Key Highlights:
- Fructose is a naturally occurring sugar present in fruits, vegetables, and honey.
- Consuming fructose in the form of high-fructose corn syrup, commonly found in processed foods, can negatively impact health.
- Previous research has associated high-fructose corn syrup consumption with an increased risk of various illnesses, including cancer.
- A study conducted by researchers at Washington University in St. Louis suggests that dietary fructose may encourage tumor growth in animal models of melanoma, breast cancer, and cervical cancer.
Fructose: A Natural Sugar with a Controversial Role
Fructose is a natural sugar present in fruits, certain vegetables, and honey. Consuming fructose from natural sources like apples or dates is generally regarded as safe and beneficial to human health due to the accompanying fiber, vitamins, and minerals. However, when fructose is consumed in the form of high-fructose corn syrup (HFCS) found in processed foods such as sodas and packaged baked goods, it becomes a cause for concern.
Over the years, scientific studies have linked high-fructose corn syrup consumption to numerous health conditions, including Alzheimer’s disease, type 2 diabetes, fatty liver disease, kidney disease, and even cancer. As Gary Patti, PhD, the Michael and Tana Powell Professor of Chemistry, Genetics, and Medicine at Washington University in St. Louis, explained, “Fructose occurs naturally in some fruits and vegetables — so humans have always been exposed to it. What has changed over the past four to five decades is that we started using it as an artificial sweetener in processed foods. As a result, many people are exposed to much higher levels than ever before. It is important to understand what impact this has on human health.”
Dr. Patti is the senior author of a groundbreaking study recently published in Nature, revealing that dietary fructose may promote tumor growth in animal models of melanoma, breast cancer, and cervical cancer. This study highlights the urgent need to reconsider our consumption of fructose, particularly from processed sources.
Why Study Fructose in Cancer Research?
In this study, researchers employed an animal model to investigate the impact of a fructose-rich diet on cancer tumors. During the research, animals were fed a diet high in fructose, providing a controlled environment to observe its effects.
“It has been well established for over a century that cancer cells are addicted to glucose,” Dr. Patti said. “We take advantage of this in the clinic all the time. Patients are given a radioactive form of glucose that shows up in PET scans. Because cancer cells take up more glucose than most other healthy cells, they light up in the images.”
Dr. Patti elaborated on the similarities between glucose and fructose: “Glucose and fructose are made up of the exact same atoms. The only difference between them is the way in which the atoms are arranged. Given the avidity that cancer cells have for glucose, it’s compelling to imagine that they might use fructose in a similar way.”
Fructose, Lipids, and Tumor Growth
Upon analyzing the study results, Dr. Patti and his team discovered that the liver converts fructose into a lipid type known as lysophosphatidylcholines (LPCs), which are associated with inflammation. For cancer cells, which require significant amounts of lipids to divide and grow, an increase in LPCs in the bloodstream provides the necessary resources for tumor growth.
“When you eat an excessive amount of food, your body converts it into fat. That is your body’s way of storing energy,” Dr. Patti explained. “High levels of dietary fructose induce a similar process. The fructose is converted into a precursor of fat in the liver, called lipids. Those lipids can then feed the tumor.”
Dr. Patti further clarified the unique nature of cancer cells: “Cancer cells are unique from most other cells in the body because they are rapidly dividing, which is what allows tumors to grow larger. For a cancer cell to divide into two, it has to make a new set of cellular contents. That requires a lot of nutrients, which ultimately come from the diet. It is therefore intuitive to imagine that dietary modifications could influence the process of tumor growth.”
Although these findings shed light on the connection between fructose and cancer growth, Dr. Patti cautioned that the relationship is complex. “The complication is that there are a lot of variables to think about, such as where the tumor is in the body, which oncogenes it has, what drugs the patient is using, what dietary components are transformed into prior to reaching the tumor, etc.,” he added. “Our understanding of these issues is only at its very early stages, but there are an increasing number of studies starting to illuminate important details. I hope our study will be part of that equation.”
Processed Foods and Cancer Risk: The Mechanisms
To understand the broader implications of this study, Medical News Today spoke with Anton Bilchik, MD, PhD, a surgical oncologist and Director of the Gastrointestinal and Hepatobiliary Program at Providence Saint John’s Cancer Institute. “We’ve been suspicious for quite a while that certain food supplements such as sweeteners and processed food increase the risk of getting cancer, but we’ve never really known the mechanism,” Dr. Bilchik explained.
Dr. Bilchik, who was not involved in the study, noted its significance: “This is one of the few studies that provides a possible mechanism for fructose, which is found in corn syrup, processed food, and sweeteners, a mechanism that may cause a variety of different cancers. So there may be some truth to the fact that people need to be very cautious about using sweeteners or using sugars that are not from fruits and vegetables, but are in processed foods.”
Dr. Bilchik also pointed to an alarming trend: “Fructose is in so many food products that we eat, and we’re now seeing a massive uptick in young people being diagnosed with certain cancers, such as colorectal cancer, and that is being linked to processed food. And we know that processed food has high contents of fructose in them, so this just provides a possible mechanism.”
Practical Steps to Decrease Fructose Intake
Reducing dietary fructose, especially from processed sources, is a practical way to mitigate potential health risks. Monique Richard, MS, RDN, LDN, a registered dietitian nutritionist and owner of Nutrition-In-Sight, shared strategies to lower fructose consumption.
“A simple way — though not always possible or easy — to avoid excessive or less beneficial types of fructose is to eat more foods that do not have packaging or labels such as produce,” Richard advised. “Say yes to fructose in fruit and ‘no, thank you’ to the fructose [in] the fruit roll-up.”
Richard emphasized the importance of whole foods: “The fiber and vitamins and minerals that naturally accompany the carbohydrates such as fructose in fruit and vegetables is less likely to be over-consumed, although portions do still matter. The fiber and nutrients are also beneficial for our gut microbiota, which we are also observing being affected by excessive fructose consumption from ultra-processed foods.”
Another critical step involves reading food labels and understanding ingredient lists. “There are numerous names for sugar,” Richard explained. “Educate yourself about the types and names of sugar so that you’re not trading one for an equal or similar product. Food manufacturers understand how to market to make money. A label could say ‘no high fructose corn syrup’ but could have just as much or more fructose, glucose, or sucrose (table sugar), just to name a few.”
Finally, Richard urged moderation. “Keep in mind, there is no reason to be obsessive and never include these items — hello holidays, Halloween, and favorite treats. But knowing how much, how often, and making sure that real food is not replaced in lieu of these things is the most important for our daily dietary patterns and enjoyment of life,” she concluded.
The Path Forward
While the study highlights the potential dangers of excessive fructose consumption, particularly from processed foods, more research is needed to confirm these findings in human populations. Clinical trials comparing the effects of artificial sweeteners and natural sugars could provide deeper insights. For now, reducing reliance on processed foods and prioritizing whole, nutrient-rich options remain practical steps for safeguarding health.
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