Vitamin C, ascorbic acid, was discovered in the process of finding ways to prevent scurvy. Most of the vitamin C in the human body is in form of reduction and only partially in oxidation. Because vitamin C has functional groups that are chemically weak. For this reason, it is necessary to be careful when cooking vegetables or fruits because vitamin C is weak in water, heat, and even light.
Vitamin C has a very strong reducing power. This reducing power appears to be antioxidant, and it can remove various types of reactive oxygen species like superoxide, hydroxy radicals, hydrogen peroxide, and singlet oxygen. Those are toxic byproducts in various organs of the body. It can have a number of beneficial effects, such as removing these reactive oxygen species to suppress aging and strengthen immunity by enhancing overall health. Vitamin C also aids in the synthesis of collagen, which accounts for one-third of the protein in the body. And it prevents scurvy and protects skin elasticity. You may also take vitamin C to prevent skin spots by suppressing melanin pigments. Vitamin C is involved in the synthesis of cortisol hormones and other steroid hormones that are secreted out of the body when stressed. These hormones actually relieve stress, so in stressful situations such as smoking, vitamin C is consumed more than necessary. Therefore, if you smoke, taking more vitamin C than usual is good for controlling blood vessel health and overall physical stress.

Water soluble (absorption and excretion)
The vitamin is not digested (or degraded) but is absorbed directly from the small intestinal epithelial cells. Because vitamin C is a water-soluble, most of it travels through transporters, which are gateways on the intestinal cell’s surface. The types of these each differ depending on the vitamins. The absorbed vitamin C is delivered to the liver through the portal vein and back from the liver to each tissue.
Most of the remaining vitamin C used in the body is water-soluble, so it is easily excreted through urine. Although its characteristic has the advantage of being absorbed and distributed, it cannot stay in the body and is quickly excreted through the liver and kidneys. The kidneys filter vitamin C out of the blood and release excess out of the urine immediately. Because of the nature of vitamin C, which does not accumulate, people who practice megadose have a basis for claiming that there is no safer way to take it.

Disadvantages
However, the overdose of vitamin C is clearly much higher than the recommended daily dose, and according to the FDA, it is 100 times the maximum intake of only 90 mg. Vitamin C is an essential nutrient with many benefits, but its high-dose use is controversial.

1. Gastrointestinal disorders: The first thing you can easily feel is the symptoms of bloating. Because vitamin C is an acidic structure, it stimulates the stomach and is accompanied by symptoms such as diarrhea, nausea, and gastric reflux. And if you eat it on an empty stomach, you can go through it even more strongly. It is recommended that those who have difficulty absorbing vitamin C or have a sensitive gastrointestinal tract should avoid the intestinal toxicity of such vitamin C.
2. Kidney stones: A portion of vitamin C in excess is converted into oxalate and the like through metabolic processes. Excess oxalic acid can meet calcium and form and increase the risk of kidney stones. However, this is the case if you continue to consume very high levels of vitamin C. If you usually consume high-oxalic acid foods such as spinach, you need to watch out for vitamin C megadose.
3. Drug-drug interaction: If you take antithrombotic drugs such as aspirin or clopidogrel, you may reduce the effectiveness of these drugs. Antacids with aluminum content can increase the absorption rate, which can lead to a risk of toxicity. Taking some tetracycline antibiotics can lower the medicinal effect and worsen conditions. It is important to consult your doctor and pharmacist about the medication you take before taking an excessive dose of vitamin C.

Linus Pauling, who encouraged excessive vitamin C doses, gradually undermined his reputation by threatening the editors of many journals publishing that excessive vitamin C doses were difficult to achieve a significant good effect. Pauling, who insisted on preventing cancer, died of prostate cancer at the age of 93. He has argued for 30 years, but it seems that consuming a large amount of vitamin C has not been a significant harm to his body. Pauling’s claim of vitamin C is still not officially recognized by the medical community today. This is because, due to its water-soluble characteristics, excess is difficult to accumulate in the body, making it difficult to exert special effects.

Intake of vitamin C
How much vitamin C should we take every day? According to the U.S. Food and Drug Administration, adults need moderate vitamin C daily. Even if we follow national standards, 75-100 mg for men and women, +10 for pregnant, and +35-40 for nursing women. That’s a small dose. But it only seems like a fundamental amount. This is because it’s the minimum amount of vitamin C as a coenzyme, which our body needs for biological reactions to survive.
Is an overdose of vitamin C necessary? No cases have been reported, but experts believe there is an excess of vitamin C. In fact, the amount of vitamin C in the multivitamin does not matter much unless the recommended intake of nutrients is seriously exceeded. Some people say that specific vitamins are adequate, but it is true that vitamin C is essential, especially for children and pregnant women. However, studies of large populations have not shown the statistical benefits of high vitamin C content.
Even a healthy diet can sometimes lack one or two nutrients, and taking vitamins can be a safeguard to prevent occasional deficiencies even with these diets. Usually, however, those who take nutritional supplements tend to eat healthier, so they don’t have significant deficiencies. Already, foods (100g) contain high levels of vitamin C: 150-170mg of bell pepper, 150mg of citrus peel, 120mg of parsley, 120mg of broccoli, and 100mg of lemon.

Superfood with vitamin C
You might want to consider superfoods as an alternative to vitamin C. The term “superfoods” refers to foods that have no definition but contain a lot of substances that are beneficial to the body. Although they have been highlighted by extensive marketing rather than natural sciences, they are actually rich in nutrients and there are many foods that contain an abundance of vitamin C. The first superfoods were called blueberries, which are native to North America. They are rich in antioxidants such as vitamin C and anthocyanins, as well as vitamin K and fiber. Green leafy vegetables like kale and broccoli are incredibly high in vitamin C. These vegetables, which also reduce cholesterol, can also prevent or slow down aging-related vision problems. Gojibury is also high in antioxidants. There is still a lack of scientific evidence that vitamin C is higher than orange and improves vision and fertility with various antioxidants.

Conclusions
Even if there is nothing harmful to the human body, excessive intake of vitamin C or minerals will exceed the amount required by the body, so the body recognizes it as waste and excretes it. Water-soluble vitamin C, unlike fat-soluble vitamins, is stored in the body and excreted in urine because it cannot be used later. Unless it has been scientifically proven, it may be more beneficial to support your diet with fresh fruits and vegetables that also contain healthy fibers than vitamin C megadose.