I never use margarine. It is marketed as a butter alternative with less cholesterol, but it is not exactly healthy due to its chemicals and colourings. I prefer olive oil, but sometimes there is no substitute for butter, such as in tagliolini with truffles. Even olive oil is not a good match. Use less butter or cook dishes that don’t need it. However, cocoa butter from chocolate pods is increasingly popular. I’d rather use cocoa butter than margarine any day.

Vitamins are delicate and will always suffer from heat, so the key is to minimise loss. Obviously, the best way to retain vitamins is to eat vegetables and raw fruit. If that’s not possible, stir-frying in a little oil for a short time is a good method. Vegetables lose nutrients when boiled and you can see it in the colour of the water when you are done. Instead of just boiling them, make a simple vegetable broth so that vitamins are not drained away.

Using more herbs and spices will just hide the fact that your dish doesn’t have enough salt. For those who really need it, pharmacies sell salt substitute with a lower salt content. Another option is to cook without salt and simply season at the table so you know the exact amount used. But overall, I recommend Maldon English Sea Salt. The pyramid shape of the crystals reacts differently on your palate, so less salt is needed for the same effect.

I recommend buying a small non-stick pan that you will only ever use for frying egg whites. Generally, I do not like non-stick pans. They can be dangerous because the bits that scratch off the surface are harmful when ingested. Egg yolks are almost pure fat, which is why egg whites often stick and why you need a non-stick pan. Use a little cotton or tissue to wipe a thin layer of oil on the pan before frying the egg whites.

French fries are soaked in oil and deep-fried, which introduces toxins to the body and takes longer to digest. If you must deep-fry, use new oil every time. When you are out and eating deep-fried food, you don’t know how long they have kept that oil. When my kids ask for French fries, I bake potatoes in a little oil and tell them that they are “Italian” French fries. The health difference is not huge. But at least you are baking and using far less oil, without soaking your potatoes in a vat of oil.

If you have no choice, soy milk tends to be fine for cooking as long as you do not mind the flavour. Personally, the only way I like soy milk is very cold with lots of sugar, which is not exactly healthy. But if you like soy milk, it can bea substitute. Another option is natural soy bean fat, called soy lecithin. It does not have much flavour but add stexture to certain dishes that require milk or cream. Natural cocoa butter is another alternative.

The goal in cooking lean or fatty meat is to retain juices and flavour, so there is not much difference in method. Lean meat can be difficult so try to use methods that promote moisture. You can stir fry meat in a little oil to keep it moist. Vacuum slow-cooking (sous vide) is very good if you have the equipment. The easiest thing is to make a roast. When you roast a piece of muscle, the process naturally relaxes the muscle and makes it succulent. Remember to slice it thin.