Which one should you take for immune support?

Once cold and flu season begins, vitamin C and vitamin D often become go-to choices for additional immune support. Both vitamins can help strengthen your immune system, but they work in different ways. Depending on your current levels, one of these may play a bigger role in whether you stay healthy or end up catching the next virus that goes around.

Vitamin C helps white blood cells

Vitamin C is a classic immune support supplement and its benefits start at the cellular level. It’s a powerful antioxidant, which means it can help protect your cells from damage and even has the potential to help prevent certain diseases.

In your body, vitamin C can:

Even with all these roles, vitamin C is not a magic shield against disease. For example, research generally shows that it doesn’t prevent colds in most people. But when you take it regularly, not just after symptoms appear, it can help you bounce back faster and experience milder symptoms.

Most adults need about 75 to 90 milligrams per day from their diet, although immune support studies often use 200 to 500 milligrams per day.

Having low levels of vitamin C is rare, as most people can get enough through their diet. On top of that, higher doses don’t seem to offer any additional benefit and can cause stomach problems, so be careful when taking supplements.

Vitamin D helps your body respond to viruses

Vitamin D plays a different type of role. It acts almost like a “messenger” that tells your immune system how to work. Adequate levels help your immune cells recognize and respond to viruses, reduce inflammation, and support healthy respiratory defenses.

Research consistently shows that people with low levels of vitamin D are more likely to suffer from respiratory infections. For these people, regular supplementation can help reduce this risk, especially during winter months or in people who don’t get a lot of sunlight.

Most adults need 600 to 800 IU of vitamin D per day, but many people fail to achieve this amount. This is why some doctors recommend higher doses based on blood tests.

Unlike vitamin C, it’s difficult to get enough vitamin D from food alone, so sunlight and supplements often make up the deficiency.

Vitamin C or vitamin D: which is more effective for immunity?

Research shows that vitamin C and vitamin D contribute to immune health, but in different ways. One is not necessarily better than the other.

Vitamin D helps support overall immune function and may reduce the risk of getting certain infections, especially in people who have low levels. Vitamin C supports the activity of immune cells and may help reduce the severity of cold symptoms.

Each vitamin plays a distinct role, and it is important to consume adequate amounts to keep the immune system functioning properly.

How should you take them?

Both vitamins are most effective when taken regularly rather than only after symptoms appear.

Vitamin D, in particular, works gradually over time and is not considered a treatment once you are already sick. It is therefore essential to maintain adequate levels throughout the year. Vitamin C may still offer some support for colds, but research suggests it works best when taken regularly instead of waiting until symptoms appear.

Many people choose to take vitamin D in the fall and winter, when sun exposure decreases and respiratory illnesses become more common. Vitamin C can also be taken during this time, but it is usually not necessary as most people get enough through their diet. If you take both, you can safely take them together because they do not interfere with each other.