What You Should Know About Vitamin D

What You Should Know About Vitamin D


Everyone should know about vitamin D, especially if you’re interested in a career in nutrition and wellness. You may have heard Vitamin D referred to as the “sunshine vitamin.” This is because the easiest and most effective way to obtain large volumes of it is through the sun.

Our bodies absorb the sunshine (ultraviolet B rays) and convert it into vitamin D3 (cholecalciferol) once it hits unprotected skin. This process happens rather quickly, especially in the warmer months where the sunshine can transform into as much as 10,000-25,000 international units (IU) of vitamin D3.

Once our bodies convert the sun into vitamin D, it is absorbed and stored by our fat cells. This means it takes the body a longer period of time to breakdown and rid the body of this vitamin compared to a water-soluble vitamin (ex: vitamin C). Since vitamin D is fat-soluble, this vitamin stays in the body for approximately two months.

It’s an important part of your future job as a nutritionist to know how we process essential nutrients, like vitamin D, and why we need them. Feel free to click through the links to learn more about each aspect of vitamin D.

The Sun and then Some – Getting Your Vitamin D

Even though obtaining vitamin D sounds easy – I mean, who doesn’t like to be outside in the sun – there are factors that make absorbing vitamin D from the sun a little more difficult. For instance:

  • Where you live – the closer to the equator you live the easier it is to obtain vitamin D. However, if you live in northern climates and don’t spend adequate time outside during the winter months it will reduce your overall vitamin D intake.
  • Time of day – middle of the day produces more UVB rays, which converts to more vitamin D.
  • Amount of skin exposed – large surface area, such as your back, produces more vitamin D.
  • Color of your skin – pale skin people need less time in the sun (15 minutes) whereas darker skinned people need more time in the sun (1 hour).
  • Sunscreen – the sun needs to be exposed to unprotected skin, ideally larger surface areas such as the back, for the duration above to turn it into vitamin D. From there, apply sunscreen to protect against skin cancer.

A Bit About Melanin

It may sound odd that the color of your skin can make a difference on vitamin D absorption but skin color has different characteristics. Melanin is a substance that determines the hue (lightness and darkness) of our skin color. The more melanin you have the darker the color of your skin. The amount of melanin in your skin therefore determines how much vitamin D can be produced.

Melanin also protects the skin against skin damage/UVB protection, which is why, as you can see in the Vitamin Council chart below, that lighter skin and features tend to burn more easily than darker skin and features. The caveat being that the more your skin is protected, the more sun exposure needed to obtain adequate levels of vitamin D.

Vitamin Council Melanin Chart

You won’t reach a toxic vitamin D level through excessive sun exposure, but too much sun can cause skin cancer so it’s still important to use sunscreens that blocks both UVA and UVB light, cover up with light colored clothes, and find shade during the hot summer months.

You can either apply sunscreen after the sun has been exposed to unprotected skin, or use sunscreen on the entire body except for one area for a short period of time. This way you’re not only obtaining vitamin D but also protecting yourself from the risk of skin cancer.

Getting Vitamin D from Food

It’s a good thing vitamin D doesn’t just come from the sun! So if you’re not able to enjoy the sunshine or you live in a northern climate, don’t worry, there are other ways to obtain vitamin D, like through your food! The Academy of Nutrition and Dietetics highlights these foods as being a good source of vitamin D:

  • Cow Milk
  • Yogurt
  • Fatty Fish
  • Beef Liver
  • Egg Yolks
  • Fortified Orange Juice
  • Fortified Cereals
  • Infant Formula

How much vitamin D do I need?

If supplementing with vitamin D is something of interest, and recommended to those who do have darker skin and/or live in northern climates, look for vitamin D3. Vitamin D3 is what the body produces when it is exposed to the sun. No matter what form, capsules, liquid, tablet, or chewable, always look for vitamin D3 rather than vitamin D2 to boost your vitamin level.

Presented in both micrograms (mcg) and International Units (IU), the National Institute of Health’s Fact Sheet For Health Professionals outlines the maximum amount of vitamin D that can be safely absorbed per day:

NIH Vitamin D Intake Chart

Data Source: Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Calcium and Vitamin D

Always check with your doctor before taking vitamin D3, especially if…

  • You are taking medication for the treatment of HIV.
  • You have high blood calcium levels.
  • You have kidney stones.
  • You have hyperparathyroidism.
  • You have Hodgkin’s or non-Hodgkin’s lymphoma or a granulomatous disease.
  • You are taking medication for an irregular heartbeat.

Why We Need Vitamin D

No matter how you obtain your vitamin D, via sunshine, food, supplements or all of the above, vitamin D is essential. Vitamin D serves several roles in your body including the regulation of calcium and phosphorous absorption, growth and bone development, promotion of immune function, as well as improved resistance to certain diseases. Essentially, vitamin D helps your body to…

  • Fight Diseases
    • Research suggests that vitamin D can help reduce the risk of multiple sclerosis, heart disease, fibromyalgia, and developing the flu.
  • Reduce Depression
    • Research shows that vitamin D could play a role in regulating mood.
  • Boost Weight Loss
    • By taking adequate amounts of calcium and vitamin D daily, it may help reduce hunger cues causing one to feel more satiated.

Without enough vitamin D, you are at an increased risk for soft bones (osteomalacia), fragile bones (osteoporosis), and a decline in immune function. Normal blood serum vitamin D levels range from 50-100 micrograms per deciliter. To measure your vitamin D level, ask your doctor as vitamin D is not checked as part of a normal blood panel.

When There’s Not Enough Vitamin D

Even though vitamin D has numerous health benefits, it is not uncommon to experience a vitamin D deficiency. Part of Healthline’s vitamin D guide, Beware of “D-ficiency,” outlines several factors that can contribute to a lack of vitamin D such as:

  • Living in a high pollution area
  • Not having any unprotected skin exposure to the sun
  • Spending time indoors
  • Having darker skin
  • Living in a northern climate and not having sun exposure during the winter

Here are some symptoms to watch out for if you are at risk of not getting enough vitamin D:

  • Lethargic – tired
  • Body aches and pains
  • Bone and muscle weakness
  • Stress fractures to the legs, pelvis, and hips (can occur at any age)

There’s no bones about it – we need vitamin D (pun intended). Whether you get it through sunshine, supplements, food, or a combination of all three, the key is to make sure your vitamin D levels are adequate. Go to your doctor to get your vitamin D levels checked, and start enjoying the impacts that vitamin D has on your body.

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