Vitamin D, often referred to as the “sunshine vitamin,” plays a crucial role in our overall health. This guide explores everything you need to know about this essential nutrient, covering its functions, sources, deficiency symptoms, potential health benefits, and more.
Understanding Vitamin D
Vitamin D is unique compared to other vitamins. It’s a steroid hormone produced from cholesterol when your skin is exposed to sunlight. Hence, it’s often referred to as the “sunshine vitamin.”
What is Vitamin D?
Vitamin D is a fat-soluble vitamin, meaning it dissolves in fats and oils and can be stored in your body for a long time. There are two main dietary forms of Vitamin D:
- Vitamin D3 (cholecalciferol):Found in animal-based foods like fatty fish and egg yolks.
- Vitamin D2 (ergocalciferol):Found in plant-based sources like mushrooms and yeasts.
Between the two, Vitamin D3 is more effective at increasing blood levels of Vitamin D.
What Does Vitamin D Do in Your Body?
Vitamin D undergoes two conversion steps to become active. Firstly, it is converted to calcidiol in your liver, which is the storage form of the vitamin. Secondly, it is converted to calcitriol, mostly in your kidneys. This is the active, steroid-hormone form of Vitamin D.
Calcitriol binds to the Vitamin D receptor found in almost every cell in your body, leading to changes in your cells. This is similar to how most other steroid hormones work. Vitamin D affects various cells related to bone health. For example, it promotes the absorption of calcium and phosphorus from your gut.
Getting Vitamin D from Sunshine
Vitamin D can be synthesized in your skin when it’s exposed to ultraviolet B (UVB) rays from the sun. If you live in an area with abundant sunshine, you can probably meet your Vitamin D needs by sunbathing a few times per week.
However, if you live in an area without adequate sunlight, getting Vitamin D from foods or supplements becomes essential.
Top Food Sources
Here are some of the best food sources of Vitamin D3:
| Food | Amount | % RDI |
| Cod liver oil, 1 tablespoon (15 ml) | 1,360 IU / 34 mcg | 227% |
| Salmon, cooked, 3 ounces (85 grams) | 447 IU / 11 mcg | 75% |
| Tuna, canned in water, 3 ounces (85 grams) | 154 IU / 4 mcg | 26% |
| Beef liver, cooked, 3 ounces (85 grams) | 42 IU / 1 mcg | 7% |
| 1 large whole egg (D is found in the yolk) | 41 IU / 1 mcg | 7% |
Remember, the only excellent dietary source of Vitamin D is fish liver oil, such as cod liver oil.
Signs of Vitamin D Deficiency
Vitamin D deficiency is one of the most common nutrient deficiencies. Some people are at a greater risk than others. For instance, older adults are at a much higher risk of being deficient.
The most well-known symptom of Vitamin D deficiency is rickets, a bone disease common in children in developing countries. Other deficiency symptoms include osteoporosis, reduced mineral density, and increased risk of falls and fractures in older adults.
Potential Health Benefits
Here are some potential benefits of Vitamin D:
- Reduced risk of osteoporosis, falls, and fractures
- Better strength
- Cancer prevention
- Depression management
- Reduced risk of type 1 diabetes
- Improved mortality
Recommended Daily Intake
The Recommended Daily Intake (RDI) for Vitamin D varies depending on age:
- 400 IU (10 mcg): Infants, 0–12 months
- 600 IU (15 mcg): Children and adults, 1–70 years old
- 800 IU (20 mcg): Older adults and pregnant or breastfeeding women
What If You Take Too Much?
Vitamin D toxicity is rare and only occurs if you take very high doses for prolonged periods. Symptoms include confusion, lack of concentration, depression, and high blood pressure.
The Bottom Line
Vitamin D is a fat-soluble vitamin that is critical for bone health and potentially other aspects of health. If you don’t spend much time in the sun or rarely eat fatty fish, you may consider supplementing. Ensuring adequate Vitamin D intake can significantly contribute to your overall health.