Saturated fats in butter, cream and meat are 'not as bad' as was once thought, say researchers
Advice given to millions to ditch animal fats in favour of lower-fat spreads and dairy in the early 1980s may have been unnecessary, say researchers.
More than three decades ago dieticians in the UK and the US adopted the guidelines in an effort to reduce coronary and cardiovascular disease but this latest study, published in the British Medical Journal (BMJ) has found that cutting down on animal fats does not necessarily lower the risk of stroke, heart disease or diabetes.
Conversely, say the researchers, the trans fats present in alternative products such as processed margarine have been found to raise the risk of death by as much as 34%. While the health implications of trans fats have been known for some time, it is still present in some commonly consumed foods, both in the UK and elsewhere.
While lead study author Dr Russell de Souza, assistant professor in the Department of Clinical Epidemiology and Biostatistics, at McMaster University in Canada, says that trans fats have "no health benefits" he also stressed that the findings did not mean consumers should increase their intake of foods high in saturated fats instead.
He says: "Trans-fats have no health benefits and pose a significant risk for heart disease, but the case for saturated fat is less clear.
"That said, we aren't advocating an increase of the allowance for saturated fats in dietary guidelines, as we don't see evidence that higher limits would be specifically beneficial to health."
Data from 50 different studies involving a total of one million people was analysed and no clear association between moderate saturated fat consumption and coronary heart disease (CHD), cardiovascular disease (CVD), stroke or type 2 diabetes could be drawn.
'Oodles of butter'
Professor of Nutrition and Dietetics at King's College London, Prof. Tom Sanders, cautioned: "It would be foolish to interpret these findings to suggest that it is OK to eat lots of fatty meat, lashings of cream and oodles of butter.
"Death rates from CVD have fallen in the UK by about 55% since 1997 despite the rise in obesity for reasons that remain uncertain but this may in part be due to changes in the food supply particularly fewer trans and more omega-3 fatty acids."
Victoria Taylor, Senior Dietitian at the British Heart Foundation, said of the findings: "The results of this review support existing guidance to avoid industrially produced trans fats. In the UK, industry action to remove these fats from manufactured foods means that our intakes are already below the recommended maximum 2% of food energy.
"While saturated fats were not robustly associated with total or deaths from CHD, this does not mean we should all go back to eating butter – the studies that this review is based on can’t show cause and effect. Rather, it highlights how difficult it is to understand the true relationship between diet and our health.
"Diets high in saturated fat are linked to raised cholesterol levels, a risk factor for CHD. But when one nutrient is reduced it will be replaced by another and, depending on what this is, it can have positive or negative health consequences."
In June this year the US Food and Drug Administration (FDA) declared trans fats "unsafe to eat" and issued guidance for food manufacturers to ditch the fat completely from their products within three years.
In 2010, the National Institute for Health and Clinical Excellence (NICE) made a number of recommendations to the UK food industry, including the elimination of trans fats, which was met with a level of disdain. Some supermarkets have since taken steps to remove trans fats from their own brand products and by 2012 the UK government had begun urging other food manufacturers to voluntarily cut down on the use of trans fats. While some food manufacturers have removed or reduced its use in response, many staple food items such as margarine, bread, doughnuts, fast food and baked goods still contain trans fats.
The World Health Organization (WHO) advises that a maximum of 2% of our daily energy requirement should be derived from trans fats, however many consumers find it difficult to identify the ingredient, leading to calls for better labelling.
NHS guidelines recommend a diet containing a maximum of 30g of saturated fat each day for men and 20g for women.
Animal products, such as butter, cheese and milk provide the majority of people with saturated and unsaturated fats as well as eggs, some fish and meats.
What are trans fats?
Artificial or man-made trans fats are made by combining plant oils with hydrogen to produce a solid or semi-solid substance. It is a cheaper alternative and has a longer shelf life, which previously meant that it was more suited to the needs of the food industry than other fats, hence its use in biscuits, cakes and other baked goods.
Natural trans fats, or conjugated linoleic and vaccenic acid, are also present in some foods such as meat and dairy products, occurring naturally in the body fat of cattle.
I'd like to cut down on trans fats, what should I look for on the label?
- Try to avoid products that list partially-hydrogenated fat as an ingredient.
- Trans fats can often be found listed among the emulsifiers.
- Some baked goods such as cakes, biscuits and pastries still contain trans-fats so try to eat these in moderation.
- Use liquid oils for cooking, solid products are far more likely to contain harmful fats.
What else do I need to know about trans fats?
According to the British Heart Foundation, in addition to CHD, CVD and stroke, trans fats are known to raise the risk of developing:
- Liver dysfunction
- Type 2 diabetes
Trans fats have also been linked to female infertility.
Why do we need any kind of fat in our diet?
For much of the past 60 years, since fat intake was first linked with heart disease, we have been encouraged to view fat as 'bad' but some fat in the diet is essential for healthy nerve tissue, brain development, for hormone production and vitamin absorption as well as for energy. It is when this consumed energy is not expended that the body stores the fat, an evolutionary advantage allowing humans to store energy for when food is scarce, that unfortunately today leads to unnecessary weight gain.
During infancy and adolescence, when brain and nervous system development peaks, the right type of fats in the diet are essential for myelin sheath development, a fatty insulating layer surrounding neurons within the brain.
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