Study: Low-Fat Diet Reduces Incidence Of Precancerous Skin Lesions

Actinic keratoses (AK) are innocuous-seeming, precancerous skin lesions. They can progress to squamous cell skin cancer. They have a high prevalence (~50%) among fair-skinned people who've had lots of sun exposure.

"Millions of Americans have AKs, and the number continues to grow. In fact, AKs are so common today that treatment for these lesions ranks as one of the most frequent reasons people consult a dermatologist."
- American Academy of Dermatology

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The following study found that a low-fat diet reduces the incidence of AKs:
Effect of a Low-Fat Diet on the Incidence of Actinic Keratosis, New England Journal of Medicine, 1994

Design:

• 76 men and women, caucasian, non-diabetic, with a history of nonmelanoma skin cancer.
• Randomly assigned to a control group (n = 38) or intervention (low-fat) group (n = 38).
• 24 month follow-up.

Results:

• Control group consumed ~40% of their calories from fat.
• Intervention group consumed ~20% of their calories from fat.
• No significant difference in the ratio of polyunsaturated fat to saturated fat between the two groups during the 24 months.
• No significant difference in body weight between the two groups during the 24 months.

Findings:

"Our dietary intervention trial clearly indicates that a large decrease in calories consumed as fat reduces the incidence of actinic keratosis."

● Control group, 40% of calories from fat

о Intervention group, 20% of calories from fat

A person in the control group:

• With no history of AK, < 65 years, had a 56% chance of having one or more AKs during the 24 months (a risk 4.7 times greater than similar patient in low-fat group).
• With a history of AK, ≥ 65 years, had a 99% chance of having one or more AKs during the 24 months (a risk 8.4 times greater than similar patient in low-fat group).

Calories were kept the same between groups such that the low-fat group were eating more carbohydrates, getting ~65% of their calories from carbs.
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