Oils and fats
For each one: how to use it, the best version, how to prepare it, what it does, and where it goes wrong.
Avocado oilThe oil for the pan. It works cold as well, and then it does something most oils do not.Read on
How to use it
Cooking and frying. It also works cold, over a salad, where it pulls more out of the salad than the salad gives you on its own.
The best version
Refined for the pan, unrefined and cold pressed for cold use. Buy from a producer that says where the fruit came from: avocado oil is expensive enough to be worth cutting with something cheaper, and that has been demonstrated on oil bought in shops.
How to prepare it
In the pan, let the oil come up to heat before the food goes in. Cold, pour it over the plate just before eating rather than stirring it through.
What it does
The fat is almost entirely the fat you are asking for: 71 percent monounsaturated, 13 percent polyunsaturated, 16 percent saturated.
Fat is what carries the pigments in your vegetables into your blood, and without it most of them stay behind. In a crossover study in healthy adults, a salad was served with 150 grams of avocado or 24 grams of avocado oil, to the same effect. Alpha-carotene in the blood came out 7.2 times, beta-carotene 15.3 times and lutein 5.1 times what the same salad gave without it.
Watch out
Avocado oil is one of the oils that gets adulterated, the way olive oil does, and you cannot taste it. Researchers have had to run shop-bought bottles through nuclear magnetic resonance to see which ones had been cut with cheaper oils such as sunflower or safflower. Buy on producer and origin, not on price.
Coconut oilFor your mouth, not your pan. As a rinse it holds its own against chlorhexidine, without the brown staining.Read on
How to use it
Oil pulling. A spoonful in your mouth, let it melt, pull it through and between your teeth for a few minutes, then spit it out.
The best version
Virgin, cold pressed, unrefined. There is nothing else to look for. For your mouth it does not need to be organic and it does not need a label on it.
How to prepare it
Spit it into the bin and not the sink, because coconut oil sets hard as soon as it cools and your drain is cold. Then brush as usual: this does not replace a toothbrush.
What it does
Against the rinse a dentist prescribes, it holds up. Twenty-nine people rinsed for four days with coconut oil and four days with 0.2 percent chlorhexidine, with a washout in between. Plaque came back to the same degree, 1.67 against 1.61, and coconut oil stained the teeth less: 0.21 against 0.47.
Watch out
Not your cooking fat. Across sixteen trials pooled together, coconut oil raised LDL by 10.47 mg/dL compared with ordinary vegetable oils, and HDL by 4.00. That is why it sits here under your teeth and not under your stove.
Olive oilThe oil you use cold. What makes it worth buying is the first thing a hot pan destroys.Read on
How to use it
Cold. Over the salad, into a dressing, over vegetables that are already off the heat. A spoonful poured over a finished plate does more than the same spoonful that sat in the pan for half an hour.
The best version
Extra virgin, in a dark bottle, with a harvest date on the label rather than only a best-before date. Taste it neat: an oil that catches at the back of your throat is full of polyphenols, and an oil that tastes of nothing has lost them.
How to prepare it
Nothing to prepare. Storage is the whole job: dark, cool, capped, and finished within a few months. Light and air do what heat does, only slower.
What it does
The polyphenols are the point, and that has been measured with the oil itself. Two hundred healthy men took the same daily amount of olive oil for three weeks at a time, in three versions that differed in phenolic content and nothing else. On the richest oil, 366 mg per kg, HDL rose by 0.045 mmol/L; on the poorest, 2.7 mg per kg, by 0.025. Oxidised LDL fell by 3.21 U/L on the richest and did not move on the poorest.
In the largest diet trial there is, 7447 people at high cardiovascular risk were put on a Mediterranean diet with extra-virgin olive oil, the same diet with nuts, or advice to eat less fat. The olive oil group came out at a hazard ratio of 0.69 for heart attack, stroke or cardiovascular death.
Watch out
Heat costs you the thing you paid for. Extra-virgin olive oil fried for three hours at 180 degrees lost phenolics, and with them 3.7 percent of its monounsaturated and 17.2 percent of its polyunsaturated fatty acids. Frying in olive oil mostly wastes what you paid extra for.
The 2018 trial is a recalculation. The investigators found afterwards that at some sites not everyone had actually been randomised, withdrew their first publication and ran the numbers again. The result held, but this is not a clean experiment and it should be read as one that was repaired.