What Are the Best Vitamin D Foods for the Immune System

Vitamin D performs a host of metabolic functions to enable optimal living. Until recently, sunlight has been our primary source of vitamin D. However, today’s hectic schedules limit our exposure to sunlight and limit our body’s vitamin D production. Therefore, the adequate consumption of vitamin D foods, another vital source of this nutrient, has become even more important. 

This article discusses the best sources of vitamin D, their benefits, recommended daily intake, and other relevant information.

Let’s jump right into it.

Vitamin D Functions

Vitamin D performs many critical roles in the body, without which life can’t go on smoothly. For example, it plays an essential role in proper bone formation and strengthening. Therefore, it’s a vital factor in osteoporosis, rickets, and osteomalacia prevention. 

This is because vitamin D promotes the absorption of calcium and phosphorus, minerals essential for adequate bone mineralization. Furthermore, maintaining normal vitamin D levels promotes joint and muscle health. 

Furthermore, adequate vitamin D intake can strengthen the immune system by triggering immune cells to produce antibodies. There’s also some evidence that adequate vitamin D intake reduces the risk of prostate, colon, and breast cancer.

There’s also evidence that adequate vitamin D intake through supplements or foods that contain vitamin D can help lower the risk of many other conditions. 

Namely, recent research associates low vitamin D levels with a high risk of hypertension, depression, osteoporosis (rickets in children), obesity, cancer, and several autoimmune diseases. 

Vitamin D Forms

Vitamin D comes in two forms—vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Both forms are fat-soluble and present in food and vitamin D supplement formulas. 

Vitamin D2 naturally occurs in yeast, plants, fungi, and fortified foods. On the other hand, vitamin D3  is found in animal-based foods such as meat and dairy, as well as fortified foods. Furthermore, this vitamin is also produced by the skin upon the sunlight exposure.

Vitamin D Synthesis

Vitamin D is also referred to as the sunshine vitamin. This is because the human skin can produce a hefty vitamin D dose upon being exposed to sunlight. 

When the skin gets exposed to UV-B radiation (290–315 nm wavelengths), it starts producing vitamin D3 from 7-dehydrocholesterol located in the epidermis. This is why science considers vitamin D to be a hormone rather than a vitamin.

In healthy individuals, vitamin D3 enters blood circulation after being produced and gets transported to the liver. There it undergoes hydroxylation and forms 25-hydroxyvitamin D3 (calcidiol)—the main circulating vitamin D3 form. 

When it reaches the kidneys, 25-hydroxyvitamin D3 undergoes a second hydroxylation aided by the enzyme 25-hydroxyvitamin D3-1 hydroxylase to produce 1,25-dihydroxyvitamin D3 (calcitriol)—the most potent vitamin D form.

However, since modern life drastically reduced our exposure to the sun, sunlight became a less reliable vitamin D source. Moreover, overexposure may lead to skin cancer. 

Therefore, adequate consumption of foods with vitamin D and supplements stands out as the best way of increasing and maintaining vitamin D levels.

The Best Vitamin D Foods 

Most foods with high vitamin D content are animal-based (meat, seafood, dairy, eggs). However, some vegetables also contain decent doses of this vitamin and serve as excellent vitamin D foods for vegan diet followers. 

Unfortunately, fruit isn’t a good vitamin D source. Therefore, there are no vitamin d fruits on this list. 

Cod Liver Oil

Cod liver oil stands out from other fish oils owing to its rich vitamin D content. Just one tablespoon of cod liver oil offers a whopping 1,360 IU (170% DV) of vitamin D. This explains its historical use in preventing and combating low vitamin D levels.

Salmon

Vitamin D content in salmon varies according to the species and preparation method. For example, 3 oz of raw sockeye salmon can provide 479 IU (60% DV) of vitamin D. Frying increases the value to 570 IU (71% DV).

Smoked chinook salmon (3 oz) offers 582 IU (73% DV), making it a top-ranking vitamin D food in this category. On the other hand, fried Atlantic salmon provides 447 IU (56% DV) of vitamin D per 3 oz. 

Canned Tuna

Canned tuna is affordable, delicious, easy to store, and one of the excellent sources of vitamin D. A 3.5-oz serving of canned tuna provides 268 IU (34% DV) of vitamin D. 

However, canned tuna should be consumed with care, as it contains methylmercury. This toxin commonly found in fish can cause various health problems if consumed in large quantities. 

Since light tuna poses less risk for methylmercury poisoning, it’s a better choice than white tuna. The safe amount of light tuna is up to 6 oz per week.

Mackerel

Mackerel, one of the favorite fish in the US, is also an excellent food high in vitamin D. Vitamin D content in mackerel depends on the species and the preparation method. 

Therefore, raw Atlantic mackerel packs 547 IU (68% DV) of vitamin D in a 3-oz serving, and the same amount of raw Spanish mackerel contains only about 248 IU (31% DV) of vitamin D.

On the other hand, 3 oz of fried mackerel can provide 388.45 IU (48% DV) of vitamin D.

Whitefish

A 3-oz serving of smoked whitefish provides 435 IU (54% DV) of vitamin D, ranking it high among foods with vitamin D. Raw whitefish offers a slightly lower vitamin D content—406 IU (51% DV) per 3 oz.

Swordfish

A 3-oz serving of fried swordfish provides 566 IU (71% DV) of vitamin D. Besides ranking high on the vitamin D foods list, swordfish is exceptionally rich in selenium and omega-3s. 

Sturgeon

Smoked sturgeon boasts a higher vitamin D content than fried sturgeon. A 3-oz serving of smoked sturgeon offers 546 IU (68% DV) of vitamin D, while the same amount of fried sturgeon provides 438 IU (55% DV). 

Besides being one of the top foods rich in vitamin D, sturgeon is also rich in vitamin B12, protein, and sodium.

Rainbow Trout

A 3-oz serving of raw farmed rainbow trout contains 540 IU (68% DV) of vitamin D. Cooking slightly increases its vitamin D content. Therefore, you can get 645 IU (81% DV) of vitamin D from 3 oz of fried rainbow trout.

Herring

Herring ranks relatively high among the food sources of vitamin D. You can get 216 IU (27% DV) of vitamin D from 3.5 oz of fresh Atlantic herring. On the other hand, 3.5 oz of pickled herring offers a significantly lower amount—only 112 IU (14% DV). 

However, you should consume pickled herring with caution since it’s exceptionally high in sodium. 

Tilapia

One fillet (3 oz) of fried tilapia offers 130 IU (16% DV) of vitamin D. On the other hand, raw tilapia contains 144 IU (18% DV) per fillet (4 oz). This makes tilapia one of the best foods containing vitamin D. 

Halibut

Fried halibut (Atlantic and Pacific) contains 196 IU (25% DV) of vitamin D per 3 oz. It’s also a rich source of sodium, potassium, and omega-3 fatty acids.

Cremini Mushrooms

One cup of raw sliced cremini mushrooms contains a meager 2.16 IU (0.36 % DV) of vitamin D. On the other hand, cremini mushrooms exposed to UV light provide a whooping 922 IU (115% DV) of vitamin D per cup. 

Cremini mushrooms are among the few vitamin D vegetables available, particularly beneficial for vegans and vegetarians.

Maitake Mushrooms

These fungi are some of the best vegan foods high in vitamin D. You can get a whopping 786 IU (98% DV) of vitamin D from one cup of diced maitake mushrooms.

Chanterelle Mushrooms

Although chanterelle mushrooms aren’t as high in vitamin D as cremini or maitake mushrooms, they also deserve a spot on this list. They provide 114 IU (14% DV) of vitamin D in a single cup.

Oyster Mushrooms

Oyster mushrooms contain a modest amount of vitamin D. A cup of sliced oyster mushrooms provides 24.9 IU (3% DV) of vitamin D.

White Mushrooms

White mushrooms are also a good source of vitamin D and one of the good alternative vitamin D foods for plant-based diet followers. One cup of raw sliced mushrooms contains 4.9 IU (0.6% DV). Boiling white mushrooms increases their vitamin D content, elevating it to 12.5 IU (2% DV) per cup.

Shiitake Mushrooms

Raw shiitake mushrooms provide 18 IU (2% DV) of vitamin D per 3.5 oz. A cup of diced cooked shiitake mushrooms offers a slightly higher value of 40.6 IU (5% DV) of vitamin D. On the other hand, dried shiitake mushrooms contain a whopping 154 IU (19% DV) per cup.

Portobello Mushrooms

One cup of diced portobello mushrooms provides only 8.6 IU (1% DV) of vitamin D. Although these mushrooms don’t rank high among the vitamin-D-rich foods, they’re a decent alternative for those abstaining from animal-sourced food.

Hot Cocoa

A single cup of homemade hot cocoa provides 112 IU (14% DV) of vitamin D.

Cheese

Despite boasting a relatively low vitamin D content, cheese could be a good source of vitamin D for vegetarians. 

It’s important to note that vitamin D content varies according to the type of cheese. For example, you can get 6.6 IU (0.7% DV) of vitamin D from a cup of Colby or Cheddar cheese. 

Mozzarella contains 12 IU (1% DV) of vitamin D per 3.5 oz. On the other hand, crumbled feta offers 24 IU (3% DV) of vitamin D per cup.

Eggs

A recent Australian study found that two eggs weighing about 2 oz can provide as much as 82% DV of vitamin D, making them one of the best sources of vitamin D for vegetarians.

Yogurt

Yogurt is also one of the good vitamin D foods for vegetarians. One cup of low-fat yogurt contains 2.45 IU (0.3% DV) of vitamin D, while whole milk yogurt offers 4.9 IU (0.6% DV) of vitamin D per cup. 

This dairy product is also rich in calcium, sodium, folate, and vitamin A.

Milk

Milk is one of the excellent sources of vitamin D. Different types of milk contain different nutrient content:

• Whole milk (3.25% fat): 124 IU (16% DV) of vitamin D per cup
• Skim milk: 115 IU (15% DV) of vitamin D per cup
• Evaporated milk (2% fat): 403 IU (50% DV) of vitamin D per cup
• Goat milk: 124 IU (16% DV) of vitamin D per cup
• Chocolate milk: 122 IU (15% DV) of vitamin D per cup

Plant-Based Milk

Plant-based milk is a perfect substitute for cow’s milk if you seek vegan foods high in vitamin D. There are different types of plant-based milk with varying vitamin D content:

• Soy milk: 114 IU (15% DV) of vitamin D per cup
• Rice milk: 97.6 IU (12% DV) of vitamin D per cup
• Almond milk: 101 IU (25% DV) of vitamin D per 8 fl oz

Most plant-based products are fortified with the sunshine vitamin because the levels of vitamin D in plants are typically lower than in animal sources.

Beef

You can get 4.25 IU (0.5% DV) of vitamin D from a 3-oz serving of grilled chuck eye steak. The same amount of broiled ground beef offers 1.7 IU (0.2% DV) of vitamin D.

Beef Liver

You can get 49 IU (6% DV) of vitamin D from a 3.5-oz serving of braised beef liver. The same amount of fried beef liver offers a similar amount of vitamin D—48 IU (6% DV).

Turkey

A 3-oz serving of cooked ground turkey offers 6.8 IU (0.9% DV) of vitamin D. 

Benefits of Vitamin D

Vitamin D provides many benefits, ranging from supporting bone health to treating particular skin conditions.

Let’s explore how adequate intake of vitamin D benefits our health. 

Maintaining Healthy Bones

Vitamin D supports bone health and strength by helping the body use and absorb calcium. In essence, our bones would go ‘soft’ without adequate vitamin D levels in the system and prone to rickets in children or osteomalacia and osteoporosis in adults. 

Taking oral vitamin D supplement products may treat hereditary bone disorders such as familial hypophosphatemia. They are also effective against bone loss in patients on corticosteroid therapy. 

The Immune System Strengthening

Vitamin D can also be effective against the flu, according to a 2018 study. However, further research is required to verify this claim.

Preventing Hypertension in Children

Studies reveal that vitamin D deficiency can lead to high blood pressure in children. This is because low vitamin D levels can produce stiffness in the arterial walls, leading to hypertension.

Allergy Prevention 

AAAAI’s reports reveal a correlation between insufficient vitamin D exposure and heightened allergic sensitization in children.

Maintaining Healthy Pregnancy

Studies suggest that low vitamin D levels during pregnancy increase the risk of premature birth and, possibly, preeclampsia. Vitamin D deficiency during pregnancy also increases the chances of gestational diabetes and bacterial vaginosis.

Treating Psoriasis

Topical vitamin D can help treat plaque-type psoriasis. Combining topical vitamin D with topical corticosteroids makes the treatment more effective.

Vitamin D Deficiency

Vitamin D deficiency has recently become a global concern. A large portion of the world’s population (at least 1 billion people) has low vitamin D levels.

The following sections tackle everything from the most characteristic cholecalciferol deficiency symptoms and diseases to causes and the main risk factors. 

Vitamin D Deficiency Symptoms

Vitamin D deficiency can manifest as:

• Susceptibility to illnesses and infections
• Slow wound healing
• Hair loss
• Fatigue
• Back and bone pain
• Moodiness
• Muscle pain

Prolonged cases of vitamin D deficiency can result in:

• Cancer (breast, prostate, and colon cancer in particular)
• Pregnancy complications
• Infections
• Autoimmune issues
• Cardiovascular diseases
• Neurological conditions

Vitamin D Deficiency Diseases

Rickets was the first known vitamin D deficiency disease that inspired the research that led to the discovery of this vitamin. As time passed and technology advanced, many other deficiency-related diseases have been identified.

Rickets

Rickets, a condition prevalent in children and adolescents, is characterized by soft, weak, painful bones, weak muscles, and deformed joints.

A similar condition, called osteomalacia, may occur in adults.

Multiple Sclerosis

Recent research links multiple sclerosis to cholecalciferol deficiency. The study revealed that MS patients showed improvement in symptoms upon increasing their vitamin D intake. Higher vitamin D levels may reduce the risk of developing brain lesions, improve long-term memory in MS patients.

Additionally, the study notes that there are more congenital MS births in parts of the world with less sunlight or during the months when there are fewer opportunities for sun exposure during pregnancy.

Rheumatoid Arthritis (RA)

The higher your vitamin D levels, the less susceptible you are to RA. Studies reveal that maintaining high vitamin D levels reduces the likelihood of developing RA by 24%. Researchers also noticed higher rates of cholecalciferol deficiency occurrence among RA patients than the general masses.

Autoimmune Thyroid Disease (AITD)

Particular studies link AITD (Hashimoto thyroiditis and Graves’ disease) patients to low vitamin D levels and a high risk of becoming deficient. As many as 26 studies highlighted vitamin D deficiency as a predisposing factor for Graves’ disease.

Type 2 Diabetes 

Particular research shows the link between the lack of vitamin D in the system and type 2 diabetes. 

Other possible vitamin D deficiency diseases include:

• Cancer 
• Depression
• Cardiovascular disease
• Infections
• Irritable bowel disease (IBD)
• Obesity
• Skeletal deformities

Groups at a Higher Risk of Vitamin D Deficiency

The leading causes of vitamin D deficiency include limited exposure to light, inadequate diet, diseases that prevent absorption or production of this essential nutrient, etc. 

Let’s look at some of the groups more prone to becoming deficient:

Lupus Patients

Lupus patients are particularly at risk of cholecalciferol deficiency due to the nature of their disease. Lupus causes photo-sensitivity that causes rashes and disease flares when exposed to sunlight. Therefore, lupus patients tend to avoid sunlight, increasing the risk of deficiency.

Vitamin D deficiency can aggravate the symptoms and disease development and increase mortality rates in lupus patients. 

Breastfed Infants

Infants who depend exclusively on breastmilk are at risk of a vitamin D deficiency, especially those with less exposure to sunlight. 

According to the American Academy of Pediatrics, all breastfeeding infants should get 400 IU of oral vitamin D supplement per day.

The Elderly

The skin’s ability to produce vitamin D steadily declines with age. Furthermore, older adults tend to have a more inadequate diet and spend more time indoors. 

People With Darker Skin 

Melanin, a pigment abundant in people with darker skin, reduces the skin’s ability to produce vitamin D. 

People With Limited Exposure to Sunlight

Spending a lot of time indoors and covering your body with clothing can also affect vitamin D production, as these practices block exposure to the sun. 

Moreover, besides protecting you from harmful UV-B rays, sunscreen with an SPF 30 also reduces your body’s ability to produce vitamin D by 95%. 

The Recommended Daily Intake of Vitamin D

You’ll find slight variations in daily dose recommendations due to different bodies using different calculation models. The following table highlights vitamin D dosage recommendations by two reputable organizations—the Institute of Medicine (IOM) and The Endocrine Society.

Vitamin D Side Effects

Vitamin D supplements are generally safe to use even during pregnancy, breastfeeding, or childhood. However, taking vitamin D supplement products may produce side effects such as:

• Weakness
• Fatigue
• Sleepiness
• Headache
• Loss of appetite
• Nausea
• Vomiting
• Metallic taste
• Dry mouth

• Hardening of the arteries (Atherosclerosis)
• Histoplasmosis infection
• Blood calcium saturation
• Hyperparathyroidism
• Lymphoma
• Kidney disease
• Sarcoidosis
• Tuberculosis

Vitamin D Overdose

While it’s practically impossible to overdose on vitamin D from sun exposure or vitamin D foods, excessive supplement intake can lead to toxicity. 

Prolonged excessive supplement intake may cause hypercalcemia (a calcium buildup in the body), which can lead to heart and kidney damage. 

The following table outlines the upper tolerable upper limit (UL) for different age groups:

Conclusion

Although we can get vitamin D from sunlight, adequate intake of vitamin D foods or supplements is essential for maintaining optimal vitamin D levels. 

The primary food sources of this essential nutrient are animal-sourced (fish oils, seafood, dairy products, meat, etc.). There’s also a limited number of vitamin D fruits and vegetables suitable for vegans and vegetarians. 

FAQ

Which vegetable is high in vitamin D?

Vegetables high in vitamin D include broccoli, spinach, kale, okra, collards, soybeans, white beans, etc. 

How can I boost my vitamin D?

The most affordable way is to get more exposure to sunlight. You can also boost your vitamin D levels by consuming food rich in vitamin D (eggs, fish, fish oil, mushrooms, fortified foods, etc.) and taking supplements.

Do bananas have vitamin D?

Bananas don’t contain vitamin D (there are no vitamin-D-rich fruits in general). 

However, they’re a rich source of magnesium—a nutrient essential for vitamin D activation. Therefore, it might be a good idea to consume bananas alongside vitamin D supplements.

What drinks are high in vitamin D?

Fortified fruit juices and milk (both plant-based and animal-sourced) are good sources of vitamin D. Whole milk, soy milk, rice milk, and almond milk can provide at least 10% DV of vitamin D per cup.

What food should I eat for vitamin D deficiency?

Eggs are a good option since a breakfast containing two eggs provides an impressive 80% DV vitamin D. 

Other foods high in vitamin D include cod liver oil with a whopping 170% DV per tablespoon, trout with about 81% DV per 3-oz serving, and UV-light-irradiated mushrooms with 46% DV of vitamin D in 1/2 cup.

Which foods contain vitamin D for vegetarians?

Mushrooms, dairy products (whole milk, yogurt), eggs, orange fruit juice, and plant-based milk are good vitamin D sources for vegetarians.

What happens if vitamin D is low?

Vitamin D deficiency can lead to various diseases and conditions such as osteoporosis, rickets, susceptibility to infections, cancer, different autoimmune conditions, and cardiovascular and neurological disorders.

What is vitamin D good for?

Vitamin D is critical for the proper functioning of the brain and other body organs. Notably, it helps reduce the risk of diseases like osteoporosis, bone loss, rickets, and other conditions resulting from a deficiency (e.g., lupus and rheumatoid arthritis). 

Hence, adequate consumption of vitamin D foods is advised.