Fats, cholesterol and your blood pressure
The type of fat you eat, and how much, is important for your heart health.
Too much fat, especially saturated fat, will raise your blood cholesterol which, like high blood pressure, can lead to heart disease and stroke.
If you have high blood pressure, keeping an eye on your fat intake will help you stay healthy in the long term.
How can fat affect your health?
You need some fat in your diet for your body to work properly and to absorb other nutrients from the food you eat.
Fats are very high in energy and any fats your body doesn’t use is stored as body fat. It’s important not to eat too much fat because being overweight will raise your blood pressure and your risk of heart disease and stroke.
Eating too much fat, especially saturated fats, also raises the amount of cholesterol in your blood. Cholesterol is a fatty substance made by the liver from the fat we eat. Your body needs a certain amount of cholesterol, but if there is too much it can build up in the walls of your arteries, making them narrower so less blood can flow through them.
This process is called atherosclerosis, and it raises your risk of heart attack and stroke.
If you have high blood pressure and high cholesterol together, this speeds up the process of atherosclerosis, raising the risks further, especially if you smoke or have diabetes. Keeping an eye on your fat intake will help to lower your cholesterol levels and your risk of serious illness.
Saturated fat
The saturated fat you eat is made into cholesterol by your liver, and eating too much saturated fat will raise your cholesterol.
Saturated fat is usually found in foods made with animal products and some plant oils, such as:
- red meat and pork
- processed meat such as sausages
- butter and ghee
- cheese
- cream and other dairy products
- baked products such as pastries, cakes and biscuits
- chocolate
- savoury snacks such as crackers
- coconut oil and palm oil
When you’re shopping, try to avoid foods high in saturated fat. Look out for foods with a red traffic light for saturated fat on the label and see other ways you can cut back below.
How much saturated fat is too much?
The government recommends that men eat no more than 30g saturated fat a day, and women have no more than 20g.
Trans fats
Trans fats are another type of fat that has a similar effect to saturated fat. They’re included in hydrogenated vegetable oils and if a food contains these oils it has to say so on the label. Most people in the UK don’t eat more than the recommended limit of 5g a day, so it’s more important to look for saturated fats on the label.
Unsaturated fats
Choosing unsaturated fats instead of saturated fats can help to lower your blood cholesterol. All fats are high in energy so can still make you gain weight if you eat too much of them, and cutting back on your overall fat intake will help to look after your heart health.
Which foods are high in unsaturated fats?
There are two types of unsaturated fat, polyunsaturated and mono-unsaturated. These fats are found in:
- olive oil, rapeseed oil and sunflower oil and their spreads
- avocados
- some nuts
- oily fish
TIP: When you’re cooking, use rapeseed oil in place of olive oil. Olive oil shouldn’t be heated to very high temperatures, but it’s perfect for salad dressings.
Is all cholesterol bad?
Not all cholesterol in the blood is bad. We need some cholesterol in the blood to function properly, but if there is too much it can clog up the arteries, leading to heart disease and stroke.
Cholesterol is carried by the blood in two main forms:
- LDL (low density lipoprotein) or ‘bad cholesterol’. This carries cholesterol around your body and to your arteries. It can build up in the artery walls.
- HDL (high density lipoprotein) or ‘good cholesterol’. This picks up excess cholesterol from the arteries and takes it to the liver to be broken down or removed from the body as waste.
The ideal is to have a low LDL level and a high HDL level.
Eating too much saturated fat raises your LDL, or ‘bad’, cholesterol, and replacing it with unsaturated fats helps to raise your HDL, or ‘good’, cholesterol.
What should your cholesterol levels be?
The amount of cholesterol in your blood can be measured with a blood test. Use the table as a general guide to what your cholesterol level should be.
| Type of cholesterol | What your cholesterol level should be (in millimoles per litre of blood, written as mmol/L) |
|---|---|
| Total cholesterol | Less than 5mmol/L or less than 4 if you have other health problems |
| LDL cholesterol | Less than 3mmol/L or less than 2 if you have other health problems |
| HDL cholesterol | More than 1mmol/L particularly if you have problems that affect your heart and blood vessels |
| Total cholesterol / HDL ratio | Below 4mmol/L is best |
How to lower your cholesterol
One of the best ways to keep your cholesterol levels healthy is to go for a balanced diet.
- Eat plenty of fruit and vegetables.
- Fill up on plenty of starchy wholegrain foods.
- Eat fish at least once or twice a week. White fish is low in fat and high in vitamins and minerals. Oily fish, such as salmon, trout and mackerel, are rich in unsaturated fats called Omega-3 fatty acids which help to control your blood pressure, the amounts of other fats in your blood, and the function of your heart and brain.
- Always choose lean meats, poultry and lower-fat dairy foods instead of fatty meats and full-fat dairy products.
- Swap saturated fats for unsaturated fats. Avoid butter, ghee, lard and full-fat dairy foods and replace them with rapeseed and olive oils, or sunflower and corn oils.
- Include beans, nuts and soya in your diet, they are also low in saturated fats.
Being physically active and stopping smoking if you smoke will also help to lower your cholesterol.
Simple cooking methods to keep foods low in fat
Some of the fat we eat comes from the cooking oils we use when frying. Try these simple tricks to help you eat less fat.
- Instead of frying foods, steam, boil, poach, grill, bake, microwave, barbecue or stir-fry them.
- Use only a small amount of oil, and choose oils high in polyunsaturated or monounsaturated fat.
- Try cooking with water or tomato juice.
- Measure oil using a teaspoon or tablespoon rather than pouring it straight into the saucepan, or use an oil spray.
- Skim the fat off sauces, gravy and casseroles.
- Trim meat of all visible fat and remove skin from poultry before cooking. Prepare curries and stews the day before and chill them overnight, this way unwanted fat becomes solid on the top and can be removed.
- When you grill or roast meat, use a trivet which allows the fat to drain off. Replace fatty ingredients with healthier alternatives, for example, use low-fat yoghurt or fromage frais in recipes that call for cream.
Switch to less saturated fat
Download our free FoodSwitch app which can help you make healthier choices when shopping. By scanning the barcode of a product the app will tell you whether it is red, amber or green in saturates (saturated fat) and suggest similar but healthier alternatives.
Wolfson Institute of Population Health, Charterhouse Square, London, EC1M 6BQ
