The Importance of Vitamin D: Sources, Benefits, and How to Ensure You're Getting Enough

Importance of Vitamin D. Explore its crucial role in bone health, immunity, mood regulation, and overall well-being. Ensure your sunshine vitamin intake with these sources.

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Often called “the sunshine vitamin”, vitamin D is partly made by your body when your skin is exposed to direct sunlight. While this is one way to get some of your vitamin D needs met, it’s rarely adequate for most of us – for reasons we’ll get into later.

But why does vitamin D matter so much and what does it do in the body? We’re covering the importance of vitamin D, including how much you need and where to get it (including vegetarian sources of vitamin D for my fellow herbivores).

What Does Vitamin D Do?

Vitamin D is an essential nutrient that supports multiple aspects of our health, playing a significant role in both physical and immune functions.

Here’s a breakdown of the importance of vitamin D and how it benefits your body:

Bone Health: Vitamin D is essential for calcium absorption in your intestines. Without it, your body can’t absorb calcium effectively. Over time, this leads to weaker bones and a higher risk of fractures. Adequate vitamin D (and other bone-supportive nutrients) helps maintain bone density, reducing the risk of conditions like osteoporosis in adults and rickets in kids.
Immune System Support: Vitamin D plays a key role in regulating your immune system. It enhances the germ-fighting effects of white blood cells, which are important for immune defense. It also helps reduce inflammation, which is an underlying factor in numerous chronic diseases today.
Muscle Function: Adequate levels of vitamin D help with muscle function and strength. As such, it may indirectly reduce the risk of falls and muscle weakness, especially in older adults.
Cardiovascular Health: Some research suggests that vitamin D may help regulate blood pressure and reduce the risk of cardiovascular diseases such as heart attacks and strokes by supporting the proper function of your heart and blood vessels.
Mental Health: Vitamin D has been linked to mood regulation and may even reduce your risk of depression. Studies have shown a connection between low levels of vitamin D and conditions like seasonal affective disorder (SAD) and general depression. (Fun Fact: This is why I used a Happy Light when I lived in the gloomy Midwest).
Cancer Prevention: Emerging research indicates that adequate vitamin D levels may help lower the risk of certain cancers, including breast, prostate, and colon cancer, by regulating cell growth and promoting overall cellular health.
Regulation of Insulin: Vitamin D may play a role in regulating insulin and supporting your glucose metabolism, which can help prevent or manage type 2 diabetes.
Respiratory Health: Some studies suggest that maintaining healthy levels of vitamin D can reduce the risk of respiratory infections, including influenza and COVID-19, due to its immune-regulating properties.

How Much Vitamin D Do I Need?

The amount of vitamin D you need depends on various personal factors such as age, life stage, skin color, sun exposure, and overall health.

The Recommended Dietary Allowances (RDAs) for vitamin D have been established to ensure most people meet their needs through a combination of sunlight, food, and supplements.

Here’s a breakdown of the RDAs by age and group:

Infants (0-12 months): 400 IU (10 mcg) per day
Babies need vitamin D early in life to support healthy bone development. Breastfed infants, in particular, may need supplementation since breast milk alone may not provide enough vitamin D.
Children (1-18 years): 600 IU (15 mcg) per day
Children and adolescents require adequate vitamin D for growth, bone strength, and immune function. This is a critical stage for bone development.
Adults (19-70 years): 600 IU (15 mcg) per day
For most adults, this amount supports bone health and helps prevent diseases such as osteoporosis. However, people who get limited sun exposure or have darker skin may require more.
Adults (71+ years): 800 IU (20 mcg) per day
Older adults have a higher risk of vitamin D deficiency because their skin is less efficient at synthesizing vitamin D from sunlight, and they are more prone to conditions like osteoporosis.
Pregnant and breastfeeding women: 600 IU (15 mcg) per day
Vitamin D is crucial for the bone health of both the mother and baby. Supplementing during pregnancy and breastfeeding helps ensure that both receive adequate amounts to prevent deficiencies.

Why Vitamin D Needs Vary

Meeting the RDA for vitamin D is essential for maintaining long-term health, but some people may need more than the recommended amounts depending on their lifestyle, health conditions, and individual needs.

Here are some of the reasons why vitamin D needs are different between groups of people:

Age: As we age, our skin becomes less effective at making vitamin D from sunlight. This is why older adults need higher amounts to maintain bone health and reduce the risk of fractures.

Geographical Location: People living in northern latitudes or areas with limited sunlight exposure may have trouble producing enough vitamin D from sunlight alone. During the winter months especially, the angle of the sun is often too low for adequate vitamin D synthesis.

Skin Color: Individuals with darker skin have more melanin (pigment), which can reduce the skin’s ability to produce vitamin D from sunlight. This is why people with darker skin may need higher amounts of vitamin D through diet or supplements to meet their needs.

Sun Exposure: Those who spend little time outdoors or consistently wear sunscreen may not get enough vitamin D from sunlight alone, increasing the need for dietary sources or supplements. Note that this is NOT a recommendation to stop wearing sunscreen or wearing sun-protective clothing, as these are super important for preventing skin cancer. It’s just an observation.

Medical Conditions: Certain conditions, like Crohn’s disease, celiac disease, or kidney and liver disorders, can impair vitamin D absorption or metabolism. If you have any of these conditions you might need higher doses to maintain adequate levels (but this should be discussed with your healthcare provider).

Body Weight: Individuals with obesity may need more vitamin D since the vitamin is stored in fat tissues (it is a fat-soluble vitamin), making it less available for use in the body. Higher doses may be needed to maintain optimal levels in larger bodies.

IMPORTANT: Before you add any old vitamin D supplement to your health routine, have your blood levels for this nutrient checked by your doctor. This is not a standard test at most facilities, so you will need to request it. This will tell you how much vitamin D is in your body, which will indicate whether a maintenance dose of vitamin D is adequate or if you have a deficiency that needs to be corrected with a higher dose supplement first.

mom and child outside in the sun getting their vitamin d

Types of Vitamin D

Vitamin D comes in two main forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).

Both types help raise blood levels of vitamin D, but there are some key differences between them, including where they come from and how effectively they maintain adequate vitamin D levels in your body.

Vitamin D2 (Ergocalciferol)

Source: Vitamin D2 is primarily found in plant-based sources, particularly in mushrooms exposed to sunlight or UV light. It is also commonly added to fortified foods such as plant-based milk alternatives (like almond or soy milk) and some breakfast cereals. Check the label to know for sure.
Supplementation: D2 is often used in vegan and vegetarian supplements since it comes from non-animal sources.
Effectiveness: While vitamin D2 can raise blood levels of vitamin D, research suggests it may not be as effective as D3 in maintaining those levels over time. D2 has a shorter shelf life and a reduced ability to stay active in the body.

Vitamin D3 (Cholecalciferol)

Source: Vitamin D3 is found in animal-based sources, such as fatty fish (salmon, mackerel, sardines), cod liver oil, and egg yolks. It is also produced naturally in the skin when exposed to sunlight. Additionally, many dairy products and some orange juices are fortified with D3.
Supplementation: D3 is the more common form of vitamin D used in supplements, as it is more effective at raising and maintaining optimal blood levels of vitamin D.
Effectiveness: Studies show that vitamin D3 is more potent than D2 and leads to greater increases in blood levels of vitamin D. D3 remains in the bloodstream longer, making it the preferred choice for supplementation, especially in people with low vitamin D levels or limited sun exposure.

Which is More Effective?

In general, vitamin D3 is considered more effective at raising and sustaining blood levels of vitamin D compared to vitamin D2.

While both forms can be used to prevent or treat deficiency, D3 has been shown to increase blood concentrations more significantly and remain in the body longer.

For those looking to optimize their vitamin D status, D3 is typically the recommended option unless there is a need for a plant-based source, in which case D2 may still be beneficial but may require more frequent dosing.

Either way, if you need a vitamin D supplement, there’s an option for you and they both work.

Vitamin D and K2 Benefits

You may have seen vitamins D an K2 combined in a number of supplements. Why?

While vitamin D increases calcium absorption, vitamin K2 ensures that the calcium is properly utilized by guiding it into the bones and preventing excess from accumulating in the arteries.

Without enough K2, taking high doses of vitamin D could potentially lead to calcium buildup in the blood vessels, increasing the risk of calcification and cardiovascular problems.

Why Take a Vitamin D and K2 Supplement?

Bone Health Support: For those concerned about bone health, especially people at risk of osteoporosis, the combination of vitamin D and K2 ensures optimal calcium absorption and utilization, helping to strengthen bones more effectively than vitamin D alone.
Cardiovascular Protection: Vitamin K2 works to reduce the risk of calcium buildup in arteries, which can occur with high vitamin D intake without sufficient K2. This combination helps maintain heart and artery health while still reaping the bone-strengthening benefits of vitamin D.
Enhanced Absorption and Function: Taking both vitamins together maximizes their effectiveness, as vitamin D ensures you absorb enough calcium, and vitamin K2 makes sure that calcium ends up in the right places—your bones and teeth.
Postmenopausal and Older Adults: Those in these life stages, who are at higher risk for bone loss and heart disease, can especially benefit from this combination, as it supports both bone density and heart health.

Vegetarian Sources of Vitamin D

The importance of vitamin D isn’t just for omnivores. Vegetarian sources of vitamin D are somewhat limited, as this vitamin isn’t naturally abundant in plant-based foods.

Most vitamin D in vegetarian diets comes from fortified products, such as plant-based milks (like almond, soy, and oat milk), fortified cereals, and orange juice.

The primary naturally occurring plant-based source is mushrooms that have been exposed to UV light, which contain vitamin D2.

However, vitamin D3, which is more effective at raising blood levels, is typically sourced from animal products like fish or lanolin (from sheep’s wool).

Recently, a growing number of supplement companies have begun using vegan-friendly D3 sourced from lichen, a type of algae, making it a good option for vegetarians and vegans.

To ensure a supplement is vegetarian or vegan, check the label for terms like “vegetarian vitamin D” or “D3 from lichen,” as well as a certification indicating it is plant-based or vegan-friendly.

Some of Our Favorite Vitamin D Supplements

Need some recs? We’ve got ’em. Here are some vitamin D supplements we recommend and why!

Future Kind Vegan Multivitamins – This product contains 2,000 IU of vegan vitamin D3 plus algae-derived omega-3 and vitamin B12, all of which are important nutrients for individuals on a plant-based diet. We appreciate that Future Kind uses 100% vegan ingredients in all of their products with science and environmental sustainability at the core.
Ritual Multivitamin for Women 18+ – This is also a multivitamin, but it provides 2,000 IU of vegan D3 plus algae-derived omega-3, K2, iron, and B12. We love that Ritual is obsessed with traceability and holding their formulations to high quality and purity standards.
Garden of Life Organics Vegan Vitamin D3 Chewable – This product contains 2,000 IU of V3 from lichen plus a blend of organic mushrooms and other organic fruits and vegetables. It’s USDA Organic and bears a Non-GMO Project and NSF Certified Gluten-free label.
THORNE Vitamin D-5000 – This is not a plant-based vitamin D supplement but does bear an NSF Certified for Sport certification, which means it has been independently tested to not only contain what it claims and in the amounts listed, but is also free from athletic banned substances. Note that this product provides 5,000 IU of vitamin D3 per capsule, which is a high dose that may be more suited for people who have confirmed low levels of vitamin D in their blood.
NATURELO Vegan K2+D3 – This one supplies 5,000 IU of vitamin D3 from lichen plus vitamin K2. It’s NSF Certified, which means it contains the ingredients labeled and in the claimed amounts. We appreciate when brands go above and beyond to obtain third-party certifications to verify the purity, quality, and safety of their products.

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Author

Lauren Panoff, MPH, RD
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