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How to Prevent Cancer With Food

By Traci Cole McCormick, M.D., radiation oncologist at Alliance Cancer Care

“Is there a cancer prevention diet?”

“What should I eat?”

“What shouldn’t I eat?”

“Does it really matter what I eat?”

“Should I stop eating sugar?”

“Should I eat more blueberries?”

“What supplements should I take?”

The questions I get about nutrition are endless. And it’s no wonder why. Every time we turn on the news, there is a new headline telling us what we should or should not eat to avoid cancer.

It’s absolutely overwhelming.

How do we know what to believe?

Can we trust what we are reading?

Is it just someone’s attempt to sell us something?

Is it something truly worthy of our attention?

Today, I’m going to help you sort through the hype and tell you exactly what you need to know about how to prevent cancer with food.

Other Health Benefits to a Cancer Prevention Diet

The good news is that there are a lot of other benefits to a cancer prevention diet. By following these guidelines, you will:

  • Cut your chances of dying from cancer by 30%
  • Decrease your risk of dying from any chronic, debilitating disease by 40%
  • Be 50% less likely to die from cardiovascular disease

So let’s get started!

1. Prevent Cancer by Eating a Healthy Diet with an Emphasis on Plant Foods

If you eat a plant-based diet, you are more likely to live longer, weigh less, and remain free of cancer, diabetes, and heart disease. It is a fact.

A plant-based diet encourages whole, plant-based foods such as fruits, vegetables, beans, whole grains, nuts, and seeds. It discourages meats, dairy products, and eggs as well as all refined and processed foods.

There is definitely some evidence that vegetarians or vegans live longer and have less disease than people that consume animal products. However, I want to emphasize that eating a plant-based diet is not the same as becoming a vegan, or even a vegetarian.

You can eat meat, dairy, eggs, and (gasp) even the occasional refined or processed foods. You should, however, consume them as a very small portion of your overall diet. As a general guideline, you should fill at least two-thirds of your plate with plant-based foods at each meal.

2. Prevent Cancer by Choosing Foods and Beverages in Amounts That Will Help Achieve and Maintain a Healthy Weight

Obesity is truly the number one health crisis we face in America today. Over 30% of us are obese. Another third of us are overweight. Scarier yet, 14% of our children are obese, and another 17% of our kids are overweight.

Being overweight is the second leading cause of cancer death in our country and is directly linked to at least 11 different types of cancer. It is also the primary cause of a multitude of other chronic and debilitating diseases, including heart disease, hypertension, diabetes, and stroke—just to name a few.

The foods we choose to eat play a HUGE role in how much we weigh. If we choose foods that are low in calories, but high in nutrition, we control our weight and put cancer-fighting foods in our bodies. If we choose foods that help us maintain our weight, we are less likely to eat refined, processed, sugary foods that are known to increase cancer risk.

When it comes to obesity and diet, one is not independent of the other.

Do you know if you are considered underweight, a healthy weight, overweight or obese? You can use this BMI calculator to see.

3. Prevent Cancer by Eating at Least Two and a Half Cups of a Variety of Vegetables and Fruits Each Day

Let me first say that there is no single fruit or vegetable that holds the power to cure or prevent cancer all by itself. There is no magic piece of produce that you should be forcing yourself to eat day in and day out.

The fact is that a variety of fruits and vegetables work together to help make your body better at fighting cancer and less susceptible to forming cancer cells in the first place. They do this in a variety of ways:

  • Fruits and vegetables are full of vitamins, minerals, antioxidants, and other substances that boost the immune system and help protect against cancer.
  • Individuals that eat more vegetables and fruits have less weight gain and a lower risk of obesity.
  • Fruit and vegetable consumption reduces the risk of other chronic diseases, making the body less susceptible to injury and inflammation that may promote cancer growth.
  • Fruits and vegetables are high in insoluble fiber. Insoluble fiber adds bulk to your stool which causes it to pass through your digestive tract more rapidly. This more rapid transit lessens the time that your gut is exposed to potential carcinogens. The interaction between fiber and the bacteria in your gut may also play a role in inhibiting cancer formation.

Supplements are not the answer.

I also want to emphasize that when it comes to preventing cancer, it is crucial that you get your nutrients from the food you eat—not from a pill. While supplements are ideal for treating some vitamin or mineral deficiencies, supplements have not been shown to be of benefit in preventing cancer. In fact, supplements can sometimes be detrimental.

Several decades ago, people were convinced that beta-carotene (a form of Vitamin A) prevented lung cancer. This belief was based on hoards of evidence that people who ate diets high in beta-carotene were less likely to be diagnosed with the disease.

So two large trials were initiated involving close to 50,000 people. The study participants took either a beta-carotene supplement or a placebo for an average of 5 years. In both studies, the participants that took the beta-carotene supplement had an almost 30% INCREASED risk of lung cancer and a nearly 20% INCREASED risk of death compared to those that received the placebo. Not the results they were expecting!

In another study, patients were given selenium and vitamin E supplements to prevent prostate cancer. The data had shown very convincing evidence that people who consumed diets high in selenium and vitamin E were less likely to be diagnosed with prostate cancer. Well, guess what? The selenium was of no benefit, and the vitamin E slightly INCREASED the risk of prostate cancer.

The lesson here is that the nutrients found in fruits and vegetables likely work synergistically to protect us from cancer and other diseases.

Our best bet is to include a variety of fruits and vegetables in our diet each day. And remember—two and a half cups is the minimum amount you should aim for. The more fruits and vegetables you eat, the better it is for your health.

4. Prevent Cancer by Choosing Whole Grains in Preference to Processed (Refined) Grains

Whole grains include wheat, barley, rye, rice, oats, and corn. Whole grains still have all three parts of the grain kernel (germ, bran, and endosperm). If the bran and germ are removed, the grain is considered refined. For example, brown rice is a whole grain, while white rice is a refined grain.

While I agree without reservation that there are people in the world who do better, feel better, and are generally healthier when they don’t eat grains (and in particular gluten), the bulk of the data shows that whole grains are good for most people.

Whole grains contain fiber, vitamins, minerals, antioxidants, and other substances known to protect cells from damage that may lead to cancer. Multiple studies show that if you eat a diet rich in whole grains, you will lessen your risk of not only cancer but also obesity, heart disease, and diabetes.

Refined grains, on the other hand, have little nutritional value and cause rapid spikes in blood sugar. These rapid spikes in blood sugar cause a hormone called insulin to surge. Insulin is a growth hormone, and excess amounts of insulin play a role in cancer development.

The bottom line: if you choose to eat grains, make sure they are whole grains and not processed or refined.

5. Prevent Cancer by Limiting Processed Meat and Red Meat

Recently, a group of 22 experts from 10 countries reviewed 800 studies. They found that if you eat 50g (4 strips of bacon or 1 hot dog) or more of processed meat a day, you increase your risk of colon cancer significantly. They also confirmed that if you regularly consume red meat, you increase your risk of colon, pancreatic, and prostate cancer.

Overall, the current evidence suggests that for every 100 grams of red meat or 50 grams of processed meat you eat per day, you increase your risk of cancer (in particular, colorectal cancer) by 20%.

Consumption of red or processed meat can contribute to cancer formation in several ways. The primary mechanism seems to be through the formation of compounds called nitrosamines. These compounds form when components found in processed or red meat combine with other substances found naturally in your gut. Nitrosamines are carcinogens that damage the cells that line your bowel and promote cancer formation and growth.

Does this mean you have to stop eating processed or red meat?

No, but it does mean that you need to limit how much you eat. You should eat no more than 18 ounces of red meat per week, and you should avoid processed meat as much as possible. For reference, a 3-ounce serving of meat is about the size of a deck of cards or a bar of soap. As for processed meat, there is disagreement about how much is safe for you to consume. Some authorities say that no amount is safe, while others say that the occasional hot dog, a slice of bacon, or deli meat sandwich is ok, as long as it isn’t a regular part of your diet.

6. Prevent Cancer by Limiting Alcohol to One Serving per Day for Women, or Two Servings per Day for Men

If you consume alcohol, you increase your risk of some cancers, including cancers of the breast, liver, rectum, throat, mouth, and esophagus. However, studies have also shown that moderate alcohol consumption decreases your risk of cardiovascular disease.

So, to drink or not to drink—that is the question.

The answer is very complicated and not at all straightforward, but here is the bottom line. You should drink no more than one serving of alcohol per day if you are female. If you are male, you should drink no more than two servings of alcohol per day. If you are young and healthy with no cardiovascular risk factors, there is no need to add alcohol to your diet. However, if you are older, smoke, or have other factors that put you at increased risk for cardiovascular disease, then it’s probably wise to get in your allowed serving or servings of alcohol each day.