How Much Milk to Drink to Get Enough Vitamin D?

November 13, 2025 •

3 min read

According to the NIH, most milk sold in the U.S. is fortified with vitamin D to help prevent deficiency, yet a single glass is often not enough to meet the daily requirements for many adults. This raises a key question: how much milk to drink to get enough vitamin D and support overall health?

Quick Summary

Fortified milk is a good source of vitamin D, but relying on it solely may not be enough to meet daily needs. Learn how much is in a cup, compare it to recommended intake levels, and find other food and lifestyle strategies to ensure adequate vitamin D.

Key Points

Milk Alone is Insufficient: Fortified milk provides a good start, but most adults cannot meet their daily vitamin D needs solely by drinking milk.
Check Fortification Levels: A standard cup of fortified milk contains about 100-120 IU of vitamin D, which is only a fraction of the daily recommendation for adults (600-800 IU).
Diverse Your Diet: To get enough vitamin D, you should supplement milk intake with other rich food sources like fatty fish, cod liver oil, or UV-exposed mushrooms.
Sunlight Remains Key: For most people, moderate sun exposure remains a significant source of vitamin D production, though it must be balanced with sun safety.
Consider Supplements: For those with limited sun exposure or specific dietary restrictions, vitamin D supplements may be necessary to ensure adequate intake.
Know Your Needs: Factors like age, skin color, and health status influence how much vitamin D you require. Consult a doctor for personalized advice.

Understanding the Vitamin D Requirement

Vitamin D is a crucial nutrient, often called the “sunshine vitamin,” that plays a vital role in calcium absorption, bone health, immune function, and mood regulation. While some vitamin D is synthesized by the skin through sun exposure, many people, due to factors like geography, lifestyle, or skin tone, cannot rely on sunlight alone. This makes dietary intake from fortified foods and supplements essential.

The recommended daily allowance (RDA) for vitamin D varies by age. For most adults between the ages of 19 and 70, the RDA is 600 International Units (IU), while for adults over 70, it increases to 800 IU. Breastfed infants require 400 IU daily from birth, as human milk is not a rich source. These figures highlight that meeting vitamin D needs requires a consistent and varied approach.

The Vitamin D Content in Fortified Milk

For many, fortified milk is a convenient and accessible source of vitamin D. In the U.S., most dairy milk and many plant-based alternatives are fortified with vitamin D during processing. A standard 8-ounce cup of fortified cow’s milk typically contains around 100 to 120 IU of vitamin D, or approximately 15% of the Daily Value.

Can Milk Alone Meet Your Needs?

Given that a cup of milk contains roughly 100-120 IU, let's consider the calculation for an average adult with an RDA of 600 IU. To meet this target from milk alone, one would need to drink at least 5 cups (600 IU / 120 IU per cup) every day. This quantity may be impractical for many people and represents a significant portion of daily caloric intake. Moreover, relying on a single food source can lead to an imbalanced diet.

Other Factors Influencing Vitamin D Adequacy

Several factors can affect how much vitamin D you absorb and need. Your body's ability to absorb fat, for instance, can impact vitamin D uptake, as it is a fat-soluble vitamin. Certain health conditions, obesity, and medications can also influence your vitamin D levels. For these reasons, health experts recommend a varied approach that combines multiple sources, including food, moderate sun exposure, and potentially supplements, as part of a balanced lifestyle.

A Broader Look at Vitamin D Sources

Fortified milk is a valuable part of the solution, but it is not the only option. Including a variety of vitamin D-rich foods and getting moderate sun exposure is a more reliable strategy. Some excellent dietary sources of vitamin D include:

Fatty Fish: Salmon, trout, and mackerel are among the best natural sources of vitamin D. A 3-ounce serving of cooked sockeye salmon can provide a substantial 570 IU.
Cod Liver Oil: This oil is a highly concentrated source, with one tablespoon containing a powerful 1,360 IU.
Mushrooms: Certain mushrooms exposed to ultraviolet (UV) light can produce significant amounts of vitamin D. Half a cup of UV-exposed white mushrooms can offer 366 IU.
Fortified Foods: Look for breakfast cereals, orange juice, and yogurt that have been fortified with vitamin D.

Comparison of Vitamin D Sources


Source	Serving Size	Approximate Vitamin D (IU)	% of RDA (600 IU)
Fortified Milk (Cow's)	1 cup (8 oz)	100-120	17-20%
Sockeye Salmon (cooked)	3 ounces	570	95%
Cod Liver Oil	1 tablespoon	1360	227%
UV-Exposed Mushrooms	1/2 cup	366	61%
Fortified Cereal	1 serving	~80	13%

Conclusion

While fortified milk is an easy and accessible way to boost your vitamin D intake, it is important to recognize its limitations. Relying on milk alone to meet your daily requirements, especially for adults, is often impractical and may not provide a balanced nutrient profile. Incorporating a variety of foods rich in vitamin D, such as fatty fish and fortified cereals, along with moderate sun exposure, is the most effective approach. Consulting a healthcare professional for a blood test is the best way to determine your specific vitamin D levels and needs.

For more detailed information on recommended dietary intake, consult the official guidelines from the National Institutes of Health.

Frequently Asked Questions

An average adult needing 600 IU would need to drink approximately five to six 8-ounce cups of fortified milk per day, as each cup contains about 100-120 IU.

Yes, most non-fat (skim), 1%, and 2% cow's milk sold in the United States is voluntarily fortified with vitamin D, typically around 100-120 IU per cup.

Many plant-based milks, such as soy, almond, and oat milk, are fortified with similar levels of vitamin D to cow's milk, but it's important to check the nutrition label, as some brands may not be.

Vitamin D was first added to milk in the 1930s as a public health initiative to combat rickets in children. It also helps the body absorb calcium, which is abundant in milk.

The best non-milk food sources of vitamin D are fatty fish (salmon, tuna), fish liver oils (cod liver oil), and some mushrooms treated with UV light.

It is extremely unlikely to get vitamin D toxicity from fortified milk alone. Most toxicity cases are caused by excessive use of high-dose dietary supplements.

Symptoms of vitamin D deficiency can include fatigue, bone or muscle pain, muscle weakness, frequent illnesses, and mood changes like depression.