Search This Blog

Thursday, 25 September 2014

Spread the news: butter may not be a yellow peril after all

New research shows that men who had had a heart attack were more likely to die from coronary heart disease when they replaced saturated fats with polyunsaturated fat in margarine

Many of us prefer the taste of butter to margarine, but are conscious of the risks to our arteries. So a new study apparently coming down on the side of animal fats in the butter-versus-margarine debate would seem cheering.
The research, published last week in the British Medical Journal, showed that men who had had a heart attack were more likely to die from coronary heart disease when they replaced saturated fats – found in dairy and fatty red meat – with polyunsaturated fat from safflower oil and safflower oil margarine.
These are surprising results, as polyunsaturated fats are usually seen to be the key to a healthy diet. However, experts have been quick to say that we shouldn’t use these findings to abandon vegetable oils found in margarine in favour of butter and lard.
“The safflower oil in the study is rarely used in this country,” says Tom Sanders, professor of Nutrition and Dietetics at King’s College, London. “It’s unusually high in omega-6 polyunsaturated fat, and people in the safflower oil intervention arm of the trial were getting 15 per cent of their energy from omega-6.
“Since 1991, UK nutrition guidelines have stated that no more than 10 per cent of our energy should come from polyunsaturates, and our current intake is around 6 per cent.”
Current thinking, then, is that you can have too much of a good thing in the shape of omega-6 rich polyunsaturated margarines. This is why margarine manufacturers have been moving away from the most omega-6 rich oils towards rapeseed and “high oleic” sunflower oil.
The latest large analysis on dietary fat and cardiovascular risk, published by the highly respected Cochrane library in 2011, said replacing saturated fat with unsaturated fats had a “small but potentially important reduction in cardiovascular risk”.
But unsaturated fats include different types of fats – such as monounsaturates, omega-3 polyunsaturates and omega-6 polyunsaturates – and increasingly it would seem that getting a balance of all three is key.
Omega-3 and omega-6 are essential fats, so-called as the body can’t make them and our diet must provide them. As integral components of cell membranes, they help coordinate cell-to-cell messaging, in particular influencing inflammatory signals between cells.
“We’ve long been aware of the anti-inflammatory nature of fish oil due to its omega-3 polyunsaturated content,” says Catherine Collins, principal dietitian at St George’s Hospital, London. “In contrast, we know that an excessively high intake of omega-6 polyunsaturates – found in sunflower and corn oils – has the opposite effect, increasing inflammation and pain. The balance between these two fats influences inflammation and contributes to cardiovascular risk.
“Monounsaturates (eg olive and rapeseed oils) are relatively inert fats, working with omega-3 fats to reduce inflammation.”
In practical terms, you’ll get the balance about right by eating one to two portions of omega-3 oily fish a week and using cooking oils and spreads that provide a balance of omega-6 polyunsaturated and monounsaturates.
But is butter ever OK? “I’d never have anything but butter on my veg,” says Prof Sanders. “And if you prefer it on your bread, too, that’s also OK, as long as you don’t trowel it on.”

Butter contains a great deal of saturated fat and also monounsaturated fat - these are highly stable. The smallest groups of fat in the butter are polyunsaturated - with more omega 6 than omega 3. The larger proportions of saturated and monounsaturated fats make it more difficult to damage the small minority of polyunsaturated fat. However that minority can still be damaged so it is still important to have fresh butter.

There are so many variables to this because plants oils in margarine are partially damaged by the hydrogenation process. It can be trans fats that are causing problems (not just polyunsaturated omega 6).

Polyunsaturated oils also easily damaged by heat, UV light and oxygen from the air. It could be the consumption of damaged oils that contributes to inflammations. Polyunsaturated omega 6 oils are valuable but should be consumed in their undamaged forms within nuts, seeds, whole grains not be heavily processed.

Omega 3 fatty acids are also polyunsaturated and susceptible to damage so should also be consumed fresh or ideally not hydrogenated.

A balance between omega 3 and omega 6 is also important for health - in controlling inflammation.

Replacing butter (mainly saturated fat) for omega 6 rich plant oils can potentially reduce the amount of damaged oils you are consuming, will increase the amount of saturated fat you are consuming and decrease the amount of omega 6 fatty acids you are consuming.

No comments:

Post a Comment