Nutrition Facts with Dr. Greger

The Best Way to Cook Vegetables

February 12, 2026

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  • Microwaving is the gentlest cooking method, preserving over 97% of vegetable antioxidants, while boiling results in the greatest loss (about 14% loss on average), though frying should be avoided due to added calories and toxic byproducts. 
  • Bell peppers are the most vulnerable vegetable to antioxidant loss during cooking (up to 75% loss), whereas artichokes, beets, and onions retain nearly all their antioxidants even when boiled. 
  • To maximize sulforaphane from cruciferous vegetables like broccoli, cauliflower, or kale, use the "hack-and-hold" technique by chopping them and waiting 40 minutes before cooking, or add mustard powder (a source of the necessary myrosinase enzyme) to cooked or frozen vegetables. 

Segments

Antioxidant Cooking Method Comparison
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(00:00:22)
  • Key Takeaway: Microwaving preserves over 97% of vegetable antioxidants, while boiling causes the greatest loss (about 14% average loss).
  • Summary: Six cooking methods were tested across 20 vegetables to measure antioxidant activity. Boiling was found to be the worst method for losing antioxidants, followed by pressure cooking. Frying should be avoided entirely due to added empty calories and toxic byproducts.
Vulnerable and Resilient Vegetables
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(00:02:10)
  • Key Takeaway: Bell peppers lose up to 75% of antioxidants when cooked, while artichokes, beets, and onions are hardly affected by boiling.
  • Summary: Bell peppers are the most vulnerable vegetable, suggesting they should be eaten raw or added at the very end of cooking. Artichokes, beets, and onions retain nearly all their antioxidants even after boiling. Asparagus is also largely unaffected by any cooking method except frying.
Antioxidant Boosters from Cooking
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(00:03:13)
  • Key Takeaway: Carrots and celery consistently increase in antioxidant value upon cooking, and green beans increase unless boiled or pressure cooked.
  • Summary: Two vegetables, carrots and celery, tend to increase in antioxidant value regardless of the cooking method used. Green beans increase in antioxidant power when cooked using methods other than boiling or pressure cooking.
Sulforaphane Hack for Cruciferous Veggies
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(00:04:24)
  • Key Takeaway: The enzyme myrosinase, necessary for creating cancer-fighting sulforaphane, is destroyed by cooking, but can be restored by chopping and waiting 40 minutes or by adding mustard powder.
  • Summary: Sulforaphane formation requires the enzyme myrosinase, which is destroyed by heat, explaining why raw broccoli suppresses cancer cells better than boiled broccoli. The ‘hack-and-hold’ technique involves chopping greens and waiting 40 minutes before cooking to allow sulforaphane to form first. Frozen vegetables lack this enzyme due to commercial blanching, but adding mustard powder (ground mustard seeds) restores the enzyme activity.