Mayonnaise

Food · Fat & Oil · Food, Typed Supps

Two-thirds fat — but mostly the unsaturated kind, which changes the story.

Stage by stage

Emulsion (Lecithin): Egg yolk lecithin holds oil suspended in water — the physics that makes mayonnaise mayonnaise.
Fat digestion (Small intestine): Bile salts and lipase break the fat down; most of it is unsaturated.
Carotenoid uptake (Micelle formation): That fat solubilises carotenoids from vegetables so they can actually be absorbed.
Sodium and sugar (Systemic): Commercial versions add around 480 mg sodium and 8 g sugar per 100 g.

Timing

On carotenoid-rich vegetables specifically — that is where the fat is doing measurable work rather than just adding calories.

Time to effect

Same meal: The absorption effect applies to the meal it is eaten with.
—: No cumulative effect beyond overall diet.

Allergens

Contains: Eggs. May contain: Mustard, Soya. Derived from what this food is, not from a product label.

Eating patterns

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

Satiety

32 on the satiety index, where white bread is 100 — low. Modelled from the Holt et al. (1995) measurements.

Environmental footprint

7.3 kg CO2e and 1098 litres of freshwater per kg, matched to "Palm oil" in Poore & Nemecek (2018), Science 360.

Cost band

Mid — roughly £8 per kg, as a band midpoint rather than a price.

Key nutrients

Fat
Vitamin E
Sodium

Nutrition per 100g

Calories: 634
Protein: 0.8g
Carbohydrate: 8.7g
of which sugars: 7.9g
Fat: 67.2g
of which saturated: 8.3g
Fibre: 0.5g
Sodium: 480mg

Food vs. supplement

Fat-free dressing is the counterproductive choice on a salad: trials show it substantially reduces absorption of the carotenoids you ate the vegetables for.

Kitchen tip

Use full-fat and use less, rather than fat-free and more — the fat is what gets the carotenoids out of the vegetables.

Common myth

“Fat-free dressing is the healthier choice on a salad.” In reality: Controlled trials show salads eaten with fat-free dressing deliver markedly less lutein, lycopene and beta-carotene — the fat is what dissolves them into a form the gut can take up. A small amount of full-fat dressing beats a generous amount of fat-free.