The Glycemic Index and Lung Cancer Connection

5 min read

The Glycemic Index and Lung Cancer Connection

If you’re not a smoker, and don’t live with one, then you may assume that you’re in the clear when it comes to lung cancer. However, as we learn more about lung cancer, we’re seeing that there are more risk factors than just smoking. You may be surprised to learn that there is also a connection between the glycemic index and lung cancer.

In a recent study, researchers examined the link between the glycemic index and lung cancer. They found that people who eat a diet heavy in high-glycemic index foods like white bread, white-flour pasta, refined cereal and instant oatmeal had a 49% higher risk of developing lung cancer.

This increased risk existed in non-smokers as well as smokers. One interesting take away from the study was that the number of carbohydrates (glycemic load) didn’t have a correlation — meaning that type of carbohydrates mattered instead of the amount.  

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The Glycemic Index and Insulin Resistance: Their Effect on Lung Cancer

What is the glycemic index?

At its most basic level, the glycemic index is a format for measuring how quickly certain foods raise the body’s blood sugar levels. Foods in the glycemic index are rated on a scale that ranges from 0-100. The higher the value on the glycemic index, the faster your blood sugar will rise. Foods with a lower glycemic index are absorbed by the body more slowly. 

It’s important to note that foods with a high or low glycemic index are not indications of their nutritional value. Most people need a mix of these types of foods for a healthy diet across all the food groups. 

What is insulin resistance?

Insulin is a natural hormone that is produced by the pancreas. Insulin allows the body to recognize and process sugars (glucose). However, for some people, there is not enough insulin present to process sugars at the right pace. For many people, the cause is too much sugar in the bloodstream. If the body doesn’t process the glucose as it should, sugar levels in the body start to rise, and in some cases to dangerously high levels. This can lead to type 2 diabetes if not controlled with diet and/or medications.

How Does Insulin Resistance Impact Lung Cancer Development? 

The link between the glycemic index and lung cancer is insulin resistance.

When insulin resistance develops, it can also lead to the activity of a certain cellular growth factor chemical that plays a role in cancer development. Previous studies have suggested a possible correlation between high-Glycemic index diets and/or insulin resistance and colorectal cancer, breast cancer, and prostate cancer. There is now an indication that it can also be connected to lung cancer. 

The lung cancer study is particularly interesting because of the association between a high-GI diet and lung cancer among non-smokers. That said, it’s important to note that these results show only an association and not a cause and effect. Keep in mind, the researchers didn’t take into account other illnesses that may cause cancer, such as heart disease, high blood pressure and diabetes.

But even so, this study contributes to the growing body of evidence that poor diet and obesity play a critical role in the development of cancer. As we seek to better understand the mechanisms of cancer, it’s empowering to know that our everyday choices could have an impact on cancer prevention.

Changing Your Diet Can Decrease the Risk of Lung Cancer and Other Cancers

There are a number of ways in which the foods and drinks we consume can either increase or decrease our risk for cancer. Alcohol consumption has been linked to a number of different types of cancer. Recent studies even suggest that alcohol may cause an increased risk of lung cancer. 

Early studies also suggest that eating diets that are higher in fruits and vegetables, or those that eliminate red meat may reduce risk factors for lung cancer. While these studies are still preliminary, following a healthy diet and some regular exercise (3 times per week) decreases the risk for a variety of different types of cancer including esophageal cancer, breast cancer, and oropharyngeal cancer, just to name a few. 

If you are looking for specific types of foods to include in your diet, focus on increasing foods with higher levels of antioxidants. This includes berries, dark leafy greens, and oats. However, antioxidant supplements have not been linked to reductions in cancer and can interfere with cancer treatments. 

Understanding the GI Diet and How It Reduces Insulin Resistance

The GI (glycemic index) diet is a nutrition plan that focuses on eating carbohydrate-containing foods that are less likely to impact your blood sugar levels. The diet plan works by assigning a number to the food based on how much it impacts your blood sugar level. Generally, the GI levels are divided into three categories:

  • Low GI: 1 to 55
  • Medium GI: 56 to 69
  • High GI: 70 and higher

The numbers above are used as a way to guide people toward healthier options with a lower GI index. For example, white bread has a GI index of 71 but whole wheat bread has a GI of 51. The idea is that over time people will learn which foods they should avoid to keep a low GI. 

There are limitations to the GI diet. For example, it doesn’t focus on portion sizes, calorie count, carbohydrates, or fats for weight loss. Because it doesn’t consider portion size, you may have to use your own reasoning to determine if a food should be avoided. For example, watermelon has a GI of 80, which is considered high. However, the digestible amount of carbohydrates in watermelon is low, so it would take a lot of watermelon to raise your blood sugar levels. 

Here is a general understanding of the types of foods that fit into each GI category:

  • Low GI: Leafy greens, most fruits, uncooked carrots, kidney beans, chickpeas, lentils, and bran cereals
  • Medium GI: Sweet corn, bananas, uncooked pineapple, raisins, oat cereals, and multigrain, oat bran or rye bread
  • High GI: White rice, white bread, and potatoes

Know All of Your Lung Cancer Risk Factors 

It’s important to be aware of the different risk factors for lung cancer. It’s always helpful to know how your lifestyle or other factors can impact your health long term. Talk to your doctor about your risk factors, and learn what you can do to minimize the chances of being diagnosed with lung cancer during your lifetime. 

If you need help with creating a dietary plan, consult with a registered dietitian. If you’re already a patient at Rocky Mountain Cancer Centers, our dietitians will be happy to help you create a healthy eating plan. It’s never too late to start eating healthier foods!

If you or someone you know has been diagnosed with lung cancer, please request an appointment with Rocky Mountain Cancer Centers today. Our lung cancer specialists care for patients in Denver, Colorado Springs, Boulder, and other locations throughout the Colorado Front Range.