Monday, April 12, 2010

Polyunsaturated Fats Associated With Cataracts

I noted in a previous post that polyunsaturated fats (PUFAs, of which omega-3 is one, e.g. flax seed oil), by nature of their high number of volatile double bonds, oxidize quickly. Oxidized fats and their metabolites have been shown to increase risk for atherosclerosis and some cancers.

I was researching eye health this morning and came across this:

Dietary Fat Intake And Early Age-Related Lens Opacities, American Journal of Clinical Nutrition, 2005

Lens opacities are cataracts.

This study found an association between high intake of PUFAs and cataracts.

It looked at many types of fat from many food sources. Only PUFAs rose to the level of significance.

Women with higher PUFA intake, and higher intake of the shorter-chain PUFAs linoleic acid (omega-6) and linolenic acid (omega-3), had an increased risk for nuclear opacity. The authors noted that a failure to find opacity in other parts of the lens (cortical or posterior subcapsular) may be related to higher concentration of antioxidants in those locations.

From the study: The following oils and food sources were associated with a higher risk for cataracts:
  • Linoleic acid (18:2n–6), an n–6 PUFA, is abundant in the Western diet. It is the major fatty acid in safflower, sunflower, corn, soybean, and cottonseed oils, and it accounts for >50% of the total fatty acid content in these oils.
  • Linolenic acid (18:3n–3) is a plant-derived n–3 PUFA found in soybean, canola, and flaxseed oils, in walnuts, and in green leafy vegetables.
I don't see the benefit in supplementing the diet with extracted, purified fat (mayonnaise, margarine, oils, oil pills). Fat found naturally-occurring in food, thus complexed with thousands of other chemicals: protein, fiber, vitamins, minerals, antioxidants, other phytochemicals), is not only adequate, but preferable.

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