NEW YORK—Over the last 20 years, Americans have developed a near-psychosis when it comes to dietary fats. On one hand, millions indulge in a daily frenzy of lipid love, gorging on foods packed with saturated fats, trans fats, and other bad stuff. At the other extreme, low-fat fascists view any sort of dietary fat as a harbinger of early death.
In the middle, are a whole lot of confused people.
In reality, both extremes can lead to ill health, and both are based on a lack of understanding of how lipids function biologically, said David Riley, MD, at a conference on Nutrition & Health sponsored by Columbia University's Rosenthal Center for Complementary and Alternative Medicine.
Physiologically, healthy lipids like avocado, flax and olive oils are nothing like lard, hydrogenated vegetable oil, and Pam cooking spray. Dr. Riley, founder and director of the Integrative Medicine Institute, Santa Fe, NM, believes physicians can make a real difference for patients struggling with overweight, diabetes, cardiovascular disease and other diet-related conditions, by teaching them how to distinguish between healthy fats and pathogenic ones.
In many ways, it is more important for overall health to focus on increasing intake of healthy fats like omega-3 rich oils, and naturally occurring mono- and polyunsaturated fats, than to try and go "fat-free."
"No Fat" Makes No Sense
Without adequate daily intake of certain fats, we could not create cell membranes, secrete hormones, maintain our brains and nerves, and mount appropriate inflammatory responses. No fat means no life. So the idea of ruthlessly eliminating fat from the diet won't lead to health, even assuming someone can stick to a fat-free regimen for very long.
The issue, said Dr. Riley, is which fats to include in the diet and how much. Yes, people at risk for diet-related diseases will benefit from reducing overall intake of high calorie foods including fats and refined carbs. But emphasis should be on cutting out as much trans fat, saturated fat, and omega-6-containing fats as possible, while boosting intake of omega-3s and healthy oils like olive, flax, avocado, and others.
Unfortunately, a lot of people have a predilection for simple, broad-stroke thinking, and many—including scientifically-trained types like doctors—know little about the basic chemistry of lipids. The result? Fats (and fat people) have been vilified, even as the fat content of much of our food has increased.
The Skinny on Fat Chemistry
All fats, explained Dr. Riley, are built out of one molecule of glycerol and three molecules of fatty acids. The astonishing variety of oils and fats in the natural world (and supermarket aisles) is due to permutations in configuration of those fatty acids around the glycerol, the variable structures of the fatty acid chains, and the placement of hydrogen double-bonds along the chains.
"Whether fats are 'good' or 'bad' depends on the configuration of the fatty acids and how they interact with other substances and receptor sites in the body," he said. "The structure of fatty acids are determined in large part by length of the water insoluble fatty chain, the number of single and double bonds and where they occur, and whether they are in a -cis or -trans configuration."
Omega-3 and 6 fatty acids are so-named because, respectively, there are hydrogen double bonds at the third and the sixth carbons in the fatty acid chains. Likewise, the omega-9 fatty acids have the double bonds at the 9th carbon. Mammal biochemical pathways cannot produce fatty acids with double bonds at the 3rd and 6th positions, so both must be obtained from foods, hence the term "essential" fatty acids.
Healthy oils, be they from fish, olives, tree nuts or seeds, have certain biochemical properties with clear physiological benefits: They can be incorporated into cell membranes; they are precursors to necessary endocrine or signaling molecules; they may contain trace minerals or other important nutrients.
Defining the Terms
Consumers hear a lot of different and confusing fat-related terminology: saturated, unsaturated, trans, essential. You can help your patients a lot by simply explaining the differences and helping them understand the potential health impact of various classes of fats.
Simply put, the term "saturated" means that all the potential bonding sites on the carbon atoms of the fatty acid chain are occupied by hydrogen atoms, meaning that there are no double bonds between the carbons. Naturally-occurring saturated fat like suet, lard, tallow, coconut oil, peanut oil, palm kernel oil and dairy-derived fat-containing products like butter and ghee are "hard" fats in that they're solid or semi-solid at room temperature.
Generally speaking, a diet heavy on saturated fats is not very healthy for sedentary individuals. They tend to promote platelet aggregability, reduce insulin sensitivity, and because they're very calorie-rich, promote weight gain. Saturated fats have always been a part of human diets, and people who do a lot of physical work and burn a lot of calories daily can usually eat a fair amount of saturated fat-rich foods without ill effects, provided they also get adequate intake of omega-3s, and other anti-inflammatory fats.
The problem is that many sat-fat rich foods that were staples for our hard-working ancestors have become deeply ingrained into many culinary cultures. When paired with a low-exertion lifestyle, these foods can become problematic.
Many people mistakenly assume trans fats are synonymous with saturated fats, since in much popular health news coverage, both are portrayed as detrimental.
In actuality, trans fats are, by definition, unsaturated fats. There's no such thing as a trans saturated fat. The trans designation has to do with the arrangement of hydrogen atoms on adjacent, doubly-bonded carbons (if there are doubly bonded carbons, the fatty acid chain is, de facto, unsaturated).
The hydrogens can either be in a cis configuration, on alternate sides of the carbon chain, which tends to make the chain more bent and kinked; or they are in a trans configuration, with both hydrogens on the same side of the carbon chain. Trans configurations make for straighter, more easily stacked fatty acid chains. Hence, trans fats, like saturated fats, tend to be more stable and solid at room temperature.
The shape and configurations of the fatty acid chains determine a fat's stability when exposed to the elements. Naturally-occurring oils with high nutritional value are rich in mono- and poly-unsaturated fats, and are relatively unstable, and degrade quickly when exposed to heat, light and air.
A massive emergence of mass-produced hydrogenated trans fats took place after World War II, driven by a desire to overcome the natural instability of commonly used food oils. While there are a few naturally-occurring trans fats, like conjugated linoleic acid, the vast quantities of trans fats in today's food supply are industrially-produced hydrogenated vegetable oils. According to the Food and Drug Administration, the average American eats nearly 5 pounds of trans fats each year.
"Modern methods for high temperature industrial refining of oils, which include degumming, bleaching, deodorizing, hydrogenating, and stabilizing, have resulted in finished products with no discernable health benefits. In fact, they're health hazards, but with long shelf-lives," said Dr. Riley.
Hydrogenation changes the chemical structure of an oil by "saturating" the bonds with hydrogen. This requires tremendous pressure, heat, and a metal catalyst. The object is to wrench the zig-zags out of the naturally occurring fatty acid chains, so they become straight and easily aggregable. The result? A nutritionally vapid fat that stays solid at room temperature, spreads like butter, and has a near-infinite shelf life. It allows low quality oils to be turned into butter-like substances or "shortenings" that can be used in commercial processed food production.
Though they were once touted as healthier than saturated fats from animal sources, hydrogenated trans fats are proving to be bad news as far as overall health. Trans fats interfere with hepatic detoxification pathways, inhibit insulin function, and impair the fluidity of cell membranes in many tissues.
The biggest negative impact seems to be on the cardiovascular system. High-trans fat levels increase both total and LDL cholesterol, while reducing HDL. They also increase platelet aggregability and raise lipoprotein-a. In an analysis of data from the Nurses' Health Study, Hu and colleagues found that the relative risk of CVD doubles for every 2% increase in trans fat consumption as a percentage of total fat intake.
Researchers at the Harvard School of Public Health have estimated that as many as 30,000 deaths each year could be attributed to disease states that are directly related to high trans fat levels.
There are also some data to suggest that diets high in trans fats also correlate with low testosterone levels and increased sperm abnormalities in men, and also with increased risk of low birth-weight.
Making an Oil Change
Rather than simply focusing on the ill effects of unhealthy fats, it is really important to learn about the good ones and encourage patients to integrate these into their daily lives. One of the most important things to understand is which ones can be safely heated and which should only be eaten cold, as flavoring or dressing oils.
The general rule is that no oil should ever be heated to the point of smoking, as this generates all sorts of free radicals and toxic byproducts, not to mention nasty flavors. Whenever using oil in a pan, try to cook with as low a temperature as possible to get the job done; this will minimize the degradation of the oil.
Oils with high nutritional value like flax, most tree nut oils (walnut, hazelnut, pumpkin seed, pistachio) should not be heated at all, as heat tends to degrade the very nutrients that make these oils valuable. The general rule is, the higher the essential fatty acid content, the lower the smoke-point; the lower the EFA content, the higher the smoke point. So save those expensive EFA-rich oils for salad dressings or for drizzling on steamed vegetables.
Avocado & Olive Oils
Avocado oil is not terribly nutritious, but it is great for cooking, since it can sustain very high heat without smoking, This oil can bear heat levels up to 500 degrees F, so it is ideal for sautées, as well as for popping corn. Dr. Riley noted that it also makes a great massage oil and natural make-up remover.
Olive oil can also be used for low-heat cooking, but be careful, because it has a fairly low smoke-point. Because it is so rich and flavorful, it is also an excellent finishing oil; a little swirl of a good olive oil puts a tasty final touch on soups, stews, pasta sauces, meat and fish dishes.
Olive oil should be stored in a cool, relatively dark place but it need not be refrigerated, as this will cause it to coagulate. Dr. Riley said it is best to buy olive oil in relatively small amounts. Once opened, a bottle should not be kept for more than 6 months. "Buy the amount you feel confident you'll use in a 6 month period."
Dr. Riley said he has mixed feelings about canola oil, increasingly popular in recent years. "It was developed in Canada as a healthy alternative, and in some ways it is." But the overwhelming majority of commercially produced canola is from genetically-modified plants. "It is very difficult to get non-GMO canola." Widespread farming of GMO canola has had detrimental effects on Canada's farm belt, with a particularly bad impact on small, independent family farms.
Flax seed, aka linseed, and the oil pressed from it, is one of nature's richest sources of essential fatty acids. It contains omega-3s and omega-6s in optimal physiologic proportions, It is also a great source of lignans, which are proving to be important nutrient allies in preventing breast cancer and possibly other hormone-mediated cancers (see Regulators Push to Ban the Trans, below).
Flax is one of the most susceptible oils to degradation from light and oxygen exposure. Buy it only in opaque plastic or glass bottles, and always keep it refrigerated. It can be used as a finishing oil or as a base for salad dressings. But because of its low susceptibility to heat, ban it from the pan.
Patients can also obtain the benefits of flax by simply incorporating more flax seed into the foods they eat. Crushed flax makes an excellent salad or cereal topping. Many German or Scandinavian-style dark breads contain flax, making them both toothsome and nutritious. Added to smoothies, crushed flax adds texture and body.
At roughly $1.50 per pound, flaxseeds are one of the most economical natural foods going. Of course, pressed oils are considerably more expensive, but they are still a great nutritional value.
Dr. Riley advises buying organic flax whenever possible. Flax/linseed is grown in vast quantities for the paint industry, and consequently, many crops are heavily sprayed with pesticides. He recommended oils by the Barleans company (www.barleans.com), which has been in the food-grade flax business for decades. Flax products are all they make. "They press the oil every day, and do not warehouse it. So they ship it the day they make it, which makes it very fresh."
Encourage your patients to read the labels on food oils carefully. At the same time, be aware that regulation on labeling is pretty slack, said Dr. Riley. For example, "Cold Pressed" really should mean that there's no heat applied during the pressing process. But it is still possible for less-scrupulous manufacturers to use heat processes, then immediately dispense the oil in cold bottles and still call the product "cold pressed." Stick with reliable large companies or small independent boutique oil producers. "You really can taste quality, so let your senses be your guide."
Dr. Riley said that in his experience, the Spectrum Organics (www.spectrumorganics.com) line of culinary oils is very reliable. The company is serious about ensuring organic certification, and their oils are fresh, flavorful, reasonably priced and well-distributed in both health food stores and many mainstream grocery chains. Plus, the company includes a heat-tolerance indicator on all its labels, which can help your patients make appropriate choices.
Regulators Push to Ban the Trans
Trans fats have definitely fallen out of favor with public health experts and policymakers.
Just over a year ago, the Food and Drug Administration required food manufacturers to list trans fat content on product labels. But labels mean little unless people understand them, which is why it is all the more important to explain to your patients what trans fats are, why they're bad, and how to avoid them.
The FDA's move builds on a 2003 memo from the federal Office of Management and Budget urging both the Department of Health & Human Services and the US Department of Agriculture to revise dietary guidelines so they promote increased consumption of Omega-3s, while reducing trans fats.
These moves had a huge impact on food producers who are now scrambling to replace those ubiquitous trans fats with healthier non-hydrogenated alternatives. No doubt this has induced more than a little hair pulling among food scientists and formulators, especially in the junk … er, we mean snack food sector.
The boldest bit of trans-trashing came from New York City's Board of Health last December; with full support of NYC Mayor Michael "No Smoking" Bloomberg, the board instituted an all-out ban on the trans in the city's eateries and bakeries. Restaurants—including everyone from Le Burger King to Le Bernardin—were required to fully eliminate trans in their frying and cooking oils by July; complete elimination of all trans in all restaurant food is slated for one year later.
The measure has strong support from medical groups and health advocates, but—no surprise here—evoked considerable pushback from the restaurant and fast food industries. It has particular impact on fast food chains desperately seeking trans-free substitutes that will work with their equipment, endure the high temperatures inherent in fast food frying, and maintain that irresistible flavor customers have come to expect.
Depending on how well the rule is enforced and how successful the restaurant community is at finding and adopting trans-free shortenings, it could have profound impact on the city's public health. In many ways, this is one of the largest public health trials in history. Will a relatively straightforward but far-reaching change in a major city's food supply have a meaningful impact on incidence of heart disease? Time will tell.