Dr Mary Enig raised America's consciousness about the dangers of trans fats almost singlehandedly.  This woman is both courageous and smart.  Check her out her article Skinny on Fats.

The following material on the dangers of trans fats is excerpted from my book Food for Vitality ...

Avoid Hydrogenates Like the Plague!

The illusion that margarine is more healthful than butter is fostered by misleading advertising.  In fact, the process of commercial oil and margarine production reads like an object lesson in how to destroy essential fatty acids.  As crops like maize do not give up their oil without a struggle, damaging high temperatures and chemical solvents are used to help extraction.  Further high-temperature processes (clarification, de-gumming, deodorizing) are then needed to make the light, clear oils we're used to.

Clarification of oils strips away the natural antioxidant vitamin E (which causes cloudiness), leaving a clear oil no longer protected against oxidation and rancidity.  Its short shelf life would lead to commercial disaster but for hydrogenation, invented to take care of this problem.

Hydrogenation forcibly adds hydrogen atoms to unsaturated oils (the essential fatty acids are unsaturated oils), making them more saturated and able to postpone rancidity for months.  This gives the oil a long shelf-life.  Also, hydrogenated oils are more solid at room temperature, so hydrogenation can transform cheap oils into something spreadable.  The margarine so created is gussied up with yellow dye to look like butter, for a fraction of butter's cost. Thus, hydrogenation is an incredibly profitable process for the edible oil industry - who then advertise this crap as good for the heart!

In fact, researchers have known for thirty years or more that margarine can raise cholesterol and make essential fatty acid deficiencies worse in laboratory animals (R. Holman et al., Perturbation of the metabolism of essential fatty acids by dietary partially hydrogenated vegetable oil, PNAS 79(4); Feb 1982: “Rats fed [trans fats] showed more severe essential fatty acid deficiency than did saturated-fat and control groups”.

Amazingly, researchers seemed to go to any lengths after this to not find margarines harmful for humans.  One study design had subjects eating a diet very rich in essential fatty acids for weeks (which would tend to build up their reserves) before they were given hydrogenated fats, which, not surprisingly, had little effect on them (F. Mattson et al., "Effect of Hydrogenated Fat on the Plasma Cholesterol and Triglyceride Level of Man", AJCN 1975, 28:726-731). But when you consider that this study was funded by Procter and Gamble, a major margarine manufacturer, perhaps it’s not quite so amazing after all.   

Recently this effect was confirmed yet again in humans, and the researchers concluded in the prestigious New England Journal of Medicine (323:439-445  August 16, 1990) that margarine's effects are "at least as unfavorable as that of cholesterol-raising saturated fatty acids, because they not only raise LDL ["bad"] cholesterol but also lower HDL ["good"] cholesterol levels"

A 1997 study in the same journal indicates that replacing trans fats in the diets of women is actually more effective in lessening heart disease than lowering the amount of fat in the diet!

Margarine Causes Heart Attacks?

Heart attack victims have been found at autopsy to have more hydrogenated fat and less animal fat in their bodies than people who died from other causes (L. Thomas et al., "Concentration of transunsaturated Fatty Acids in the Adipose Tissue of Decedents Dying of Ischaemic Heart Disease Compared with Controls", J Epidemiology and Community Health, 37:22-24 (1983))  This means that these unfortunate people probably did their best to avoid cholesterol and protect themselves from heart disease by switching from butter to hydrogenated margarine!

The heart attack death rate in different countries varies directly with the amount of essential linoleic acid (from vegetable oils) in body fat. The one-third fall in the American heart-death rate since 1968 was accompanied by a one-third rise in body-fat linoleic acid, following the U.S. public health campaign promoting vegetable oils over animal fat (see page 213).  There was no such campaign in the U.K., and no such fall in heart attacks.  In fact, the U.K. heart attack rate remains among the highest in the world.

In 1920, there were virtually no heart attacks in America, although atherosclerosis was as widespread then as it is now. Then, during the Depression years, hydrogenated margarines and cooking fats took the market over from more expensive butter, and by 1950, over 80% of heart deaths were from heart attacks. The introduction of margarine was the only qualitative change in the American diet - and while there was 8% more saturated fat in the 1950 U.S. diet than there was in 1909, there was also 38% more linoleic acid! (R. Rizek et al., "Symposium: Status of Fat in Food and Nutrition", Journal of the American Oil Chemists' Society, 51:244-250 (1974); A high linoleic acid diet is strongly protective against heart attacks, so it is likely that nothing can protect against margarine.

I doubt that this was due to chance! The day that I put together graphs of heart attacks and margarine consumption in America and saw how closely the curves matched (click here), I threw out all the margarine in my fridge! Since a working prostaglandin metabolism appears to lower cholesterol naturally, there is no health reason to use margarine. In fact, elevated cholesterol in the blood may even be the body's way of encouraging the manufacture of more cholesterol-lowering prostaglandins, since the essential fatty acids are transported in the bloodstream attached to cholesterol.

Cover Up?

Unfortunately, a great many existing studies on the effects of hydrogenates on health were funded by the edible oil industry, and are flawed by bias in their research methods.  They were clearly designed to avoid bad effects by, for example, pre-feeding essential fatty acids to crowd out the hydrogenates so that they could have no harmful effect. (F. Mattson et al., "Effect of Hydrogenated Fat on the Plasma Cholesterol and Triglyceride Level of Man", The American Journal of Clinical Nutrition, 28:726-731, (1975) see link above)  Or the experimental period was kept so short, there simply wasn't time for bad effects to surface.  But the cleverest ruse of all involved the choice of experimental animal.

Rats and mice - animals often used for these biased studies - have completely different essential fatty acid requirements from us primates, needing far less of the omega-3's. It took a long time for me to spot this, but there are studies which show without any shadow of doubt that monkeys develop the same problems as humans (bad mood, indigestion, poor skin) when they're fed low-omega-3 diets, diets on which rats and mice could live happily ever after.

American researcher Dr. Donald Rudin concludes from these experiments that as a population, we are suffering from the same complaint as the omega-3-deprived monkeys, which he has called the "new pellagra." We don't all develop the three "d's" of pellagra (dermatitis, dementia and diarrhea) at the same time, but vast numbers of us get these symptoms individually, just like the deprived monkeys.

Pellagra is the vitamin B3-deficiency disease, and B3 is vital for the essential fatty acid-to-prostaglandin pathway (page 46). Rudin believes that B3 deficiency inhibits prostaglandin production and causes pellagra's triad of symptoms. He reasons that an essential fatty acid deficiency at a time when we have sufficient B3 will cause less severe prostaglandin shortages and give rise to mild forms of one of pellagra's symptoms. In other words, we should get a kind of group pellagra - which is exactly what we have.

Television advertisements are convincing evidence of this, for most prime-time pitches are for over-the-counter remedies for just these conditions. Skin diseases from acne to itching, digestive difficulties (such as indigestion, hemorrhoids, constipation and irritable bowel), and mood disorders like irritability, depression and PMT (for which we take pain-killers) are epidemic amongst us.

Read the Label

You've probably got the message by now that hydrogenates are bad for you, but how can you steer clear of them? The chances are that products with long shelf-lives like biscuits, cake mix and potato crisps are loaded with them. There's only one way you can find out for sure - read the label! Any product with a label which includes the words "hydrogenated" or "partially hydrogenated" will not support your health.

On the other hand, let's keep our sense of proportion. I'm not saying you should never eat another chocolate digestive biscuit! Just keep hydrogenate-containing foods to a low level in your diet so their unhealthful effects are drowned out by the other good stuff you're eating - after all, this strategy protected the laboratory animals in those biased studies!

Hydrogenation Fosters Essential Fatty Acid Deficiency

Unfortunately, polyunsaturated oils are especially vulnerable to damage from hydrogenation. Almost as a side effect, hydrogenation has an appalling effect on essential fatty acids, changing those it doesn't destroy from the natural cis form - in which the molecules are shaped like Js - to trans forms which are shaped like I's. ("cis" and "trans" locate the hydrogen atoms at the double bonds between carbon atoms of the essential fatty acid's skeleton. "cis" means "on the same side, and "trans" means across. Since hydrogen atoms repel each other, a "cis" bond is bent and a "trans" bond is straight)

The true disaster of hydrogenation is that these straighter, trans-form essential fatty acids are worthless as essential fatty acids - prostaglandins cannot be made from them, and they can only be burned for calories. And unlike natural saturates like butter, trans fats actually make essential fatty acid deficiency symptoms worse by getting in the way of the essential fatty acid pathway enzymes, so they act as "anti-essential fatty acids". On average, about 14% of fat in the national diet is in the trans form.

When trans essential fatty acids are incorporated into cell membranes, the membranes lose flexibility because the straighter trans molecules pack closer together, reducing red blood cells' ability to squeeze through tight capillaries and lessening the cell-killing effectiveness of white immune-system cells. German researcher Dr. Johanna Budwig has shown that the straighter trans molecules allow less oxygen, and more pollutants, through the membrane into the cell. Budwig has almost single-handedly so raised the European consciousness of trans fats that certified trans-free products are now available in Germany and Holland.

Incredibly, American and U.K. authorities include trans fatty acids in estimating our essential fatty acid intake, reckoned to be 5-10% of calories. A true estimate must reduce this by the 14% of trans essential fatty acids, and then by another 14% to account for the trans fats' "anti-essential fatty acid" effect. This leaves 4-7%, which is below the American National Research Council's recommendation of 8-10% of calories as essential linoleic acid.

It is even more amazing that this clear and present health danger is being ignored, even as the links between essential fatty acid deficiency and heart disease - our number one killer - are strengthening daily.