What Happens to Your Immune System When You Take Vitamin C

Vitamin C can indeed help boost your immune system and support your body’s ability to fight infections. But when it comes to treating or preventing colds, the answer is not as straightforward.

1. Vitamin C Helps Your Body Create Immune Cells

Vitamin C can stimulate the production and activity of white blood cells. White blood cells are part of your immune system. These are the primary white blood cells:

• Lymphocytes (T cells and B cells)
• Neutrophils
• Eosinophils
• Basophils
• Monocytes

When you get sick or injured, white blood cells travel to the site of inflammation and fight off the infection.

2. It Improves Immune Cell Function

Vitamin C also enhances the functioning of your white blood cells.

Vitamin C can enhance the function of neutrophils and lymphocytes, helping them kill microbes more effectively. It does this by improving:

• Chemotaxis: Movement of the white blood cell.
• Phagocytosis: The process of the white blood cell surrounding, engulfing, and killing the microbe or foreign substance.

Another specific way that vitamin C helps your immune system is by promoting B-cell differentiation.

B cells are a type of white blood cell that produce antibodies, proteins that help your immune system identify foreign invaders. B-cell “differentiation” basically means that the B cells are maturing into plasma cells, which release significant quantities of antibodies.

Vitamin C can help accelerate the B-cell differentiation process, contributing to better long-term immunity.

3. It Protects Against Free Radicals

Vitamin C is an antioxidant that can indirectly support the immune system by protecting against damage from unstable molecules in the body.

During an immune response, the body produces reactive oxygen species (unstable molecules). It has been demonstrated that white blood cells can transport vitamin C across their cell membranes to help protect against oxidation, which could otherwise damage and destroy immune cells.

Can Vitamin C Really Help Colds?

Despite its reputation as an immune booster, there is no evidence to suggest that taking vitamin C will prevent the common cold in the average person.

However, there is evidence that vitamin C supplementation may:

• Reduce the severity of cold symptoms by about 15%.
• Shorten the duration of severe colds (though it doesn’t affect the duration of mild or moderate colds).

That said, vitamin C won’t affect the length of the cold when it’s taken after a cold has already started. Infections can deplete your stores of vitamin C because your immune system uses it up as it fights off the infection.

Overall, the evidence on vitamin C and colds remains inconsistent, and more research is needed.

Other Benefits of Vitamin C

Beyond protecting and stimulating your immune system, vitamin C offers numerous additional benefits. These include:

• Producing collagen, which helps maintain healthy skin, bones, and other tissues
• Producing certain neurotransmitters (chemical messengers)
• Supporting wound healing
• Acting as an antioxidant and can regenerate other antioxidants like vitamin E
• Potentially protecting against cardiovascular diseases and certain cancers
• Improving absorption of nonheme iron, which is found in plant-based foods
• Preventing attacks of gout

Vitamin C From Food and Supplements

Your body cannot produce vitamin C or store it for long periods, so it’s essential to regularly consume foods, drinks, or supplements containing vitamin C to maintain adequate levels.

Some of the best food sources of vitamin C include:

• Citrus fruits (such as orange, lemon, lime, grapefruit, yuzu, and pomelo)
• Red and green bell peppers
• Kiwifruit
• Mango
• Strawberries
• Broccoli
• Brussels sprouts
• Fruit juices (such as orange juice, grapefruit juice, and tomato juice)
• Fortified breakfast cereal

You can also take vitamin C supplements. The recommended daily allowance of vitamin C is 90 to 120 milligrams (mg) for adults. There’s conflicting evidence on whether taking more than that amount provides additional health benefits.