High-Fat Diets Increase Breast Cancer Risk and Metastasis

• A high-fat diet had a significant effect on platelet activation — Platelets in mice fed a diet consisting of 60% fat did not behave normally. They became excessively sticky and aggressive, and began forming clumps, especially in the lung tissues.

• Aggressive platelets didn’t just randomly cluster — These cells specifically released a protein called fibronectin, which significantly enhances the cancer cells’ ability to stick to blood vessels. Fibronectin acts like glue, providing cancer cells with a firm grip onto blood vessel walls.

Without fibronectin, cancer cells would struggle to latch onto the blood vessels in the lungs, severely limiting their potential to invade and spread. But when fibronectin levels are elevated, as it happens with high-fat diets, cancer cells easily attach, survive, and rapidly proliferate in new areas.

• Fibronectin damages cellular health — To confirm how pivotal fibronectin was, the researchers conducted an additional test — they blocked fibronectin’s action. In doing so, they dramatically slowed cancer spread, emphasizing how damaging a high-fat diet can be by ramping up fibronectin production.

• Reversing the harmful effects is doable — When the researchers switched the test mice from a high-fat diet back to a normal one, they noticed a significant reduction in platelet activation and cancer spread.

The change didn’t take long, showing that dietary adjustments provide rapid and powerful protection against metastasis. It’s a convincing reason to take immediate action, especially if you’re constantly consuming high-fat meals.

• Blood coagulation provides a clue to cancer risk — Another observation was related to blood coagulation times. Blood from the animals on high-fat diets coagulated faster — a change that accurately predicted worse outcomes. Essentially, faster blood-clotting indicates platelet hyperactivity, making your bloodstream a more hospitable environment for cancer cells.

By monitoring blood clotting times, health care providers can identify individuals at greater risk of aggressive cancer spread due to dietary factors, enabling earlier and more targeted interventions.

• The mechanism of platelet hyperactivation is closely linked to dietary fats — As noted earlier, activated platelets secrete high amounts of fibronectin, setting the stage for cancer metastasis by enhancing cancer cell adhesion to the blood vessels and lung tissues. But there’s another mechanism at play — they also shield cancer cells from your immune system.

Normally, your immune cells patrol your bloodstream, identifying and eliminating rogue cancer cells. However, these clumped platelets form a protective barrier around cancer cells, making them practically invisible to immune surveillance. As a result, cancer cells survive longer, multiply rapidly, and spread more efficiently throughout your body.

• Obesity compounds the risks of a high-fat diet — According to the researchers, having excess weight worsens the metastasis:

“As well as affecting primary BC [breast cancer] tumor growth, obesity enhances the metastasis of these cells to the lungs in a manner that is dependent on neutrophils, involving vascular dysfunction and increased endothelial transmigration of the tumor cells.

Moreover, obesity also induces chronic inflammation, while enhancing pro-thrombotic signaling in both platelets and endothelial cells, and promoting a state of hypercoagulability in cancer patients.”

• High polyunsaturated fat (PUF) intake is harmful — The study identified PUFs, particularly omega-6, as particularly detrimental. As noted by the researchers:

“[O]verall caloric intake has a larger impact on the development of obesity, which is linked to redox and hormonal abnormalities that promote tumor proliferation …

[E]xcess oxidative stresses may activate many transcription factors, including those that control the expression of genes implicated in pro-inflammatory pathways. The effect of polyunsaturated fatty acids (PUFAs) on cancer risk has been shown to depend on the ratio of -6 to -3 PUFAs. In vivo findings demonstrated that -6 PUFAs stimulate tumor development, while -3 PUFAs are protective.”

• Timing and duration of fat consumption influence cancer risk — Researchers noted that consistent consumption of high-fat foods over several years markedly amplified the risk. In other words, prolonged exposure to these dietary fats created cumulative damage, increasing the likelihood of breast cancer diagnosis later in life.

• The underlying biological mechanisms of fat intake on cancer — Excess fat consumption elevates your body’s levels of harmful substances called reactive oxygen species (ROS). These are unstable molecules that cause oxidative stress in cells, leading directly to DNA damage and cancerous changes.

Chronic oxidative stress doesn’t just damage individual cells — it sets off a chain reaction of inflammatory reactions, activating genes known to drive breast cancer growth.

• High intake of unhealthy fats disrupts hormone levels — The researchers noted that excess body fat tissue actively produces estrogen, and elevated estrogen levels strongly correlate with breast cancer development, especially in postmenopausal women. The estrogenic activity accelerates breast cell growth. Thus, consuming high-fat diets also indirectly amplifies the body’s own hormonal environment.

1. Cut back on linoleic acid — Linoleic acid (LA) is a harmful type of fat commonly found in vegetable oils and processed foods, as it promotes inflammation that fuels cancer growth. Start checking labels carefully and avoid foods containing soybean oil, corn oil, sunflower oil, safflower oil, and ultraprocessed foods.

Choose healthier fats like grass fed butter, ghee, or tallow instead, as these fats do not contribute to inflammation and help protect your cellular health. For more information on how LA causes cellular damage, read my article “Linoleic Acid — The Most Destructive Ingredient in Your Diet.”

2. Moderate your fat intake — As the earlier research noted, high levels of fat are strongly linked to breast cancer, but completely eliminating fat is neither realistic nor healthy — the key is moderation. Aim for dietary balance, because your body still needs fat to function properly.

For metabolic efficiency, aim for a daily fat intake of about 30% of daily calories, and ensure they come from healthy sources, including full-fat raw dairy, which is a primary source of the essential odd-chained fat C15:0. Glucose is the preferred fuel for your cells, so those should make up the bulk (45% to 55%) of your calories.

3. Switch to whole, nutrient-dense foods — If you’re regularly eating processed or fried foods, now’s the right time to make a change. Swap out processed meals and snacks for natural, nutrient-dense whole foods.

Good choices include fresh vegetables, fruits, pasture-raised meats, wild-caught seafood, pastured eggs, and raw, grass fed dairy. These foods provide essential nutrients that support your immune system and promote optimal health.

4. Optimize your carb intake for healthy cells — Your cells rely heavily on carbohydrates for energy, so severely restricting carbs is not a good idea. Instead, choose healthy carbohydrates to fuel cellular energy without triggering inflammation.

Whole fruits (with pulp), cooked root vegetables, and easily digestible sources like white rice will provide stable, beneficial carbohydrates. These carbs support balanced hormone levels and reduce the oxidative stress that feeds cancer growth.

5. Get regular exercise — Supporting your healthy diet by adding regular exercise is an effective way to protect your health against cancer. Research shows that higher muscle strength and cardiovascular fitness reduced all-cause mortality by 31% to 46% across different cancer types and stages.⁴

Now, what kind of exercises are good for you? The best, and easiest one, you can do right away is go for a walk outside — aim for 10,000 steps a day. If you’re doing strength training, the sweet spot is around 40 to 60 minutes per week.

Any longer than that, your longevity becomes the same as if you weren’t exercising at all. For a more detailed explanation on this topic, read my article “Physical Fitness Strongly Linked to Improved Cancer Survival, Study Shows.”