News and views on the latest health issues

Articles


Articles

The fats of life

Tags: diet , fats , saturated

The fats of life‘The trick is to get a good balance of the right fats,’ explains Lyndel Costain, registered dietician and member of Dieticians in Obesity Management (UK).

 ‘You need some fat in your diet to absorb fat–soluble vitamins A, D, E and K, to build cell membranes and provide essential fats that the body cannot make.

You also need some fat stores to insulate and cushion the body and make vital hormones.’
 
Even those who want to shed pounds need fat. Studies have shown that including small amounts of fat in their diet helps people to lose weight; a little fat helps fill you up. Another recent study in the Journal of Clinical Nutrition found that drizzling a small amount of fat–based dressing over vegetables boosts the absorption of carotenoids, which are potent, disease–fighting antioxidants.
 
‘Never try to cut fat out completely – your body needs it,’ warns registered nutritionist Anita Bean. ‘Including foods rich in essential fats – oily fish, avocados, nuts, olives and seeds – in moderation can help you burn body fat more efficiently, improve your aerobic capacity and boost your immunity. Plus, foods rich in essential fatty acids – olive oil, flaxseed oil, walnut oil, nuts, seeds and oily fish – are good for the skin, as well as for strengthening connective tissue around fat cells.’

The good guys

According to Anita Bean: ‘You should aim for most of your fat to be the monounsaturated or polyunsaturated kind, avoiding saturated fats as far as possible.’

Monounsaturated fats

‘These fats are good at raising levels of good cholesterol and lowering bad cholesterol, and can also cut your heart disease and cancer risk,’ she says.

Olive oil is the best–known source of monounsaturated fat, but it is also found in rapeseed oil, avocados, sunflower and sesame seeds, soya oil and nuts such as peanuts, almonds and cashews.

‘These fats are good at raising levels of good cholesterol and lowering bad cholesterol, and can also cut your heart disease and cancer risk,’ she says.

Olive oil is the best–known source of monounsaturated fat, but it is also found in rapeseed oil, avocados, sunflower and sesame seeds, soya oil and nuts such as peanuts, almonds and cashews.

Polyunsaturated fats

Lyndel Costain explains: ‘There are two families of polyunsaturated fats, each headed by a “parent” essential fatty acid: linoleic acid (Omega 6 family), and alpha–linoleic acid (Omega 3 family). These fatty acids are needed for cell membranes, growth and to produce eicosanoids – chemical messengers that help regulate blood clotting, blood pressure and immunity.’

Omega 3s

Found in oily fish such as sardines, mackerel, fresh tuna, salmon, trout, herring, pumpkin seeds, flaxseeds and flaxseed oil, soya oil and Omega 3–enriched eggs. Experts say they’re easily absorbed into cell membranes, which means they have far–reaching benefits: they’ve been found to help keep the heart, brain, joints and skin healthy, as well as enhance mood.

Fish oils are thought to strengthen brain cell membranes and improve brain function by boosting blood flow; it’s believed the DHA (docosahexaenoic acid) in fish oils may also help stave off dementia and aid memory and concentration.

They are particularly beneficial to a foetus’s developing brain, too; pregnant women are encouraged to up their intake of oily fish in the last few months of pregnancy. Breast–feeding mothers, too, are advised to include fish in their diet.

Omega 3 fatty acids found in fish oils are a natural anti–inflammatory and can help with rheumatoid arthritis. Research published in the medical journal Drug Discovery Today showed that taking fish oil supplements can slow down the destruction of cartilage and alleviate joint inflammation.

Fish oils can also be an effective mood booster. Research published in the American Journal of Psychiatry found that fish oil supplements helped six out of ten people suffering from depression.

‘Until now, medical research has demonstrated a benefit from Omega 3 fats in protecting people from heart and circulatory disease. This systematic review of numerous studies concludes that there is no clear evidence either way,’ he says.

 ‘More research is needed to establish why some studies have shown a slightly increased risk associated with eating very high amounts of oily fish, which is possibly related to mercury levels.’

Omega 6s

These fatty acids include linoleic acid and gamma linoleic acid (GLA) which are found in sunflower oil, soya, corn and safflower oils. It’s also found in evening primrose oil and borage (starflower) oil.

‘The trouble with these fatty acids is they’re easier to find in foods than Omega 3s,’ explains Anita Bean. ‘Most people eat too much Omega 6 in relation to Omega 3, which results in an imbalance of prostaglandins, or “mini hormones”, responsible for controlling blood clotting, inflammation and the immune system.’

We should be aiming for a ration of no more than five times the amount of Omega 6 to Omega 3 (most diets have a ratio of 10:1). Good combinations of the two can be found naturally in sunflower seeds, sesame, pumpkin, hemp and linseed (flax).

Evening primrose oil and starflower oil are rich in GLA; it is converted into prostaglandins and clinical trials have found that increased intakes of GLA can help alleviate menstrual breast pain and PMS. It’s also been found to alleviate eczema.

The bad guys: saturated fats

These include butter, lard, block margarine and cooking fat (they’re the fats that are hard and solid at room temperature). They’re mainly found in animal products such as meat, dairy foods, and in pastries, cakes, biscuits and deep–fried food.

‘Too many saturates have been found to raise levels of harmful cholesterol in the blood which can be deposited in the arteries, leading to heart disease,’ says Anita Bean.

‘These fats raise levels of bad low–density lipoprotein (LDL) blood cholesterol and cause a fatty, cholesterol–rich build–up on blood vessels, which restricts blood flow to your cells.’

Cutting your intake of saturated fat can reduce women’s risk of breast cancer, according to a recent study reported in the Journal of the American College of Cardiology. The research showed that women who eat more than 90g of fat per day are twice as likely to develop breast cancer as those who eat 40g of fat or less each day.

UK health experts suggest women eat no more than 70g of fat each day – ‘as little as 40g a day may be hard to maintain’ according the British Nutrition Foundation – but by keeping your intake of saturated fats to a minimum (10–20g a day), and making sure you stick to the healthiest kinds, you can reduce your risk.

The really bad guys: trans–fatty acids

These start off as unsaturated fats but become ‘trans–fatty acids’ when hydrogen gas is added to vegetable oils to make them more solid – it also increases their shelf life. They’re found in processed foods like cakes, biscuits and other convenience foods.

‘They’re actually more harmful than saturated fats,’ warns Anita Bean. ‘Trans–fats raise levels of bad LDL cholesterol in your body to a greater extent than saturated fats, while reducing the levels of good HDL cholesterol – something saturated fat doesn’t do. They’re best avoided altogether.’

Researchers at the University of Oxford have called for food labels to list trans–fats as well as cholesterol and saturated fat. A recent analysis found a 2 per cent increase in the energy intake from trans–fatty acids was associated with a 23 per cent increase in the occurrence of coronary heart disease. In fact, the harmful effects of trans–fatty acids were seen even when intake was really low, only 3 per cent of total daily energy intake (20–60 calories).

These start off as unsaturated fats but become ‘trans–fatty acids’ when hydrogen gas is added to vegetable oils to make them more solid – it also increases their shelf life. They’re found in processed foods like cakes, biscuits and other convenience foods.

‘They’re actually more harmful than saturated fats,’ warns Anita Bean. ‘Trans–fats raise levels of bad LDL cholesterol in your body to a greater extent than saturated fats, while reducing the levels of good HDL cholesterol – something saturated fat doesn’t do. They’re best avoided altogether.’

Fat facts worth knowing

It doesn’t take much to whizz past the recommended daily allowance for fat, unless you have some idea of the fat content of the foods you are eating. Here are just a few examples, but be warned, most of the fat in these will be ‘baddies’!

  • one chocolate bar (average): 14g fat
  • average supermarket cheese and tomato pizza: 118g serving (half a thin and crispy pizza) contains 9.5g fat
  • a slice of Victoria sponge (average): 12g fat
  • 40g packet of crisps: 13.5g fat
  • takeaway chicken chow mein (average): 25g fat.

Eat your fats

Your body needs one to two servings of essential fatty acids and monounsaturated fats each day for energy, eye function, brain–power and healthy skin and hair. Here’s where to get them:

  • 80g (quarter to one half) of an avocado
  • One tablespoon of olive or rapeseed oils
  • Half an ounce (10g) butter
  • 2 tablespoons of low–fat mayonnaise
  • 2 tablespoons of sunflower or pumpkin seeds
  • 4–6 walnuts
  • 3–4 tablespoons hummus
  • 150g oily fish such as sardines or mackerel
  • Oily fish: salmon, trout, mackerel, sardines, herring.

back to top


Sign up to our monthly Better Health newsletter to receive updates on our latest health and wellbeing updates.


Sign up to newsletter

Ask the expert

Got a question about health or wellbeing?
Our team of medical experts are ready to help.