Wednesday, April 16, 2008

Some trans fats are good for you

Natural trans fats found in yogurt, some meats are actually beneficial, U of A research shows. Another hole in the conventional wisdom

Not all trans fats are bad for your heart, new research from the University of Alberta has found. In fact, natural trans fats found in yogurt, cheese, milk and your favourite cut of beef or lamb chop may actually lower your cholesterol and help reduce your risk of cardiovascular disease, obesity and diabetes, says Flora Wang, a PhD student in the U of A's agricultural, food and nutritional science department. "We want people to realize that natural trans fats are not necessarily detrimental," Wang said.

She noted that the natural trans fats are far different than the industrial trans fats bursting from butter tarts, doughnuts and margarine squares. "We want to attract more attention and focus in the protective effect of these natural trans fats which might even be beneficial in those people with higher risk of heart disease."

Wang's research focused on foods with trans vaccenic acid, the most prominent natural trans fat found in dairy and beef products. For 16 weeks, she fed obese and diabetic rats a diet enriched with trans vaccenic acid and discovered their total cholesterol was reduced by approximately 30 per cent. Low-density lipoprotein -- or bad cholesterol which can build up in and clog the arteries that feed the heart and brain -- was lowered by 25 per cent.

Triglyceride levels -- a form of fat that is elevated in people who are obese, smoke and drink a lot or eat too many carbohydrates -- went down by more than 50 per cent. "It's kind of challenging the traditional idea of bad trans fat," Wang said. "People, if they know there might be some beneficial components of the fatty acid in the dairy product, they probably could make better choices and have wider alternatives."

With this new information, Wang and her supervisor, Spencer Proctor, want Health Canada to reconsider how they instruct manufacturers to label their foods. Cookie-makers and dairy producers are required to report all trans fats (except a healthy fatty acid called conjugated linoleic acid) on their food labels, but they don't need to differentiate between the good trans fats and the bad trans fats. Most likely, any trans fats identified in a carton of milk or tub of yogurt is 90 to 95 per cent natural -- and good -- trans fats, Proctor said. "We shouldn't be calling all trans fats equal," he said.

He said fast-food outlets and doughnut shops also need to know that as they drain their foods of bad trans fats because of public pressure to offer healthier alternatives, they may be inadvertently getting rid of the good trans fats, too. Wang and Proctor are now searching for funding and planning a clinical trial to feed diets rich in trans vaccenic acid to people. If the natural fat actually lowers people's risk for obesity, diabetes and heart disease, Proctor imagines dairy technology could, in the future, increase the levels of good trans fats in foods to offset the bad ones


Beware of the dog: you may catch MRSA

They might be man's best friend, but dogs should be sold with a health warning, a study suggests. Letting a dog lick your face, picking up its mess or allowing it to sleep on your bed could put you at risk of catching salmonella, campylobacter or MRSA.

Research commissioned by the Department for Environment, Food and Rural Affairs (Defra) from the University of Liverpool Veterinary School, has identified health risks in the interaction between man and dog. The findings, published in The Veterinary Record, may enrage the country's 6.5 million dog owners. Men, in particular, may have to learn cleaner habits because it seems they have a problem picking up dog mess.

Risks of infection from dog to Man at present are low. Carri Westgarth, a researcher on the project, insists that she has no wish to create a scare. Owning a dog has positive health benefits ? people who walk them tend to be fitter and have lower blood pressure.

The research has irritated dog lovers. Caroline Kisko, secretary of the Kennel Club, said that Defra should be spending resources on policies to help to tackle animal welfare. She said: "It has told us nothing, except perhaps to use a bit of common sense."

Carolyn Menteith, a dog behaviourist, was also dismissive. "You are more likely to catch a disease from a child than a dog. I do agree owners should clear up after their dogs, otherwise they cause a social nuisance. Men are worse at it and somehow think it's unmanly to be walking around with a nappy sack. But if you can't do that, don't get a dog, get a stuffed toy."



John A said...

But - but - but - only yesterday "Trans-fats linked to breast cancer risk in study"

Yeah. And every murderer in prison can be linked to the use of dihydrogen monoxide.

Anonymous said...

The article you mention says a certain trans fat is not unhealthy.

The theory in nutrition books (not a very good as a theory since it's not falsifiable easily) is that different fats alter the FLEXIBILITY of cell membranes, the minor-component composition of which (unlike cholesterol) are actually determined by the types of fats you eat. Flexible membranes are said to be important since rather many enzymes and ion etc. transporter protein assemblies that exist in the membrane literally find it easier to function as moving micro-machines if a membrane is more flexible.

Suddenly this hand-waving theory is starting to make me wonder if it really has any basis.

For one thing, most membrane proteins don't even require the membrane to flex much, since they anchor themselves into the membrane via a solid torus and the moving stuff happens inside that fence.

[I will digress to say that the latest evidence indicates that humans, as they moved out of Africa, did so ALONG THE COAST, areas that are now covered in water, but that this may explain why we have no sea-unfriendly fur like other primates, but also that our most recent evolution may have been not so much adaptation to agriculture (which has only had a few thousand years instead of many thousand years to change a gene or two to adapt us to new diets), but adaptation to SEAFOOD (!). That means fish oil.]

But, as a chemist, my first urge is to LOOK at the various oils being said to either fix or ruin our health. So here are pictures of the main players:¤t=FattyAcids-1.jpg

(A) "Natural" trans fat (Vaccenic Acid).
(B) The major trans fat in "partially hydrogenated vegetable oil" products like crackers or margarine (Elaidic Acid).

Notice that the "natural" one is exactly the same length yet has the double-bond in a mere adjacent position in the middle of the chain. That this would effect health would thus require very strong evidence, comparing the two directly, and even then, to be good science it would require at least a hand-waving mechanism since "stiffness" obviously is no different between the two, so another mechanism would be needed. Then again, the "natural trans fat is healthy" study may be crap in the first place, so maybe both are bad for us.

(C) The major oil of olives, a mono-unsaturated fat, Oleic Acid.
(D) The "evil" saturated fat of bacon etc., Stearic Acid.
(E) One of two major Omega–3 "fish oils", Docosahexaenoic Acid.

I note only that Omega-3 fat E is "really crazy" stuff. First, what I didn't know, it has SIX rather than just ONE double bond. That it's literally "all kinky" indeed could mean it acts as a "crystal defect" in a membrane made primarily of a liquid crystal of mainly fats with no double bonds. Far from being "more flexible" my bechtop synthetic chemistry intuition tells me this sort of thing nor more flexible than a thick rope full of knots every inch or two. Sticking a few of these a membrane would indeed cause havoc in an otherwise tightly packed flexible crystal.

Note that Wikipedia shows a very misleading display of olive oil vs. trans fat, that shows the trans fat as being pencil-straight and olive oil as a broken pencil:

But note that if you zoomed in and saw a movie of the membrane it would be in bustling motion much like people trying to fit into a full subway car just as the doors are about to close. In other words, without much extra energy at all, the "crookedess" of a cis vs. trans double bond means very little, since the rest of the chain for most fats (except fish oils) are full of HIGHLY flexible hydrocarbon chains, meaning a single twist or two and your "unhealthy" trans fat can be just as straight as or crooked as it wants to be. It's more appropriate to think of such long chains more as ropes than as rods.

Well, I'm thinking outloud, but I conclude that from structure alone, different types of fatty acids are more similar to each other than they are different, with the "fun house" exception of fish oil.