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Do Antioxidants Protect Cancer Cells?Antioxidant foods for cancer prevention -
Many of the trials were sponsored by the National Cancer Institute. The results of these nine trials are summarized below.
Initial: no effect on risk of developing either cancer; decreased risk of dying from gastric cancer only Later: no effect on risk of dying from gastric cancer. Initial: lower total cancer and prostate cancer incidence and all-cause mortality among men only; increased incidence of skin cancer among women only.
Later: no evidence of protective effects in men or harmful effects in women within 5 years of ending supplementation. Initial: no reduction in incidence of prostate or other cancers—trial stopped early.
Overall, these nine randomized controlled clinical trials did not provide evidence that dietary antioxidant supplements are beneficial in primary cancer prevention. In addition, a systematic review of the available evidence regarding the use of vitamin and mineral supplements for the prevention of chronic diseases, including cancer, conducted for the United States Preventive Services Task Force USPSTF likewise found no clear evidence of benefit in preventing cancer It is possible that the lack of benefit in clinical studies can be explained by differences in the effects of the tested antioxidants when they are consumed as purified chemicals as opposed to when they are consumed in foods, which contain complex mixtures of antioxidants, vitamins, and minerals 3.
Therefore, acquiring a more complete understanding of the antioxidant content of individual foods, how the various antioxidants and other substances in foods interact with one another, and factors that influence the uptake and distribution of food-derived antioxidants in the body are active areas of ongoing cancer prevention research.
Several randomized controlled trials , some including only small numbers of patients, have investigated whether taking antioxidant supplements during cancer treatment alters the effectiveness or reduces the toxicity of specific therapies Although these trials had mixed results, some found that people who took antioxidant supplements during cancer therapy had worse outcomes, especially if they were smokers.
In some preclinical studies, antioxidants have been found to promote tumor growth and metastasis in tumor-bearing mice and to increase the ability of circulating tumor cells to metastasize 29 — Until more is known about the effects of antioxidant supplements in cancer patients, these supplements should be used with caution.
Cancer patients should inform their doctors about their use of any dietary supplement. Home About Cancer Cancer Causes and Prevention Risk Factors Diet Antioxidants and Cancer Prevention. Cancer Causes and Prevention Risk Factors Age Alcohol Cancer-Causing Substances Chronic Inflammation Common Cancer Myths and Misconceptions Diet Hormones Immunosuppression Infectious Agents Obesity Radiation Sunlight Tobacco Genetics Cancer Prevention Overview Research.
Antioxidants and Cancer Prevention On This Page What are free radicals, and do they play a role in cancer development? What are antioxidants? Can antioxidant supplements help prevent cancer? Should people already diagnosed with cancer take antioxidant supplements? What are free radicals, and do they play a role in cancer development?
MAX Study, France 19 — 22 Daily supplementation with vitamin C mg , vitamin E 30 mg , beta-carotene 6 mg , and the minerals selenium µg and zinc 20 mg for a median of 7. Print Email. Initial: no effect on risk of developing either cancer; decreased risk of dying from gastric cancer only Later: no effect on risk of dying from gastric cancer Later: no effect on risk of dying from gastric cancer.
Initial: increased incidence of lung cancer for those who took beta-carotene supplements Later: no effect of either supplement on incidence of urothelial, pancreatic, colorectal, renal cell, or upper aerodigestive tract cancers.
Daily supplementation with 15 mg beta-carotene and 25, International Units IU retinol. People at high risk of lung cancer because of a history of smoking or exposure to asbestos. Initial: increased risk of lung cancer and increased death from all causes—trial ended early Later: higher risks of lung cancer and all-cause mortality persisted; no effect on risk of prostate cancer.
No effect on cancer incidence, cancer mortality, or all-cause mortality in either smokers or non-smokers. Some people experience gluten sensitivity without overt celiac disease. In these people, gluten may contribute to inflammation in the intestines, which might in turn increase the risk of gastrointestinal cancers.
However, this possible link is not well-proven. There is very little evidence linking gluten intake to risk of gastrointestinal cancers in the general population. The bottom line: For people without celiac disease, there is no evidence that consuming a gluten-free diet is linked with a lower cancer risk, and many studies suggest that consuming whole grains, including those containing gluten, probably reduces the risk of colon cancer.
Glycemic index is a measure of the increase in the blood level of glucose a type of sugar after eating a specific carbohydrate-rich food, compared with eating a standard amount of glucose. Foods with a high glycemic index release glucose quickly and lead to a rapid rise in blood glucose. Foods with a low glycemic index release glucose into the blood more slowly, with a lower overall peak in blood glucose over time.
In general, high glycemic index foods are highly refined, processed grain products with added sugars and low fiber content, as well as some starchy vegetables. The glycemic index can be considered a measure of carbohydrate-rich food quality.
Beyond glycemic index, glycemic load captures both the quality and quantity of carbohydrates consumed. The glycemic load gives a truer picture of how blood glucose is elevated in relation to intake of a specific food item. A lot of research has looked at the potential impact of the glycemic load of a diet and cancer risk.
Most recent reports have found that eating a dietary pattern high in glycemic load is linked with a higher risk of endometrial cancer. More research is needed to determine the impact on other types of cancer. However, the role of inflammation in causing cancer has been recognized more recently, and the relationships between diet, inflammation, and the risk of cancer as well as heart disease and dying at an earlier age are still an evolving area of research.
A combination of lab and human studies has identified certain foods and chemicals in them that promote inflammation in certain body tissues. This is the basis of anti-inflammatory dietary patterns, which share some traits with the recommendations in this guideline, such as being high in vegetables and fruits and low in red and processed meats.
Food irradiation applying ionizing radiation to food is a technology that improves the safety and extends the shelf life of foods by reducing or eliminating germs and insects.
Like pasteurizing milk and canning fruits and vegetables, irradiation can make food safer. Irradiation does not make foods radioactive, affect nutritional quality, or noticeably change the taste, texture, or appearance of food. In fact, changes made by irradiation are so minimal that it is not easy to tell if a food has been irradiated.
The US Food and Drug Administration FDA has evaluated the safety of irradiated food for more than 30 years and has found the process to be safe. The World Health Organization WHO , the US Centers for Disease Control and Prevention CDC , and the US Department of Agriculture USDA have also endorsed the safety of irradiated food.
There is currently no evidence that irradiation of foods causes cancer or has harmful human health effects. Can periods of limiting food intake to juices remove toxins and help protect against cancer? Fruit and vegetable juices can be a convenient way to get some healthy food components from vegetables and fruits.
In moderation, they can be a worthwhile part of healthful dietary patterns. However, juices contain less fiber, lower levels of some other healthy nutrients, and more naturally occurring sugar than the whole fruits and vegetables they are made from, so they are not the best way to get nutrients from plant-based foods.
There is no scientific evidence to support claims that consuming only juices for one or more days, known as juice cleansing or juice detoxification , reduces cancer risk or provides other health benefits.
Toxins that enter our body through foods and beverages are constantly removed by the kidneys and liver, regardless of whether a person is consuming liquid or solid foods.
Although vegetable juicing may be one way to increase nutrient intake, a diet limited to juice may also be lacking in some important nutrients, and in select cases it may contain dangerous levels of some substances that can cause kidney damage and other health problems.
Microwaves are a form of non-ionizing electromagnetic radiation, and their use in cooking does not increase cancer risk. On the other hand, grilling, smoking, or pan-frying meats including red meats as well as poultry and fish at high temperatures can cause chemical reactions that form cancer-causing heterocyclic amines.
Goals of food preservation, processing, and preparation that are relevant to individual and public health include:. On the other hand, certain methods of preserving red meats introduce nitrates into them, which can be converted in the stomach into cancer-causing N-nitroso compounds.
Contamination of foods by substances from storage containers or cookware is another concern of some consumers. Plastic containers can release substances such as phthalates some of which are classified as possible carcinogens or phenolic compounds such as bisphenol A a probable carcinogen during storage of food or during cooking in a microwave oven.
Use of Teflon-coated cookware may release perfluorooctanoic acid PFOA, a possible carcinogen into foods. These substances have been found to have negative biological effects in some lab studies, and they may influence onset of puberty, a possible factor in the long-term risk of some cancers such as breast cancer.
However, evidence of the impact of long-term exposure to these chemicals on cancer risk in human studies is lacking. Nonetheless, people who are concerned about possible harm from these exposures can choose glass or metal storage containers and cookware. Non-nutritive sweeteners are substances used instead of sugars like sucrose, corn syrup, honey, agave nectar to sweeten foods, beverages and other products.
Several non-nutritive sweeteners are now approved by the FDA, including aspartame , acesulfame potassium, saccharin, sucralose, and stevia. These sweeteners contain few or no calories, or nutrients. They may be derived from herbs and other plants, or sugar itself, and typically are many times sweeter than sugar, allowing smaller amounts to be used.
Other sugar substitutes include sugar alcohols such as sorbitol, xylitol and mannitol. There is no clear evidence that these sweeteners, at the levels typically consumed in human diets, cause cancer.
Questions about artificial sweeteners and cancer risk arose when early studies showed that saccharin caused bladder cancer in lab animals, but studies in humans have shown no increased cancer risk. With this exception, all these sweeteners appear to be safe when used in moderation, although larger amounts of sugar alcohols may cause bloating and abdominal discomfort in some people.
Under USDA regulations, animal-derived foods that are labeled as organic come from animals raised without the addition of hormones or antibiotics to the feed they eat. Plant foods that are organic come from agricultural methods that do not use most conventional pesticides or herbicides, chemical fertilizers, or sewage sludge as fertilizer.
Organic foods also exclude the use of industrial solvents or food irradiation in processing, and genetically modified foods are also excluded.
A main benefit of consuming organic foods is to support environmentally sustainable agricultural practices. Many consumers also believe that organic foods may provide health benefits, but there is little evidence that organic produce has higher nutrient levels than conventionally grown produce.
Little research has been done on the link between organic food consumption and cancer risk, although a recent study found eating more organic produce was linked with a lower risk of non-Hodgkin lymphoma.
While this finding needs to be confirmed by other studies, it is in line with the strong and consistent link between workplace pesticide exposure and this type of cancer. Washing conventionally grown produce can remove some of the pesticide residue. Insecticides and herbicides can be toxic when used improperly in industrial, agricultural, or other workplace settings.
In addition, malathion is linked with a higher risk of prostate cancer, and diazinon is linked with a higher risk of lung cancer.
Washing conventionally grown produce can remove some of the pesticide residues, and is also important to minimize the risk of microbial contamination. Increasing evidence suggests important interactions among sleep, diet, physical inactivity, and cancer risk:. As with other beans or legumes, soy and foods derived from soy are excellent sources of protein, so they provide a healthier alternative to meat.
Soy contains several bioactive food components, including isoflavones, which have a similar structure to estrogens and can bind to estrogen receptors on cells. The effects of this binding can vary, depending on conditions, the specific body tissue, and the amount consumed.
There is some evidence from human and lab studies that consuming traditional soy foods such as tofu may lower the risk of breast and prostate cancer, but overall the evidence is too limited to draw firm conclusions. Many of the studies that have found such links looked at Asian populations with high lifelong consumption of soy foods, and their relevance to soy consumption at lower levels and for shorter durations in Western populations remains uncertain.
There are no data to support the use of supplements containing soy phytochemicals or soy protein powders used in some food products for reducing cancer risk. In fact, a recent study found increased risk for estrogen receptor ER -negative breast cancer an aggressive type among users of soy supplements.
Therefore, while soy from food sources appears to be safe and may even have beneficial health effects, soy supplements should be used with caution, if at all. Several types of sugars are found in foods and beverages. These sugars vary in their chemical structures, but once they are consumed, they all have similar metabolic effects in the body.
All sugars in foods and beverages add to calorie intake, which can lead to obesity, so eating a lot of sugar can indirectly increase cancer risk.
There is also evidence that a dietary pattern high in added sugars affects levels of insulin and related hormones in ways that may increase the risk of certain cancers. Brown unrefined sugar contains the same chemical form of sugar sucrose as white refined sugar.
Fructose , the natural sugar in fruit and in many sugar-sweetened beverages in the form of high-fructose corn syrup, is similar to sucrose in its effects on weight and insulin levels, as is honey, which contains a mixture of fructose and glucose another form of sugar.
Lab studies have shown that metabolism of glucose the main sugar used as an energy source in the body is faster in cancer cells than in normal cells. It can also lower insulin secretion in people with metabolic conditions such as pre-diabetes or type 2 diabetes.
Thus, vegetarian diets may be helpful for cancer risk reduction. Many studies of vegetarians indicate a lower risk of cancer overall, compared to people who also eat meat.
But whether vegetarian diets confer any special health benefits over diets that include smaller amounts of animal products than are typically consumed in Western diets is less clear. Indeed, in a large British study, people who ate fish but not other meats appeared to have the same overall cancer risk as vegetarians.
The available evidence supports the recommendation of a dietary pattern that is mainly foods from plant sources, with limited if any intake of red and processed meats. In addition to a modest level of risk reduction for some forms of cancer, vegetarian dietary patterns are linked with lower risks of heart disease and type 2 diabetes and are generally more affordable.
People on strict vegetarian diets that omit all animal products including milk and eggs , referred to as vegan diets , often need supplementation with vitamin B12, zinc, and iron or foods fortified with these nutrients , especially for children and premenopausal women.
It's important that people on strict vegetarian diets, referred to as vegan diets that do not include animal products including milk and eggs , talk with their doctor or a dietitian or nutritionist about supplements they may need.
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