Does Red Meat Really Cause Cancer?

Earlier this week the World Health Organization (WHO) announced that processed red meats are a “human carcinogen” and red meats a “probable human carcinogen” that increase your risk of cancer. Those are powerful words and unsurprisingly they spread like wildfire within just a few hours.

Perhaps not too many people are surprised to read that traditional processed meats (e.g. hot dogs, salamis, sausages), with so many fillers and additives, are not good for your gut health. But, where do naturally and pasture-raised meats without preservatives or additives, like bacon and homemade sausages fit in?

However, what many health professionals (including myself) are shocked about, is that red meat (e.g. steak, lamb, veal, etc.) was also included. Red meat is one of nature’s best sources of healthy fat, essential amino acids, iron, zinc, and B12 so how did it get lumped in with the processed meats?

Unfortunately, in today’s Twitter world of 140 characters or less, a controversial headline gets a lot of media play. Let’s take a closer look at the WHO summary and see what the document actually reveals.

Processed Red Meat is a Human Carcinogen

The WHO defined processed red meat as a “human carcinogen” because they believe there is sufficient evidence that the agent causes cancer in humans and/or animals. They believe (and there is good evidence) that carcinogenic compounds like nitrosamines and polycylic aromatic hydrocarbons (PAHs) – produced during curing, salting and smoking – are leading to an increase risk of cancers. It’s these specific compounds that worries the WHO and led to their conclusions.

The Group 1 category also includes things like smoking, radiation, plutonium, etc. However, the report notes that just because smoking and processed red meat are both included in Group 1, it doesn’t mean they confer the same risk of cancer.

Relative Risk vs. Absolute Risk

The report states that processed red meat and red meat consumption increases your risk of colorectal cancer (not all types of cancer) by 17% for every 100g. This seems high, but you must remember that “relative risk” is a statistical term researchers use to compare the risk between two groups.

For example, the WHO has just stated you’re at 17% increase risk of colorectal cancer if you eat processed red meat. However, your true risk getting this type of cancer – called absolute risk– is only 5% for your lifetime according to the American Cancer Society.1 Using the relative risk term typically makes the “risk” seem greater than it actually is.

Other major risk factors for colorectal cancer are smoking, weight gain, obesity, diabetes, low fiber diet, sedentary lifestyle and alcohol use. If the meat you consume is placed between two buns with an order of fries and a sugar-laden soda at a fast food restaurant, then your choices will definitely be putting you at greater risk. However, it’s very different if you eat red meat as part of a healthy diet, rich vegetables, healthy fats and complex carbohydrates.

Why Is Red Meat Lumped In With Processed Meat?

This is where things get very grey. The direct quote for classifying red meat as a “possible carcinogen” in the report is based on, “limited evidence from epidemiological studies… that a positive association has been observed.” The evidence from the report gets even more speculative in the next sentence, stating “other explanations for the association (chance, bias, confounders) could not be ruled out”.

Association is not causation. Fire trucks appear at every fire in the city, and therefore are associated with fires, but they do not cause fires. The most troubling statement is that the relationship is so thin that “coincidence” or “luck” might explain the association. In fact, the WHO stated in their report that “red meat has known health benefits”, but not surprisingly this didn’t make the media headlines. Why then the tough stance on red meat?

High Temperature Cooking & Carcinogens

The root of the WHO’s concern with processed and natural red meat seems to stem from how we cook it. When we cook red meat – grilling, sautéing, searing, etc – it can lead to the production of carcinogenic compounds called nitrosamine, heterocyclic amines (HAs) or polycyclic aromatic hydrocarbons (PAHs), if it’s cooked with an open flame. These compounds are the real “bad guys” the WHO is concerned about and the likeliest reason processed red meat was included in Group 1 “human carcinogen” and red meat included in the Group 2A “possible carcinogen” category. However, what isn’t included in the report is that PAHs are found in the same concentrations in vegetables and grains, and even more concerning, virtually double the amount in the ambient environment (i.e. dust).2,3 That’s right, you get just as much PAHs from the rest of your dinner plate and are virtually exposed to them everyday in the environment. Seems unlikely they alone are the smoking gun.

Can You Mitigate The Negative Effects of Cooking Red Meat?

The good news is there are numerous cooking techniques that help to mitigate the potential negative effects of grilling or sautéing your meat. For example, marinating your meats (spices, honey, vinegars, etc.), cooking at lower temperatures (slow-cooker, braising, simmering, etc.) and choosing medium-rare over a “well done” steak, all significantly reduce the formation of carcinogens.

The research also shows that if you add leafy greens or green vegetables with your red meat it offsets the DNA damage from these carcinogens.4 The vegetables you add to your plate, along with fruit and friendly starches – potatoes, rice, yams – dramatically increase your fiber intake, building up “good” gut bacteria and reducing your risk of colorectal cancer.

Remember, the biggest risk factors for colorectal cancer are sedentary lifestyle, weight gain, obesity, diabetes, lack of fiber and constipation. Physical inactivity leads to a 10% increase in risk of colon cancers, and for every 4 inches you add to your waist, your risk of colorectal cancer increases by 20%.5,6 For two-thirds of the population who are classified as overweight or obese, it is especially important to promote good gut health, physical activity and a high-fibre, low carbs/sugar diet to reduce risks. If your bowel movements don’t occur daily and you “miss” days in the week, toxins build-up in the large intestine and put you at greater risk of colorectal cancer.

Animal protein, especially red meat, is one of the most nutrient dense foods on the planet. Marinated, cooked at moderate temperature, and served over a plate of leafy greens as part of diet high in fiber (e.g. the Paleo diet), red meat promotes good health, slimmer waistline and improve body composition. I see this everyday in clinical practice. While too many processed meats do present a potential risk factor and should be consumed in moderation, if you stay active, maintain a healthy weight and fill your plate with leafy greens your lifetime risk of developing colorectal cancer is only 5%.

Yours in health,
Dr. Marc Bubbs ND, CSCS

Can Paleo Improve Low Mood and Depression?

Low mood and depression are increasingly prevalent symptoms of 21st century living. While the current statistics from the Center for Disease Control show one in ten people suffer from depression, in clinical practice we see much higher rates of people struggling with unreported low mood or depressive symptoms.

The World Health Organization has estimated that by the year 2050, one-third of the global population will suffer from either anxiety or depression. What is going on? Why are we more prone to depression today than in generations past?

As with any complex condition, there are many factors at play that conspire to create an environment where low mood and depression can thrive. Let’s look at how a Paleo diet can lay the framework for better mental health by addressing influential systems of the body.

AVOID BLOOD SUGAR AND INSULIN DYSFUNCTION

Today, 75% of the North American population are classified as overweight or obese and the annual consumption of processed and simple sugars tops a whopping 160 pounds of sugar per person. This leads to worsening blood sugar control and insulin dysfunction. Research from Scandinavia has uncovered a clear association between elevated HbA1c (a three-month average of blood sugars) and insulin levels with increased risk of depression. A recent study found that young men with insulin resistance were three times more likely to suffer from severe depression.1

Another study in Diabetes Care of over 4,000 people showed depressive symptoms were associated with higher fasting and 30-minute insulin levels.2 The authors specifically noted that antidepressant medications did not alter this association because the medications target neurotransmitters (e.g. serotonin, dopamine) and do not address blood sugar and insulin dysfunction.

Adopting a Paleo diet can dramatically improve blood sugars and insulin levels, an important first step for reducing risk factors for low mood and depression.

COOL LOW-GRADE SYSTEMIC INFLAMMATION

Inflammation is another potential root cause of low mood. Low-grade systemic inflammation leads to the over-production of pro-inflammatory cytokines that are associated with depression.3 The prestigious New England Journal of Medicine recently published a review of the growing connection between chronic inflammation and the development of today’s most common chronic diseases, including depression.4 The current medical literature tells us that if you are overweight or obese, you likely have low-grade systemic inflammation.5

A Paleo diet’s high nutrient density provides a robust intake of antioxidants that help to cool inflammation and reduce the damaging effects of reactive oxygen species (ROS) produced during the inflammatory response. A Paleo diet is also a rich source of anti-inflammatory omega-3 fats that support positive mood. Studies show low levels of omega-3 fats are associated with a chronic stress state and increased risk of depression.6

PROMOTE A HEALTHY GUT

The microflora of the gut plays a key role in your health and is in constant communication with the brain. Key neurotransmitters targeted by medications for improving symptoms of depression – serotonin and dopamine – are actually concentrated in the gut. The research shows that if you are overweight, you will likely have poor zonulin function, a key molecule that regulates gut permeability.(7)Poor zonulin function leads to symptoms of a leaky gut, which exacerbates inflammatory levels and can contribute to the cytokine storm that leads to low mood and depression.

You don’t need to be overweight to suffer from leaky gut. The research is clear that chronic or excessive use of NSAIDs – non-steroidal anti-inflammatory drugs – like ibuprofen and naproxen are also a direct cause of leaky gut, which will worsen inflammation.8,9A Paleo approach to eating supports the growth of good gut bacteria and, therefore, superior intestinal health.

OVERCOME A SEDENTARY LIFESTYLE

Movement is a critical component of mental health and overall wellbeing. Busy workdays make it difficult for people to find time to exercise, however this is a critical component of any mental health plan. A recent meta-analysis of 92 studies on more than 4,310 people showed that light to moderate exercise significantly reduced the incidence of depression.10 Try adding 15-20 minute walks at lunch or the end of your day to increase your activity level.

Strength training can also play a key role in mental health. Basic movements like squatting, lunging, bending, pushing, and pulling are deeply engrained in our DNA and exert tremendous positive benefit on multiple systems of the body: improving blood sugars and insulin, reducing inflammation, boosting testosterone (low levels have been associated with depression), and supporting healthy gut flora. If you’re not active, start slowly with 10-20 minutes of strength training 2-3 times weekly and focus on bodyweight type movements.

There is no “magic bullet” to fix depression. It’s a complex multi-factorial condition that is impacted by numerous systems of the body. By addressing blood sugar imbalances, weight gain, inflammation and dysbiosis, a Paleo diet can provide the body with the building blocks it needs to support positive mood.

If you suffer from depression, talk to your doctor about how you can incorporate a Paleo Diet and exercise, along with treatment into your action plan.

(This article originally appeared @ThePaleoDiet.com)

 Dr. Marc Bubbs ND, CISSN, CSCS

Want to learn more? High blood sugar and insulin levels are strongly associated with depression. Listen to diabetes expert Dr. Jason Fung MD in Episode #15.

 

Check out more articles in the PALEO SERIES...

REFERENCES

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2. Pyykkonen AJ et al. Depressive symptoms, antidepressant medication use, and insulin resistance: the PPP-Botnia Study. Diabetes Care. 2011 Dec;34(12):2545-7.

3. Felger J, Lotrich FE. Inflammatory cytokines in depression: neurobiological mechanisms and therapeutic implications. Neuroscience. 2013 Aug 29;246:199-229.

4. Emerging Risk Factors Collaboration. Diabetes mellitus, fasting glucose, and risk of cause-specific death. New England Journal Medicine, Mar 2011;364;9:328-341.

5. G. S. Hotamisligil, N. S. Shargill, and B. M. Spiegelman, “Adipose expression of tumor necrosis factor-α: direct role in obesity-linked insulin resistance,” Science, vol. 259, no. 5091, pp. 87–91, 1993.

6. Larrieu T, et al. Nutritional omega-3 modulates neuronal morphology in the prefrontal cortex along with depression-related behaviour through corticosterone secretion. Transl Psychiatry. 2014 Sep 9;4:e437.

7. Moreno-Navarrete JM et al. Circulating zonulin, a marker of intestinal permeability, is increased in association with obesity-associated insulin resistance.. PLos One 2012;7(5):e37160.

8. VanWijck K et al. Aggravation of exercise-induced intestinal injury by Ibroprofen in athletes. Med Sci Sports Exerc. 2012 Dec;44(12):2257-62.

9. Matsui H et al. The pathophysiology of non-steroidal anti-inflammatory drug (NSAID)-induced mucosal injuries in stomach and small intestine. J Clin Biochem Nutr. 2011 Mar;48(2):107-11.

10. Rebar A, et al. A Meta-Meta-Analysis of the effect of physical activity on depression and anxiety in non-clinical adult populations. Health Psychol Rev. 2015 Mar 5:1-78.