Fat facts

By Cindy Green

Good fats, bad fats, what’s the difference? They all store energy in our fat cells that will bulge over our waistbands if we stockpile too much. In moderation, fats are essential for good health — helping us absorb vitamins and replenish cells.

But some fats carry more bad baggage than good; they can raise low-density lipoprotein (LDL) or “bad” cholesterol, and lower high-density lipoprotein (HDL) or “good” cholesterol —
jeopardizing hearth health.

To separate the villains from the helpers, here’s a simple guide to fats:
 

Fat anatomy
The term “fat” is used interchangeably with “fatty acids.” There are three types — saturated, monounsaturated and polyunsaturated. All are chains of carbon molecules with hydrogen atoms attached.

The abundance of hydrogen atoms and how they’re attached differentiates the three main fatty-acid types. Some have hydrogen atoms clinging all around the carbon chains — as much as they can hold; they are called “saturated” fats. Fatty acids with missing pairs of
hydrogen atoms are “unsaturated” fats; if one pair is missing on each chain it’s “monounsaturated” and if multiple pairs are missing it’s “polyunsaturated.”

Generally fat is a mixture of all three types, although animal fats are predominantly saturated and plant-derived oils are mostly unsaturated.Some seafoods are also unsaturated.
 

Detecting saturates, unsaturates
Saturated fats are found in animal and dairy products, such as meat and whole milk, and in some plant-based oils, such as coconut and palm oil and cocoa butter. Saturates are generally solid at room temperature and don’t combine with oxygen, so they don’t easily turn rancid.

Monounsaturates are liquid at room temperature but start to solidify or become cloudy in the refrigerator, such as canola, olive and peanut oils. Avocados and nuts also contain
monounsaturated fat.

Polyunsaturates stay liquid in and out of the refrigerator and are found in safflower, sesame, sunflower, corn and soybean oils, some nuts, seeds, and fatty fish such as salmon and herring. They are the most susceptible to combining with oxygen and becoming rancid.

Enter trans fats
Although small amounts of trans fats occur naturally in some meat and dairy products, most is manufactured. Hydrogen atoms are pumped into unsaturated liquid fats to make them solid at room temperature — a process called “partial hydrogenation.”
 

“Trans” means hydrogen-atom pairs are on opposite sides of the carbon chain (rather than paired on one side as other fatty acids are structured). Although unhealthy trans fats are being eliminated from many products, they are common in margarines, shortening, snack foods, crackers, baked goods, fried foods and even energy and nutrition bars.
 

The cholesterol effect
Whether a fat is considered “bad” depends on how it affects cholesterol — both the “good” HDL and “bad” LDL types.

Saturated fats have been shown to increase LDL cholesterol, which increases the risk of coronary heart disease. The American Heart Association recommends limiting saturated fats to 7 to 10 percent of total calories and less if a person has heart disease.
 

“Trans fats pose an even higher risk of heart disease than saturated fats,” says Charan Wadhawan, AURI food scientist. Some scientists say trans fats raise LDL more than saturates — and go a step further by lowering good HDLs.

The FDA has not established any recommended level of trans fats and, as of January 1, 2006, requires that trans fat content be listed on all nutritional labels. The 2005 U.S. Dietary
Guidelines recommend keeping trans-fat consumption as low as possible.■