Can Diet and Lifestyle influence your Risk of getting Cancer? Let the Science Speak (2024)

By Dr Frank Yap, MD - April 26, 2024

This article compiles and analyses over 300 research references and supporting studies related to cancer and the realm of supplements, diet and lifestyle.

Most of us know Steve Jobs, Chadwick Boseman (Black Panther), Robin Gibb (Bee Gees), Donna Summer, Farrah Fawcett, Eartha Kitt, Peter Jennings, Paul Newman, Patrick Swayze, Sydney Pollack, Michael Crichton, Bob Denver, Ted Kennedy, Jerry Orbach, Anne Bancroft, William Rehnquist, and Tony Snow, just to name a few. What do they have in common? They all died from 'cancer'.

Prevention holds greater value than both cure and early detection. Nonetheless, the incentive for profit often leans away from investing in preventive measures. This tendency is reflected in the limited coverage of preventative strategies within mainstream media channels.

The quest for cancer prevention and treatment has been shrouded in ambiguity when it comes to the world of dietary supplements. The bewildering array of options leaves us questioning their efficacy, for without robust scientific evidence, their true potential remains enigmatic.

Can foods and diet really influence your risk of getting cancer? What types of foods reduce your risk and types that might increase your risk? What about vitamin and mineral supplements? Can supplements reduce your cancer risk or do they actually increase your cancer risk? We have answers to all of these questions and more.

This article here is developed as a consumer guide and is not meant to share the various technical theories related to cancer but to share practical preventive strategies that we could put into action immediately. There is comprehensive information about cancer here. The goal of this article is to summarize the relevant, updated and practical points so that you could have your personal blue-print to prevent and how to give yourself the best possible outcome if you get cancer. We have filtered out all those unproven ‘internet noise’ out there in the virtual world and have summarized the overwhelming information out there into the following list of ‘actionable’ strategies.

AACR Cancer Progress Report 2014

What is Cancer?

Cancer is the name given to a collection of related diseases. In all types of cancer, some of the body’s cells begin to divide without stopping and spread into surrounding tissues. (National Cancer Institute).

Genetic changes that cause cancer can be inherited from our parents. They can also arise during a person’s lifetime as a result of errors that occur as cells divide or because of damage to DNA caused by certain environmental exposures. Cancer-causing environmental exposures include substances, such as the chemicals in tobacco smoke, and radiation, such as ultraviolet rays from the sun. As shown from the image below, environmental factors contribute up to 95% of cancers.

There are many types of cancer treatment. The types of treatment that you receive will depend on the type of cancer you have and how advanced it is. Surgery, radiation, and chemotherapy are the standard types of treatment for cancer. While your cancer specialist is focusing on staging your disease, the type of surgery, radiotherapy or chemotherapy, many people tend to lose focus on their nutrition. There is also a lot of confusion due to the overwhelming mixing of credible scientific information and marketing hypes available on the internet.

There are also many phoney “cancer treatment” with amazing claims but devoid of any scientific data to back them up, typical of health scams. Cancer is a life threatening disease and therefore many consumers fell prey to these phoney cancer treatments.

Good nutrition

When you’re healthy, eating enough food to get the nutrients and calories you need is not usually a problem. Most nutrition guidelines stress eating lots of vegetables, fruits, and whole-grain products; limiting the amount of red meat you eat, especially meats that are processed or high in fat; cutting back on fat, sugar, alcohol, and salt; and staying at a healthy weight. But when you’re being treated for cancer, these things can be hard to do, especially if you have side effects or just don’t feel well.

Good nutrition is especially important if you have cancer because both the illness and its treatments can change the way you eat. They can also affect the way your body tolerates certain foods and uses nutrients.

During cancer treatment you might need to change your diet to help build up your strength and withstand the effects of the cancer and its treatment. This may mean eating things that aren’t normally recommended when you are in good health. For instance, you might need high-fat, high-calorie foods to keep up your weight, or thick, cool foods like ice cream or milk shakes because sores in your mouth and throat are making it hard to eat anything. The type of cancer, your treatment, and any side effects you have must be considered when trying to figure out the best ways to get the nutrition your body needs.

Therefore, nutrition is not an option or a desire but rather a basic necessity. That makes it all the more important reason to make nutrition as part of your overall strategy to fight the cancer battle. Do not give up. Many people with cancer have been cured or survived longer than those without cancer.

The following are the essential things you should know about nutrition and cancer.

Carbohydrates

Carbohydrates are the body’s major source of energy. Carbohydrates give the body the fuel it needs for physical activity and proper organ function. The best sources of carbohydrates – fruits, vegetables, and whole grains – also supply needed vitamins and minerals, fiber and phytonutrients to the body’s cells. (Phytonutrients are chemicals in plant-based foods that we don’t need to live, but that might promote health.)

Whole grains or foods made from them contain all the essential parts and naturally occurring nutrients of the entire grain seed. Whole grains are found in cereals, breads, flours, and crackers. Some whole grains, such as quinoa, brown rice, or barley, can be used as side dishes or part of an entree.

Fiber is the part of plant foods that the body cannot digest. There are 2 types of fiber. Insoluble fiber helps to move food waste out of the body quickly, and soluble fiber binds with water in the stool to help keep stool soft.

Other sources of carbohydrates include bread, potatoes, rice, spaghetti, pasta, cereals, corn, peas, and beans. Sweets (desserts, candy, and drinks with sugar) can supply carbohydrates, but provide very little in the way of vitamins, minerals, or phytonutrients.

After studying (BMJ, 2018) more than 100,000 adults for years, French researchers found that eating processed food was more closely linked with cancer risk than one's age, sex, body mass index, height, level of physical activity, smoking and drinking habits, calories consumed, or family history.

This harmful "ultra-processed" food, as the researchers called it, may include packaged sweet pastries and muffins, chips, candy, sodas, frozen dinners like meatballs and fish sticks, instant ramen noodles, sugary cereals, and pretty much anything else you can imagine that's cheap and comes in a ready-to-go packet or container at the store.

Fats

Fats play an important role in nutrition. Fats and oils are made of fatty acids and serve as a rich source of energy for the body. The body breaks down fats and uses them to store energy, insulate body tissues, and transport some types of vitamins through the blood.

You may have heard that some fats are better for you than others. Choose monounsaturated and polyunsaturated fats more often than saturated fats or trans fats.

Monounsaturated fats are found mainly in vegetable oils like olive, canola, and peanut oils. Polyunsaturated fats are found mainly in vegetable oils like safflower, sunflower, corn, and flaxseed. They are also the main fats found in seafood.

Saturated fats are mainly found in animal sources like meat and poultry, whole or reduced-fat milk, cheese, and butter. Some vegetable oils like coconut, palm kernel oil, and palm oil are saturated. Trans-fatty acids are formed when vegetable oils are processed into margarine or shortening. Sources of trans fats include snack foods and baked goods made with partially hydrogenated vegetable oil or vegetable shortening. Trans fats also are found naturally in some animal products, like dairy products. Trans fats can raise bad cholesterol and lower good cholesterol; try to eliminate them from your diet.

Researchers estimated that during the heyday of trans fats in the 1990s, they led to roughly 50,000 preventable deaths every year in the US. The US FDA rolled out a near-universal ban on trans fats in June 2015.

Proteins

We need protein for growth, to repair body tissue, and to keep our immune systems healthy. When your body doesn’t get enough protein, it might break down muscle for the fuel it needs. This makes it take longer to recover from illness and can lower resistance to infection. People with cancer often need more protein than usual. After surgery, chemotherapy, or radiation therapy, extra protein is usually needed to heal tissues and help fight infection.

Good sources of protein include fish, poultry, lean red meat, eggs, low-fat dairy products, nuts and nut butters, dried beans, peas and lentils, and soy foods.

Water

Water and liquids or fluids are vital to health. All body cells need water to function. If you do not take in enough fluids or if you lose fluids through vomiting or diarrhea, you can become dehydrated (your body doesn’t have as much fluid as it should). If this happens, the fluids and minerals that help keep your body working can become dangerously out of balance. You do get some water from the foods you eat, but a person should drink about eight 8-ounce glasses of liquid each day to be sure that all the body cells get the fluid they need. You may need extra fluids if you are vomiting or have diarrhea. Keep in mind that all liquids (soups, milk, even ice cream and gelatin) count toward your fluid goals.

Vitamins, minerals and supplements

Supplement and cancer - An interesting and challenging topic. When it comes to vitamins and minerals it is confusing due to the many choices, claims and promises created by the healthcare supplement industry. While alluring claims and network marketing sell products, the products are not always suitable for cancer patients.

The body needs small amounts of vitamins and minerals to help it function properly. Most are found naturally in foods. Vitamins and minerals help the body use the energy (calories) found in foods.

A person who eats a balanced diet with enough calories and protein usually gets plenty of vitamins and minerals. But it can be hard to eat a balanced diet when you are being treated for cancer, especially if you have treatment side effects that last for a long time. In this case, your doctor or dietitian may suggest a daily multivitamin and mineral supplement.

If you are thinking of taking a vitamin or supplement, be sure to discuss this with your doctor first. Some people with cancer take large amounts of vitamins, minerals, and other dietary supplements to try to boost their immune system or even destroy cancer cells. Vitamins and minerals alone are not sufficient to fight cancer. Remember, nutrition is not about vitamins and minerals but there are other important elements (e.g. protein, water etc.) as well.

Clinical trials on vitamins and minerals are expensive and funding is difficult from the private sector. One high-profile example is the Selenium and Vitamin E Cancer Prevention (SELECT) trial of a decade ago, which cost US$114 million and demonstrated no meaningful benefit. Exacerbating the problem is the lack of a strong business model: drug companies have little incentive to invest in trials of a product that is cheap and widely available.

Some of these substances can be harmful, especially when taken in large doses. In fact, large doses of some vitamins and minerals may make chemotherapy and radiation therapy less effective.

The term anti-cancer supplements can be a little misleading. Some supplements may help reduce a person’s risk of developing cancer or support the body during cancer treatment.

"Anti-cancer supplements" is a misleading term. Some supplements may help lower your risk of developing cancer (prevention) or support your body during treatment. However, there's no guaranteed cure or prevention. It's important to distinguish between these two concepts. Supplements with evidence for reducing cancer risk fall under prevention, while those that might help manage the disease or improve survival rates are considered supportive during treatment.

That said, here is a list of studies that have given hope to the cancer community:

1. Vitamin D3 and K2

Is vitamin D the most powerful anti cancer supplement? Vitamin D can absorb calcium and help the immune, muscle, and nervous systems function properly. There are more than 11,000 search results on vitamin D and cancer on PubMed.

A 2023 systematic review and meta-analysis of 14 RCTs (randomized controlled trials), published in Ageing Research Reviews (Kuznia 2023) found vitamin D3 supplementation reduced cancer mortality by 6%. This wasn’t considered statistically significant, but when only studies involving daily vitamin D intake were analyzed, cancer mortality dropped by a significant 12%.

The first randomized-controlled trial (DO-HEALTH) trial to investigate the combination of three complementary treatments for the prevention of cancer and suggest that the combination of daily vitamin D3, supplemental marine omega-3s, and a simple home exercise program may be effective in the prevention of invasive cancer among generally healthy and active adults aged 70 and older.

Findings from a 3 year Randomized Controlled Trial with more than 2,000 participants observed a 61% reduction in the risk of invasive cancer among patients who completed a home exercise program and took vitamin D3 and omega-3 fatty acids daily.

These results, from the DO-HEALTH trial (ClinicalTrials.gov identifier NCT01745263), were published in Frontiers in Aging 2022.

Interestingly, several studies have been done on vitamin K2 and certain types of cancer. Two clinical studies suggest that vitamin K2 reduces recurrence of liver cancer and increases survival times (Trusted Source, Trusted Source). Additionally, an observational study in 11,000 men found that a high vitamin K2 intake was linked to a 63% lower risk of advanced prostate cancer, whereas vitamin K1 had no effect (Trusted Source).

2. Fish Oil (Omega-3 Fatty Acids)

PubMed has indexed more than 3,000 research studies on Omega-3 and cancer. Most people use fish oil supplements to enhance the amount of omega-3’s in their diet.

The first randomized-controlled trial to investigate the combination of three complementary treatments for the prevention of cancer and suggest that the combination of daily vitamin D3, supplemental marine omega-3s, and a simple home exercise program may be effective in the prevention of invasive cancer among generally healthy and active adults aged 70 and older.

These results, from the DO-HEALTH trial (ClinicalTrials.gov identifier NCT01745263), were published in Frontiers in Aging 2022.

3. Vitamin C and E

PubMed has indexed more than 3,000 research studies on vitamin C and cancer and more than 5,000 studies on vitamin E and cancer. United States Preventive Services Task Force has recommended the use of Vitamin C and E supplementation for cancer prevention (R).

2022 - An umbrella review* (Xu 2022) to assess the existing systematic reviews and meta-analyses for the association between vitamin C intake and multiple health outcomes; showed that vitamin C intake was associated with reduced risk of all-cause mortality, cardiovascular disease (CVD), oesophageal cancer, gastric cancer, cervical cancer and lung cancer with an increment of 50–100 mg per day.

Beneficial associations were also identified for respiratory, neurological, ophthalmologic, musculoskeletal, renal and dental outcomes. A total of 76 meta-analyses (51 papers) of randomised controlled trials and observational studies with 63 unique health outcomes were identified. Harmful associations were found for breast cancer and kidney stones for vitamin C supplement intake.

*Umbrella review: An umbrella review, or a review of reviews, is a systematic review that only considers other systematic reviews as an eligible study type for inclusion.

2022 - Obese women who took vitamin C and B6 at amounts that exceeded the recommended daily intake levels were associated with a lower risk of breast cancer, according to a five-year long South Korean cohort study. 40,432 women without a history of cancer at baseline were included in this study.

2022 - A meta-analysis to review the association between vitamins and brain cancer showed that intake of vitamin C, β-carotene, and folate can reduce the risk of brain cancer, while high serum α-tocopherol (vitamin E) concentration also has a protective effect on brain cancer.

A 2017 meta-analysis of 11 studies concluded that patients with lower concentrations of serum vitamin E (the vitamin E level in your blood) had a higher risk for colorectal cancer.

4. Turmeric (Curcumin)

Curcumin is one of the nutrients with the most evidence-based literature supporting its use against cancer. There are more than 7,000 search results on curcumin and cancer on PubMed and more than 50 clinical trials with curcumin, most of which are still ongoing. The spice turmeric can be extremely helpful when it comes to fighting cancer.

Interestingly, curcumin appears to be universally useful for just about every type of cancer (Arslan 2022), which is really odd since cancer consists of a wide variety of different molecular pathologies.

A review paper published in 2022, analysed 21 human studies. Sixteen out of 21 clinical trials were associated with the effectiveness of curcumin or turmeric on various types of cancer, and the other five clinical trials were related to the evaluation of the efficacy of curcumin or turmeric in relieving the side effects of cancer chemotherapy and radiotherapy. The emerging data from the clinical trials confirm that curcumin has the potential for cancer prevention and intervention.

Both curcuminoids and related turmeric products have been sanctioned by the U.S. Food and Drug Administration (FDA) as safe.

5. Magnesium and Molecular Hydrogen

PubMed has indexed more than 5,000 research studies on magnesium and cancer.

Magnesium and Colorectal Cancer

Several studies have demonstrated an association between high magnesium intake and reduced risk of colorectal cancer (CRC).

An analysis of the prospective, Swedish Mammography Cohort (JAMA 2005), evaluated 61,433 women aged 40 to 75 without a history of cancer for a mean follow-up of 14.8 years. The highest quintile of magnesium intake was associated with a significantly lower risk of CRC compared with the lowest quintile. This benefit was observed for both colon and rectal cancers.

A case-control study evaluated 2204 subjects from the Tennessee Colorectal Polyp Study (2007), which demonstrated that increasing total magnesium intake was significantly associated with decreasing risk of CR.. The highest tertile of dietary magnesium intake (>298 mg/day) was significantly associated with reduced risk of CRC in an age-adjusted model.

A study of 140,601 postmenopausal women from the Women’s Health Initiative (2015) with an mean follow-up of 13 years demonstrated a significant reduction in CRC risk with the highest quintile of total magnesium intake compared with the lowest quintile of magnesium intake. The benefit was driven by colon cancer, with a trend for rectal cancer.

Magnesium and Pancreatic Cancer

A study of 66,806 subjects aged 50 to 76 at baseline from the Vitamins and Lifestyle cohort (Nature 2015) evaluated magnesium intake and the incidence of pancreatic cancer during a mean follow-up of 6.8 years. Subjects with magnesium intake below the recommended dietary allowance were more likely to develop pancreatic cancer, particularly in those whose intake was less than 75% of the recommended dietary allowance. In this study, a 100 mg/day decrease in magnesium intake resulted in a 24% increase in risk of pancreatic cancer.

Molecular Hydrogen and Cancer

There is little evidence to show that molecular hydrogen can reduce the risk of cancer.

However, in terms of cancer management or treatment, studies involving the effects of H2 on cancer were systematically reviewed. More than 600 articles related to molecular hydrogen and cancer were retrieved from Cochrane, PubMed and Google Scholar, and 27 articles were included for this systematic review (2023).

Based on the authors' analysis, "H2 plays a promising therapeutic role as an independent therapy as well as an adjuvant in combination therapy, resulting in an overall improvement in survivability, quality of life, blood parameters, and tumour reduction."

Although H2 has demonstrated significant anti-cancer effects, the underlying mechanisms have not yet been elucidated. Many studies have shown that H2 therapy can reduce oxidative stress. This, however, contradicts radiation therapy and chemotherapy, in which ROS (Reactive Oxygen Species) are required to induce apoptosis and combat cancer.

Related: Best Molecular Hydrogen Tablets

Note: Most Molecular Hydrogen tablets uses pure elemental magnesium as its carrier and provides you with approximately 80 mg of magnesium per tablet. So, you receive also highly bioavailable magnesium for a healthy brain, muscles, cells, kidneys, and heart.

6. Melatonin

PubMed has indexed more than 3,300 research studies on melatonin and cancer. Melatonin is one of the most important antioxidant molecules. In the human body — aside from having direct antioxidant effects — it also stimulates the synthesis of glutathione and other important antioxidants like superoxide dismutase and catalase.

Many people are not aware that only 5% of your body’s melatonin — which is also a potent anticancer agent — is produced in your pineal gland. The other 95% is produced inside your mitochondria — provided you get sufficient near infrared exposure which is typically from sun on your bare skin. This is why vitamin D is more than likely a biomarker for sun exposure, which is intricately involved in melatonin production. (R)

The Mediterranean Diet (MD) dietary pattern is also rich in antioxidants, such as melatonin. A systematic review published in Antioxidants (Elena 2023) showed high melatonin contents in MD-related foods, such as tomatoes, olive oil, red wine, beer, nuts, and vegetables. The consumption of specific MD foods increases melatonin levels and improves the antioxidant status in plasma.

Melatonin - Treatment

2022 - An umbrella review of meta-analyses based on randomized controlled trials (Pharmacological Research 2022):

"Survival at one year (P < 0.005) significantly increased with cancer patients."

2020 - A case series of 14 advanced cancer patients (Trends in Oncology 2020), treated with high dose (1,000 mg/day) of melatonin; achieved a disease control of 54% of the patients:

"Moreover, this preliminary study may also suggest that high dose melatonin has no toxicity in cancer patients with poor clinical status, as well as in healthy subjects."

2005 - A systematic review of 10 randomized controlled trials (J Pineal Res 2005):

"All trials included solid tumor cancers. All trials were conducted at the same hospital network, and were unblinded. Melatonin reduced the risk of death at 1 yr (relative risk: 0.66). Effects were consistent across melatonin dose, and type of cancer. No severe adverse events were reported. The substantial reduction in risk of death, low adverse events reported and low costs related to this intervention suggest great potential for melatonin in treating cancer."

7. Green Tea (EGCG)

PubMed has indexed more than 2,000 research studies on EGCG and cancer. The Minnesota Green Tea Trial (MGTT. 2015) is the largest and longest double-blind, placebo-controlled, randomized intervention study that specifically evaluated the effects of oral GTE (green tea extract) containing defined quantities of EGCG on established biomarkers of breast cancer risk.

They randomized and stratified 1075 healthy postmenopausal women at high risk of breast cancer according to their breast tissue density and catechol-O-methyltransferase genotypes and divided them into two groups: 537 placebo and 538 green tea groups. Green tea group participants took 4 capsules that contained 843 mg EGCG, whereas the placebo group took capsules without green tea extracts.

Researchers measured changes in percent mammographic density, circulating endogenous sex hormones, and proteins of the insulin-like growth factor axis. Their results showed that supplementation with green tea extract could modify and reduce mammographic density (MD) and protect against breast cancer, even though it was only significant in younger women (50–55 years) and had no effect in older women (R), an age-dependent effect similar to those of tamoxifen.

According to a 2018 review, EGCG and green tea extracts may help prevent or delay cancer onset, cancer recurrence, and secondary growths from cancer.

8. Quercetin

PubMed has indexed more than 4,000 research studies on quercetin and cancer. The safety and potential usefulness of quercetin for the prevention and treatment of cancer have been documented in both animal experiments and a phase I clinical trial.

2022 - A paper published in August 2022 in Nutrition Research analyzed the pro-apoptotic effect that quercetin has on aging cells. The paper reviewed preclinical and early phase data using quercetin as a senolytic agent and found the data showed it was effective in “preventing or alleviating cancer formation.”

The authors reviewed the importance of cellular aging in the development of cancer cells and the effect that quercetin may have on the suppression of cancer cell proliferation.

Cellular senescence is a dynamic and multi-step process that is associated with alterations in metabolic activity and gene expression. This can compromise tissue regeneration and contribute to aging. On the other hand, by removing senescent cells, age-related dysfunction can be attenuated and potentially extend the lifespan.

According to Mount Sinai, quercetin should be used with caution as it may interact with certain antibiotics by reducing the effectiveness of the drug. It may also enhance the effect of some blood thinners, which can increase your risk of bleeding. In addition to these, it may interact with corticosteroids, digoxin, cyclosporine and fluoroquinolones.

9. Garlic (Allicin) and Onion

PubMed has indexed more than 1,200 research studies on garlic and cancer. Garlic and onions belong to the Allium genus of plants.

2023 - A randomized controlled trial (RCT) on garlic and gastric cancer (GC), published in January 2023, found a significant reduction in the risk of developing GC with increasing dietary intake of allium vegetables, particularly garlic vegetables.

The study was conducted on the basis of the Shandong Intervention Trial, a randomized, placebo-controlled, factorial-designed trial (1995-2003) in a well-recognized high-risk area for GC in China. Participants were continuously followed up to December 2017 for 22.3 y (1995-2017). A total of 3,229 subjects were included.

2020 - A meta-analysis of 11 studies, published in January 2020, did find evidence that garlic could reduce the risk of ColoRectal Cancer.

Another study published in the Asia Pacific Journal of Clinical Oncology (2019) revealed the odds of getting ColoRectal Cancer were 79% lower in those who a diet high in allium vegetables, which include garlic, leeks and onions.

One study of 543,220 participants found that those who ate lots of Allium vegetables, such as garlic, onions, leeks and shallots, had a lower risk of stomach cancer than those who rarely consumed them (Source).

10. Coffee and Cancer

Based on data from a large observational study nested in a clinical trial, are in line with earlier studies showing a connection between regular coffee consumption and improved outcomes in patients with non-metastatic colorectal cancer. The study is being published by JAMA Oncology (2020).

Can antioxidant supplements help prevent cancer?

Many observational studies, including case–control studies and cohort studies, have been conducted to investigate whether the use of dietary antioxidant supplements is associated with reduced risks of cancer in humans. Overall, these studies have yielded mixed results (Source). Because observational studies cannot adequately control for biases that might influence study outcomes, the results of any individual observational study must be viewed with caution.

Randomized controlled clinical trials, however, lack most of the biases that limit the reliability of observational studies. Therefore, randomized trials are considered to provide the strongest and most reliable evidence of the benefit and/or harm of a health-related intervention. To date, nine randomized controlled trials of dietary antioxidant supplements for cancer prevention have been conducted worldwide. Many of the trials were sponsored by the National Cancer Institute.

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 (Source), published in 2013.

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 (Source). 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.

If your oncologist says it is OK for you to take a supplement during treatment, it may be best to choose a supplement with no more than 100% of the Recommended Daily Value (RDV) of vitamins and minerals.

If you want to take in more antioxidants, health experts recommend eating a variety of fruits and vegetables, which are good sources of antioxidants. Taking large doses of antioxidant supplements or vitamin-enhanced foods or liquids is usually not recommended while getting chemo or radiation therapy. Talk with your doctor to find out the best time to take antioxidant supplements.

Related: Best Antioxidant Supplements 2024

Safety considerations for nutrition, supplements and cancer

Many people believe that if they find a pill or supplement in stores, it is safe and it works. Remember, a 'natural' product does not mean its a 'safe product. Some poisons are also natural but they are certainly not safe.

The US Food and Drug Administration (FDA) put out rules in 2007 to help ensure that supplements contain what their labels claim they do, but the supplement’s safety and its effects on the body are not addressed by any FDA rules. The FDA does not make manufacturers of these products print possible side effects on their labels. And the FDA cannot pull a dietary supplement or herbal product from the market unless it can prove that the product is unsafe. Stop taking the product and call your doctor right away if you have side effects, like wheezing, itching, numbness, or tingling in your limbs.

Tell your health care team about any over-the-counter products or supplements you are using or are thinking about using. Take the bottle(s) to your doctor to talk about the dose, and be sure that the ingredients do not interfere with your health or cancer treatments.

Quit smoking

If you are a non smoker, then your risk of cancer will be reduced. Smoking is by far the leading risk factor for lung cancer. In the early 20th century, lung cancer was much less common than some other types of cancer. But this has changed once manufactured cigarette became readily available and more people began smoking.

About 80% of lung cancer deaths are thought to result from smoking. The risk for lung cancer among smokers is many times higher than among non-smokers. The longer you smoke and the more packs a day you smoke, the greater your risk.

On top of that, you should also try to cut down on your visits to places where people tend to smoke e.g. pubs etc. Passive smoking is just as bad.

Diet and Physical Activity

For those of you who do not use tobacco, one of the most important cancer risk factors that can be modified are body weight, diet, and physical activity. One-third of all cancer deaths in the United States each year are linked to diet and physical activity, including being overweight or obese, while another third is caused by tobacco products.

Although our genes influence our risk of cancer, most of the difference in cancer risk between people is due to factors that are not inherited. Avoiding tobacco products, staying at a healthy weight, staying active throughout life, and eating a healthy diet may greatly reduce a person's lifetime risk of developing or dying from cancer. These same behaviors are also linked with a lower risk of developing heart disease and diabetes.

Many consumers are also unaware that grilling some popular food items can produce cancer-causing compounds called heterocyclic amines (HCAs). For more information on foods that contain the highest concentrations of HCAs: http://www.cancerproject.org/media/news/fiveworstfoodsreport.php. HCAs, a family of mutagenic and cancer-causing compounds, are produced during the cooking of many animal products, including chicken, beef, pork, and fish. In January of 2005, the federal government officially added HCAs to its list of known carcinogens.

These are the summary recommendations from the ACS Guidelines on Nutrition Physical Activity for Cancer Prevention:

Choose foods and drinks in amounts that help you get to and maintain a healthy weight.
Limit how much processed meat and red meat you eat.
Eat at least 2½ cups of vegetables and fruits each day.
Choose whole grains instead of refined grain products.
Drink no more than 1 alcoholic drink per day for women or 2 per day for men.

Colo-rectal cancer is a type of cancer that Chadwick Boseman (Black Panther) and Robin Gibb (Bee Gees) died from. Alice Bender, MS, RD, a nutritionist for the American Institute for Cancer Research, says the evidence on fiber and colon cancer, while mixed, is strong enough to make recommendations. “Our 2007 expert report looked at all the studies and concluded that foods high in fiber, not necessarily the fiber itself, can lower risk for colorectal cancer,” she tells WebMD. “We know that a plant-based diet rich in fruits, nonstarchy vegetables, legumes, and whole grains is associated with a lower risk of a number of the most common cancers – colorectal, stomach, mouth, pharynx, larynx, and esophageal” Bender says.

In a 2020 review published in BMJ, key messages were:

Obesity and alcohol increase the risk of several types of cancer; these are the most important nutritional factors contributing to the total burden of cancer worldwide
For colorectal cancer, processed meat increases risk and red meat probably increases risk; dietary fibre, dairy products, and calcium probably reduce risk
Foods containing mutagens can cause cancer; certain types of salted fish cause nasopharyngeal cancer, and foods contaminated with aflatoxin cause liver cancer
Fruits and vegetables are not clearly linked to cancer risk, although very low intakes might increase the risk for aerodigestive (airway and digestive tracts) and some other cancers.

Achieve and maintain a healthy weight throughout life

The American Cancer Society released guidelines in 2020 for reducing the risk of cancer.

The recommendations include the latest research on diet and physical activity, as well as policy and systems changes that reduce barriers to healthy living. The update focuses on increasing physical activity and developing healthy eating patterns at every age.

Avoid excess weight gain at all ages. For those who are overweight or obese, losing even a small amount of weight has health benefits and is a good place to start.

Get regular physical activity and limit intake of high-calorie foods and drinks as keys to help maintain a healthy weight.

Adults: Get at least 150 minutes of moderate intensity or 75 minutes of vigorous intensity activity each week (or a combination of these), preferably spread throughout the week.

Children and teens: Get at least 1 hour of moderate or vigorous intensity activity each day, with vigorous activity on at least 3 days each week.

Limit sedentary behavior such as sitting, lying down, watching TV, and other forms of screen-based entertainment.

Fasting and Cancer

Fasting may help reduce obesity-associated cancers. “There’s a lot of obesity-associated cancers,” said Dr. Jason Fung, a nephrologist and fasting expert. “There’s about 13 cancers that are well accepted that they are associated with obesity; fasting might help decrease that.”

Fasting can potentially starve cancer cells. When fasting, the body uses fats and produces ketones for energy. Cancer cells rely heavily on glucose, making them less efficient at using ketones.

Additionally, fasting reduces insulin levels. Elevated insulin levels are linked to an increased risk of breast, prostate, and colorectal cancers. Eating continuously can contribute to hyperinsulinemia.

That said, not every type of fasting is effective and safe. Intermittent fasting is the preferred option. Extended or extreme fasting can be counter-productive.

Related: Fasting as an Effective Anti-Cancer Strategy: Inspiring Success Stories

Stay away from Carcinogens

Many people worry that substances or exposures in their environment may cause cancer. As part of the American Cancer Society's role in informing and educating people about cancer and its possible causes, this document provides lists of substances and exposures that are known or suspected to cause cancer. The lists below have been developed by two highly respected agencies – the International Agency for Research on Cancer (IARC) and the US National Toxicology Program (NTP). Some related information is included on how these and other agencies and groups test and classify possible carcinogens. Read more here: List of Human Carcinogens

Heavy exposure at work to certain pesticides, dyes, and chemicals may increase the risk of getting cancer of the pancreas. Steve Jobs passed away due to pancreatic cancer. Though this may not be directly related to his pancreatic cancer, Steve confirmed his drug use (marijuana and LSD) during college days. Read more here: FBI-reports-Steve-Jobs-did-LSD. Many researchers agree that marijuana smoke contains known carcinogens, or chemicals that can cause cancer much like those in tobacco smoke. Read more here: marijuana and cancer.

Reduce Stress

I know, it’s not possible to remove stress from our daily lives; especially with the on-going pandemic. However, it’s important to understand the role of stress on cancer progression. Scientists know that psychological stress can affect the immune system, the body’s defense against infection and disease (including cancer).

The body responds to stress by releasing stress hormones, such as epinephrine (also called adrenaline) and cortisol (also called hydrocortisone). The body produces these stress hormones to help a person react to a situation with more speed and strength. Stress hormones increase blood pressure, heart rate, and blood sugar levels. Small amounts of stress are believed to be beneficial, but chronic (persisting or progressing over a long period of time) high levels of stress are thought to be harmful.

Stress that is chronic can increase the risk of obesity, heart disease, depression, and various other illnesses. Stress also can lead to unhealthy behaviors, such as overeating, smoking, or abusing drugs or alcohol, that may affect cancer risk.

Some studies have indicated an indirect relationship between stress and certain types of virus-related growths. Evidence from both animal and human studies suggests that chronic stress weakens a person’s immune system, which in turn may affect the incidence of virus-associated cancers, such as Kaposi sarcoma and some lymphomas.

It is difficult to separate stress from other physical or emotional factors when examining cancer risk. For example, certain behaviors, such as smoking and using alcohol, and biological factors, such as growing older, becoming overweight, and having a family history of cancer, are common risk factors for cancer.

Studies have shown that stress might promote cancer indirectly by weakening the immune system's anti-tumor defense or by encouraging new tumor-feeding blood vessels to form. But a study published in The Journal of Clinical Investigation shows that stress hormones, such as adrenaline, can directly support tumor growth and spread.

Key Takeaways

Although this is a comprehensive guide, please do not consider this guide as personal medical advice, but as a recommendation for use with professional providers. Consult with your doctor and discuss with her/him.
Our aim here isn't to replace your doctors' advice. It is intended as a sharing of knowledge and information. Do take note that most strategies are not 100% protective against cancer. It's a continuous struggle between the immune system and the cancer cells.
Cancer prevention should be part of a multi-modal approach in order to provide the best possible outcome. The above Diet and lifestyle recommendations are proven methods to reduce your cancer risk. That said, there is no miracle diet or treatment that can prevent all cancers.
You could also complement your research and read more from the American Cancer Society site. The site has comprehensive information on cancer. You could read more on cancer prevention by cancer type here: http://www.cancer.gov/cancertopics/prevention

References:

https://www.cancer.org/treatment/survivorship-during-and-after-treatment/staying-active/nutrition/benefits.html

https://www.cancer.gov/about-cancer/causes-prevention/risk/diet/antioxidants-fact-sheet

More diet related topics > Diet series

Cancer Care: The Role of Repurposed Drugs and Metabolic Interventions in Treating Cancer

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Top 10 Repurposed Drugs and Metabolic Interventions to Control Cancer: Evidence based (2024 Edition)

https://www.cnbc.com/2019/10/03/ashton-kutcher-steve-jobs-fruit-diet-health-effects.html

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