Celeriac

Food · Vegetable · Food, Typed Supps

Celeriac looks like a dirt-covered brain, but it's really celery's underground cousin — and it's loaded with vitamin K, potassium, and fiber.

Stage by stage

Chewing & Prep (Mouth): Peeled and diced, celeriac's fibrous, starchy flesh is broken down by chewing and salivary enzymes, releasing its earthy, celery-like flavor compounds.
Stomach Breakdown (Stomach): In the stomach, gastric acid and enzymes dismantle cell walls and starches, releasing embedded vitamin K, potassium, and B vitamins for further digestion.
Intestinal Absorption (Small Intestine): The small intestine absorbs celeriac's soluble fiber, potassium, and fat-soluble vitamin K (helped along by whatever fat the dish contains), while insoluble fiber moves on to feed gut bacteria.
Bone & Blood Use (Liver & Bone): Absorbed vitamin K travels to the liver and bones, where it activates proteins involved in blood clotting and bone mineralisation — the reason people on blood thinners like warfarin are told to keep their vitamin K intake consistent rather than eliminate it.

Timing

Vitamin K1 is fat-soluble, so eating celeriac with some added fat — roasted in oil, mashed with butter, or dressed with vinaigrette — improves absorption compared with eating it completely fat-free.

Time to effect

Days to months: Digestive and mild blood-pressure benefits from celeriac's fiber and potassium can appear within days of regular intake, while any contribution to bone health from its vitamin K content depends on months of consistent consumption, since bone remodeling and osteocalcin activation are gradual processes.

Allergens

Contains: Celery. Derived from what this food is, not from a product label.

Eating patterns

Fits: Vegan, Vegetarian, Pescatarian, Halal, Kosher, Gluten-free. Depends on the product: Keto, Low-FODMAP.

In season

September to March in the northern hemisphere, March to September in the southern.

Satiety

The satiety index is measured on 240 kcal servings. At 42 kcal per 100 g that is 577 g of this, which is not a serving anyone eats — so the index has nothing to say about it.

Environmental footprint

0.4 kg CO2e and 28 litres of freshwater per kg, matched to "Root 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

Vitamin K
Potassium
Fiber
Vitamin C

Nutrition per 100g

Calories: 41.6
Protein: 1.7g
Carbohydrate: 5.4g
of which sugars: 3g
Fat: 0.2g
of which saturated: 0g
Fibre: 5.5g
Sodium: 21mg

Food vs. supplement

Celeriac delivers its vitamin K, potassium, and fiber as a package deal with water and bulk, unlike an isolated vitamin K supplement, which provides a concentrated dose of the vitamin alone.

Kitchen tip

Peel celeriac's rough, knobby skin thickly with a knife rather than a vegetable peeler, and hold cut pieces in acidulated (lemon or vinegar) water to prevent browning until you're ready to cook or serve them.

Common myth

"Celeriac is just the root dug up from the same celery plants sold as stalks." In reality: Celeriac and stalk celery are both Apium graveolens, but they're different cultivated varieties (var. rapaceum vs. var. dulce) bred for different growth habits: celeriac plants are selected to swell into an edible underground hypocotyl/root mass, while stalk celery plants are selected to grow long fibrous petioles, so celeriac bulbs are not harvested from the same plants that produce grocery-store celery stalks.