Vitamin C is a superior micronutrient and an excellent antioxidant. It can donate one of its electrons to neutralize a free radical, and some say that going without it could be lethal. But what happens when you take too much of it? New evidence is emerging that may lead you to consider lowering your dose of vitamin C.

Upset Stomach

In nature, we get vitamin C from fruits and vegetables loaded with fiber. This allows for easier absorption of vitamin C because it allows the plasma to uptake the nutrient without making as much direct contact with the tissues of the intestines. When you take a supplemental form (especially on an empty stomach), it is concentrated, and the tissues can become irritated. Then, the body responds by flushing the vitamin C out with water, creating an osmotic effect¹.

The diarrhea that goes along with this is a nuisance, but not your biggest problem! When the epithelial cells of the intestines allow water into the digestive tract, the tight junctions open (the space between the cells). While the tight junctions open, toxins can escape through the openings and enter your bloodstream.

You’re Taking the Wrong Form of Vitamin C

According to cancer researchers, much of the industrial vitamin C they use to treat patients is wrong.² For vitamin C to be effective, it must be in its reduced form (L-ASC, ascorbate), but most of the time, suppliers produce the oxidized form of dehydroascorbic acid, DHA). Humans are one of the only vertebrates that do not make their vitamin C, so the transport mechanisms are different (GLUT-2 and GLUT-8 transport sites).  These transport mechanisms evolved over thousands of years to allow natural vitamin C to enter the body, not the oxidized form made by most supplement companies. This reduces the absorption and can lead to health problems.

Iron Oxidation

Iron is an essential mineral for just about every organism. We use it to carry oxygen through the bloodstream so that the mitochondria can perform glycolysis, which produces energy. Bacteria also use iron, an essential mineral, in forming biofilms, providing them shelter and protection. Bacteria require iron in a certain form (ferrous iron), and unabsorbed vitamin C has the unfortunate side effect of reducing ferric iron (F+3) into ferrous iron (F+2)³. If you are having issues with SIBO, you may want to try iron chelation to prevent the bacteria from using your vitamin C supplement to strengthen their biofilms.

Homeostasis

The half-life of vitamin C in the plasma is estimated at only about thirty minutes.⁴ That’s how long it takes for the body to use it to clear out free radicals! In the meantime, consuming antioxidants can reduce the liver’s production of glutathione, the body’s master antioxidant. Glutathione is superior to vitamin C because it can be recycled and used again. Suppose you consume too much vitamin C over a long enough period. In that case, your body will compensate by producing less glutathione—which defeats the purpose of taking vitamin C in the first place!

Absorption is Not Constant

Your body absorbs vitamin C as it needs it. Since the body is constantly fluctuating, sometimes it absorbs more, sometimes less.⁵ If you are ill, under stress, traveling, or injured, your body will activate more vitamin C transport proteins, which will lead to greater absorption. If you are rested, well, and happy, your body makes less of them, meaning more vitamin C will get left behind in the intestines, which could cause health issues. We should try to get most of our vitamin C from food during these times and only supplement when necessary.

Many people have poor diets and don’t get enough vitamin C. Please don’t exacerbate your health issues by consuming an excessive dose! For most people, 200 milligrams is more than enough, but if you need more, spread out your doses throughout the day and always take vitamin C with food.