Most people are familiar with the terms trans, saturated, polyunsaturated and monounsaturated fat. But how do they differ, and what do they do?
The first thing to understand is that fats are classified by their "saturation". This means the amount of hydrogen atoms attached to the fat molecules.
The Loveable Rogue: Saturated Fat
Saturated fats are completely "saturated". In other words, each fat molecule is completely covered in hydrogen atoms.
Saturated fats remain solid at room temperature. They’re found in meat and dairy products, cooking fats and hard margarines. They're typically to blame for the high calorific value of most cakes, biscuits, chocolates and puddings!
Unfortunately, these are also the fats that raise blood cholesterol levels, promote hardening of the arteries, and contribute to blood clots, heart attacks and strokes.
Your Oily Ally: Polyunsaturated Fat
These fats are typically liquid at room temperature and are not "saturated" with hydrogen atoms.
Polyunsaturated fat may help prevent heart disease by lowering blood cholesterol levels, and could reduce the symptoms of joint problems and certain skin diseases. They include the healthy heart and brainfood fat, omega-3, which is found in oily fish salmon, mackerel, sardines and fresh (not canned) tuna.
Your Mediterranean Mate: Monounsaturated Fat
Found in vegetable oils that remain liquid at room temperature, monounsaturated fats are also not "saturated" with hydrogen atoms.
Monounsaturated fats are found in olives, olive oil, groundnut oil, nuts, and avocados. The so-called "Mediterranean diet" is rich in monounsaturated fat. Monounsaturates, have been shown to lower blood cholesterol levels and therefore help in reducing the risk of heart disease.
The Frankenstein Fat: Trans Fat
Trans fats are created in an industrial process that adds hydrogen to liquid vegetable oils to make them more solid. They're found in processed, fried (especially doughnuts) and baked goods (including partries and biscuits).
They've been popular in the past because they're cheap, easy to use and last a long time. However, recent research has shown that trans fats raise your bad (LDL) cholesterol levels, lower your good (HDL) cholesterol levels, and increase your risk of developing heart disease.
How Much is Too Much?
All fats are equally high in calories and should be eaten in moderation. A good place to start is to look at the labels on the back of foods.
- High fat is considered anything more than 20g fat per 100g
- Low fat is 3g fat or less per 100g.
- High levels of saturated fat is more than 5g saturates per 100g
- Low levels of saturated fat is 1.5g saturates or less per 100g
Trans fats don't need to be labelled separately under European law. However, hydrogenated vegetable oil must be listed, and this may contain trans fats.
Don’t be Fooled by “Low-Fat” Labels
Don't always assume that 'low fat' on a label means that it's a healthy choice.
All the 'low-fat" really means is that the food is 25% lower in fat than the standard equivalent. If the food is high in fat in the first place, then the low-fat version may still be high in fat!