Should I take Vitamin C to Prevent Colds, Lower Heart Risk, or Fight Cancer?

Vitamin C is one of the most recognized nutrients in wellness circles, often touted as a defense against colds, a booster for immunity, and even a fighter of serious diseases.

While it’s crucial for our health, the true benefits of vitamin C are frequently exaggerated or misunderstood. Before you start purchasing supplements, here are some important points to consider.

What exactly is vitamin C, and why does our body need it?

Vitamin C, also called ascorbic acid, serves several vital functions in the body.

It acts as a powerful antioxidant, guarding cells from damage. Vitamin C also supports immune health, enhances iron absorption, and plays a role in wound healing.

Additionally, vitamin C helps produce collagen, a protein that holds tissues together and is essential for skin and gum health. Severe deficiency causes scurvy, a condition where the body can’t produce enough collagen, leading to gum disease, tooth loss, and blood vessel rupture, which causes internal bleeding.

Humans cannot make vitamin C on their own; we must obtain it through our diet. Most of our vitamin C comes from vegetables (about 40%), fruits (around 19%), and fruit or vegetable juices (approximately 29%).

The vitamin C found in supplements is chemically identical to the kind found in food. Your body cannot distinguish between them.

However, supplements lack the fiber, flavonoids, other vitamins, minerals, and phytochemicals present in whole foods, which may work together with vitamin C for better absorption and greater health benefits.

These accompanying compounds help your body absorb vitamin C more effectively, provide additional antioxidants, and together offer health benefits that vitamin C alone cannot deliver.

Historically, sailors often suffered from scurvy due to limited diets. Today, if you maintain a balanced diet, supplementing with vitamin C isn’t necessary.

What conditions does vitamin C treat or not treat?

Common Cold

Vitamin C has been promoted as an immune booster and is widely believed to prevent or treat colds and flu. However, comprehensive reviews show that taking 200 mg or more of vitamin C regularly does not decrease the likelihood of catching a cold.

Though regular vitamin C intake can shorten the duration of colds, doses exceeding 1,000 mg may slightly lessen symptoms’ severity. Taking vitamin C only when cold symptoms appear doesn’t seem to impact how long the cold lasts or how bad it gets. Some limited benefits were noted in studies where high doses were taken daily before illness onset, but these effects are minimal overall. Experts suggest routine vitamin C supplementation for colds is generally not justified.

Heart Disease and Stroke

Evidence indicates that vitamin C supplements do not significantly influence the risk of cardiovascular issues such as heart attacks, strokes, or angina. Some studies suggest that taking over 200 mg daily might reduce systolic blood pressure by about 4 mmHg and diastolic pressure by around 2 mmHg—these are very small changes and may not be clinically meaningful compared to the effects of regular aerobic exercise or prescribed medications, which typically lower systolic blood pressure by at least 12 mmHg.

Cancer

Multiple studies consistently show that vitamin C supplements do not prevent various cancers, including gastrointestinal, lung, breast, prostate, and colorectal types.

Can you consume too much vitamin C?

The daily Recommended Dietary Allowance (RDA) for adults is 45 mg, which can easily be obtained from a small glass of orange juice. The upper safe limit is 2,000 mg per day.

Since vitamin C is water-soluble and expelled in urine, excess intake generally isn’t stored in the body. Therefore, mega-dosing offers no real benefit and might cause health issues.

High doses above 2,000 mg can lead to side effects such as diarrhea, nausea, stomach cramps, and in men, a higher risk of kidney stones. For individuals with chronic kidney disease, excess vitamin C can accumulate, increasing the risk of stone formation due to impaired kidney function.

Should you take a vitamin C supplement?

Most individuals can get sufficient vitamin C through a balanced diet rich in citrus fruits, berries, tomatoes, peppers, broccoli, and kale. Taking supplements isn’t necessary for maintaining good health. The scientific evidence does not support claims that vitamin C supplements prevent colds, heart disease, or cancers. In some cases, the potential risks may outweigh any perceived benefits.

If you’re concerned about high blood pressure, check out studies on unhealthy habits that may raise blood pressure and how green tea might help lower it.

For additional insights on managing high blood pressure, see recent articles on best foods to eat or avoid and foods that naturally reduce blood pressure.

Written by Nial Wheate, Ian Jamie, Wai-Jo Jocelin Chan. The Conversation.