Vitamin D – Learn the Unbiased Truth (Information, Benefits, Effects, and Important Facts)

Throughout childhood, you may have been told to go outside and get some Vitamin D without knowing what this even meant.

As an adult, you are likely familiar with a relationship between Vitamin D and healthy bones but is that all to Vitamin D?

This article will go over the “ins and outs” of Vitamin D along with the many researched benefits.

What is Vitamin D?

Vitamin D is a fat-soluble vitamin that is obtainable from either dietary intake or produced by your skin when exposed to the sun.

Unlike any other vitamin, Vitamin D acts as a hormone, or messenger, in the body. It helps to coordinate and control other activities throughout our body.

Though before Vitamin D can do anything, it must be converted to its active form.

Types of Vitamin D

While there are several forms of Vitamin D, the two major types are:

• cholecalciferol, vitamin D3
• ergocalciferol, vitamin D2

These two types of Vitamin D can be easily retrieved in your diet.

Vitamin D3 is found in animal-based foods like liver, egg yolk, butter, and fish oils. Vitamin D2 is found in plant-based foods like mushrooms and fortified foods. Vitamin D3 is also the type of Vitamin D that your skin will make when exposed to the sun.

Both Vitamin D2 and Vitamin D3 are considered inactive forms of Vitamin D. The liver metabolizes D2 and D3into a different form called calcifediol.

Calcifediol is further hydroxylated into its final form of active Vitamin D in the kidneys called calcitriol.

This final step allows Vitamin D to now act as a hormone and complete important roles in our bone health.

Important Roles of Vitamin D

The most well-known role of Vitamin D is role it plays in benefits of bone health. Vitamin D increases calcium absorption in the gut which enables normal mineralization of the bone.

This plays a part in controlling osteoblasts and osteoclasts which helps with bone growth and remodeling.

Besides keeping our bones healthy, other roles of Vitamin D involve cell growth, neuromuscular and immune function, and reduction of inflammation.

These functions help your muscles to move and carry messages to your body through nerves.

Benefits

While a lot of factors play into developing diseases or disease progression, here are some potential benefits of sufficient Vitamin D:

1) Supports healthy bones

Vitamin D prevents rickets in children and osteomalacia in adults. With the help of calcium, Vitamin D can also prevent osteoporosis in older adults.

2) Reduces cancer risk and cancer progression

Studies have shown that a lack of Vitamin D and the sun can increase the risk of cancer.

In a study with mice, Vitamin D supplementation decreased cancer cell growth, stimulated cancer cell death, and reduce tumor blood vessels ^[4].

3) Reduces cognitive decline in older individuals

A study published in JAMA Neurology found Vitamin D prevents cognitive decline. The study recruited 382 participants with an average age of 75.5 years.

Vitamin D levels and cognitive tests were assessed every year for 5 years. Participants with lower Vitamin D levels showed a greater decline in cognitive ability ^[5].

4) Decreases risk for hypertension

Vitamin D increases an enzyme called renin which regulates the amount of blood and fluid in the veins along with controlling artery restriction.

These roles of renin help control blood pressure and prevent hypertension when correctly regulated.

5) Protects against diabetes

Scientists analyzed 21 studies which together had 76,220 participants. There was a significant association between lack of sunshine and/or Vitamin D supplements with type 2 diabetes risk ^[6].

6) Supports healthy pregnancies

Inadequate Vitamin D intake during pregnancy has been associated with preeclampsia, gestational diabetes, and cesarean section.

These issues can increase the risk of low birth weight, hypocalcemia, rickets, asthma, and type 1 diabetes.

7) Boost immunity

With Vitamin D’s role in immunity and inflammation, supplementing it can reduce the chances of getting the flu.

8) Combats depression

Studies have found symptoms of Seasonal Affective Disorder, a mood disorder featuring depressive symptoms during seasons with less sunlight, maybe due to changing levels of Vitamin D3.

This may affect serotonin levels which contributes to well-being and happiness ^[7].

Vitamin D excess

Excessive intake of Vitamin D can lead to a Vitamin D toxicity. Symptoms of Vitamin D toxicity can include anorexia, weight loss, heart arrhythmias, and polyuria.

Potentially, the most serious issue is elevated blood calcium leading to calcification in blood vessels and organs.

Long-term effects of calcification may damage the heart, blood vessels, and kidneys.

Excessive Vitamin D was from sun exposure won’t likely happen as your skin only absorbs the amount needed. The majority of Vitamin D toxicities develop from Vitamin D supplementation.

Tolerable Upper Intake Levels (ULs) of Vitamin D are 4000 IU daily for ages 9 and above. For children ages 8 and below, levels range from 1000-3000 IU.

Recommended Guidelines of Vitamin D

Studies have shown different recommendations for Vitamin D intake. Recommendations maybe different for individuals based on the amount of sunlight received.

Another study suggested that overweight or obese individuals may require higher amounts of Vitamin D ^[9].

A daily Vitamin D intake of 1000-4000 IU, or 25-100 micrograms, should be enough to ensure sufficient Vitamin D levels. For individuals 18 and younger, the recommended dietary allowance (RDA) is 400-800 IU daily.

Vitamin D Sources

Only a few foods contain Vitamin D naturally. In certain areas of the world, foods come fortified with Vitamin D.

Fish liver oils and flesh of fatty fish like salmon, tuna, and mackerel contain the best sources of Vitamin D. Smaller amounts of Vitamin D are found in beef liver, cheese, egg yolks, and some mushrooms.

Bottom line

It comes in many different forms but is not as plentiful in food as other vitamins.

Vitamin D supplementation may be recommended for certain individuals, especially those who do not receive direct sunlight often.

You should speak with your medical provider about Vitamin D before you begin supplementation.

Samantha Carter, MS, RD, LD

Samantha is a clinical registered dietitian nutritionist in Houston, Texas. Samantha has worked in many clinical areas of nutrition inc... [Read Full Bio]