Can you overdose on vitamin C?
Vitamin C, also known as ascorbic acid, has many benefits for our health and body and is a nutrient that is important to be consuming daily. The benefits include protecting our cells from damage, it aids in collagen formation which is essential for bone, skin and tissue growth and repair and wound healing. Vitamin C also helps produce white blood cells, which eliminate harmful foreign invaders like cold and flu viruses and bad bacteria. In fact, Dietitian Mascha Davis explains in her book, 'Eat Your Vitamins', the body needs ascorbic acid to use macronutrients such as carbohydrates, fats and proteins more efficiently.
How much vitamin C can you take?
Dietitian Clare Keating explains, “The recommended daily intake for vitamin C is around 75-90 mg for adults, but the safe upper limit is considered to be 2,000 mg per day for most people. The good news is that you can usually get all the vitamin C you need from a healthy and balanced diet with lots of fruits and vegetables.”
Madeline Calfas, a nurse and naturopath says “Our body cannot make it (we are one of the few animals that can't), so we are required to ensure adequate intake of ascorbic acid from our diet or supplementation. Because it is water-soluble nutrient, your body will use what it needs, and generally excrete any excess in your urine. This makes it almost impossible to reach toxic levels, especially when it is from your diet alone, but consuming too much vitamin C from supplementation can make it easier to reach the upper limits of tolerance.”
Taking vitamin C when sick
When we think of vitamin C, we may feel the need to load up on vitamin C when we get sick by taking them in supplement form. There is no evidence to confirm that vitamin C prevents the cold, although Harvard reports that there is some evidence that high-dose vitamin C will, at most, shorten a cold by one day.
However, it seems increased vitamin C intake may be needed and helpful when fighting an infection, according to Dr Jenna Macchiochi, in her book, 'Your Blueprint for Strong Immunity'. She writes, “When you are fighting an infection your immune system uses much more vitamin C. Increasing consumption of vitamin C rich foods such as citrus fruits and berries, or supplementing with up to 1g a day, can reduce the duration and severity of symptoms".
Can you overdose on vitamin C?
If you are planning to take extra vitamin C, Keating says it’s helpful to know that though it is relatively rare to overdose on vitamin C, it is possible.
According to Calfas, there are signs of vitamin C overload that let you know when you've had too much. “These include diarrhoea, vomiting, nausea, headaches, abdominal cramping. If you take very high doses, of more than 2,000 mg per day, you could experience more serious side effects like kidney stones or damage to your red blood cells.”
Calfas says how much is too much also will depend on each individual and their circumstances. “Gut issues can affect absorption, so people with irritable bowel syndrome, crohns and coeliac disease will find it harder to absorb vitamin C through their diet and some forms of supplements. Whereas people dealing with underlying kidney issues may need to be more cautious when supplementing with Vitamin C".
Dietitian Clare Keating says, “If you smoke, have certain medical conditions, or are going through a stressful period, you might need more due to the oxidative stress this can create.” Keating advises that it's always a good idea to talk to your doctor before taking any new supplements.
Interestingly, Dietitian Mascha Davis explains in her book, that vitamin C absorption decreases with increased intake, so if it is more than 1 gram, your absorption is less than 50 per cent.
“Like everything in life, there is such a thing as too much of a good thing,” Calfas says. “This motto can also be applied to nutrients, and Vitamin is no different. As Paracelsus said, "All things are poison, and nothing is without poison: the dosage alone makes it so a thing is not a poison".