Wednesday, February 10, 2010

the big fat question

Working the Give Kids a Smile dental clinic this past weekend (and playing calcium Twister for 7 hrs) was a perfect precursor to my renal rotation this week. Calcium is one of the key markers we watch in this population, in addition to phosphorus, potassium, albumin, and PTH (parathyroid hormone).

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In other news, meet my new favorite oatmeal topper, which ties nicely into today’s post topic:

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Aha, but it’s not regular peanut butter. Mixing equal parts PB + Almond Breeze is my new fave thing…food processors are magical.

Since I’m slowly making my way through the macronutrients [see carbohydrates here], I figured I continue with fat, which has taken its fair share of slams throughout history.

There has been a lot of controversy surrounding the types, amounts, and sources of fat and its contribution to disease. When things get confusing, I find it helpful to go back to what I know….the basics.

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[demystifying fat: part I-types of fat]

We talk about it all the time, but what exactly is fat?

Fat is a type of lipid (the other type is oil).  Most dietary fat is found in triglyceride form, and the body also stores fat as triglycerides (TG).

Do we really need triglycerides?

YES….for storage of energy, insulation, and transport of fat-soluble vitamins (A, D, E, K). TG are the main fuel for muscles while at rest and during light activity. During endurance exercise and short bursts of intense activity, the muscles also use lots of carbs + fatty acids from triglycerides.

Two basic types of fatty acids exist: 

1:: unsaturated fatty acids: liquid at room temperature

sat fat

polyunsaturated:

  • sources: safflower oil, sunflower oil, corn oil, and soybean oil
  • also includes the essential fatty acids: omega 6 (poultry, avocado, eggs, soybean oil, sunflower oil, corn oil, vegetable oils) & omega-3 (salmon & fish oil, flax seed, walnuts)
  • we generally get plenty of omega-6 in our diets, and omega-3 fatty acids are linked to decreased inflammation and blood clots.

monounsaturated:

  • sources: canola oil, olive oil, avocados, nuts, etc.

2:: saturated fatty acids: solid at room temperature

faat

  • sources: mostly animal sources-dairy & meat, baked goods, fried food, *coconut oil [does not contain cholesterol]

Why are saturated fats labeled as more harmful than unsaturated fats?

Fat’s negative connotation is derived from its link to heart disease. Saturated fatty acids have the greatest effect on increasing cholesterol levels, which are linked to the incidence of coronary atherosclerosis and increased risk of coronary heart disease [side note: I have explored some alternatives to this viewpoint, which will be discussed later].

However, something to note:

Big misconception: saturated fats get stuck in the arteries, clogging them and leading to heart disease.

Truth: inflammation (which can be triggered by many factors) leads to the formation of plaque, which can rupture and cause cardiovascular events.

Is saturated fat the worst kind?

Trans fat is the worst kind of fat to consume because it raises LDL (“bad” cholesterol) and lowers HDL (“good” cholesterol). TF is also linked to heart disease, stroke, and type 2 diabetes. The American Heart Association recommends consuming no more than 1% of total calorie intake from trans fats. I’d say, eliminate them all together if you can.

What are the current recommendations for dietary fat?

In general: No RDA for fat exists. In dietetics, we generally recommend that fat compose 20-35% of total calories with < 7% saturated fat (2005 Dietary Guidelines say under 10%),  <10% of calories from polyunsaturated fat, and <20% from monounsaturated fat.

{sources: *Position of the American Dietetic Association and Dietitians of Canada: dietary fatty acids. Kris-Etherton PM, Innis S,J Am Diet Assoc. 2007 Sep;107(9):1599-611. *Wardlaw, G. (2003). Contemporary Nutrition. New York, NY: McGraw Hill.}

Now, that we’ve cleared up some of the basic fat info, we can move on to some more complex issues…like medium chain triglycerides and why I advocate the use of coconut oil, a saturated fat.

As always, comment if you still have questions…see you soon for part II.

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