Vitamin D – Benefits, Sources, Deficiency Symptoms and Side Effects

vitamin d

Vitamin D is a fat soluble vitamin that is stored in the liver and fatty tissues. This means that increased body fat has the ability to absorb Vitamin D and keep it from being used within our body. This vitamin is somewhat different than other vitamins because our body makes most of our Vitamin D on its own, rather than solely relying on food sources.

The way that our bodies make Vitamin D is to convert sunshine into chemicals that are used by the body. The cholesterol in our skin converts “previtamin D” and makes it into usable vitamin D3 which is sometimes also called provitamin D. Previtamin Ds first travels through the kidneys and liver in the blood stream, and then is converted into a biologically active and usable substance called calcitriol.

Vit. D actually becomes a hormone within our body, particularly a secosteroid hormone. What we know as Vitamin D is really a precursor to a steroid hormone. It impacts not only our skeletal structure, but also our blood pressure, immunity, mood, brain function, and ability to protect ourselves from cancer.

Vitamin D is one of the most intensely studied yet widely debated nutrients in health research over the past decades. The research debate over this vitamin has focused partly on its roles in the body, and more recently on its optimal levels in the body and on the relationship of those levels to dietary intake

Would you believe that the majority of the population — up to 90% of adults in the United States — is believed to have a Vitamin D deficiency? Many physicians are starting to take this vitamin deficiency very seriously; in fact Vitamin D is one of the most recommended supplements by physicians today.

Most adults are believed to be at least somewhat deficient in Vitamin D, however, people with dark skin, who live in northern regions of the world where less year-round sun exposure is experienced, and those who are overweight have an even greaterchance to be deficient..


  • Contributes to Bone Health

Vitamin D plays a role in calcium absorption into the bones. Calcitriol (converted Vitamin D) works with the parathyroid hormone to maintain calcium levels. Additionally, Vitamin D has an effect on other important vitamins and minerals that contribute to both health including Vitamin K and phosphorus.

This vitamin is partially responsible for maintaining phosphorous levels in the blood and since it affects the ability of calcium to bind to proteins, it is believed that it is also linked to Vitamin K.

A deficiency in Vitamin D can result in a softening of the bones called osteomalacia, or a bone abnormality called rickets. Additionally, a deficiency increases the risk for developing osteoporosis and experiencing fractures or broken bones.

Studies have shown that Vitamin D in doses of 800-5000 IU/day can improve musculoskeletal health, naturally slow aging of the skeletal structure, and reduce the rate of fractures and falls in older adults that are over 65. Older adults with adequate vitamin D levels are more likely to be active, have improved muscle strength, and are less prone to falls and injuries.

When vit. D levels are low, the parathyroid becomes overactive. This is known as hyperparathyroidism and results in drops in phosphorous. Phosphorus, in addition to calcium and other compounds, is needed in order to properly mineralize bone density.

  • Helps Manage Blood Sugar Levels and Can Prevent Diabetes

Diabetes results from lack of insulin or inadequate insulin secretion following increases in insulin resistance. According to studies, since calcium is necessary for insulin secretion, Vitamin D may contribute to maintaining insulin secretion.

Vitamin D supplementation can increase insulin sensitivity and decrease inflammation, and studies support a role for Vitamin D in the prevention and management of both types of diabetes (type 1 and type 2).

  • Protects Against Cancer

Vitamin D deficiency symptoms have been correlated with increased risks for cancer development, especially breast, colon, and prostate cancers.  Vitamin D can affect the risk of breast, colon and ovarian cancers possibly due to its role in the cell life cycle or its ability to block excess estrogen.

  • Helps Fight Heart Disease

A growing number of research points to the fact that a Vitamin D deficiency is linked to increased risks for cardiovascular disease, since it is involved in regulating blood pressure, cholesterol levels, and inflammation.

According to the latest studies, it is still unclear if Vitamin D can help prevent heart disease, heart attack, and stroke, but we do know that people who are deficient are more likely to die from coronary heart disease and other heart related symptoms.

  • Enhances Our Immune System

Vitamin D helps with healthy cell replication and may play a role in protecting against the development of autoimmune conditions in addition to less serious common colds and the flu.

Our immune cells contain receptors for this Vitamin, and it’s been shown that Vit. D seems to prevent prolonged or excessive inflammatory responses. Inflammation is often at the root of many modern, chronic diseases and autoimmune disorders: multiple sclerosis, rheumatoid arthritis, irritable bowel syndrome and other digestive disorders, high blood pressure, and more.

  • Facilitates in Hormone Regulation and Helps Improve Our Mood

Because it acts like a hormone within our body and effects brain function, Vitamin D deficiency has been linked to an increased risk for mood disorders including depression, seasonal depression (known as the “winter blues” but actually more serious), severe mood problems experienced during PMS, insomnia, and anxiety.

Low levels of this Vitamin can also interfere with proper testosterone and estrogen production, leading to imbalances which can result in many unwanted symptoms.

  • Helps with Concentration, Learning, and Memory

Several studies have shown that this Vitamin also effects our ability to making decisions, concentrate, and to retain information. Some studies have shown that people with lower levels of vit. D perform poorly on standardized exams, may have poor decision making skills, and have difficulty with tasks that require focus and attention.

Additionally, some research has shown a correlation between low levels of Vitamin D and an increased risk for developing schizophrenia and multiple sclerosis.


Deficiency Symptoms

  • Osteoporosis
  • Heart disease
  • High blood pressure
  • Cancer
  • Autoimmune diseases
  • Depression
  • Insomnia
  • Arthritis
  • Diabetes
  • Asthma
  • Multiple Sclerosis
  • Chronic pain
  • Psoriasis
  • Fibromyalgia
  • Autism



Vitamin D is also found in a small number of foods. Good food sources are:

  • sunlight
  • oily fish – such as salmon, sardines and mackerel
  • eggs
  • fortified fat spreads
  • fortified breakfast cereals
  • some powdered milks


World’s Healthiest Foods ranked as quality sources of vitamin D

Food Serving
Cals Amount
Salmon 4 oz 157.6 511.43 128 14.6
Sardines 3.20 oz 188.7 175.09 44 4.2
Cow’s milk 4 oz 74.4 62.22 16 3.8
Tuna 4 oz 147.4 92.99 23 2.8
Eggs 1 each 77.5 43.50 11 2.5
Mushrooms, Shiitake 0.50 cup 40.6 20.30 5 2.2


How much vitamin D do I need?

Most people should be able to get all the vitamin D they need by eating a healthy balanced diet and by getting some summer sun.

Groups of the population at risk of not getting enough vitamin D are:

  • all pregnant and breastfeeding women
  • babies and young children under the age of five
  • older people aged 65 years and over
  • people who are not exposed to much sun – such as people who cover up their skin when outdoors, or those who are housebound or confined indoors for long periods
  • people who have darker skin, such as those of African, African-Caribbean and South Asian origin


Side Effects

If you take vit. D supplements, do not take more than 25 micrograms (0.025mg) a day, as it could be harmful. However, taking less than this is unlikely to cause any harm.

Your body doesn’t make too much vitamin D from sun exposure, but always remember to cover up or protect your skin if you are out in the sun for long periods.

Taking too many vitamin D supplements over a long period of time can cause more calcium to be absorbed than can be excreted.

The excess calcium can be deposited in and damage the kidneys. Excessive intake of vitamin D can also encourage calcium to be removed from bones, which can soften and weaken them.

Luckily your skin is able to regulate D vitamin conversion according to heat and other factors. It can store pre-vitamin D for future use, and destroy amounts above and beyond what is safe. So deficiency is usually a much bigger concern than consuming too much of this Vitamin.

Because this Vitamin is a fat soluble vitamin, it ideally needs to be consumed with fat in order to have optimal absorption. If you are going to eat a food source of Vitamin D, it’s best to combine it with some more of essential fat source too, like ghee, coconut oil, nuts, seeds, or fish.


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