Glycemic Index, Glycemic Load, and Head and Neck Cancer

Glycemic Index, Glycemic Load, and Head and Neck Cancer

Review of Cancer Causes Control 2003;14(7):657-662.

Two important risk factors for head and neck cancers (upper aero-digestive tract) are tobacco (smoking and chewing) and alcohol (drinking). But even for individuals who have a history of smoking, chewing tobacco, and/or using alcohol, certain types of diet may increase or decrease risk of these cancers. Glycemic Index has become a hot topic in cancer research. Recent research is telling us that many types of cancer may be linked to this measure. A recent study published in the journal Cancer Causes and Control looked at high glycemic index foods and high glycemic load diets and risk of head and neck cancers (upper aero-digestive tract). This article review discusses the findings of this study. This study indicates that eating more foods with a high glycemic index and eating a diet with a higher glycemic load INCREASES the risk of upper aero-digestive tract cancers. We provide PRACTICAL information on what these findings mean. We explain what glycemic index and glycemic load are. Most importantly, we provide ideas for using this information in a dietary plan to reduce risk of upper aero-digestive tract cancers. Factors such as past history of smoking, age, and genetics cannot be changed, but diet and nutrition can! This type of information will allow people to take concrete and practical steps to decrease their risk of upper aero-digestive tract cancers.

This article also appears in the Esophageal Cancer Section of this Website.

Note: Numbers appearing at the end of sentences indicate research references. References are listed at the end of each article.

Background

The two biggest risk factors for head and neck cancers (oral cavity, pharynx, esophagus, and larynx; also called the upper aero-digestive tract) are tobacco (smoking and chewing) and alcohol (drinking) (1-4). But even for individuals who have a history of smoking, chewing tobacco, and/or drinking, certain types of diet may increase or decrease risk of these cancers (5). And even though tobacco and alcohol are the major causes of head and neck cancers, dozens of studies tell us that diet and nutrition are important in the prevention of these cancers (6-31). Most of this research has focused on specific foods and categories of foods. More recently, the concept of glycemic index has become a hot topic in cancer research. A study published in the journal Cancer Causes and Control looked at high glycemic index foods and high glycemic load diets and risk of head and neck cancers (32). It is hoped this type of research will help identify dietary factors that increase or decrease risk of these cancers. Factors such as past use of tobacco and alcohol, age, and genetics cannot be changed, but diet and nutrition can! This type of information will allow people to take concrete and practical steps to decrease their risk of head and neck cancers.

What Are Glycemic Index & Glycemic Load?

About Glycemic Index

Glycemic Index (GI) is a number value that tells us how quickly the carbohydrate in a certain food will raise blood sugar in the body. The higher the number, the more quickly the carbohydrate from a given food will raise your blood sugar. These numbers are compared to how quickly a reference food with a GI of 100, usually white bread or white table sugar, raises blood sugar. Foods with a GI below 100 raise blood sugar more slowly than white bread. Foods with a GI above 100 raise blood sugar more quickly than white bread.

What is glycemic load and why is it important?

Glycemic Load (GL) can be a more useful measure than Glycemic Index (GI). Glycemic Load considers both the GI of a food and how many carbohydrates are in a normal SERVING size. For example, carrots have a  GI of 131 and white pasta has a GI of 71 (33). However, a SERVING of carrots has a Glycemic Load (GL) of 5.2 while a serving of pasta (1 cup) has a very high GL of 28 (33). In order to have the same glycemic load from carrots, you would have to eat nearly TWO pounds of them. This shows how glycemic index can be misleading. Some foods with a high glycemic index, do NOT raise blood sugar quickly, when eaten in a normal serving size!

What The Study Found

For this study (32), researchers combined people from three smaller studies together to allow them to better study the connection between Glycemic Index (GI), Glycemic Load (GL) and risk of head and neck (upper aero-digestive tract) cancers. This includes cancers of the oral cavity, pharynx, esophagus, and larynx. A total of 1,362 men and women with upper aero-digestive tract cancers and 3,322 men and women without these cancers were asked about their diet. This information was used to classify the men and women regarding the amounts and types of different foods they had eaten in the past. In particular, the researchers looked at how many high Glycemic Index (GI) foods these people had eaten and they looked at the overall Glycemic Load (GL) of people's diets. This is important to study because eating more high glycemic index foods may increase risk of diabetes, heart disease, and some cancers (34). Information on other lifestyle factors was collected and accounted for in the study. Researchers used this information to examine whether or not GI and GL were related to having a history of head and neck cancer. Two important results came out of this study.

First , researchers found that the men and women who ate a diet with the highest average Glycemic Index (GI) had 50% higher risk (1.5 times the risk) of upper aero-digestive tract cancers when compared to people eating a diet with the lowest average GI. In other words, the study suggested that eating more high Glycemic Index foods increases the risk of upper aero-digestive tract cancers. 

As part of this result, researchers determined that for every additional 10 units of GI that people ate each day on average, they raised risk by 20%. In other words, for each increase in 10 units of GI, risk of upper aero-digestive tract cancers increased by 20% (1.2 times).

Second , researchers found that men and women eating a diet with the highest Glycemic Load (GL) had 80% higher risk (1.8 times the risk) of upper aero-digestive tract cancers when compared to people eating a diet with the lowest Glycemic Load. In other words, the study suggested that a diet with a higher Glycemic Load increases the risk of upper aero-digestive tract cancers. 

As part of this result, researchers determined that for every additional 100 units of GL that people ate on average, they raised risk by 20%. In other words, for each increase in 100 units of GL, risk of upper aero-digestive tract cancers increased by 20% (1.2 times).

What do these results mean?

If we assume that the people studied are similar to most people, then this study suggests that eating a diet with more high GI foods increases risk of head and neck (upper aero-digestive tract) cancers. Having a diet with an overall high Glycemic Load (GL) increases risk of head and neck cancers even more! This is one of the first studies to look at how these particular measures, Glycemic Index (GI) and Glycemic Load (GL), affect risk of these cancers. However, other research tells us that eating high GI foods and more sugar may increase risk of other cancers including ovarian, endometrial, breast, colorectal, pancreatic and lung cancers (35-42). Therefore, it makes sense that this may be the case for upper aero-digestive tract cancers too.

How can I change my diet to reduce my risk of head and neck (upper aero-digestive tract) cancers?

Clearly, the most important things you can do to reduce your risk of head and neck cancers are to stop using tobacco (smoking & chewing) and to stop using alcohol (beer, wine, hard liquor), if you currently use these products. Tobacco, in particular, is a large risk factor for these types of cancer. Alcohol is a small to moderate risk factor for these cancers.  Using both tobacco and alcohol together is a very large risk factor for head and neck cancers. However, it is important to remember that even for people with these other risk factors, diet may protect against these cancers to some degree. Even for those who have a long history of smoking and drinking, a good diet may help reduce risk of head and neck cancers. You can't change your past use of tobacco and alcohol, but you can stop using these products today AND improve your diet to decrease your risk of these deadly cancers!

In general, WHOLE plant foods, such as vegetables, fruits, whole grains, and especially legumes (beans) have a LOW Glycemic Load (GL) If you base your choices around these foods, you will do well to keep your GL low. In addition to this, there is plenty of research that tells us that plant foods, especially fruits and vegetables, can reduce risk of many types of cancer (43). Therefore, if you focus your diet around WHOLE plant foods, you will eat a diet with a low GL AND you will be including the cancer fighting nutrients found in plant foods.

What about the Atkins' Diet?

The Atkins' Diet is a very popular weight loss diet. The Atkins' Diet focuses on low glycemic index foods and has a low glycemic load overall. Why isn't this diet a good one to follow?

The Atkins' Diet does have a low glycemic load, which can be a good thing. However, the downside of this diet is the LACK of healthy cancer fighting foods! The Atkins' Diet requires you to cut out most of the VERY FOODS that we know fight cancer the best - vegetables and fruits (43). For this reason, the Atkins' diet is not ideal for people who want to reduce risk of cancer.

In addition to this, the Atkins' diet can be loaded with saturated fat. Numerous studies tell us that saturated fat may increase risk of many types of cancer as well as heart disease, the two biggest killers in the United States (44). For all of these reasons, a plant-based diet that contains plenty of vegetables, whole grains, legumes, and fruit appears to be the much better choice for people who are concerned about their risk of cancer. This type of diet will have a low glycemic load. More importantly, unlike the typical Atkins' diet, eating plants will give you a diet that contains thousands of healthy cancer-fighting nutrients.

Use the following chart to help you pick the best, cancer-fighting, low GL foods! We have divided them into Red and Green foods.

Red means, "Stop, Use These Foods Only Occasionally."

Green means, "Eat These Healthy Foods Often."

Red High GL Use ONLY Occasionally	Green Low GL Eat As Often As You Can
Beverages	Beverages
Soda Pop	Skim Milk
Fruit Punches	Soy Milk
Juice Cocktails	Kefir (fermented milk)
Most Sport Drinks	Tomato Juice
Apple Juice	Grapefruit Juice
Orange Juice	Water
Desserts	Whole Fruit
Cakes, Cookies, Candies	Whole Vegetables, except potatoes
Doughnuts & Pastries	Legumes (Beans)
Candy Bars & Hard Candy	Nuts & Seeds
Snack foods such as chips & pretzels	Air popped popcorn
Sugar-added cereals	High Fiber Muffins (e.g. whole bran)
Sugary breakfast 'tarts' & 'bars'	Whole grain cereals
Foods containing corn syrup or high fructose corn syrup	Whole grains such as barley & buckwheat

A Few Additional Tips

• Always pick whole fruit over fruit juice. An orange has a very low GL of approximately 4-5. A glass of orange juice has a much higher GL of about 13-15!
• Remember that GI can be misleading. Carrots have a GI ranging from 80 to 130, based on the type of carrot. This seems very high. However, the GL of a SERVING of carrots is very, very low, at just 1!
• Eat beans! Beans are nutrition power-houses and they contain healthy fiber and cancer fighting nutrients. Most beans have a very low GL of between 5 and 10.
• Read labels. Scan the first 4-6 ingredients in the list. The higher an ingredient is listed, the more of it you find in the food. If you see the terms, corn syrup, high fructose corn syrup, brown sugar, or cane sugar near the top of the ingredient list, this food is likely to have a higher GL.
• As a general guide, foods with a GI below 50 and foods with a GL below 10 are the best options. GI numbers below 50 and GL numbers below 10 are considered low, and therefore healthy.
• Always use WHOLE GRAIN breads, bagels, baked goods and pastas. Here's a tip: If you see the word 'enriched' in the ingredient list, this product is NOT whole grain. Instead look for words such as 'whole grain' , 'stone ground', 'whole ground', 'whole wheat flour', 'whole oat flour', or 'whole barley flour'. These words tell you that a bread product is a whole grain.
• Generally, the more fiber and protein a food contains, the lower its GL will be.

NOTE: If you are in cancer treatment, these diet changes may not be right for you.

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Publish Date: 12/2003