Vitamin C, also called ascorbic acid, is important to many functions in the body. For example, it is needed to grow and repair tissues throughout the body. Vitamin C is a popular remedy for the common cold, but research is mixed on whether it helps or prevents the sniffles. Dietary sources of vitamin C include many fruits and vegetables. Sources with the most vitamin C are fresh, raw cantaloupes, citrus fruits, kiwis, mangos, papayas, pineapples, strawberries, raspberries, blueberries, watermelon and cranberries, according to National Institutes of Health (NIH). Red and green peppers, spinach, cabbage, cauliflower, turnip greens and other leafy greens, tomatoes, potatoes, broccoli, winter squash and Brussels sprouts are other good sources of vitamin C. The body uses vitamin C in many different ways. Vitamin C is needed by the body to form collagen. According to the NIH, the body also uses vitamin C to make skin, tendons, ligaments and blood vessels. It also uses this vitamin to repair and maintain cartilage, bones and teeth, to heal wounds and to form scar tissue.
Vitamin C may also prevent cancer by blocking the damage made by free radicals. “Vitamin C is a vital antioxidant that helps protect cells from damage caused by free radicals that we are exposed to in the environment such as air pollution, cigarette smoke and ultraviolet light from the sun,” said Dr. Sherry Ross, OB/GYN and Women’s Health Expert at Providence Saint John’s Health Center in Santa Monica, California. Many people tout vitamin C as a cure-all for a wide range of diseases. Many of these have not been proven. “Health benefits of vitamin C that have been proposed but not scientifically proven include a lower risk of certain cancers, cardiovascular disease, diabetes, age-related macular degeneration and cataracts,” said Ross. A study by the National Eye Institute, however, did find that an intake of 500 mg per day of vitamin C, along with beta-carotene, vitamin E and zinc supplements, slowed the progression of advanced age-related macular degeneration by about 25 percent.
It also helped slow visual acuity loss by 19 percent for those who are already at high risk of developing the disease. The vitamins did not have significant effect on the development or progression of cataracts, though. The medical community is split over the benefits of vitamin C on the heart. Some studies suggest that vitamin C may prevent heart attacks by slowing down hardening of the arteries by preventing LDL ("bad") cholesterol. Other studies show that vitamin C does not prevent heart attacks. A study by Johns Hopkins found that vitamin C has a “modest” effect on lowering high blood pressure and does not currently suggest supplements as a treatment option. Vitamin C is often taken to prevent or cure the common cold. Research shows that most people taking high doses of Vitamin C still get the common cold just as often as those who don’t take high doses. It may shorten the amount of time a person is sick, though, and may also lessen the symptoms. [Related: Does Vitamin C Really Help Colds?]
Vitamin C deficiency is fairly common. Smoking cigarettes can lower the amount of vitamin C in the body, so smokers are more prone to a deficiency, according to the University of Maryland Medical Center. Often, doctors will suggest a vitamin C supplement to smokers to prevent or cure a deficiency. Not getting enough of this vitamin can cause easy bruising, gingivitis and bleeding gums, dry and splitting hair, rough, dry, scaly skin, a decreased wound-healing rate, nosebleeds and a decreased ability to ward off infection, according to the University of Maryland Medical Center. An extreme lack of vitamin C for long periods of time can cause scurvy. Symptoms of scurvy are skin that bruises easily, bleeding gums, joint pain and poor wound healing. “An estimated 40 percent of men and 38 percent of women are getting insufficient amounts of vitamin C. If you’re not eating your fruits and veggies, it’s a good idea to supplement,” said Dr. Brian Dixon, an expert in molecular and cellular biology and executive director of Health and Science Education at USANA Health Sciences.
The recommended daily allowance (RDA) for vitamin C varies, depending on age, gender and other factors. Typically, the RDA is 75mg for women and 90mg for men, according to Oregon State University. Pregnant and nursing women should take 80mg to 120 mg, depending on age. Most of the population can take substantially more than the RDA without any side effects since vitamin C is water soluble. This means that it is not stored by the body. It is filtered out and leaves the body in urine, according to the NIH. “However, some people taking more than 2,000 mg could experience some gastrointestinal upset. And those who are prone to form kidney stones should get clearance from their doctor before taking high doses of Vitamin C,” said Dixon. Dr. Kristine Arthur, internist at Orange Coast Memorial Medical Center in Fountain Valley, California told Live Science, “You can take too much. (It) may lead to kidney stones, irregular heart beat and diarrhea.” Vitamin Poisoning: Are We Destroying Our Health with Hi-Potency Synthetic Vitamins?
Read the Full ArticleFor humans, a source of vitamin C in the diet is literally necessary for survival. Early sailors deprived of fresh foods for extended lengths of time often suffered from “scurvy,” a nasty affliction characterized by bleeding gums, loss of teeth, a weakened condition, and sometimes death. It wasn’t until the late eighteenth century that Captain James Cook, the first European to visit the Hawaiian Islands, taught the British Admiralty how to prevent scurvy by adding fresh fruit or lime juice to its sailors’ daily ration of rum (thus earning them the nickname of “Limeys” that endures to this day). In the early 1900s, ascorbic acid was isolated and identified as the nutrient that prevented scurvy. Humans, it was discovered, are among the few animals that cannot manufacture vitamin C in their own bodies, and must obtain it from an outside source (fresh fruits, vegetables, or vitamin C pills) on a regular basis in order to avoid illness. Dogs, however, can produce vitamin C in their bodies, and because of this ability, nutritionists have long considered it unnecessary to add C to a dog’s diet.
Until recently, few dog food makers added vitamin C to their products – or if they do, it was for the preservative action of the vitamin, rather than its nutritive value. Vitamin C benefits the sick and the stressedThis may be appropriate when dealing with healthy unstressed animals, but recent clinical observations indicate that when dogs are sick or stressed, they can rapidly deplete their bodies’ output of vitamin C. A 1942 study noted that dogs with skin diseases usually have very low amounts of vitamin C in their blood. Other researchers have found the blood levels of vitamin C to be low – and even non-existent – in dogs with fevers and dogs who have exercised to their limits (sled dogs after a race, for example, or hunting dogs in the middle of hunting season). Stress is the best-known cause of vitamin C depletion in dogs. Physical stress comes in many forms: gestation, lactation, growth, hard work (dogs used for herding, hunting, tracking, etc.), vaccinations, injuries, tail-docking or ear cropping, or illness.
Emotional stress, whether caused by relocation, weaning, or demanding training, can also deplete this reserve. In fact, researchers can measure the level of stress a dog experiences by measuring the degree of depletion of the vitamin in the dog’s blood. Conversely, many studies have found that dogs (as well as humans) that are supplemented with vitamin C show greater resistance to disease, and a better ability to recover from injuries or illness. What C does for dogsWendell O. Belfield, DVM, is perhaps the world’s best-known and most ardent advocate of vitamin C supplementation for dogs. In his book, “How to Have a Healthier Dog,” Belfield describes how he first came to experiment with (and appreciate) the power of vitamin C in his veterinary practice. Following a particularly heartbreaking episode, where he was unable to save the life of a beloved family dog that had distemper, he began researching viral diseases. In the course of his studies, he came across an article about a doctor who used massive doses of vitamin C to successfully treat viral diseases such as polio and hepatitis in the 1940s.
Belfield began wondering whether C could be used to combat canine viral diseases. One day in 1965, another client came to Belfield’s office with a dog that was suffering from distemper. Belfield decided to try an injection of vitamin C on the dog, and it responded dramatically, surviving what he had been taught in veterinary school was a fatal disease for which there is no successful treatments. Following this success, Belfield began experimenting with vitamin C treatments for all kinds of conditions in dogs. His trials and studies have convinced him of the tremendous power that the vitamin holds for dogs. According to the “Encylcopedia of Nutritional Supplements,” by Michael T. Murray (1996, Prima Publishing), vitamin C improves immune function by enhancing white blood cell function and activity. It also increases the blood levels of interferon (the body’s natural antiviral and anticancer compound) and antibodies (proteins that bind to and destroy foreign material such as bacteria, viruses, and toxins).
Vitamin C is commercially available by itself or combined with other nutrients in a number of forms. See “Which Form of Vitamin C is the Best?” on page 8 for information about your options. Suggested usesTime and further studies are bearing out Belfield’s findings. Today, vitamin C is routinely prescribed by holistic veterinarians for a number of illnesses, including cancer, kennel cough and other respiratory infections, abscesses, and other bacterial infections. Due to its important role in maintaining the health of collagen, it appears to be especially helpful for slowing – and some say, reversing – degenerative joint disease, hip dysplasia, and spinal disorders. The use of vitamin C as a preventative and immune booster are also celebrated. Some veterinarians suggest giving C to dogs before and after vaccination, to dogs that have been exposed to contagious diseases, to pregnant and lactating dogs, and for healthy teeth and gums. According to Belfield, young dogs and old dogs can benefit the most from routine vitamin C supplements.
Due to the extensive stresses faced by puppies and young dogs, such as numerous vaccinations, surgical procedures on dewclaws, tails, and ears, and the demands of rapid growth, he suggests that all young dogs receive C. As they get old, dogs become less proficient at producing their own supply of vitamin C, and more in need of antioxidants. Administering vitamin C to even very old and feeble dogs, says Belfield, can reinvigorate and strengthen them. DosageThe average dog normally produces about 18 milligrams of vitamin C per pound of body weight per day. Therefore, for a dog that is free of clinically significant symptoms but is experiencing unusual stress, supplementation with about that much C per day appears be a conservative maintenance dosage. (About 500 milligrams for a 28-lb. dog daily.) To increase absorption, veterinarians recommend splitting the total daily dosage into several feedings during the day. However, many holistic veterinarians routinely suggest maintenance doses that are three to four times that amount.
They explain that modern, domestic dogs need more vitamin C than the theoretical “natural” dog, since their bodies must deal with so many challenges: stress, pollution, chemicals and pesticides, and poor diets, to name a few. Too much vitamin C, especially if given in one dose, will cause diarrhea in dogs. What amount is too much varies from dog to dog, so, when administering the maximum amount of C for a therapeutic (not just maintenance) dose, many veterinarians will suggest that you increase the dose in 100-500 milligram-per-day increments until the dog develops diarrhea, then reduce his daily dose to the previous day’s dose. (This is often referred to as dosing to “bowel tolerance.”) Individuals dogs may be more or less tolerant of vitamin C supplements, and their tolerance may change with environmental conditions. For instance, a dog that is experiencing great stress may tolerate 4,000 milligrams without diarrhea, but develop the condition as the stress is removed.
The owner’s awareness of the quality of the dog’s stool is critical to appropriate dosing. The type of illness being treated should also be considered when determining the dose. Some guidelines published by holistic veterinarians include: Richard Pitcairn, DVM, “Dr. Pitcairn’s Complete Guide to Natural Health for Dogs and Cats.” Pitcairn suggests giving 100-500 milligrams (based on the dog’s size) of vitamin C daily to dogs that are exposed to unusually high amounts of pollutants. Cheryl Schwartz, DVM, “Four Paws, Five Directions: A Guide to Chinese Medicine for Cats and dogs.” Schwartz suggests giving vitamin C to dogs with a variety of illnesses, including upper respiratory conditions (small dogs, 125 to 500 mg. twice daily; medium dogs, 250-1,500 mg. twice daily; large dogs, 500-1,500 mg. twice daily), arthritis (to bowel tolerance), infected ears (small dogs, 250-500 mg. twice daily; large dogs, 500-1,000 mg. twice daily), and skin allergies (small dogs, 125 mg. twice daily; medium and large dogs