Can Vitamin C Lower Your Cancer Risk?

Vitamins are organic substances that are found mainly in plants and are essential in small amounts for your health, growth, reproduction, and maintenance.

You need to consume vitamins regularly, since they either cannot be made at all or are not made in sufficient quantities in your body. For instance, vitamin C is considered to be an “essential” nutrient because you cannot make it at all in your body, so you must get all the vitamin C you need from the foods you consume.

Vitamin C occurs naturally in two forms, along with several other related compounds with vitamin C-like activity, including salts of ascorbic acid as well as oxidized forms, such as dehydroascorbic acid (DHA) – along with natural compounds known as bioflavonoids.

Bioflavonoids are widely present in plants and are important for flower coloration. They produce yellow or red/blue pigmentation in petals that are designed to attract pollinator animals such as bees and birds.

Bioflavonoids are also involved in higher plant functions such as UV filtration, symbiotic nitrogen fixation, and floral pigmentation. In some instances, they may act as chemical messengers, physiological regulators, and cell cycle inhibitors.

Why Is Vitamin C an “Essential Cofactor”?

In your body, vitamin C acts as an essential cofactor in many enzymatic reactions. A cofactor is a compound needed for an enzyme to function optimally – and “essential” means that many enzymes simply cannot do their job without vitamin C.

Enzymes are biological proteins that dramatically increase the speed and efficiency of hundreds of chemical reactions in the cells in your body.

For instance, vitamin C is an essential cofactor for the enzymatic reactions by which collagen – a fibrous protein that is the structural basis of skin, tendon, bone, cartilage, and all other connective tissue – and other biologically important substances are made in your body.

Vitamin C is crucial for the growth and repair of your body’s tissues, for making skin, tendons, and blood vessels, helping wounds heal faster, and keeping bones and teeth healthy.

Along with being a cofactor, vitamin C is also a powerful antioxidant. An antioxidant prevents or reduces the damage caused by reactive oxygen species (ROS) or free radicals – both of which react chemically with cellular structures, damaging them and contributing to aging and chronic diseases such as diabetes, heart disease, and cancer.

Vitamin C is the main antioxidant both in blood and in your body’s cells, where it acts to protect proteins, fats, carbohydrates, DNA, and RNA from damage by free radicals and ROS that are generated both by the normal daily workings of your body, as well as a result of exposure to toxins and pollutants like pollution, chemotherapy drugs, and cigarette smoke, among others.

Importantly, vitamin C also helps to re-activate other important antioxidants, such as vitamin E, from their inactive to an active form.

Multiple studies show that a higher vitamin C intake, either from diet or supplements, is linked to a lower risk of cardiovascular disease, including both coronary heart disease and stroke.

The Link Between Vitamin C and Stomach Cancer

Gastrointestinal cancers account for 20 percent of all cancers in the U.S. Geographic and ethnic differences in stomach cancer incidence worldwide clearly indicate that there is a close link between this disease and diet.

Evidence from multiple studies strongly suggests that stomach cancer risk increases with consumption of alcohol, traditional salt-preserved foods and grilled, smoked, and processed meat – specifically, carcinogenic N-nitroso compounds present in these meats, along with the risk of being overweight and/or obese.

Promisingly, stomach cancer risk is reduced in response to high intake of fruit and vegetables. Laboratory and animal studies suggest that vitamin C is the most likely candidate responsible for this. Consuming fiber, lycopene, and selenium may also potentially reduce the risk for stomach cancer.

The most obvious and effective way to reduce your risk of developing stomach cancer is to reduce consumption of processed and salted foods, while simultaneously increasing consumption of fresh fruits, vegetables, and vitamin C supplements.

Specifically, vitamin C is believed to block the formation of carcinogenic N-nitroso compounds in the stomach. While higher dietary vitamin C has been linked to a lower risk of stomach cancer in numerous studies, it’s not yet clear how vitamin C intake via diet relates to blood levels when it comes to stomach cancer risk.

To understand this relationship, vitamin C levels were measured in the blood of 215 patients with stomach cancer relative to 416 control subjects without the disease. This was done within the European Prospective Investigation into Cancer and Nutrition (EPIC), a large cohort involving 10 European countries.

Interestingly, subjects with the highest blood levels of vitamin C were at a significantly lower risk relative to those with the lowest blood levels. This so-called “inverse association” was seen more clearly in subjects who regularly consumed red and processed meats, which is likely to increase production of carcinogenic N-nitroso compounds in the body.

Infection with H. pylori – a type of bacteria that grow in the digestive tract and attack the stomach lining, causing ulcers to form in the stomach and small intestine – is an established risk factor for stomach cancer, but thought to be insufficient on its own.

A 1998 study showed that vitamin C levels in the stomach liquids of 19 patients infected with H. pylori were significantly lower than those in 10 subjects who were H. pylori-negative, even though both groups had similar blood levels of vitamin C.

Evidence further suggests that vitamin C supplementation along with standard therapy used to eradicate H. pylori increases the efficacy of the therapy. In other words, vitamin C may prove to be effective as a preventive therapy for H. pylori infections, indirectly lowering stomach cancer risk.

The Impact of Vitamin C on Colorectal Cancer Risk

Colorectal cancer is the world’s third most common cancer and is the second leading cause of cancer deaths in the U.S. While 90 percent of new cases appear in people who are 50 years or older, anyone with a parent, sibling, or child who has colorectal cancer has a two- to three-fold risk of developing this disease themselves.

Most colorectal cancers are adenocarcinomas – in other words, they begin in cells that make mucus and other fluids, and typically first appear as a growth called a polyp on the inner wall of the colorectal or rectum. Some of these polyps eventually turn into colorectal cancer.

In a 2016 laboratory study, ascorbic acid was seen to selectively kill up to three different types of colorectal cancer cells. However, human studies have not always been so clear-cut.

For instance, a 2010 study looked at the possible links between consumption of vitamins A, C, and E and risk of colorectal cancer using data from 13 cohort studies in which over 5000 colorectal cancer cases were identified in 676,141 men and women.

Interestingly, consumption of vitamins A, C, and E obtained from food alone did not alter colorectal cancer risk. However, higher combined intakes of vitamins C and E from both food and supplements, as well as multivitamin supplementation, were seen to significantly lower colorectal cancer risk.

Because of its known toxicity towards cancer cells, vitamin C has been successfully administered along with non-steroidal anti-inflammatory drugs (NSAIDS) in order to maximize anti-cancer efficacy of these drugs and reduce their side effects.

Intravenous (IV) administration of very high doses of vitamin C has been shown to be very effective in treating colorectal cancers bearing KRAS and BRAF gene mutations, which don’t respond very well to conventional therapies, including chemotherapy.

Interestingly, vitamin C given to patients in this way appears to get converted into its oxidized form known as dehydroascorbic acid (DHA) – which is easily able to enter cancer cells. Once inside, DHA is converted into ascorbic acid, causing cancer cells to commit programmed cell death, or apoptosis.

Treating treatment-resistant colorectal cancers using IV vitamin C has been shown to help cancer patients live four times longer than average. Today, high-dose, IV vitamin C drips are used in many progressive cancer clinics as part of their cancer treatment protocols.

Why the Recommended Daily Allowance for Vitamin C Is Likely Too Low

The current recommended dietary allowance (RDA) for vitamin C for adult non-smoking men and women is 60 milligrams (mg) per day. Recent evidence indicates that a much higher intake of vitamin C is necessary to lower the risk of developing chronic diseases such as cancer, cardiovascular disease, and cataracts. Specifically, non-smoking men and women need to consume 90-100 mg vitamin C daily for optimum reduction of chronic disease risk.

The Linus Pauling Institute goes even further and states that there is sufficient evidence to support a daily vitamin C intake of at least 200 mg/day. In fact, because of the very high benefit-to-risk ratio of vitamin C supplementation, the Institute recommends a daily vitamin C intake of at least 400 mg for all adult men and women.

This is because maximizing vitamin C blood levels is considered important for optimum protection against oxidative damage to our body’s cells. Also, in older adults aged 60-96 years, the same dose of vitamin C led to lower blood levels compared with younger individuals – which is why at least 400 mg daily is considered the minimum necessary for adults older than 50 years, especially those who are at higher risk for heart disease, stroke, certain cancers, and cataracts.

Consuming at least five servings (2.5 cups) of fruit and vegetables daily will provide about 200-250 mg of vitamin C. Papayas, bell peppers, guavas, dark leafy green vegetables, broccoli, strawberries, raspberries, kiwi, citrus fruits such as oranges, limes, and lemons, peas, and lightly-cooked tomatoes are all rich in vitamin C.

Additionally, the Linus Pauling Institute recommends taking supplemental vitamin C in two separate 250- mg doses daily, once in the morning and once in the evening.

Conclusion

Vitamin C is a crucial component in our diet, acting as an essential cofactor in various enzymatic reactions and as a potent antioxidant. The link between Vitamin C and a reduced risk of cancers, specifically stomach and colorectal cancers, has been supported by numerous studies. Higher intake of Vitamin C is associated with a lower incidence of these cancers, potentially due to its role in blocking the formation of carcinogenic compounds and its toxic effect on cancer cells.

The current recommended daily allowances are debated to be lower than optimal, with institutions like the Linus Pauling Institute suggesting much higher daily intakes for maximizing protection against chronic diseases and oxidative damages. Nevertheless, enhancing Vitamin C intake either through diet or supplements is advisable, especially for its myriad of health benefits and its role in potentially mitigating cancer risk.

It’s imperative to remember that while Vitamin C has promising potential in cancer prevention and may enhance the efficacy of treatments, relying solely on Vitamin C intake without considering other lifestyle and dietary factors would be simplistic. A comprehensive approach that involves a balanced diet rich in various vitamins, regular exercise, maintaining a healthy weight, and avoiding risk factors like alcohol and processed meats is essential in effectively reducing cancer risk.