The Top Natural Sources of Vitamin D
Almost 50% of the worldwide population is insufficient in vitamin D!
Vitamin D is one of the most crucial vitamins to your overall health. Research suggests vitamin D may help treat or prevent autoimmune diseases, cancer, depression, chronic pain, heart disease and even osteoporosis.
In addition, vitamin D’s most critical roles are to aid calcium absorption, regulate your immune system, and support cell contraction. There’s almost nothing this vitamin isn’t good for.
You may assume that, like other vitamins, it’s found in food. But did you know there are very few good food sources of vitamin D?
Vitamin D: The “Sunshine” Vitamin
Exposure to natural sunlight is the major source of vitamin D for children and adults.
When the sun’s UV-B rays hit the skin, a reaction takes place that enables skin cells to manufacture vitamin D. If you’re fair skinned, going outside for 10 minutes in the midday sun with 40% of your skin exposed – in shorts and a sleeveless top (with no sunscreen) will give you enough exposure to produce about 10,000 international units (IU) of the vitamin!
Some experts say getting a healthy dose of 10-15 minutes of summer sun 2 to 4 times per week is enough (unless you are already severely deficient).
This isn’t true in the Spring and Fall when the sun is lower in the sky, let alone in winter months. In the winter, it’s impossible to produce vitamin D from the sun if you live north of latitude 37 degrees north (which cuts midway through California to the west and Virginia to the east). Therefore more than half of Americans and all of Canadians are at high risk for vitamin D deficiency.
Geographic latitude and season aren’t the only variables:
- Time of day, cloud cover, and smog affect UV ray exposure and vitamin D production. Complete cloud cover halves the energy of UV rays, and shade reduces it by 60%.
- Industrial pollution filters sun exposure and have been found to contribute to developing vitamin D deficiency diseases (rickets).
- Sunscreens with a sun protection factor (SPF) of 8 or greater block the UV rays that produce vitamin D.
- Other factors reducing the skin’s production of vitamin D3 include aging and increased skin pigmentation/tanning.
The reality is, the majority of world’s population is not getting enough sunlight. So while sun exposure is the top natural source of vitamin D, foods and supplementation are going to ensure you aren’t slipping into deficient levels.
Note: Scientific data shows that the health risks of too much sun (melanoma) is outweighed by the health hazards of too little vitamin D – by 10 to 1! However, if your doctor or physician has advised you to avoid or limit your sun exposure, or you simply don’t feel comfortable getting your vitamin D from the sun, supplementation may be your best bet. Skip down to the last section of this article for more on vitamin D supplements.
The Top 10 Vitamin D Food Sources
From caviar to raw oysters, the top 10 vitamin D-rich foods may surprise you…
|Food||International Units(IU) |
|Recommended Daily Intake |
|3.5 oz (100g) Wild-Caught Salmon|| |
|1 tsp. Cod Liver Oil|| |
|3.5 oz (100g) Canned Sardines|| |
|6 Raw Oysters|| |
|Canned Light Tuna|| |
|1 large Shrimp|| |
|Fortified Foods (milk, dairy, cereals)|| |
|1 tbsp. Caviar|| |
|1 large Egg Yolk||18 IU||5%|
|1 cup of Mushrooms|| |
*RDI= Recommended Daily Value. RDI’s are reference numbers developed by the Food and Drug Administration to help consumers determine if a food contains a lot or a little of a specific nutrient. RDI’s are calculated based on complicated formulae, but in layman’s terms, they are the minimum amounts needed to be healthy. For example, the RDI for vitamin D is 400 IU for adults, but most of the scientific community argues for several times higher consumption of Vitamin D. Please bear this in mind as you look at the food data presented here!
The best source of naturally occurring vitamin D is fatty fish. Salmon is a great choice. A 3.5 ounce serving of salmon contains between 360 IU and 1,300 IU according to nutrient databases. Whether it’s wild or farmed also makes a difference. A 2009 study, for example, found that wild-caught salmon contains 988 IU of vitamin D for a 3.5 ounce (300 gram) serving. Farmed salmon is said to have approximately 25% of the vitamin D as wild salmon.
In addition to vitamin D, sardines are one of the top sources of omega 3 fatty acids. They contain significant amounts of protein per serving and many important minerals to support your overall health and bone health! Furthermore, they’re also one of the least contaminated (lower on the food chain) and sustainable sources of fish, which is why you’ll commonly see sardines in omega 3 supplements.
Not the most appealing food on the list for some, raw oysters are low in calories and high in nutrients. In addition to being a good food source of vitamin D, (six raw oysters contain 269 IU or 67% of your RDI) they also contain vitamin B12, copper, phosphorus, and zinc. Copper, for instance, has been shown to have a positive impact on bone health.
Cod Liver Oil
Cod liver oil, a traditional omega 3 fatty acid, and vitamin D supplement have come a long way in taste since it was recommended in the 1960s. But, you still might prefer eating a can of tuna fish or fresh wild salmon instead! Note: most refined cod liver oils today have the vitamin D removed! Check your label to be certain.
Canned tuna is widely enjoyed because of its subtle flavor and convenience – as most households have one or two cans of tuna stowed away in their pantry at all times. Use it in sandwiches or salads to reap the benefits of this nutrient-dense food. One hundred grams (about the size of a hockey puck) contains 59% of your RDI vitamin D needs, plus magnesium, phosphorus, potassium, and selenium. Worried about heavy metals associated with larger fish, like tuna? A new selenium-containing compound called selenoneine has recently been identified in the bloodstream of tuna that may help explain why fish that contain more selenium than mercury is good for us. Selenoneine increases the rate at which mercury is detoxified and excreted by the fish –and thus their healthful effects on us, when we consume them. In other words, when we maintain healthy essential mineral levels, we are able to resist toxic ones. In fact, our Bone Health Expert Lara Pizzorno eats 1 Brazil nut, which is a selenium-rich food, after a meal that includes any type of fish (or includes it in the meal itself chopped up in a salad or in pesto etc.) as a detoxification method.
A popular type of shellfish that is low in fat compared to the other seafood sources with vitamin D. Four large shrimp contain 11% of your RDI of vitamin D. They also contain vitamin A, magnesium, phosphorus, and potassium.
Since there are very few natural food sources that have adequate amounts of vitamin D, the solution has been to fortify foods with vitamin D. This began in the 1930s when the vitamin D deficiency disease called rickets was a major public health problem in the US. A milk “fortification” program was put in place, which, to its credit, nearly eliminated the condition. Currently, 98% of the milk supply in the US is fortified with 400 International Units (IU) of vitamin D per quart. Other foods that are commonly fortified with vitamin D include breakfast cereals, fruit juices, bread (in the leavening yeast) and margarine or other veggie spreads. Note: In a 2006 article in the American Journal of Clinical Nutrition, researchers stipulated that vitamin D2, the variety used to fortify some foods, is inferior to vitamin D3. Other research found this to be because vitamin D2 has markedly lower potency and its effects don’t last nearly as long compared to vitamin D3. Check the label on your foods to see whether they have D3, listed as cholecalciferol, or D2, ergocalciferol.
Caviar is a salt-cured roe (fish eggs) that can be eaten fresh or pasteurized. It can be eaten by itself, on crackers or even on scrambled eggs! If you do find yourself eating this delicacy know that black or red caviar contains 37 IU of vitamin D in just one tablespoon.
While the protein of an egg is found mostly in the egg white, vitamin D is mostly found in the egg yolk. Conventional egg yolks contain about 5% of your RDI of vitamin D – not high at all. However, free-range eggs have been shown to offer higher levels of vitamin D – as much as four times higher! Other pasture-raised animals like pigs may also produce more vitamin D. Pigs have skin like humans, which can store vitamin D in their fat under their skin. Exposure to sun, in addition to being grass-fed, contributes to pasture-raised animals having better mineral status. For instance, pasture-raised pigs also have 74% more selenium and 300% more vitamin E than conventional pigs, according to Professor Don C. Mahan from Ohio State University.
Portobello, morel, button, white, and shiitake mushrooms all contain ergosterol, a vitamin D precursor. One cup still only has 13-15 IUs of the vitamin. According to some reports, you can set mushrooms out in the sun to boost their vitamin D content! The UV rays trigger a process called photosynthesis. This process increases Vitamin D levels in sun-exposed mushrooms and humans alike.
Does Cooking or Processing Affect Vitamin D Content of Foods?
You have probably heard that cooking can diminish vitamins in food, especially plant foods. Vitamin B and C are the most vulnerable to heat and are lost in vegetables and fruit when steamed or boiled because they leach into cooking water. But what about vitamin D?
The effect of cooking on the vitamin D content in fish varies depending on the variety of fish. Research from 2009 found that when salmon was baked, almost all of the vitamin D content (240 IU of vitamin D3) remained from 3.5 ounces of salmon. The initial amount in the uncooked salmon was 245 IU of vitamin D3. However, when the salmon was fried in vegetable oil, only 50% (123 IU) remained.
A study from 2014 looking at the impact of cooking on vitamin D3 in eggs, margarine and grains (boiling, frying and baking) showed the level of vitamin D in eggs and margarine in an oven for 40 min at normal cooking temperature retained only 39-45%. Frying was better, at 82-84%. Boiled eggs retained 86-88% of their vitamin D. The retention of vitamin D in rye bread at 69% was lower than in wheat bread at 85%. The researchers stated, “Vitamin D retention after cooking should be taken into account in future calculations of dietary intake of vitamin D.”
On the other hand, according to scientist Michael F. Holick, vitamin D levels in mushrooms remain intact when cooked. Holick says the heat may even make vitamin D easier for people to absorb.
Note: Defatting milk, meaning skim or 1%, does not affect absorption of vitamin D. Even though D3/cholecalciferol, the form added to cow’s milk, is fat-soluble – so you’d think there might be less in fat-free milk, vitamin D in any type of milk is mainly bound to the proteins in it, not fat. And it is in the proteins that vitamin D is transported in the blood.
The Benefits of Vitamin D
Vitamin D is different from other vitamins in that it influences your entire body.
Receptors that respond to vitamin D have been found in almost every type of cell from your brain to your bones. The primary function of vitamin D is to help absorb calcium and phosphorus in your intestines, and this affects a multitude of essential processes. Optimizing your vitamin D levels could help you to prevent a dozen types of cancer (including pancreatic, lung, breast, ovarian, prostate and colon). In fact, research states that 600,000 cases a year of breast and colorectal cancer could be prevented by adequate intake of vitamin D.
Beyond cancer, increasing vitamin D3 could ward off other diseases that claim one million lives worldwide each year, according to the World Health Organization. Having a healthy amount of vitamin D is known to reduce heart disease, diabetes, inflammatory bowel disease, Rheumatoid arthritis, multiple sclerosis and, of course, osteopenia and osteoporosis.
For more on vitamin D, go to our Vitamin D Benefits page.
The Best Way to Get Your Vitamin D is to Supplement!
Unless you can afford to take a sunny holiday closer to the equator once a month, you’ll need to take bottled sunshine.
The Institute of Medicine (IOM) recommends a daily intake of 600 IU for adults up to 50 years of age; 600 IU for adults 51 to 70 years of age; and 800 IU for adults 71 years or older.
However, most experts and organizations in the vitamin D research community disagree. The Vitamin D Council, for instance, recommends adults get 5,000 IU per day. The IOM assures supplemental vitamin D intakes of up to 4000 IU a day is safe, while researchers maintain 10,000 IU per day has shown no danger.
Best to test!
Rather than guessing at the level of supplementation, if any, is needed, we recommend asking your doctor for a circulating vitamin D blood test to find out exactly what level you have in your bloodstream. After receiving your test results, you can discuss where your current levels are and what you can do to increase or maintain your levels. We recommend you take the test now so that you can make use of the summer sun to top up your vitamin d, if you are low.
In addition to vitamin D, other fat-soluble items such as K2 and calcium should be taken together as they work synergistically to support strong bones. They also work well with other minerals like magnesium and zinc.
Our flagship product, AlgaeCal Plus, contains 1600 IU of D3 along with the other synergistic minerals and vitamins that boost vitamin D’s effectiveness. Learn more here.
1600 IU per day is sufficient for many, but be sure to get tested as circulating vitamin D can vary quite a lot from one person to another. Then, you can top up accordingly.
Please don’t leave vitamin D to chance. As you know, it affects just about every tissue in your body – not just your bones. So get out in the sun for vitamin D!