Wednesday, December 12, 2018

Vitamin C – Should You Supplement?

When you get a cold, do you start popping the vitamin C tablets? If you do, you might want to think twice. Vitamin C supplements don’t do a whole lot to cut your cold chances and they might even be bad for your kidneys.

Does vitamin C prevent colds? Taking a vitamin C supplement regularly before you get a cold, may decrease the time you have the cold – but just a little. An analysis of 44 studies showed that 1000 mg a day can cut the time you have a cold by about half a day. The usual recommendation is 500 mg twice a day. But taking vitamin C after you have a cold, probably won’t do you much good. 1000 mg a day may also lower your risk of gout. A lower dose 60 to 250 mg may help prevent cataracts – but too much can actually increase your risk of cataracts.   

But, too much can be dangerous. Taking 2000 mg a day for a long time may damage the kidneys and increase the risk of kidney stones. So if you do supplement, keep it to 1000 mg a day or less. Vitamin C supplements can also cause diarrhea and intestinal upset.

I don’t typically recommend vitamin C supplements for my patients.  I do recommend that you get lots from your foods. Some studies show an association between higher intakes from food and a lower risk of stroke, some cancers, and overall health. Men need 90 mg a day of vitamin C and women need 75 mg a day. It’s a good idea to get more than that from your diet for optimal disease prevention. Luckily, it’s easy to get lots of C from your foods.  

How can you increase your dietary vitamin C intake? Here is a list of the foods highest in vitamin C:

Foods High in Vitamin C:
1/2 cup red pepper                  95 mg
¾ cup orange juice                  93 mg
1 cup strawberries                   84 mg   
1 orange                                  70 mg
1 medium kiwi fruit                  64 mg
1/2 grapefruit                           42mg
1/2 cup raw broccoli                80 mg 
½ cup cooked broccoli            58 mg
baked or sweet potato            25 mg
1/2 cup turnip/collard greens  20 mg

So as you can see, a diet high in fruits and vegetables can easily supply your daily need for vitamin C – and then some. Does this mean you should ditch your vitamin C supplement? Not necessarily – just don’t overdo it. Stick with no more than a 500 mg twice a day if you want to continue vitamin C supplements.  Just don't let a vitamin C supplement take the place of high C foods!

Hemila H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2013 Jan 31

Beth Kitchin PhD RDN
Assistant Professor, Nutrition Sciences 
University of Alabama at Birmingham 

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