Vitamin C is arguably one of the most recognized vitamins due to its reputation as a support tool for immunity and its ability to help relieve cold symptoms.
It is a very important vitamin in our diets that plays a huge role in our health. It helps to absorb iron, form blood vessels, muscle, collagen, and cartilage, as well as assists our immune system as an antioxidant.1
Antioxidants assist your immune system by helping to protect against free radicals. These are damaging cells that seek out healthy cells and try to destroy them. Free radicals can occur from tobacco smoke, radiation, UV light, x-rays, and more.1
Our bodies cannot naturally produce vitamin C, so we need to get it from our diet. It is mainly found in citrus fruits, broccoli, peppers, spinach, berries, potatoes, and tomatoes. We can also get it from supplements if diet alone isn’t enough, or we need extra support during an illness.
Side Effects of Vitamin C
The supplement form of vitamin C can sometimes cause side effects if taken in high doses or if taken improperly. Side effects include stomach pain, heartburn, nausea, vomiting, and diarrhea.
Products marketed to promote immune support sometimes contain high doses of vitamin C, and while they are considered safe, they could actually act as a laxative.
Vitamin C increases gastric motility, meaning it speeds up your digestion and pushes things through your system quicker. This means your immune supplement could be causing your diarrhea!
Inadequate Vitamin C Intake
The reverse side of this is that low levels of vitamin C can actually lead to constipation.2 It’s not advised to take vitamin C supplements to relieve constipation, because you can easily take too much, which can often lead to diarrhea.
A doctor can tell if you have low vitamin C through a blood test, and if it comes back low, they may prescribe you a supplement that they can monitor so that you don’t end up with diarrhea.
Those who are at risk of low vitamin C, and therefore increased risk for constipation, include smokers, those exposed to secondhand smoke, those with limited food variety, and people with malabsorption disorders like Crohn's disease and ulcerative colitis.
Extremely low vitamin C is known as a condition called scurvy, but this isn’t very common in the United States.
Takeaways
So, overall, the answer is yes and no, low vitamin C can cause constipation, but high vitamin C can cause diarrhea.
It’s important because of this to make sure you are taking the recommended dosage and not overdosing.
The recommended daily allowance is 75-90 mg/day for most adults with the upper limit being 2,000 mg. Therapeutic dosages can be higher depending on the reason, but that should be determined by a doctor.
If you are experiencing constipation, it is not recommended to self-treat with a vitamin C supplement, instead, try to increase your intake of citrus fruits, fiber-filled foods like whole-wheat bread, and increase your water intake.
Related Post: Vitamin C for IBS: What Effect Does It Have?
References
- A. Bendich, L.J. Machlin, O. Scandurra, G.W. Burton, D.D.M. Wayner, The antioxidant role of vitamin C. Advances in Free Radical Biology & Medicine. 1986;2(2):419-444.
- Panarese, Alba et al. “Chronic functional constipation is strongly linked to vitamin D deficiency.” World journal of gastroenterology vol. 25,14 (2019): 1729-1740.
