Can I Increase My Vitamin D by Drinking Milk?

According to the NIH Office of Dietary Supplements, very few foods naturally contain vitamin D, which is why most of the US milk supply is fortified. Drinking this fortified milk can contribute to your daily intake and help increase your vitamin D levels, but it may not be sufficient on its own for everyone.

Quick Summary

Fortified milk can boost vitamin D intake, but it's often not enough to correct a deficiency alone. This article examines the amount of vitamin D in milk, its role in diet, and compares it with other key sources.

Key Points

• Fortified Milk is a Source: Fortified cow's milk and many plant-based alternatives contain 100-120 IU of vitamin D per 8-ounce serving, contributing to daily intake but not typically sufficient alone.

• Sunlight is a Primary Source: The body produces vitamin D primarily through sun exposure, though this is influenced by location, season, and skin tone.

• Consider Other Sources: Dietary sources like fatty fish (salmon, trout) and UV-exposed mushrooms provide more concentrated vitamin D than milk.

• Supplements May Be Necessary: For those with a deficiency or limited sun exposure, supplements are often the most reliable way to achieve and maintain adequate vitamin D levels.

• Absorption is Key: Factors like age, body weight, and certain medical conditions can affect how well your body absorbs and utilizes vitamin D.

• Calcium Synergy: The vitamin D in milk aids in the absorption of milk's natural calcium, which is crucial for strong bones.

• Consult a Professional: It is best to consult a healthcare provider to determine if your vitamin D intake is sufficient and to address any deficiencies.

The Role of Fortified Milk in Vitamin D Intake

Milk is not naturally rich in vitamin D. It has been fortified with the nutrient since the 1930s to help prevent rickets, a bone-softening disease in children. This practice continues today, with most milk in the United States and Canada containing added vitamin D. A standard 8-ounce glass of fortified cow's milk contains approximately 100 to 120 International Units (IU) of vitamin D. This dosage is a valuable part of a balanced diet but often represents only a fraction of the daily intake needed, especially for those with low levels.

Beyond bone health, vitamin D plays a critical role in immune function, cell growth, and nerve and muscle function. The vitamin enhances the body's absorption of calcium, making the calcium-rich properties of milk even more effective. Therefore, including fortified milk in your diet is a beneficial strategy, but its effectiveness depends on your individual needs and other lifestyle factors.

How Much Vitamin D Is in a Glass of Milk?

The amount of vitamin D in milk is standardized for fortified products, but natural, unfortified milk contains very little. Most processed cow's milk in the U.S. contains 100 IU per 8-ounce serving. Many non-dairy alternatives like soy, almond, and oat milks are also fortified to a similar level. It's crucial to check the nutrition label, as the amount can vary by brand and product type.

Factors Affecting Vitamin D Absorption and Levels

Drinking fortified milk contributes to your vitamin D level, but several factors can influence your body's ability to produce and absorb the nutrient. These include:

• Sunlight Exposure: The sun is the primary natural source of vitamin D, as the skin produces it when exposed to UVB rays. Location, time of year, and skin pigmentation all affect how much vitamin D can be synthesized from sunlight.
• Age: The skin's ability to produce vitamin D decreases with age. This makes dietary sources like fortified milk and supplements more critical for older adults.
• Obesity: Fat cells can sequester vitamin D, making it less bioavailable. Individuals with obesity may need higher doses of vitamin D to achieve healthy blood levels.
• Health Conditions: Certain conditions, such as Crohn's disease, celiac disease, and cystic fibrosis, can impair the intestinal absorption of vitamin D. Kidney and liver diseases can also interfere with the body's ability to convert vitamin D into its active form.

Can Fortified Milk Alone Fix a Deficiency?

While regular consumption of fortified milk can prevent a deficiency for some, it is unlikely to correct an existing one for those with low levels. A cup of milk provides a modest amount, and research suggests that a significantly higher daily intake is needed for those with deficient levels. For many, combining fortified foods with sensible sun exposure and, if necessary, supplements is the most effective approach.

Comparison Table: Vitamin D Sources

Source	Vitamin D Content (approx.)	Notes
Fortified Cow's Milk	~100-120 IU per 8 oz	A reliable, common dietary source.
Sockeye Salmon	~570 IU per 3 oz	One of the best natural food sources.
Canned Light Tuna	~40 IU per 3 oz	Contains a smaller amount than salmon.
UV-Exposed Mushrooms	~366 IU per 1/2 cup	A plant-based source of vitamin D2.
Cod Liver Oil	~1,360 IU per tbsp	A highly concentrated source.
Sunlight	Highly variable	Can produce significant amounts, but affected by many factors.
Supplements	Variable (often 1,000-5,000+ IU)	The most direct way to correct a deficiency.

Beyond Milk: Other Dietary and Lifestyle Strategies

To ensure adequate vitamin D, a holistic approach is recommended. This includes more than just drinking milk. Diverse food sources, responsible sun exposure, and careful consideration of supplements are all part of a comprehensive strategy. For those with significant deficiencies or risk factors, medical advice is crucial.

Diversifying Your Food Intake

In addition to fortified milk, incorporate other sources into your diet. These can include:

• Fatty fish, such as salmon, trout, and mackerel.
• UV-exposed mushrooms.
• Fortified breakfast cereals.
• Fortified orange juice.
• Egg yolks and beef liver contain small amounts.

Safe Sun Exposure

During periods when sunlight is strong, brief, unprotected sun exposure can help your body produce vitamin D. The amount needed varies based on location, time of day, and skin tone. However, due to the risk of skin cancer, many experts recommend obtaining vitamin D from dietary sources and supplements rather than relying solely on the sun.

Considering Supplements

For many, especially during winter months or for those at high risk, supplements are the most reliable way to ensure sufficient intake. Supplements are available in two main forms: D2 (ergocalciferol) and D3 (cholecalciferol), with D3 generally considered slightly more effective. A doctor can help determine if supplementation is necessary based on blood tests.

Conclusion: A Multi-Source Approach is Best

Drinking fortified milk is a simple and effective way to modestly increase your vitamin D intake, but it is rarely a complete solution, especially for those with a pre-existing deficiency. For most people, a combination of fortified foods like milk, occasional sensible sun exposure, and potentially supplements will be needed to maintain healthy vitamin D levels. The best strategy is a diversified one, personalized to your individual health needs and lifestyle, and ideally discussed with a healthcare professional.

The History of Fortification

Vitamin D fortification was implemented widely in the 1930s to combat widespread rickets. This public health measure dramatically reduced the prevalence of the disease in developed countries and is a testament to the power of food fortification in addressing nutritional deficiencies. Today, the practice continues to serve a vital role in public health, providing a convenient source of this essential nutrient for populations with limited sun exposure.

The Synergy with Calcium

One of the most significant benefits of getting vitamin D from milk is the synergy between vitamin D and calcium. Vitamin D facilitates the absorption of calcium, which is abundant in milk. This combination is particularly important for promoting strong bones and preventing conditions like osteoporosis and osteomalacia.

Yale Medicine's Vitamin D Overview

Frequently Asked Questions

Does milk naturally contain vitamin D?

No, milk does not naturally contain significant amounts of vitamin D. The vitamin D content in almost all commercial milk is added during processing through a public health initiative called fortification.

How much vitamin D does one glass of fortified milk provide?

An 8-ounce glass of fortified cow's milk typically provides about 100 to 120 International Units (IU) of vitamin D.

Is drinking milk enough to treat a vitamin D deficiency?

For most individuals with a vitamin D deficiency, drinking fortified milk alone is not enough to correct it. Higher doses, often through supplements, are usually needed to raise blood levels back to a healthy range.

What are better dietary sources of vitamin D than milk?

Better dietary sources of vitamin D include fatty fish like salmon and trout, fish liver oils, and UV-exposed mushrooms, which contain naturally higher concentrations of the vitamin.

How does sunlight compare to drinking milk for vitamin D?

Sunlight is the body's most efficient natural source of vitamin D, producing more than fortified milk. However, factors like season, latitude, and skin tone affect synthesis, and sun exposure carries skin cancer risks.

Do plant-based milks have vitamin D?

Many plant-based milk alternatives, such as soy, almond, and oat milk, are fortified with vitamin D to a level comparable to cow's milk. Always check the nutrition label to confirm.

Why is vitamin D added to milk in the first place?

Vitamin D was first added to milk in the 1930s to combat widespread rickets in children. The fortification practice continues because vitamin D is not naturally abundant in many foods, and it aids in calcium absorption.