Trans-Fats

By: 

Martin Hum, DHD Nutritional Therapist and health journalist

Issue: 
Autumn
Year of publication: 
2010

In June this year, NHS watchdog the National Institute for Health and Clinical Excellence (NICE), recommended that artificial trans fats in foodstuffs be banned, echoing a similar call from the UK Faculty of Public Health.

These “toxic fats” are already illegal in Denmark, California and New York City. So, just what are they and what risks do they pose to our health?

Trans-fats are chemically altered vegetable oils. They are produced artificially in a process called hydrogenation, which bubbles hydrogen through hot oil, changing it into solid fat. During hydrogenation, the shape of the fatty acid molecule is altered as most

of the normal “cis” double bonds are converted into “trans” double bonds.

Trans-fats are almost unknown in nature, being produced only by bacteria living in the guts of ruminants, such as cows. Very small amounts of natural trans-fats are present in beef, milk and other dairy products but these have not been linked to any health problems.

Food companies like to use artificial trans-fats because they’re cheap to produce and chemically stable, so they have a long shelf life. They are also flavourless and give foods a desirable texture and “mouth feel”. Some restaurants and fast food outlets tend to favour trans-fats for deep-frying foods, since they can be reused many times in commercial fryers.

Trans-fats (usually listed in ingredients as “partially hydrogenated vegetable oil”) can be found in thousands of processed foods – but especially in fried foods such as crisps and doughnuts, baked goods such as biscuits, pastries and pies, as well as in hard margarines, sauces and soups.

Although hydrogenation started out in 1903 as a means of producing hard fats for candle-making, food manufacturers soon discovered that partial hydrogenation resulted in fats that looked and behaved like lard. Wartime rationing of butter led to a massive rise in the production and consumption of margarine, which was given a further boost in the early 1980’s when saturated animal fats were linked to heart disease.

Whilst trans-fats have no nutritional value, they were long thought to be a healthier choice than saturated animal fats. Then, in 1993, the New England Journal of Medicine reported that trans-fats had been found to raise blood levels of bad LDL cholesterol while lowering good HDL cholesterol. Worse still, this adverse effect on HDL/LDL ratio was double that of saturated animal fats.

Since then, hundreds of scientific papers have not only confirmed the role of trans-fats in heart disease and stroke but have implicated them in a wide range of other chronic diseases and health concerns. Trans-fats appear to be uniquely bad for human health because they are unnatural. They confuse the human body and its various metabolic pathways, ending up in the wrong places, doing the wrong things.

By becoming incorporated into cell membranes, trans-fatty acids disrupt our most basic metabolic processes at the cellular level, for example by reducing cellular response to hormones like insulin.

A Harvard Medical School study that monitored over 84,000 women for 14 years concluded that a 2% increase in trans-

fat consumption (as a proportion of total calories) led to a 39% increase in diabetes risk.

The structural integrity of neuronal membranes in the brain is particularly vulnerable to damage from trans-fats, the consumption of which has been linked to cognitive decline and mental illness. A study of 815 elderly people in Chicago found a strong correlation between trans-fat consumption and the development of Alzheimer’s disease.

Prostate cancer has been associated with trans-fats in a study that measured blood levels in 476 men diagnosed with the disease and a group of healthy, matched controls. Those with trans-fat levels in the top 20% had more than double the risk of developing prostate cancer than men with levels in the lowest 20%.

Trans-fats may also adversely affect fertility. Another large cohort study from Harvard Medical School, involving 18,555 married, premenopausal women, found that obtaining 2% of energy from trans-fats rather than from monounsaturated fats correlated with a more than doubled risk of ovulatory infertility.

According to new research, trans-fats are also implicated in endometriosis, a condition where tissue similar to the lining of the uterus occurs elsewhere in a woman’s body, causing pain and, in many cases, infertility. The study, which followed 70,709 American nurses for 12 years, found that those who ate the most trans-fats had a 48% increased risk of endometriosis, compared with those who ate the least.

These epidemiological studies suggest that trans-fats are harmful to health, even though they do not conclusively demonstrate cause and effect. Based on the available evidence, a British Medical Journal editorial earlier this year claimed that reducing average trans-fat consumption to just 1% of total calorie intake could prevent 11,000 heart attacks and 7000 deaths annually, in England alone. Such a move would impact most strongly on groups consuming the most trans-fats, mainly young people and those on low incomes.

No safe level of trans-fat consumption has been established, although the Committee on Medical Aspects of Food Policy (COMA) recommended in 1994 that average intake should not exceed 2% of food energy. This somewhat arbitrary figure has not been adjusted in light of new findings on health effects and has been used by the food industry to argue that it has already done enough to reduce levels in products. Perhaps the time has come for our industrialists and politicians to show more concern for human life than for shelf life.

Keywords: 
FOOD, Trans Fats,
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