NMU 89 – How the High-fat North American Diet Shown to Initiate Colon, Breast and Pancreatic Cancer
Nutrition / Natural Medicine Update No. 89 (May 3, 2018)
with Dr. James Meschino
Topic: How the High-fat North American Diet Shown to Initiate Colon, Breast and Pancreatic Cancer
Source: Journal Cell Reports (April 2018)
A brilliant study was published in the journal Cell Reports in April 2018, that helps explain the strong association between eating the typical high-fat North American diet, being overweight and increased risk of colon cancer, breast cancer, and pancreatic cancer. It also explains why being overweight and eating a high-fat diet are not linked to increased risk of lung cancer in human observational studies. This study is important because colon cancer is the second-leading cause of cancer death (when combining male and female data), breast cancer is a leading cause of cancer death in women and pancreatic cancer is the tenth most diagnosed cancer in the U.S. and has a very poor prognosis in most cases.
So, here’s how the story unfolds. We know that cancer develops in stages. In the first stage, a normal cell in the body becomes transformed into a cancer cell. This is the initiation stage of cancer. The transformed malignant cell can sit there idly for many years without dividing rapidly into a malignant tumor. It can just sit there hiding in the weeds for many years, sometimes 10-25 years, before proliferating into a malignant tumor mass. Or it may never produce a tumor at all. In many cases, however, the transformed malignant cell starts dividing after a period of time, forming a malignant tumor. When this happens, it’s referred to as “the tumor promotion stage”. Then, tumor cells can spread through the lymphatic system or the bloodstream to start new tumors in other areas of the body. This is called, “tumor progression” or metastasis. Malignant tumors can also invade tissues that are adjacent to them in the tumor progression stage as well.
Over the years many studies have revealed the mechanisms through which being overweight promotes tumor promotion and malignant progression (e.g., oxidative stress, chronic inflammation, dysbiosis, and hormonal alterations), but it has remained unclear as to how a high-fat diet and being overweight cause the initiation, or the first step, in cancer development. The study in Cell Reports in April 2018 sheds light on this process. What the researchers revealed is that normal colon cells, breast cells and, pancreatic cells can sense when a malignant cell is starting to form in the neighborhood. And without the help of the immune system, the healthy normal cells in the neighborhood can exert anti-tumor activity on their own and eliminate or eradicate the emerging malignant cell. This process has been termed “epithelial defense against cancer” (EDAC).
These researchers went on to show that in the presence of being over weight or the regular consumption of a high-fat diet, healthy normal colon, breast and pancreatic cells were unable to eliminate and destroy the emerging malignant cells. They went on to show that certain fats, especially saturated fats and the omega-6 fat linoleic acid, which accounts for 7% of calories in the North American diet, were the worst offenders – suppressing the ability of healthy cells to eliminate malignant cells in their vicinity.
Many vegetable oils are high in linoleic acid, and thus most health experts suggest using olive oil and canola oil, which are rich in health-promoting monounsaturated fat (oleic acid), as an alternative to most vegetable oils. The study also showed the protective effect of flaxseed oil, which increased the ability of healthy cells to eliminate transformed malignant cells. Flaxseed oil is rich in the omega-3 fat, alpha linolenic acid. The high fat diet, mostly containing the undesirable saturated fats and omega-6 fats also promoted inflammation, and the omega-6 fat linoleic acid increased the production of specific local hormones called prostaglandin series-2 that are known to promote cancer development via several mechanisms.
The intake of omega-6 fat was also associated with greater infiltration of inflammation-promoting fibroblasts and macrophage cells, which are linked to increased cancer development as well. Providing mice with aspirin, which blocks the conversion of omega-6 fats into prostaglandin-series 2, helped to decrease the number of malignant transformed cells. Now, I routinely take a supplement each day containing curcumin and other natural anti-inflammatories that block prostaglandin-2 synthesis for this reason. But that’s another subject altogether.
The study also showed that saturated fats gave the malignant transformed cells an available source of energy that increased their energy production and cell survival capacity (using aerobic metabolism). Another observation was that the high-fat diet did not inhibit the ability of lung cells to continue to eradicate transformed malignant cells, which is consistent with the finding the high-fat diets and obesity do not appear to increase the risk for lung cancer. The researchers concluded, “our work demonstrates that obesity can profoundly influence competitive interaction between normal and transformed cells (malignant cells) providing insights into cell competition and cancer preventive medicine”.
Here is my take. Studies indicate that at least 70% of colon cancer and 50% of breast cancer are linked to faulty dietary and lifestyle practices (J Natl Cancer Inst 1996 – Willett W). The high-fat North American diet, rich in saturated fats and the wrong kind of polyunsaturated fats (linoleic acid from many vegetable oils and arachidonic acid from beef and pork products), as well as trans-fats, are strongly linked to the development of many cancers. Consuming saturated fats is also strongly linked to being overweight and risk of obesity. The study in the April 2018 issue of Cell Reports helps us understand how these bad fats, as well as being over weight, undermines the ability of normal healthy cells to eradicate any malignant cells that are emerging in the vicinity within the colon, breast and pancreas. Failure to eliminate these malignant cells (cancer initiation) paves the way to cancer promotion and cancer progression, at a later date, especially if these dietary and lifestyle practices remain in place to propel the stages of cancer forward.
So, once again, I suggest you strongly consider the following practices:
- Replace most vegetable oils with extra virgin olive oil, canola oil, or use grapeseed oil for stir-fries (as it has a high smoke point).
- Minimize your intake of animal foods high in saturated fat (beef, pork, high-fat dairy products) as well as trans-fats and palm oil (even coconut oil).
- Eat fish twice a week and consider taking an Essential Oil supplement daily that contains fish oil and flaxseed oil (I also like the addition of borage seed oil because it is also shown to reduce inflammation).
- Don’t over eat carbohydrates to prevent their conversion into fat and related weight gain.
- Do at least 30 minutes of endurance exercise, 4-7 times per week, which among other benefits will help you achieve and maintain your ideal weight.
The evidence becomes more convincing over time that regular consumption of the bad fats, as well as being overweight, are important contributing factors to the development of many common cancers, including colon, breast and pancreatic.
I have included a link to the research paper in the text below.
Sasaki A, Nagatake T, Egami R et al. Obesity suppresses cell-competition-mediated apical elimination of RasV-12-transformed cells from epithelial tissues. Cell Reports, vol 23, issue 4. P:974-982. April 2018. https://www.cell.com/cell-reports/fulltext/S2211-1247(18)30480-7
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