Vitamin C (ascorbic acid) is the most popular supplement in the world, and it's no wonder; it does many good things for your body. Some of vitamin C's most important actions include protecting fat-soluble vitamins from oxidative damage and producing collagen to strengthen connective tissues. Vitamin C is also a powerful antioxidant, and it helps protect against damage from free radicals. It may also prevent plaque buildup in the arteries by lowering LDL (bad) cholesterol. Vitamin C is also useful for regulating your immune system and helping your body deal with stress, and it has anticancer properties as well. One of its most well-known powers is its ability to shorten the duration of the common cold.
How It Fights Allergy or Asthma Symptoms: Research shows that vitamin C helps prevent histamine from being released by stabilizing the membranes of mast cells. Mast cells are the storage units for histamine, and when their cell membranes rupture, histamine is released, causing allergic symptoms. Vitamin C can also break down histamine once it has started circulating in your body. In a 2013 study, researchers found that when they injected allergic people with vitamin C, their blood levels of histamine went down.
In another 2013 study published in Allergy, Asthma, and Immunology Research, Korean children ages 6 to 12 with high intakes of vitamin C had fewer symptoms of allergic rhinitis (hay fever) than kids who did not increase their daily vitamin C intake.
How to Get It: You can easily get vitamin C from foods, and nearly everyone should try to eat some of this vitamin daily. Focus on foods like acerola berries, cauliflower, guavas, kiwis, mangoes, melons, oranges, peppers, strawberries, and tomatoes. The current RDA for vitamin C is 60 milligrams per day, and this is likely just enough to prevent a person from developing a deficiency. In my practice, I have used dosages exceeding 50,000 milligrams without adverse effects. When using vitamin C therapeutically, dosages of greater than 6 grams per day are frequently used.
There is a large variety of vitamin C supplements available, including liquid, tablet, capsule, powdered crystalline, and effervescent forms. For allergies and asthma, I generally recommend taking vitamin C in divided dosages ranging from 6 to 10 grams (6,000 to 10,000 milligrams) per day. For some people, I find that using intravenous vitamin C provides the quickest results.
Contraindications and Things to Consider: It is important to know that dosages of vitamin C greater than 3 to 4 grams (3,000 to 4,000 milligrams) taken at once may result in gastrointestinal discomfort and diarrhea. To help prevent this, vitamin C can be taken in divided doses throughout the day. (For example, 2,000 milligrams, three times per day.)
While dietary intakes of vitamin C are generally safe, the use of vitamin C supplements may produce unwanted reactions when combined with certain medications. Blood-thinning medications, such as warfarin, may lose some of their effectiveness when combined with vitamin C, so people taking those medications should consult with their physicians before starting to take vitamin C or starting to take any new medications while taking vitamin C.