Does diet affect cancer risk?

Diet's Impact on Cancer Risk

Diet significantly affects cancer risk, with approximately one-third of all cancer deaths in the United States attributed to dietary factors. 1 The evidence is particularly strong that dietary choices can substantially reduce lifetime cancer risk through multiple mechanisms.

How Diet Affects Cancer Risk

Plant-Based Foods as Protective Factors

• Fruits and vegetables: Evidence is particularly strong that increased consumption of fruits and vegetables reduces the risk of colon cancer 1, 2
• Recommended intake: At least five servings of fruits and vegetables daily 1, 2
• Protective mechanisms: Plant foods contain complex combinations of beneficial compounds including:
  • Vitamins and minerals
  • Fiber
  • Phytochemicals that may work synergistically 2
• Whole grains and legumes: Should be included several times daily 1
  • Choose whole grains over processed (refined) grains
  • Include beans as an alternative to meat

Dietary Factors That Increase Cancer Risk

1. High-fat diets:

   • Substantial evidence links excessive fat intake to increased risk of developing cancers of the breast, colon, and prostate 1
   • Recommendation: Reduce total fat intake to 30% or less of total calorie intake 1
   • Limit consumption of meats, especially high-fat meats 1

2. Processed foods:

   • Limit consumption of salt-cured, smoked, and nitrite-preserved foods 1
   • Smoked foods contain carcinogenic tars similar to those in tobacco smoke 1

3. Alcohol consumption:

   • Heavy drinking increases risk for cancers of the oral cavity, larynx, and esophagus 1
   • Risk is greatly magnified in cigarette smokers 1
   • Some evidence suggests regular alcohol consumption increases breast cancer risk in women 1
   • Recommendation: Limit consumption of alcoholic beverages, if you drink at all 1

Comprehensive Dietary Approach for Cancer Prevention

American Cancer Society Guidelines 1, 2

1. Choose most foods from plant sources:

   • Eat five or more servings of fruits and vegetables each day
   • Include grain products in every meal
   • Choose whole grains over processed grains
   • Choose beans as alternatives to meat

2. Limit high-fat foods, particularly from animal sources:

   • Choose foods low in fat
   • Limit consumption of meats, especially high-fat meats
   • Reduce consumption of fats, oils, and foods rich in fats

3. Maintain healthy weight and be physically active:

   • Be at least moderately active for 30 minutes or more most days
   • Stay within healthy weight range
   • Obesity increases cancer mortality risk by up to 55% in women and 33% in men 1

Important Considerations and Caveats

• Supplements vs. whole foods: Recent clinical trials of beta-carotene supplements showed that smokers taking the supplement developed lung cancer at higher rates than those taking placebo 1

  • This suggests that isolated nutrients may not provide the same benefits as whole foods
  • Taking single nutrients in large amounts may produce adverse effects

• Dietary pattern matters: Cancer risk reduction is best achieved through an overall dietary pattern rather than focusing on single foods or nutrients 1

• Preventable proportion: 30-50% of all cancer cases are preventable by following a healthy diet and lifestyle 3

• Combined approach: For maximum cancer risk reduction, dietary improvements should be combined with:

  • Weight management
  • Regular physical activity
  • Limited alcohol consumption
  • Avoidance of tobacco

The evidence clearly demonstrates that a diet rich in plant foods, low in animal fats, and moderate in calories can substantially reduce cancer risk when combined with other healthy lifestyle practices.