What is the dietary intake of vitamin D?

December 12, 2025 •

4 min read

Globally, roughly 1 billion people experience vitamin D deficiency, emphasizing the importance of a proper dietary intake of vitamin D. Dietary intake, whether through foods, fortified products, or supplements, is crucial for many individuals.

Quick Summary

The article explores the dietary intake of vitamin D from natural and fortified sources. It highlights recommended daily intakes across different life stages and factors affecting absorption, including sun exposure and supplements.

Key Points

Importance: Vitamin D is essential for bone health by enabling calcium and phosphorus absorption, and also supports immune function and cell growth.
Sources: Fatty fish like salmon and certain UV-exposed mushrooms are the best natural sources of vitamin D.
Fortification: Many foods, including milk, cereals, and orange juice, are fortified with vitamin D to help prevent deficiency.
Absorption: Vitamin D absorption is enhanced when consumed with fat. Conditions affecting fat absorption can increase the risk of deficiency.
Recommendations: Daily intake recommendations vary by age, ranging from 400 IU for infants to 800 IU for adults over 70, assuming minimal sun exposure.
Supplements: Supplements containing vitamin D3 are the most reliable way to meet daily needs and treat deficiency for those with low sun exposure.
Risk Factors: Age, darker skin pigmentation, and certain health conditions can increase the risk of vitamin D deficiency and necessitate focus on dietary intake and supplementation.

Vitamin D is a fat-soluble nutrient essential for various bodily functions, often referred to as the "sunshine vitamin." Its main role involves aiding the absorption of calcium and phosphorus, which are essential for maintaining healthy bones, teeth, and muscles. A deficiency can cause bone deformities in children, such as rickets, and in adults, osteomalacia, leading to bone pain and muscle weakness. While sun exposure enables the body to produce vitamin D, dietary intake is vital, particularly during winter or for those with limited sun exposure.

Functions of Vitamin D in the Body

Beyond bone health, vitamin D plays a role in several physiological processes. It supports the immune system, assisting the body in fighting infections by increasing the production of peptides that defend against pathogens. It is also involved in modulating cell growth and reducing inflammation, which may influence managing chronic diseases. Research suggests that sufficient vitamin D levels are linked to reduced risks of cardiovascular disease, certain cancers, and autoimmune conditions such as multiple sclerosis.

Recommendations for Daily Intake

Official recommendations for the dietary intake of vitamin D vary by health organization and age group. These amounts are expressed in both micrograms (mcg) and International Units (IU), with 1 mcg equating to 40 IU. These recommendations assume minimal sun exposure and rely on diet or supplements.

Recommended Dietary Allowance (RDA)

The National Institutes of Health (NIH) provides the following guidelines for daily intake:

Birth to 12 months: 10 mcg (400 IU)
Children 1–13 years: 15 mcg (600 IU)
Teens 14–18 years: 15 mcg (600 IU)
Adults 19–70 years: 15 mcg (600 IU)
Adults 71 years and older: 20 mcg (800 IU)
Pregnant and breastfeeding teens and women: 15 mcg (600 IU)

These are general guidelines, and individual needs can vary based on factors like skin pigmentation, location, and overall health.

Natural Food Sources of Vitamin D

Very few foods naturally contain significant vitamin D amounts. The best natural sources are typically animal-based:

Fatty Fish: Examples include salmon, trout, mackerel, tuna, and sardines. A 3-ounce serving of cooked sockeye salmon offers 14.2 mcg (570 IU).
Cod Liver Oil: This is an exceptionally rich source, with one tablespoon providing 34 mcg (1,360 IU).
Other Animal Products: Smaller amounts are found in beef liver, egg yolks, and cheese.
Mushrooms: Some mushrooms, especially those exposed to UV light, can contain significant vitamin D2. For instance, UV-exposed raw white mushrooms can have 523 IU per 50g.

Food Fortification: A Modern Strategy

Since few foods naturally have vitamin D, food fortification is a public health approach, particularly in Western countries. Many commonly consumed products have vitamin D added:

Milk (both dairy and plant-based alternatives like soy and almond milk)
Breakfast cereals
Orange juice
Some yogurts and margarines

Factors Influencing Vitamin D Absorption

Several factors can affect the body's absorption of vitamin D from food:

Fat Presence: As a fat-soluble vitamin, D is best absorbed with some dietary fat.
Digestive Health: Conditions that affect fat absorption, like celiac disease, Crohn's disease, and cystic fibrosis, can lead to vitamin D deficiency.
Gastric Bypass Surgery: This can affect the part of the intestine where vitamin D is absorbed, raising the risk of deficiency.
Aging: The skin's capacity to produce vitamin D from sunlight decreases with age, making dietary intake more critical for older adults.

Comparison of Vitamin D Food Sources


Food Source	Serving Size	Vitamin D Content (IU)	Naturally Occurring or Fortified	Notes
Sockeye Salmon	3 ounces, cooked	570	Naturally Occurring	High in vitamin D3 and omega-3s.
Cod Liver Oil	1 tablespoon	1,360	Naturally Occurring	Highest concentration from a natural source.
Fortified Milk	1 cup, 2% milkfat	120	Fortified	Common and accessible source.
UV-Exposed Mushrooms	½ cup, white, raw	366	Enhanced	Vegan source of vitamin D2.
Fortified Cereal	1 serving (10% DV)	80	Fortified	Content varies by brand.
Egg Yolk	1 large egg, scrambled	44	Naturally Occurring	Amount depends on chicken's diet.

Addressing Insufficiency with Diet and Supplements

For many, especially those with limited sun exposure or absorption issues, relying on diet alone may be insufficient to achieve sufficient vitamin D levels. In such cases, supplementation is necessary. Vitamin D supplements are widely available in D2 (ergocalciferol) and D3 (cholecalciferol) forms. D3 is considered more effective at raising blood levels of the vitamin. Consulting a healthcare professional before starting supplementation is advisable to determine the correct dosage. Excessive intake can cause toxicity, characterized by nausea, vomiting, and kidney issues.

Conclusion: Optimizing Your Vitamin D Intake

Achieving and maintaining healthy dietary vitamin D intake involves understanding its sources, both natural and fortified, and being aware of personal risk factors. A combination of sensible sun exposure and a diet including fatty fish and fortified foods can be adequate for most people. For those with a higher risk of deficiency—such as older adults, individuals with darker skin, or those with malabsorption disorders—supplements offer a safe and effective way to ensure adequate levels. Prioritizing vitamin D intake is a proactive step toward supporting strong bones, a resilient immune system, and overall health. Consulting with a healthcare professional or reliable sources like the NIH is recommended.

For more information on dietary supplements: NIH Office of Dietary Supplements: Vitamin D Fact Sheet

Frequently Asked Questions

Fatty fish, such as salmon, trout, and mackerel, are among the best food sources of vitamin D, as is cod liver oil. Some mushrooms exposed to UV light also contain significant amounts of vitamin D. Additionally, many foods are fortified with the vitamin, including milk, cereals, and some orange juices.

It is difficult to get sufficient vitamin D from diet alone, particularly when sun exposure is limited. Dietary sources are few, often requiring supplementation with sunlight or supplements to meet daily requirements.

Recommended daily intake varies with age. For adults aged 19-70, the recommended dietary allowance (RDA) is 600 IU (15 mcg). Adults over 70 need 800 IU (20 mcg). Infants require 400 IU (10 mcg) daily.

Fortified foods can contribute significantly to daily vitamin D intake. Common fortified products such as milk and cereal provide a regular, measurable amount of the vitamin but are often insufficient to meet total needs without other sources or supplements.

Sunlight exposure on bare skin is a primary way the body produces vitamin D. Diet provides a smaller, but essential, amount. Dietary intake is critical when sun exposure is limited due to climate, lifestyle, or skin tone.

Vitamin D2 (ergocalciferol) comes from plant and fungi sources, while vitamin D3 (cholecalciferol) is produced in animal skin and found in fatty fish. Research suggests that vitamin D3 is more effective at raising and maintaining blood levels of the vitamin.

Yes, dietary factors can affect vitamin D absorption. Since it is fat-soluble, it is absorbed most efficiently when consumed with fat. Conditions that affect fat absorption can also lead to vitamin D deficiency.

Low intake may lead to a deficiency. Mild deficiency symptoms can include fatigue and bone or muscle pain. Severe, long-term deficiency can cause bone-weakening diseases like rickets in children or osteomalacia in adults.

References

1
Vitamin D - Health Professional Fact Sheet