. Symptoms of hypercalcemia include:

Do You Have Vitamin D Deficiency?

  • Nausea
  • Vomiting
  • Anorexia
  • Weakness
  • Polyuria (excessive urination)
  • Polydipsia (excessive thirst)
  • Insomnia
  • Nervousness
  • Pruritus (intense itching)
  • Renal failure

Treatment of hypercalcemia involves discontinuing the vitamin D supplement and restricting how much calcium is consumed. If you are currently taking any medication, or if you suffer from liver or kidney disease, it is recommended that you talk with your physician before starting vitamin D supplementation.

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