Meat, Vegetables, and Colorectal Cancer


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The standard American diet, also called the Western pattern diet, doesn’t have a great reputation - and rightly so. It consists of refined foods, high amounts of meat, added fats, and sugary drinks.  

According to

  • About three-fourths of the population has an eating pattern that is low in vegetables, fruits, dairy, and oils
  • More than half of the population is meeting or exceeding total grain and total protein foods recommendations, but are not meeting the recommendations for the subgroups within these (such as whole grains)
  • Most Americans exceed the recommendations for added sugars, saturated fats, and sodium

Recent trends in health foods and lifestyle diets (paleo, vegan, raw food, gluten-free, keto, Whole 30, and others) have challenged the way many think about what’s for dinner.

Cancer Prevention

Before we dive into what is known about nutrition, it’s important to highlight that the best method of colorectal cancer (CRC) prevention is through regular recommended screening. Why? Because CRC can happen even to those who are following the healthiest diet. 

What Does the Research Say About Meat?

Diets high in processed and red meats have been linked with a higher risk of colorectal cancers (American Cancer Society, 2015). A recent study published in Cancer Epidemiology, Biomarkers and Prevention indicated that processed meats increase the risk of developing colon and rectal cancer in women.

This is hardly the first study to show that red and processed meat can increase the risk of developing cancer. In fact, in 2015, the World Health Organization (WHO) classified all meats as carcinogens (something that can cause cancer).

According to the WHO, eating red meat is classified as a Group 2A carcinogen, meaning red meat can probably cause cancer in humans; however, the classification is based on limited studies. Processed meat is classified as a Group 1 carcinogen, indicating that there is strong enough evidence to show the association between processed meats and cancer.

If you eat red meat, it is recommended to limit consumption to no more than 12-18 ounces of cooked red meat per week. This equates to eating red meat 2-3 times a week if you are eating a standard 4-6 ounce portion. Even small amounts of processed meats have been linked to increased risk for CRC. Therefore, limit them as much as possible.  Chelsey Wisotsky, CSO

Just recently, data from a meta analysis suggested that not all processed meats are created equal. Scientists from Queen’s University Belfast found that not all meats carry the same cancer risk. They discovered that meat containing sodium nitrite, a preservative that extends the shelf life of food, was associated with a higher risk of developing cancer than processed meat not treated with nitrites. 

To make the situation murkier, in October 2015 a study showing that meat consumption isn’t linked to heart disease and cancer made headlines when it was discovered that the principal investigator had ties to the meat industry. 

With all of the conflicting research and reports in the news, it’s hard to know what to believe. As expected, more research is needed on diet, nutrition, and the effect of red and processed meat. 

What we do know is that diets rich in fruits and vegetables improves the effects of diabetes, supports weight management, and reduces the risk of cardiovascular disease and stroke. Additionally, people following vegetarian diets (fruits, vegetables, dairy, and grains) have a lower risk of developing colorectal cancers, and pescovegetarians (vegetarians who eat fish occasionally) have an even lower risk.

Cancer Recurrence

Preliminary studies on prostate and breast cancer led to a hypothesis that vegetable proteins slow tumor growth, and animal proteins speed up tumor growth. Although exciting to consider, the research is very limited and does not suggest that restricting animal proteins puts cancer into remission. In addition, no studies have been done specific to CRC in this regard.

One study did have early results showing that stage III colon cancer patients who continued to follow the standard American diet had a threefold increase in recurrence than those stage III CRC survivors who strayed from the standard American diet by reducing their meat and sugar consumption and increasing their veggies and healthy grains.

Diet Trends

  • Raw food: There is no shortage of raw food related cancer remission blogs. Yet contrary to some beliefs, cooked foods may actually be easier for the body to digest than eating salads. Breaking down the cell walls of veggies by cooking them actually makes their nutrients more available for our bodies to digest and easily use, an important consideration for CRC patients with colons functioning below-optimal levels. Eat vegetables and fruits in a way that you enjoy - cooked or raw!
  • Keto diet: Talk to your doctor about whether or not this high protein meal plan is for you. Check out our 2019 blog on this trending diet. 
  • Cleansing/Juice fasting: Drinking juice every now and again as a way to get nutrients, and enjoying a tasty beverage is great. However, drinking juice only, as a way to “detox” or “cleanse” the body, is not something that has been proven to be effective. The human body is already built to detox itself from chemicals through the complicated systems of the liver, colon, and kidneys. Additionally, limiting calories by only drinking juice can be detrimental to health overall, eventually leading to feelings of weakness, and slow metabolism.
  • Whole 30: The Whole 30 diet is based on cutting certain foods and food groups out of the diet for 30 days - these include sugar (including honey and other sweeteners), dairy, alcohol, grains, and legumes. It’s important to talk to your doctor about the pros and cons of the Whole 30 diet - and if you decide to go for it, be kind to yourself if you don’t make it the whole way.

What's the Takeaway?

Although some diet trends are harmless, others over-restrict entire food groups, and are not backed by science. The best type of dietary pattern to follow for cancer prevention is a plant-based diet. Plant-based diets focus on consuming mostly plant-based foods such as fruits, vegetables, whole grains, herbs and spices and including protein from plants. Choosing a bean or legume based meal or snack such as lentil or bean chili, or unsalted nuts and seeds are some ways to make your diet more plant based. If you include animal protein, focus on lean options such as skinless chicken breast and omega-3 rich fish like salmon, tuna or sardines.

Chelsey Wisotsky, CSO

Pay attention and make changes where you can. Paying attention to diet after a CRC diagnosis may be a worthy complement to treatments, but switching to a vegan diet in lieu of surgery, radiation, or chemotherapy has not been shown to be effective. 

Anecdotal accounts of remission purely as a result of diet change can be found on the web, but remember that everyone is different – every diagnosis requires a personalized treatment plan. As you move through treatment and survivorship, simply consider limiting your intake of red meats and processed foods and swapping them for fish, eggs, tofu, and cooked veggies.

Reduce the amount of meat you eat. That doesn’t mean you need to eliminate it completely, but try not to eat it every day, and try cutting down portion sizes.

Eat a wide variety of foods. There are so many fruits, vegetables, and grains out there to experiment with! Try something new, you might like it!

Use caution. Always talk to your doctor about any dietary changes you plan to make, and use caution when reading about the latest health food fads which claim to be a cure-all.

Be kind to yourself! Healthy is a relative term. Remember that sometimes cost of food and access to food can affect what we eat. Additionally, our personal dietary needs and health situation can affect what we eat. For some people, eating white bread is healthier than whole wheat because that is what their bodies can handle at that time. Additionally, be compassionate with yourself and don’t beat yourself up if you eat a slice of bacon occasionally. Similarly, cake and sweets are delicious and celebratory. If you have a slice at a birthday party, enjoy it and move on. Do the best you can! As a survivor, your body has been through so much - be kind to yourself!

These simple lifestyle adjustments could reduce the risk of recurrence and make you feel better about taking steps towards better health.

Chelsey Wisotsky, CSO is a Board Certified Specialist in Oncology Nutrition at Savor Health. Check out this 2017 Taboo-ty Podcast where Chelsey talks about the role of fiber, sugar, and meat play in nutrition.

For more information: Guide in the Fight, Low Residue Diet