Reviewed by Dietitian Annie Nguyen, M.A., RD
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A new study suggests acidogenic foods may raise your gastrointestinal cancer risk.
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Acidogenic foods, like red and processed meats, create acid in your body.
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Eating more plants has been correlated with a lower risk of GI cancers.
Our bodies work hard 24/7 to maintain internal stability—called homeostasis—with the multitude of processes going on inside them. One of these processes is maintaining a healthy pH, which is the balance between acid and base. The pH scale runs from 0 to 14, with 7 being neutral—anything below 7 is acidic, and anything above it is basic or alkaline.
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For example, stomach (hydrochloric) acid needs to be very acidic for proper digestion. It ranks at about a 1, just above battery acid, but your blood pH should be at a neutral 7. And our bodies have amazing built-in mechanisms for regulating and maintaining blood pH. For example, if your body senses excessive levels of acid, your lungs and kidneys go to work to remedy the situation by expelling carbon dioxide through breathing and urinating. Or the pancreas will secrete bicarbonate, a compound that helps buffer acid.
While the body is designed to adjust to its environment to bring it back to center, there are some questions as to whether too much of certain foods might play a role in creating a more acidic environment, especially in the gastrointestinal (GI) tract. This then lends to questioning whether a more acidic GI tract increases the risk of GI cancers, including liver, colorectal, gastric (stomach), pancreatic and esophageal cancers.
Researchers in Korea observed that there is some evidence that people who eat a Western-style diet—one high in fat and sugar—create a more acidic environment in their bodies that is favorable for malignant cell growth. They took a closer look at this theory and recently published their findings in the European Journal of Clinical Nutrition. Let’s break them down.
Related: Best Foods to Eat for Gut Health
How Was This Study Conducted?
Data was drawn from a long-term Korean study called the Cancer Screenee Cohort, which began in 2002. Almost 11,000 participants were used for this current study, about 64% of them female, with an average age at baseline of 53. Participants were followed on average for eight years.
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Participants had completed food frequency questionnaires, from which researchers calculated “dietary acid loads” using three different methods. Researchers determined the number of GI cancer cases using the 2020 Korea National Cancer Incidence Database, which records most instances of cancer in the country. In addition, they checked electronic medical records to catch any cases that might not have been recorded in the cancer incidence database.
Demographic information that would be adjusted for during statistical analyses included BMI (which was measured by trained staff), physical activity levels, education level, occupation, marital status, first-degree family history of cancer, smoking status and alcohol intake.
What Did This Study Find?
Overall, researchers found that individuals who were diagnosed with GI cancer tended to have a more acidogenic diet than those without GI cancer. And as the dietary acid load score increased, so did the risk of GI cancer. This association was much stronger in males compared to females. For this study, researchers note red and processed meats as being the primary acidic foods.
Researchers aren’t sure why male participants had a higher risk of GI cancers than female participants, even when dietary acid load scores were similar, but offer a few possible explanations. First, they state that females tend to have better kidney function than males, thereby giving females a greater capacity for acid-base balance maintenance. They also state that there could be sex hormones involved, since estrogen tends to have a protective effect at the cellular level—which then raises the question for post-menopausal women. Lastly, in this analysis, the males tended to have higher acidic diets, including higher alcohol intake.
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It’s important to note a few limitations of this study. First, this study cannot determine causation. In other words, it cannot conclude that more acidic foods, which include red and processed meats, cause GI cancer. It can only suggest a strong association between the two. There may be other factors at work, as well, such as genetics or smoking and high alcohol intake, though these were adjusted for in the analysis.
Researchers also note that they could not take supplement use into consideration as a confounder since there wasn’t enough information on that (certain supplements may raise or lower acid load). Finally, they note that the study population was relatively small, which may have reduced the statistical power of the analysis.
Related: https://www.eatingwell.com/search?q=red+meat
How Does This Apply to Real Life?
You’ve probably seen ads for alkaline water, thanks to companies jumping on the idea that we can control the acid-base balance in our bodies. And though this study would certainly lean that direction, there is still so much we don’t yet know.
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While our bodies are designed to constantly work to maintain internal stability, is it possible that they can go into acid overload from certain foods that end up hijacking the body’s biological systems? There is evidence that suggests yes, but don’t go investing in expensive bottled water just yet.
These researchers suggest a simpler swap—red and processed meats for fruits and veggies, which tend to be more alkaline. Exceptions include citrus fruits and tomatoes, which rank from 2 and 4 on the pH scale. But this doesn’t mean you shouldn’t eat them. Citrus fruits and tomatoes offer loads of nutrition and health benefits, including immune support and antioxidants that calm inflammation. Citrus fruits are even connected with a lower rate of colon cancer—which raises the question about whether it’s really the acid load or something else about red and processed meats that might increase the GI cancer risk, since citrus fruits are more acidic.
The key is to eat a variety of foods, including different types of plants—fruits, veggies, nuts, seeds, whole grains and legumes. This ensures you not only get the nutrients your body needs, but it also spreads out the pH levels among the plants you’re eating.
Do a quick assessment of your eating pattern. Are you including a lot of red and processed meats? How about foods and beverages with high levels of added sugar? Where can you start rotating in more plants?
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Eating habits, like other habits, are pathways in our brains. These pathways were forged somewhere in your past and became automatic. To start new habits, you need to make purposeful, intentional choices because otherwise, your brain will automatically choose the path of least resistance.
Related: The #1 Habit You Should Start to Live Longer, According to Health Experts
Habit change tends to be easier for people if they start small. Choose an area you’re likely to have success with, so that you can build on that success over time. For example, could you exchange one of your daily sodas or energy drinks for a flavored sparkling water (so you’re still getting the bubbles)? If you typically have that beverage for a mid-afternoon energy boost, could you instead have an energizing snack—like a handful of nuts and a piece of fruit—to accomplish the same thing? Or sometimes we just need to change our physiology for an energy boost, in which case, taking a quick break from your desk and walking a lap or two around your house or office space might do the trick.
These researchers also mention the Mediterranean diet as an eating pattern characterized by high fruit and vegetable intake and low or moderate meat intake. Because of this, the Mediterranean diet is associated with high levels of adiponectin, a compound known for its protective role against cancer.
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If you’re ready to dive in and work on changing your overall eating pattern, we’ve got plenty of Mediterranean diet meal plans and recipes to choose from. We suggest starting with our 7-Day Mediterranean Diet Meal Plan for Beginners or our 30-Day Mediterranean Diet Meal Plan for Beginners. We’ve also got Mediterranean diet meal plans based on specific needs, whether you’re looking for more energy, less inflammation, or a heart- or gut-healthy plan, there’s something for everyone.
Related: 8 Best Heart-Healthy Mediterranean Diet Foods, According to a Dietitian
The Bottom Line
This study suggests that regularly eating highly acidic foods, including red and processed meats, may increase the risk of GI cancers. These foods have also been linked with higher rates of dementia, diabetes and heart disease, so by limiting or avoiding them, you’re doing your body good on many levels. Start swapping these foods with more plants, including plant-based proteins, like legumes, whole grains, nuts and seeds, to help lower inflammation and your overall disease risk.
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