Foods High in Vitamin D

Introduction

Vitamin D is a crucial nutrient that plays several important roles in maintaining overall health. The body requires intake through the diet and/or synthesis from sun exposure. Extensive reviews on vitamin D status in the world have been published over the last decades. Although vitamin D status can be considered satisfactory in some countries, vitamin D deficiency still is very common in many countries throughout the world and in many higher-risk groups. [1]

This article will cover how to obtain vitamin D through your diet, best practices for getting it via sunlight and how to supplement correctly.

Vitamin D Basics

Vitamin D is a fat-soluble vitamin that acts as a hormone in the body. It primarily helps the body absorb and retain calcium and phosphorus, which are essential for building and maintaining strong bones and teeth. Beyond bone health, vitamin D also supports muscle function, immune system regulation, and may have protective effects against various diseases [2]

The two major forms of vitamin D are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).

Vitamin D2 and D3 are the two main forms of vitamin D. Vitamin D2 (Ergocalciferol): This form of vitamin D is primarily obtained from plant sources. [3]

Vitamin D3 (Cholecalciferol): Vitamin D3 is the more potent and biologically active form of vitamin D. 

It can be synthesised by the body when the skin is exposed to sunlight (UVB radiation) and is also found in some animal-based food sources.

For more in-depth information check out our comprehensive article on Vitamin D: Benefits and how to get it.

Getting Vitamin D from Sunlight

Vitamin D is often referred to as the "sunshine vitamin" because our bodies can produce it when our skin is exposed to sunlight. However, many people don't get sufficient vitamin D from sun exposure alone due to several factors [4] :

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Factors Limiting Vitamin D Production from Sunlight

1. Cloud Cover: Cloudy weather significantly reduces UVB radiation reaching the skin, limiting vitamin D synthesis. On overcast days, vitamin D production can take longer or be minimal.

2. Indoor Lifestyle: Many people spend most of their time indoors, especially during peak sunlight hours. UVB rays don't penetrate glass, so exposure through windows doesn't produce vitamin D.

3. Skin Tone: Individuals with darker skin require more sun exposure to produce the same amount of vitamin D as those with lighter skin. This is because melanin, which gives skin its colour, acts as a natural sunscreen.

4. Skin Coverage: Clothing blocks UVB rays from reaching the skin. The more skin that's covered, the less vitamin D can be produced.

Be aware that even if you live in a hot country but do not spend that much time outside due to the heat you can still be at risk of being vitamin D deficient.

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Sun Exposure Guidelines

The amount of sun exposure needed for adequate vitamin D production varies based on several factors, including weather conditions:

• Generally, about 10-30 minutes of midday sun exposure to face, arms, and legs, 2-3 times a week, can be sufficient for many people with light skin.
• Cloudy Days: On overcast days, it may take 2-3 times longer to produce the same amount of vitamin D compared to sunny days.
• Part Sunny Days: Partially Cloudy: The duration needed falls between that of sunny and fully cloudy days, typically requiring 15-45 minutes of exposure.

It's important to note that these are general guidelines. Factors like latitude, season, time of day, and individual characteristics (skin tone, age, etc.) all play a role in determining the optimal sun exposure time. Additionally, it's crucial to avoid sunburn, as excessive sun exposure can increase skin cancer risk [5].

For many people, especially those living in northern latitudes or with limited sun exposure, dietary sources and supplements may be necessary to maintain adequate vitamin D levels throughout the year.

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Foods High in Vitamin D

Here are some foods high in Vitamin D, showing the Vitamin D content per 100g for various foods, as well as some other benefits:

Herring

680

Rich in omega-3 fatty acids and protein

Trout

635

High in omega-3 fatty acids, good for brain function

Halibut  

635

Contains protein and B vitamins

Wild-Caught Salmon 

600

High in healthy fats and protein

Swordfish 

560

Good source of B12 and selenium.

Mackerel 

360

Contains protein, omega-3s, and essential minerals

Canned Tuna

260

Rich in calcium and omega-3s.

Mushrooms

260

High in protein and selenium

Farmed Salmon 

250

Excellent source of protein and B vitamins

Sardines 

192

Provides potassium and magnesium

Fortified Orange Juice

190

Rich in Vitamin C

Fortified Milk  

140

Contains calcium, supports bone and tooth health

Egg yolk

56

Good source of choline and B-vitamins

Fortified Plant-Based Milk

52

Rich in vitamin A, iron, and B vitamins

Fortified Cereal 

52

Provides calcium and protein, supports bone health

Supplementing with Vitamin D

While it's ideal to obtain vitamins from natural sources, vitamin D presents unique challenges that often make supplementation necessary for many people, especially at certain times of the year. 

How much vitamin D should adults aim to get in a day?

In terms of amounts, here is a scale from deficient to excess.

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The biggest improvement you will see is moving from a deficient or insufficient level into a sufficient or optimal range. However, If you are deficient, it will be challenging to correct this with food alone. 

This is where supplementation can be beneficial. Using the Vitamin D spray, which provides 3000iu per spray would be ideal to treat a deficiency and maintain optimal levels. It is a convenient way to supplement with Vitamin D.

As you will see the supplement contains vitamin K2 as well. We added Vitamin K2 to our Vitamin D Spray due to the supporting evidence of the synergistic relationship between these two. Vitamin K2 supports the effectiveness of Vitamin D in bone and cardiovascular health by ensuring that calcium is utilised properly within the body, through its direction to appropriate areas in the body, such as the bones and teeth [6].

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Conclusion

Vitamin D is crucial for bone health, muscle function, and immune system regulation with the two main forms being D2 (from plants) and D3 (from sunlight and animal sources). Sunlight exposure is a key source, but factors like cloud cover and indoor lifestyle can limit production. Dietary sources include fatty fish, fortified foods, and egg yolks but getting enough to maintain optimal levels can be challenging. Supplementation may be necessary, especially for those with limited sun exposure or dietary intake. The recommended daily intake varies, with 2000-3000 IU per day during the winter months and 800-1000iu during the summer months being sufficient for most adults. Vitamin K2 is often combined with Vitamin D supplements for enhanced effectiveness in bone and cardiovascular health. 

For an easy way to supplement check out the MARCHON Vitamin D and K2 spray.

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Frequently Asked Questions 

Can you get enough Vitamin D from food alone?

While it's possible to obtain vitamin D from food sources, it's generally difficult to get enough vitamin D from diet alone. Some foods are naturally rich in vitamin D or fortified with it:

• Oily fish: Salmon, sardines, herring, and mackerel are good sources of vitamin D.
• Egg yolks: Especially from free-range chickens.
• Mushrooms: Particularly those exposed to UV light.
• Fortified foods: Many products like cow's milk, plant-based milk alternatives, breakfast cereals, and orange juice are fortified with vitamin D.

Despite these sources, it's challenging to get sufficient vitamin D from food alone for several reasons:

1. Limited natural sources: Very few foods naturally contain high levels of vitamin D.
2. Variability in content: The vitamin D content in foods can vary. For example, farmed salmon typically contains less vitamin D than wild salmon.
3. Dietary restrictions: Vegetarians and vegans may have fewer options, as many rich sources are animal-based.
4. Insufficient quantities: Even if consuming vitamin D-rich foods regularly, the amounts may not meet daily requirements for many people.

Due to these challenges, it is recommended to have a mixture of sources such as:

1. Getting some sun exposure (while being careful to avoid sunburn).
2. Consuming vitamin D-rich foods.
3. Taking a vitamin D supplement, especially during autumn and winter or year-round for at-risk groups.

How does Vitamin D absorption vary with age?

Vitamin D absorption and metabolism change significantly with age, impacting overall vitamin D status in older adults. Here's an overview of how vitamin D absorption varies with age:

Decreased Cutaneous Synthesis

As people age, their skin becomes less efficient at producing vitamin D:

• The concentration of 7-dehydrocholesterol (the precursor to vitamin D) in the skin decreases by more than 50% from ages 20 to 80 years [7].
• Aged skin produces approximately 40% less vitamin D than younger skin when exposed to the same amount of sunlight1.
• Vitamin D production decreases by about 13% per decade, with production at age 70 being roughly half of that at age 20 [8].

Reduced Gastrointestinal Absorption

Aging also affects the body's ability to absorb vitamin D from food sources:

• Older adults experience relative vitamin D resistance in stimulating calcium absorption in the gastrointestinal tract.
• This decreased absorption efficiency contributes to the higher vitamin D requirements for older individuals

Despite these challenges, it's important to note that even older individuals can produce significant amounts of vitamin D with adequate sun exposure. A single 15-minute sun exposure to >40% body area can result in considerable vitamin D production, even in older adults [8]. However, for many older individuals, especially those who are housebound, vitamin D supplementation is often necessary to maintain adequate levels.

Can you overdose on Vitamin D?

Yes, it is possible to overdose on vitamin D, though it's rare and typically only occurs from excessive supplementation rather than from sun exposure or diet alone. Here are the key points about vitamin D overdose:

Causes of Vitamin D Toxicity

• Vitamin D toxicity, also called hypervitaminosis D, usually results from taking very high doses of vitamin D supplements over an extended period.
• It's extremely difficult to get too much vitamin D from sunlight or food sources alone.

Symptoms and Effects

The main consequence of vitamin D toxicity is hypercalcemia (excessive calcium in the blood), which can cause:

• Nausea and vomiting
• Weakness
• Frequent urination
• Bone pain
• Kidney problems, including kidney stones2

Severe cases may lead to:

• Kidney failure
• Abnormal heart rhythm
• Confusion
• Dehydration

Safe Dosage vs. Toxicity

• The recommended daily intake varies, with 2000-3000 IU per day during the winter months and 800-1000iu during the summer months being sufficient for most adults. 
• Toxicity has been shown to occur at doses of 60,000 IU per day taken for several months.

What are some common vegan sources of Vitamin D?

Here are some common vegan sources of vitamin D:

1. Sunlight exposure: While not a food source, sunlight remains one of the best ways for vegans to get vitamin D. The body produces vitamin D when skin is exposed to sunlight.
2. Mushrooms: Especially for those exposed to UV light, mushrooms can be a good natural plant-based source of vitamin D. Some varieties can provide up to 450 IU per 100-gram serving.
3. Fortified plant-based milks: Many soy, almond, oat and other plant milks are fortified with vitamin D, typically providing about 100-120 IU per 250ml.
4. Fortified cereals: Many breakfast cereals are fortified with vitamin D, often providing around 120 IU per serving.
5. Fortified orange juice: Some brands of orange juice are fortified with vitamin D, usually containing about 100 IU 250ml.
6. Fortified tofu: Certain brands of tofu are fortified with vitamin D, providing around 100 IU per 100g serving.
7. Vitamin D supplements: Many vegans opt for vitamin D supplements to ensure adequate intake. Look for vegan D3 supplements.

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