You've been doing it forever. As soon as you feel that tickle at the back of your throat, you grab a vitamin C supplement packet, dump it in a glass of water and chug.

The vitamin C you consume naturally plays important roles in your body, but does taking a megadose of it actually provide benefit? 

Can a vitamin C supplement really keep you from getting sick?

Despite it's popularity as a remedy for the common cold, there's actually no evidence to suggest that a large dose of vitamin C can actually prevent one — or any other type of illness, for that matter.

And while you may have heard that a large dose of vitamin C can slightly reduce the duration of a cold, this only applies if you take that large dose every single day of the year — even when you're not sick. This means that if you rip that vitamin C packet open after your symptoms begin, there's no evidence to suggest it'll actually shorten the length of your cold.

As it turns out, boosting your immune system is more complicated than just downing a packet or a pill. And while vitamin C does play an important role in supporting your immune system, it doesn't take megadoses like the ones found in supplements — which often contain 1667% more vitamin C than you actually need every day.

Is taking a huge dose of vitamin C bad for me?

Vitamin C is an important nutrient, but — as the old saying goes — too much of a good thing can be a bad thing.

After taking too much vitamin C, you may experience symptoms such as:

• Diarrhea
• Headache
• Heartburn
• Insomnia
• Nausea
• Stomach cramps

So how much vitamin C is too much?

For adults, the daily upper limit of vitamin C is 2,000 mg. For teens, it's 1,800 mg. For children, the upper limit depends on age, and it ranges from 400 to 1,200 mg per day.

In addition, vitamin C is water-soluble, making it hard for your body to store it — with excess being secreted in your urine. So even if you're adult and can handle the 1,000 mg in each vitamin C packet or pill, just know that your body can't absorb (or, therefore, use) more than about 400 mg. This means that most of the vitamin C in that supplement you're taking just goes down your toilet (literally).

All this to say, however, that getting the recommended amount of vitamin C is still a critical step in staying healthy, as this vitamin plays many important roles in your body. But, you don't need to take a supplement to make that happen.

Why getting vitamin C through your diet is important

Vitamin C is an important nutrient for your body since it:

• Acts as an antioxidant
• Contributes to wound healing
• Helps with iron absorption
• Improves mood
• Promotes healthy skin
• Supports your immune system

In addition, vitamin C is thought to have beneficial effects on your overall health, including reducing your risk of cancer, heart disease and the most common causes of vision loss (age-related macular degeneration and cataracts).

While vitamin C is an important nutrient, your body doesn't actually make it — so it's important to make sure you're getting enough vitamin C from your diet.

The amount you need depends on your age and gender, but, in general, adults should aim to get between 65 to 90 mg of vitamin C per day. You can get all the vitamin C you need by drinking a glass of orange juice or eating a cup of strawberries, bell pepper, broccoli, Brussels sprouts or kale. In addition, some of the herbs you commonly cook with also contain significant amounts of vitamin C, including thyme and parsley.

Another reason to get the recommended amount of vitamin C through your diet, rather than a supplement, is that healthy, whole foods also contain other beneficial vitamins, minerals, antioxidants and fiber.

Most people following a healthy diet have no problem getting the recommended amount of vitamin C every day. However, if you think you aren't, you can always consider taking a multivitamin — as most contain the recommended amount of vitamin C you need every day.