Onions

Nutrition per ~85 g · 1 onion

6.5 g net carbs after fiber.

Vitamins

Minerals & other

Bioactives estimated

Representative amounts for this food, not measured for this item. Real content varies widely by variety, ripeness and storage.

What drives the score weighted inputs

These are the scored components, not a sum: the published score also reflects normalisation across the catalog, so the parts above will not add to 83.

What it feeds primary sources only

Systems

Pathways

Overview

Onions (Allium cepa) originated in Central Asia and have been cultivated for over 5,000 years across civilizations. They contain unique bioactive compounds including quercetin (a flavonoid), organosulfur compounds (thiosulfates, sulfoxides), and inulin (a prebiotic fiber). Red and yellow onions contain significantly higher polyphenol concentrations than white varieties. The sulfur compounds in onions are activated when cells are damaged—cutting, chopping, or cooking—making preparation method crucial for bioavailability. For longevity, onions support cardiovascular health through anti-inflammatory and lipid-modulating mechanisms, promote glycemic control via inulin and chromium content, and provide prebiotic fiber supporting gut microbiota diversity. Studies suggest regular onion consumption is associated with reduced cardiovascular disease risk and improved bone density, particularly in postmenopausal women. The quercetin in onions exhibits antioxidant and anti-cancer properties in vitro and animal models, though human evidence remains emerging. Onions are calorie-sparse but nutrient-dense, making them ideal for longevity-focused diets emphasizing whole-food density over volume.

Health benefits 5

Pairs with

• Pair raw onions with tomatoes in salads because raw preparation maximizes organosulfur compound bioavailability, and tomato lycopene absorption is enhanced by dietary fat from olive oil dressing
• Combine caramelized onions with garlic because both contain complementary organosulfur compounds that synergistically enhance anti-inflammatory effects
• Pair onions with cruciferous vegetables (broccoli, cabbage) because both provide glucosinolates and organosulfur compounds that work through overlapping detoxification pathways
• Combine onions with healthy fats (olive oil, avocado) because quercetin is fat-soluble, requiring dietary lipids for optimal absorption in the small intestine

In the kitchen

• Consume onions raw or lightly cooked to preserve heat-sensitive organosulfur compounds; cooking beyond 20 minutes significantly reduces thiosulfate concentrations
• Store whole onions in cool, dark, well-ventilated conditions (50-70°F) to extend shelf life up to 2-3 months without refrigeration; avoid plastic bags which trap moisture
• Slice or chop onions 10-15 minutes before consumption or cooking to allow enzymatic activation of organosulfur compounds; let sit at room temperature to maximize conversion
• Prioritize red and yellow onions over white varieties, which contain 2-3x higher quercetin and polyphenol concentrations for equivalent intake

When to eat it anytime

Onions lack bioactive compounds requiring specific circadian timing. Consuming throughout the day optimizes cumulative prebiotic fiber intake and polyphenol exposure. Raw or lightly cooked preparations at any meal support consistent anti-inflammatory and metabolic benefits.

Fasting-compatible

Raw onions are compatible with fasting protocols; organosulfur compounds bioavailability is unaffected by fed/fasted state. Timing of intake relative to meals does not significantly alter quercetin or inulin efficacy.