How much vitamin D do I get from a glass of milk?

November 8, 2025 •

3 min read

Most pasteurized cow's milk in the United States is fortified with vitamin D, a public health initiative that began in the 1930s to combat rickets. Fortification means that the amount of vitamin D is added intentionally during processing, because milk does not contain significant amounts of the vitamin naturally. So, the vitamin D you get from a glass of milk depends entirely on whether it has been fortified.

Quick Summary

Fortified milk typically contains 100-120 IU of vitamin D per 8-ounce serving, providing a helpful boost toward your daily nutritional goals. Unfortified milk contains only trace amounts.

Key Points

Fortification is Key: The vitamin D in milk is added during processing; it is not naturally high in content.
Typical Amount in Fortified Milk: An 8-ounce glass of fortified milk contains approximately 100 to 120 IU of vitamin D.
Not a Complete Daily Source: A single glass provides only a fraction (15-20%) of the recommended daily intake for most adults.
Comparability with Plant-Based Options: Many plant-based milks are also fortified with a similar amount of vitamin D.
Consider Other Sources: Since milk alone is insufficient, a balanced diet including fatty fish, eggs, and sun exposure is important for meeting total vitamin D needs.

Understanding Vitamin D Fortification

Vitamin D is a fat-soluble vitamin crucial for bone health and immune function. Unlike vitamin C, which is found in many fruits and vegetables, very few foods naturally contain significant levels of vitamin D. The most potent natural source is sunlight, which triggers its synthesis in the skin. However, factors like season, latitude, sunscreen use, and time spent indoors mean many people rely on dietary sources to meet their needs.

To address widespread vitamin D deficiency, the practice of fortifying common foods like milk was introduced. In the U.S., most dairy milk producers voluntarily fortify their products with approximately 100 IU of vitamin D per 8-ounce (one-cup) serving, while some countries mandate it. This practice has been credited with making deficiency diseases like rickets a rarity in developed nations.

The Difference Between Fortified and Unfortified Milk

It is critical to distinguish between fortified milk and raw or unfortified varieties. Raw, unpasteurized milk contains only trace amounts of vitamin D, as does human milk. Therefore, relying on unfortified dairy products will not help you meet your vitamin D needs. When purchasing milk, checking the nutritional label for the explicit listing of added vitamin D is essential to confirm its status. Most processed milks, including whole, 2%, 1%, and skim, are fortified to similar levels, typically around 100 IU per cup.

The Vitamin D Content in a Glass of Milk

An 8-ounce glass of fortified milk generally provides around 100 to 120 International Units (IU) of vitamin D. This amount typically represents 15-20% of the Daily Value (DV) for vitamin D, depending on the specific product and formulation. While a single glass provides a notable contribution, it is not a sole solution for reaching the total recommended daily intake, which is typically around 600-800 IU for adults. Other food sources and potentially supplements are often needed to fill the gap.

Vitamin D in Plant-Based Milks

For those who consume plant-based alternatives, these products are also commonly fortified with vitamin D. The amount is usually comparable to dairy milk. For example, many soy, almond, and oat milks contain between 100 and 144 IU per cup, depending on the brand. As with dairy milk, it is important to check the nutritional label of any plant-based milk to confirm fortification and the exact amount of vitamin D.

Combining Milk with Other Sources for Your Daily Intake

Because a glass of milk provides only a portion of your daily vitamin D needs, it's important to integrate it into a balanced diet that includes other sources. Fatty fish like salmon and tuna, cod liver oil, and some fortified cereals are also excellent contributors. The following table compares the vitamin D content of an 8-ounce glass of fortified milk with other common dietary sources.


Food Source	Serving Size	Approximate Vitamin D (IU)
Fortified Cow's Milk	1 cup (8 oz)	100-120 IU
Sockeye Salmon	3 oz, cooked	570 IU
Cod Liver Oil	1 tbsp	1,360 IU
Tuna (Canned)	3 oz, drained	40 IU
Fortified Cereal	1 serving	Varies, check label (e.g., 80 IU)
Egg Yolk	1 large scrambled	44 IU

Importance of a Varied Diet

Achieving adequate vitamin D levels is best approached through a combination of sources. While sun exposure is a natural way to produce vitamin D, dietary sources are more reliable, especially during winter months or for individuals with limited sun exposure. Integrating fortified milk with other nutritious foods and potentially consulting a healthcare provider about supplementation is a comprehensive strategy for maintaining sufficient vitamin D.

Beyond bone health, proper vitamin D levels support the immune system and can help reduce inflammation. Fortified milk's long history as a public health tool demonstrates the effectiveness of widespread fortification in improving nutritional status. To learn more about recommended dietary intakes and nutrient sources, the National Institutes of Health Office of Dietary Supplements is an authoritative resource to explore. NIH Vitamin D Fact Sheet.

Conclusion

In summary, a standard glass of fortified cow's milk contains a useful amount of vitamin D, typically 100-120 IU. This is not naturally present but added during processing to enhance public health. It's a convenient way to boost your daily intake, but it is not sufficient on its own to meet daily needs for most adults. Pairing fortified milk with other vitamin D-rich foods and considering supplements, especially if dietary intake is low, is the most effective approach to ensure a healthy vitamin D status.

Frequently Asked Questions

No, not all milk contains vitamin D. The vitamin D content in milk comes from fortification, which is the process of adding the nutrient during production. Most commercial cow's milk in the U.S. is fortified, but raw or unfortified milk will have only trace amounts.

An 8-ounce glass of fortified milk contains approximately 100 to 120 International Units (IU) of vitamin D.

Vitamin D is added to milk as a public health measure to help prevent nutritional deficiencies, most notably to combat rickets in children. The fortification also aids in the absorption of calcium from the milk, promoting bone health.

It is unlikely you can get all your vitamin D from milk alone. A glass provides a good percentage of the Daily Value, but other dietary sources and sensible sun exposure are also necessary to meet the full daily requirement.

Yes, many plant-based milk alternatives, such as soy, almond, and oat milks, are fortified with similar amounts of vitamin D. Always check the nutrition label, as the levels can vary by brand.

Raw, unpasteurized milk contains only trace amounts of vitamin D. It is not considered a significant dietary source of the vitamin.

The fat content itself does not significantly affect the added vitamin D, as most manufacturers fortify all varieties (whole, 2%, 1%, skim) to similar levels. However, unfortified whole milk naturally contains very little vitamin D, despite being fat-soluble.

Drinking fortified milk does contribute to your overall vitamin D intake and can help increase blood levels of the vitamin. However, it should be part of a broader strategy that may include other food sources and sun exposure.