Not micronutrients, but like them they act in small amounts: what is established, what is plausible, and the precautions.
A spice is counted in pinches: 1 to 2 g in a dish, rarely more. At that dose, its carbs, proteins and calories weigh nothing, and its minerals next to nothing. Cumin is one of the spices richest in iron, 66 mg per 100 g; a teaspoon, 2 g, brings about 1.3 mg, less than a serving of lentils.
What makes them interesting is their active compounds: the gingerols in ginger, the curcumin in turmeric, the capsaicin in chilli. A few have an effect measured in trials, often modest and at doses cooking does not reach. Others call for a precaution, and they are often the same ones.
In Europe, no health claim is authorized for a spice: plant claims have been awaiting assessment since 2010 (EU register). A jar promising to "support immunity" or "burn fat" goes beyond what is established.
Ginger is the best-studied spice against nausea. In pregnant women, a meta-analysis of twelve trials, nearly 1,300 women, finds it eases nausea better than a placebo, with no clear effect on vomiting and no notable side effect (Viljoen, 2014). The doses studied are around 1 g a day, in several takes.
Against motion sickness, the evidence is thinner. A trial at sea on 80 naval cadets found less vomiting and cold sweating with 1 g of ground ginger than with a placebo (Grøntved, 1988); later studies are split. It remains less effective than motion-sickness drugs, but does not make you drowsy.
It is taken as fresh ginger, grated into an infusion, or ground: the powder is simply more concentrated, 1 g of powder being worth about 5 to 10 g of fresh root.
At cooking doses, no known risk. In capsules, more than a gram a day: caution with anticoagulants, and during pregnancy, ask the doctor or midwife.
Cinnamon is sold for blood sugar. A meta-analysis of ten trials in type 2 diabetics finds a drop in fasting blood sugar, but no effect on glycated hemoglobin, the marker that counts over time (Allen, 2013); the Cochrane review finds no clear effect (Leach, 2012). It is not a treatment.
Its real subject lies elsewhere. Chinese cinnamon, cassia, the most common in supermarkets, contains coumarin, toxic to the liver. EFSA sets its tolerable dose at 0.1 mg per kilo per day (EFSA, 2008), 6 mg for a 60 kg adult: what 1 to 2 g of cassia brings, half to one teaspoon. Ceylon cinnamon, dearer, contains almost none.
A pinch in a dessert, no worry. A spoonful every day in porridge is cassia's limit: choose Ceylon if you put it in everything, and half as much for a child.
Turmeric owes its color to curcumin, which makes up only about 3% of its powder. It is one of the most studied molecules in the lab, for inflammation in particular, but it crosses the gut very poorly: most of it leaves without being absorbed.
Black pepper changes the picture: its piperine slows the removal of curcumin, and 20 mg of piperine multiplied the amount absorbed twentyfold in volunteers (Shoba, 1998). Hence the habit of pairing them, in cooking as in capsules.
Kitchen turmeric raises no known problem. Concentrated supplements, especially with piperine, have caused hepatitis (case review, 2024): avoid with liver or bile duct disease, or on anticoagulants. Piperine also alters the absorption of some drugs.
The burn of cayenne pepper comes from capsaicin. A meta-analysis finds it raises energy expenditure a little, around 50 kcal a day, and slightly curbs appetite (Ludy, 2012): real, but too small to slim anyone on its own.
Paprika is a sweet pepper, dried and ground: little or no capsaicin, but plenty of carotenoids, which give it its color. Cayenne pepper can irritate the stomach and worsen reflux.
Cumin, coriander, cardamom: everyday spices, mostly for flavor. No established health effect at cooking doses, no particular precaution.
Clove: rich in eugenol, the compound dentists use to soothe a tooth. Its effect stops there.
Fenugreek: its seeds are rich in soluble fiber, and taken at several grams a day, far beyond cooking, it lowers diabetics' blood sugar a little (meta-analysis, 2024). It makes sweat smell of maple syrup.
Saffron: a few small studies on mood, with 30 mg of extract a day, too few to conclude. A dish holds a few tens of milligrams; it is the dearest spice, and the most adulterated.
Nutmeg is toxic in large amounts. From about 5 g, a whole nut, myristicin causes nausea, palpitations and hallucinations; one poison center recorded dozens of cases in ten years, often teenagers seeking the effect (Marseille, 2019). Kitchen pinches are safe.
Licorice raises blood pressure if overdone: its glycyrrhizin, which gives it its sweet taste, holds on to salt and drives out potassium. One dessert a day at most, and avoid it with high blood pressure, pregnancy, or heart or kidney disease. It also flavors our homemade ice cream and Build your dessert.
The surest benefit of spices comes from no molecule at all: they bring flavor without salt or sugar. A dish lifted with cumin, paprika or pepper does better without salt; a dessert with cinnamon, vanilla or licorice tastes sweeter than it is.
That is the principle of our recipes: the vanilla and licorice in the homemade ice cream, the cocoa in Build your dessert. And it is the same movement as on the Sugars page: the less you sweeten, the more your sense of sweetness recalibrates.