Vitamin C is a vital nutrient that is common in daily diets because of its prevalence in many fruits and vegetables. This is a good, as vitamin C supports proper immune and brain health, as well as wound healing.
Vitamin C also boosts collagen production, a type of protein that is found naturally in your skin. It has also become a popular option for preventing and treating the common cold.
However, there is such thing as too much vitamin C. Now, there’s no such thing as eating too many oranges or overdosing on strawberries. The truth is, it’s nearly impossible for you to get too much vitamin C from your diet alone. In healthy people, the extra vitamin C that is consumed in the above ways is simply flushed out of the body.
The problem arises when you take too much of a vitamin C supplement. If you overdo it, it could actually have negative effects on your health.
How Much Is Too Much?
For safety guidance, the Food and Nutrition Board Institute of Medicine established tolerable upper intake levels at 2,000 milligrams (mg) for vitamin C in adults. This means that a normal, healthy adult can take up to 2,000 mgs per day without experiencing any side effects.
In doses higher than 2,000 mg per day, initial symptoms of too much vitamin C include digestive upset and diarrhea. The research also shows that too much vitamin C can have adverse effects on vital organs.
Digestive Distress Is The Common Side Effect
The most common side effect of too much vitamin C is digestive distress. This doesn’t happen when you eat foods that contain vitamin C. Instead, this is a sign of overdoing it on the supplements.
Diarrhea and nausea are the most common symptoms. Some have also reported acid reflux, but this doesn’t show up in the research.
If you experience digestive problems from too much vitamin C, simply cut back your supplement dose or avoid vitamin C supplements altogether.
Vitamin C Supplements Can Increase Risk For Kidney Stones
When there is a high amount of oxalate in your body, it becomes harder for your kidneys to eliminate bodily wastes. The oxalate can also bind to other minerals and create kidney stones.
What does the above have to do with vitamin C? Well, taking high-doses of vitamin C supplements can increase your oxalate levels, which increases the risk of kidney stones.
One study showed that vitamin C supplementation could even be linked to cases of kidney failure, but this is still considered to be a rare occurrence.
Too Much Vitamin C Can Damage Your Thyroid
When you take too much vitamin C, it’s possible that it can boost your iron absorption. Specifically, it can boost non-heme iron, which comes from plant-based foods. This side effect is generally considered a benefit. But high doses can cause iron toxicity or iron overload.
Iron overload is a serious condition that can cause long-term damage to your thyroid. But that’s not all. It can also cause serious damage to your heart, liver, and central nervous system.
Choose The Right Supplement
To make sure you aren’t overdoing it on the vitamin C supplements, a good rule of thumb is to look for one that stays at or near 100 percent of the recommended daily intake for vitamin C.
For an adult woman, the recommendation of vitamin C is 75 mg per day. For adult men, the recommended daily intake is 90 mg.
When You Should Talk To Your Doctor
If you have a condition like hemochromatosis—where there is already an increased risk of iron accumulation in the body—then you should talk to your doctor before taking any vitamin C supplements.
The same goes for anyone who is prone to kidney stones. Consulting your primary healthcare provider is a good idea.
The Bottom Line
For most people, vitamin C is generally safe. This is especially true when you are getting it from your diet. The greater risk comes when you are taking vitamin C supplements. Consuming too much can cause side effects and have negative effects on your health.
To prevent these potential negative side effects, you can avoid vitamin C supplements altogether. Or, just take a supplement that’s near the recommended daily intake.
Unless you have a vitamin C deficiency—which is extremely rare in healthy people —taking large doses just isn’t necessary.