The Paleo Diet and Cancer
Imagine waking up in your cave ready to carpe diem – seize the day. After all, you never know when that pesky saber-tooth tiger living next door is finally going to be the death of you. But it’s time to catch fresh salmon for breakfast and forage for berries to complement the meal.
We know what you’re thinking: We have lost our minds. But no, this is how our ancestors ate in the Paleolithic Era, which dates between 2.5 million to 10,000 years ago.
The Paleolithic diet (or the paleo diet) is also known by several monikers – caveman diet, hunter-gatherer diet, or stone-age diet. The idea behind the food is to mimic what our ancestors ate. So, you would eat what a hunter-gatherer would be able to find.
However, dietary habits have changed vastly over just the past century. (And they continue to get worse with the abundance of convenient and overly processed foods.) Plain and simple, we were not designed to eat like this.
The paleo diet is a way to throw it back, way back, to a time before McDonald’s, Taco Bell, and Cheetos. Ditch those foods to get back to whole foods – fruits, vegetables, healthy fats, and proteins that our bodies crave and thrive off of.
The great thing about eliminating processed foods is you are no longer consuming the chemicals, additives, and preservatives in processed foods. Anything man-made is a “no go” on the diet. Hence, the menu tends to be a bit on the expensive side; you’re ditching cheap processed foods for whole, organic non-GMO foods.
Technically, the paleo diet is a low-carb diet. It eliminates grains, starchy vegetables, and legumes. However, paleo is not as strict as the ketogenic and Atkins diets. You do not have to monitor ketones, macronutrients, carb count, or worry about the keto flu.
The paleo diet allows many of the fruits and vegetables not allowed on either keto or Atkins diets. You do not have to calculate daily macronutrients or track your carbohydrates. Instead, apples, bananas, carrots, and many other options that are too carb-dense for the other diets are OK to eat.
The paleo diet can be traced back to gastroenterologist Walter Voegtlin, who penned The Stone Age Diet in 1975. The modern version of the diet is thanks to Dr. Loren Cordain, who wrote The Paleo Diet in 2002.
The diet has a considerable following and remains one of the most popular diets today. A quick search produces hundreds of articles and blogs on paleo, including guides, meal plans, and more books. In fact, “paleo” had an average google search of 49,000 per month in 2019.
What science says about paleo
The paleo diet encourages a whole food diet. It consists of lean proteins, fruits, vegetables, nuts, and healthy fats. It’s no wonder why the paleo diet is healthy if done correctly. The food primes the body to prevent chronic health issues such as inflammatory/autoimmune disorders, diabetes, and high blood pressure.
Inflammation is a huge factor when you are dealing with any chronic illness. “Worldwide, 3 of 5 people die due to chronic inflammatory diseases like stroke, chronic respiratory diseases, heart disorders, cancer, obesity, and diabetes.”  A recent study showed that the paleo diet, along with exercise, patients exhibited a promising reduction of inflammation after a 4-week period. 
Research has shown the importance of the gut microbiome in supporting the body’s immune system. For context, combating and preventing inflammation supports a healthy gut microbiome.
“The human microbiome is composed of bacteria, archaea, viruses, and eukaryotic microbes that reside in and on our bodies. These microbes have tremendous potential to impact our physiology, both in health and in disease. They contribute to metabolic functions, protect against pathogens, educate the immune system, and, through these basic functions, affect directly or indirectly most of our physiologic functions.” 
The spotlight on ‘urbanization'
According to Segata et al., “By contrasting the gut microbiomes of African hunter-gatherer and European subjects, a new study reveals that urbanization is associated with a loss of microbial organisms and genes. What will be the consequences of the lost biodiversity in the sanitized, western-diet world?”  This alludes to the idea that, over time, our continual dietary habit changes have decreased the amount of healthy bacterial populations in the GI tract microbiome.
When left unchecked, chronic inflammation and misregulated metabolic conditions can lead to more permanent diseases such as type 2 diabetes. The Center for Disease Control (CDC) found that in 2020, 34.2 million people in the United States have diabetes. That is more than 1 in 10 people.  A 14-day study utilized the paleo diet to understand the effects on 14 patients with type 2 diabetes. The results were promising and included metabolic changes such as lowered triglycerides, improved glucose tolerance, and stable glucose levels. 
However, significant questions remain. Challenges to address from this study include long term effects of the paleo diet and the inability to continue the dietary regimen. Because the paleo diet is so restrictive, it may only be a short-term solution. Our paleolithic ancestors had significantly shorter life spans, so there may be some conflicting evidence on whether or not they were healthier in the long term. Thus, the study gives some perspective and future directions regarding possible links between changes in diet, metabolism, and chronic disease progression.
An indicator of metabolic disorders is high blood pressure. In fact, “the number of Americans at risk for heart attack and stroke just got a lot higher. An estimated 103 million U.S. adults have high blood pressure, according to new statistics from the American Heart Association. That’s nearly half of all adults in the United States.” 
“We’ve made incredible inroads in cardiovascular disease,” said Benjamin, a professor of cardiology at Boston University’s School of Public Health. “There’s a real focus on improving health by adopting a healthy lifestyle, not just waiting to develop the disease before one focuses on risk factors.”
High blood pressure is a common metabolic condition that many people are treating daily with medications. To better understand the effects of nutritional changes on metabolism, a three-month randomized study was done on 13 patients with type 2 diabetes to compare the Paleo diet and a diabetic diet.
In addition to positive changes in metabolism, the researchers found that patients on the paleolithic diet had improved blood pressure levels.  Whether you are taking a diuretic, beta-blocker, ACE inhibitor, or some other form of blood pressure medicine, a diet change may be able to help. (You should never change your dietary regimens or medications without consulting your physician first.)
Moderation and balance with the paleo diet
Chronic inflammation and metabolic disorders increase cancer risk. In some cases, as discussed above, diet showed promise when used as a tool to prevent the progression of disease. However, the main problem with the paleo diet is the emphasis on meat.
“Based on at least six cohorts, summary results for the consumption of unprocessed red meat of 100 g day-1 varied from nonsignificant to statistically significantly increased risk (11% for stroke and for breast cancer, 15% for cardiovascular mortality, 17% for colorectal and 19% for advanced prostate cancer).” 
Examining the above evidence – due to the loose guidelines of the paleo diet – red meat potentially could cause harm to cancer patients. The paleo diet is also known to restrict some very healthy foods like legumes. This restriction may make it hard for vegetarians to incorporate and maintain the menu while keeping an optimal protein intake and getting a variety of micronutrients. Moderation and balance are essential with any diet, and there needs to be a variety of colorful fruits and vegetables incorporated to provide essential micronutrients.
- If you are not consuming processed foods, you are more likely to have a healthier lifestyle
Clinical studies have reported the following promising preliminary results:
- Lower triglycerides, improved glucose tolerance, and stable glucose levels, which is a great thing, especially if you have diabetes 
- Improved blood pressure 
- Reduces inflammation (anti-inflammatory) 
- Studies have also shown an increase in the microbiome, which promotes a healthy gut. 
- It can be costly
- Long-term commitment to the diet is difficult
- Our ancestors had significantly shorter life spans so there may be some conflicting evidence on whether or not they were healthier long-term
- The paleo diet restricts some very healthy foods like legumes, which would make it extremely hard for vegetarians to maintain the diet
- The menu emphasizes meat products. High consumption of meat, especially red meat, increases mortality and colorectal cancer risk 
There are many ways to do the paleo diet since there are no strict guidelines. If approached the wrong way, however, the menu could potentially be unhealthy. Far from an end-all, be-all list, these are foods on a general paleo diet:
Paleo Diet Food List
- Lean meat, such as chicken, turkey, pork, lean beef, and buffalo (bison)
- Fresh fruit
- Non-starchy vegetables, such as lettuce, asparagus, green beans, broccoli, cabbage, Brussels sprouts, cauliflower, and spinach
- Nuts, like almonds, walnuts, cashews, pecans, and pistachios (no peanuts)
- Seeds, like pumpkin and sunflower
- Plant-based oils, such as olive, walnut, grapeseed, and coconut oil
What Can’t You Eat on the Paleo Diet?
- Grains, such as oats, wheat, barley, and rice — which means no cereal, bread, pasta, bagels, crackers, or granola bars
- Starchy vegetables, such as potatoes and corn, as well as potato and corn chips, tortillas, and popcorn
- Legumes or beans — so no peanuts or peanut butter; no soy foods, such as soy milk, tofu, or edamame; no hummus or beans of any kind
- Dairy products — so no milk, yogurt, cheese, or ice cream
- High-fat meats, such as salami, bologna, pepperoni, hot dogs, ground meat, rib roast, and ribs
- Sugars, such as soda, honey, jam or jelly, syrup, candy, cakes, cookies, and sports drinks
- Processed foods or trans fats, such as doughnuts, french fries, fruit snacks, or macaroni and cheese
- Salty foods, such as crackers, chips, pretzels, soy sauce, added-salt foods, or sports drinks 
As always, it’s essential to work with your physician if you are making dietary changes, especially if you have an underlying health condition.
When compared to the current Standard American Diet (S.A.D), the paleo diet has promising attributes to encourage better eating habits. (The menu nixes convenient and overly processed foods.) Prevention is key with any chronic health issue. A better dietary regimen can prevent many metabolic diseases.
Studies have shown that the paleo diet has the potential to help with metabolic and some chronic disorders, such as high blood pressure and type 2 diabetes. Still, the diet is not a“one size fits all” and could be potentially unhealthy. Overconsumption of red meat is a concern and can contribute to certain cancers like colorectal and prostate cancers. Long term effects of the paleo diet are also unknown.
If you have an underlying health condition and plan to change your dietary habits, consult with your physician before making any changes.
- Paleo Diet: What is it and why is it so popular? https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/paleo-diet/art-20111182
- Chronic Inflammation. https://www.ncbi.nlm.nih.gov/books/NBK493173/
- Carbohydrate-restricted Diet and High-intensity Interval Training Exercise Improve Cardio-metabolic and Inflammatory Profiles in Metabolic Syndrome: A Randomized Crossover Trial. https://www.ncbi.nlm.nih.gov/pubmed/31700709
- The gut microbiome in heath and in disease. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4290017/
- Gut Microbiome: Westernization and the Disappearance of the Intestinal Diversity. https://www.ncbi.nlm.nih.gov/pubmed/26196489
- National Diabetes Statistics Report, 2020. https://www.cdc.gov/diabetes/library/features/diabetes-stat-report.html
- Metabolic and physiologic effects from consuming a hunter-gatherer (Paleolithic)-type diet in type 2 diabetes. https://www.ncbi.nlm.nih.gov/pubmed/25828624
- More than 100 million Americans have high blood pressure, AHA says. https://www.heart.org/en/news/2018/05/01/more-than-100-million-americans-have-high-blood-pressure-aha-says Accessed <3/25/20>
- Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study. https://www.ncbi.nlm.nih.gov/pubmed/19604407
- Potential health hazards of eating red meat. https://www.ncbi.nlm.nih.gov/pubmed/27597529
- Dietary patterns and risk of colorectal adenoma: a systematic review and meta-analysis of observational studies. https://www.ncbi.nlm.nih.gov/pubmed/27412573
- Pros and Cons of the Paleo Diet. https://share.upmc.com/2016/04/pros-cons-paleo-diet/