Sources of linoleic acid (C18:2)

[Guest guest]

We recently discussed the Hegsted equation and used it to calculate

the effect of various fats on serum cholesterol. We have seen various

Pubmed publications that support the conclusion that oils high in

linoleic acid such as grape seed oil, sunflower oil, and safflower oil

can play a significant role in reducing blood cholesterol levels.

However, read labels carefully when selecting oils high in linoleic

acid. Not all oils are created equal regardless of their plant source.

Thre are two considerations: 1) the quality of the oil, and 2) the

fatty acid content of the oil.

The best quality oils are unrefined cold pressed or expeller pressed

oils packed in dark glass bottles filled with an inert gas. These oils

recommend refrigeration after opening. The labels may contain the

words " high in polyunsaturated fats " and sometimes include the

percentage of linoleic acid. If the label says " high in

monounsaturated fats " , the oil is high in oleic acid and may not lower

blood cholesterol levels. The Nutrition Facts Label provides the best

guide for choosing the oils because it lists the grams of saturated,

polyunsaturated, and monounsaturated fat per serving. Make sure that

the quantity of polyunsaturated fat is at least 3 times greater than

the monounsaturated fat. For example, in a serving of 14 grams, if

there are 3 grams of monounsaturated fat, there should be at least 9

grams of polyunsaturated fat.

I just examined 12 different brands of oils at a Whole Foods

supermarket to see if they met this requirement and got the following

results:

* Grape seed oil: All 4 out of 4 met the requirement.

* Sunflower oil: Only 2 out of 3 met the requirement.

* Safflower oil: Only 1 out of 5 met the requirement.

The oils that did not meet the requirement had 5 times less

polyunsaturated fat than monounsaturated fat, approximately the same

as olive oil (2 grams of polyunsaturated fat, and 10 grams of

monounsaturated fat in a 14 gram serving).

In these days of selective breeding, genetic engineering, and

marketing hype you have to be more alert. I was amazed to find that

most of the safflower oil in the stores is the high-oleic variety.

Tony