The number one reason is... Smoking

You think of cancer as something inevitable, like death and taxes, with emphasis on the first. The statistics are truly terrifying: in 2019, cancer overtook heart disease as the leading cause of death in middle-aged adults living in wealthy countries. Almost 4 in 10 Americans will be diagnosed with cancer this year, and nearly 600,000 will die from the disease. However, you shouldn’t feel powerless: in fact, 30 to 50 percent of cancer cases can be completely prevented, says the World Health Organization. How? By avoiding these common cancer-causing habits. Keep reading to learn the number one cause and the rest of this life-saving list.

1. SMOKING

The most common cancer is lung cancer, and the most common cause of lung cancer is smoking. Tobacco smoke contains 7,000 chemicals, and at least 70 of them are carcinogenic, which increases the risk of cancer in almost every part of the body. According to the WHO, tobacco use is the leading avoidable risk factor for cancer death; it kills almost 6 million people a year worldwide.

2. EATING TOO MUCH SUGAR

Americans consume too much added sugar, and it may increase the risk of cancer. The latest dietary guidelines for Americans recommend consuming no more than 12 teaspoons of sugars per day. The average American consumes 17 teaspoons! Eating too much added sugar can lead to obesity and inflammation, both of which are risk factors for cancer.

Cut back on added sugars in your diet. It's easier to do now that food manufacturers must list them as a separate line on nutrition labels. Check them on every packaged product you buy.

3. EATING PROCESSED MEAT

In 2015, the International Agency for Research on Cancer officially classified processed meat as a human carcinogen; it is prepared with chemicals known to damage the cells of the colon and rectum. In fact, eating just 1.8 ounces a day can increase your risk of colorectal cancer by 18 percent. What counts as processed meat? Ham, sausage, hot dogs, pepperoni, salami, jerky, and deli meats, including turkey and roast beef.

MD Anderson Cancer Center recommends eating processed meat less frequently or not at all and increasing the number of plant-based or meatless meals you eat each week.

4. EATING PROCESSED FOODS

"Processed foods are full of countless toxic chemicals that can increase cancer risk," says Yeral Patel, MD, a board-certified family medicine doctor in Newport Beach, California. "Eating processed foods causes inflammation, one of the main contributors to cancer, and these foods also lack key micronutrients (essential vitamins and minerals) that our body relies on to rid itself of harmful toxins."

Fill your diet with as many whole foods as possible and make sure that the packaged foods you buy contain the fewest ingredients possible.

5. WORKING AT NIGHT

Women who work the night shift have a 19 percent increased risk of cancer, according to a 2018 meta-analysis of studies published in the journal Cancer Biomarkers and Prevention. Researchers theorize that staying awake at night disrupts the production of the sleep hormone melatonin, which may protect against disease.

If you work the night shift, you may want to switch to the day shift.

6. USING TALC

A study published in Epidemiology found that using talc (baby powder) in the genital area increases the risk of ovarian cancer by 33 percent. Another study found that using talc powders increased the risk of endometrial cancer by 24 percent. Why? Some researchers theorize that the mineral used to make talcum powder is often contaminated with asbestos, a potent carcinogen.

Avoid talc. For personal hygiene, use a natural alternative like cornstarch.

7. USING PLASTICS

Some plastic containers contain BPA, a synthetic hormone that can disrupt the body's endocrine system and potentially increase the risk of breast cancer.

It is not definitive that plastic actually causes cancer. But it's a good idea to choose plastics that are BPA-free and use alternative containers, like glass, whenever possible.

8. EATING FRIED POTATOES (French fries or chips)

Acrylamide is a chemical found in tobacco smoke and industrial products. It also forms when vegetables, like potatoes, are heated, which contain certain sugars. These foods include fried potatoes, potato chips, crackers, breads, and breakfast cereals. Animal studies show that acrylamide can damage DNA, increasing cancer risk. Although research is not definitive in humans, why take the risk?

Reducing the amount of processed foods you eat in general is a proven way to reduce cancer risk and improve heart health. (Anyway, you should cut down on those French fries and chips.)

9. POOR ORAL HYGIENE

A 2018 study published in the Journal of the National Cancer Institute found that gum disease is associated with a 24 percent increase in lung and colorectal cancer. Why? Researchers theorize that gum disease may either change immune responses or spread harmful bacteria throughout the body.

Practice good oral hygiene: Brush and floss twice a day and visit your dentist twice a year.

10. WORRYING

There is no solid evidence that stress directly causes cancer. But, the National Cancer Institute notes, people who are stressed are likely to develop bad habits such as "smoking, overeating, or drinking alcohol, all of which increase the risk of cancer."

Take active steps to reduce stress, such as exercising, socializing, doing relaxation exercises, or speaking with a mental health professional.

11. EATING CHARRED MEAT

According to the National Cancer Institute, studies have found that grilling or frying meat at high temperatures can form chemicals that can damage DNA, increasing cancer risk.

Avoid charred meats. Baking, roasting, and broiling are safer cooking methods. If you can't live without grilling and barbecues, don’t overcook the meats. Marinating meat for 30 minutes before grilling and/or microwaving it for 60 seconds afterward drastically reduces the cancer-causing compounds formed by grilling over open flames.

12. USING PARABENS

According to research published in the Journal of Applied Toxicology, parabens (chemical preservatives used in toothpaste, shampoos, deodorants, and cosmetics) are easily absorbed through the skin and may stimulate the growth of breast cancer cells.

Look for products that don’t contain parabens. Common parabens include methylparaben, propylparaben, ethylparaben, and butylparaben.

13. IN THE BEDROOM

Sorry to tell you. According to a study published in the Journal of Clinical Oncology, cases of oropharyngeal cancer have increased in the United States over three decades, and the culprit is HPV (human papillomavirus).

Good news: Research has shown that the HPV vaccine protects against oral cancer in addition to cervical cancer. The FDA recently approved the vaccine for use up to age 45.

14. INHALING SECONDHAND SMOKE

Just like smoking itself, inhaling secondhand smoke causes lung cancer. It has also been linked to an increased risk of breast cancer, nasal cavity cancer, and nasopharyngeal cancer in adults and leukemia, lymphoma, and brain tumors in children, says the National Cancer Institute.

Avoid secondhand smoke whenever possible. Researchers at Stanford University suggest staying at least six feet away from smokers to reduce exposure.

15. DRINKING IN EXCESS

According to the National Cancer Institute, drinking alcohol can increase the risk of mouth, throat, esophagus, larynx, liver, and breast cancer. The more you drink, the higher your cancer risk.

Health experts, including the American Cancer Society, recommend drinking in moderation: no more than two alcoholic drinks a day for men and one for women.

16. NOT EXERCISING REGULARLY

"One of the main causes of cancer is living a sedentary lifestyle," says Patel. "The human body needs to move. Exercise is crucial for helping to eliminate harmful toxins from the body."

"Just sweating a bit from walking (or doing some form of cardiovascular exercise) for 30 to 40 minutes a day is enough exercise to reduce the risk," says Patel.

17. CHRONIC INFLAMMATION

Inflammation is a good thing: it’s the first step when the immune system kicks in to heal a wound. But chronic inflammation throughout the body, when there is no injury, can damage DNA and lead to cancer. What causes chronic inflammation? Smoking, excessive alcohol consumption, and a poor diet filled with processed foods and added sugars.

Don’t smoke, drink moderately or not at all, and follow an anti-inflammatory diet like the Mediterranean Diet, which emphasizes fruits and vegetables, lean proteins, and healthy fats while minimizing added sugars and processed foods.

18. EXCESSIVE SUN EXPOSURE

Sunlight produces ultraviolet (UV) radiation, which is the leading cause of skin cancer, including squamous cell carcinoma and basal cell carcinoma. Having a sunburn just once every two years can triple the risk of melanoma, the deadliest type of skin cancer.

Use sunscreen with at least 30 SPF during prolonged sun exposure. Avoid tanning beds. Perform a self-check once a month for moles or spots that have changed shape, size, appearance, or color, or are bleeding. And ask your healthcare provider to do a full-body check for signs of skin cancer once a year.

19. BEING OVERWEIGHT

According to the International Agency for Research on Cancer, 13 cancers are linked to being overweight or obese, including esophagus, thyroid, postmenopausal breast, gallbladder, stomach, liver, pancreas, kidney, ovaries, uterus, colon, and rectum. Researchers are unsure how excess fat leads to cancer, but the statistics are stark and clear: an analysis by the CDC found that 40% of cancers diagnosed in the U.S. are now associated with overweight or obesity.

Maintain a healthy weight as a lifestyle through regular exercise and a sensible diet based on plenty of whole foods.

20. NOT EATING ENOUGH FRUITS AND VEGETABLES

According to a study published in Cancer Prevention Research, "poor consumption of fruits and/or vegetables has been associated with the risk of head and neck, esophagus, stomach, and colorectal cancer." Researchers hypothesize that this is because fruits and vegetables are rich in fiber, antioxidants, and detoxifying enzymes.

At every meal, try to fill half your plate with fruits and vegetables. The current Dietary Guidelines for Americans recommend eating at least 2 ½ cups of vegetables and 2 cups of fruit every day.

The #1 Reason You Could Get Cancer, According to Science | Eat This Not That