July 29, 2025
Obesity is a major risk factor for cancer, linked to at least 13 different cancer types and higher cancer-related mortality. It promotes tumor growth through high insulin levels, high blood sugar, lipid abnormalities, and chronic inflammation. Moreover, obesity weakens the body’s natural anti-tumor immune defense.
But does the type of fat in our diet matter?
On July 25, 2025, researchers from Harvard Medical School answered this question in a landmark study published in Nature Metabolism:
“The source of dietary fat influences anti-tumour immunity in obese mice.”
Key Findings: Not All Fats Are Created Equal
The research compared the effects of animal fats (lard, beef tallow, butter) and plant fats (olive oil, coconut oil, palm oil) in high-fat diets on tumor growth and immune function in obese mice.
✔ Animal fats:
- Increased tumor size by 40–60%
- Reduced infiltration of CD8 T cells and NK cells in tumors
- Lowered production of IFN-γ, a key immune molecule
✔ Plant fats:
- Did not accelerate tumor growth significantly
- Preserved immune cell function and anti-tumor activity
Why? The LCAC Link
Mice on animal-fat diets showed higher blood levels of long-chain acylcarnitines (LCACs)—molecules that impair immune cells.
Plant-fat diets did not trigger this harmful effect.
What Does This Mean for Cancer Risk?
- Not all high-fat diets are equal for cancer risk.
- For obese individuals, choosing plant-based fats may help maintain immune protection—even without losing weight.
- Future cancer therapies could target dietary fat composition, not just calories.
Take-Home Message
- Avoid animal fats like lard, beef tallow, and butter.
- Prefer plant fats like olive oil and coconut oil for better immune health.
What you eat matters—not just how much.
Reference:
Harvard Medical School, Nature Metabolism (2025).
