Swiss Chard
Food · Vegetable · Food, Typed Supps
One cup of cooked Swiss chard packs a huge dose of vitamin K — great for most people, but something to watch closely if you take blood thinners like warfarin.
Stage by stage
- Chewing & Release (Mouth): Chewing ruptures chard's leaf cells, releasing vitamin K, carotenoids, vitamin C, and minerals bound in the plant tissue.
- Acid Breakdown (Stomach): Stomach acid and enzymes continue breaking down plant fibres, while bile is primed for release to help handle the fat-soluble vitamins.
- Intestinal Absorption (Small Intestine): In the small intestine, vitamin K and carotenoids are absorbed with help from dietary fat, while potassium and magnesium pass into the bloodstream and oxalates bind up a portion of the calcium and iron.
- Vitamin K Activation (Liver): The liver uses absorbed vitamin K as a cofactor to activate clotting factors and bone proteins like osteocalcin.
Timing
Eating chard alongside a source of fat, such as olive oil or cheese, improves absorption of its fat-soluble vitamin K and vitamin A.
Time to effect
- Days to weeks: Vitamin K reaches the bloodstream within hours of eating chard, but measurable effects on clotting-factor activity and bone-related markers build with days to weeks of consistent intake.
Allergens
None of the fourteen major allergens. Derived from what this food is, not from a product label.
Eating patterns
Fits: Vegan, Vegetarian, Pescatarian, Halal, Kosher, Keto, Low-FODMAP, Gluten-free.
In season
June to November in the northern hemisphere, December to May in the southern.
Satiety
The satiety index is measured on 240 kcal servings. At 19 kcal per 100 g that is 1.3 kg of this, which is not a serving anyone eats — so the index has nothing to say about it.
Environmental footprint
0.5 kg CO2e and 108 litres of freshwater per kg, matched to "Other vegetables" in Poore & Nemecek (2018), Science 360.
Cost band
Cheap — roughly £2.5 per kg, as a band midpoint rather than a price.
Key nutrients
Nutrition per 100g
- Calories: 19
- Protein: 1.8g
- Carbohydrate: 3.7g
- of which sugars: 1.1g
- Fat: 0.2g
- of which saturated: 0g
- Fibre: 1.6g
- Sodium: 179mg
Food vs. supplement
Whole Swiss chard delivers vitamin K bundled with fiber, potassium, magnesium, and carotenoids that an isolated vitamin K supplement can't replicate, and most people should meet their needs through food rather than supplementation.
Kitchen tip
Steam, sauté, or boil chard rather than eating large amounts raw — cooking softens its fibrous stalks, and boiling lets you discard the cooking water along with some of its oxalate content.
Common myth
"Swiss chard's high calcium content makes it a great dietary source of absorbable calcium." In reality: Chard is high in oxalates, which bind calcium in the gut into insoluble complexes, so only a small fraction of its calcium is actually absorbed compared with low-oxalate greens like kale or bok choy.
Recipes that use it
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