Even Good Fats Can Cause Blindness

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http://www.mercola.com/2005/apr/30/good_fats.htm

 

Age-related cataract, a cataract that occurs in the elderly and is

characterized by an initial opacity in the lens, is an extremely

common disorder that has both substantial health and economic effects.

In fact, age-related cataract is the leading cause of blindness in the

world. Although the visual impairment associated with cataract can be

corrected surgically, it is at a major social cost, as cataract

removal is the most frequently performed surgical procedure among

Medicare patients, costing some $3.5 billion a year in the United

States.

 

This study examined the association between specific types of fat in

the diet, measured over a period of 10 to 15 years, and the

development of cataracts. This is the first published study to perform

this extensive type of dietary analysis with cataracts.

 

Polyunsaturated fats (PUFAs) are essential fats and consist of omega-6

and omeg-3 fats. PUFAs have generally been considered to be healthy

elements of the diet. Linoleic acid is an 18-carbon omega -- 6 PUFA.

It is abundant in the Western diet and is the major fatty acid in

safflower, sunflower, corn, soybean and cottonseed oils, as it

accounts for more than 50 percent of the total fatty acid content in

these oils. Although linoleic acid is an essential fatty acid, the

consumption of modest amounts, equivalent to 1 percent of total

calories, is adequate to protect against essential fatty acid

deficiency.

 

Linoleic acid constitutes up to 0.5 percent of the total fatty acids

in the lens membrane. Because linoleic acid is prone to being

oxidized, increasing concentrations in the lens membrane may cause

free radical damage.

 

Linolenic acid is an 18-carbon omega -- 3 PUFA. Spelling wise there is

only a difference of one " n, " but it makes all the difference in the

world. Linolenic acid is the omega-3 fat of vegetable oils found in

flax, walnuts and green leafy vegetables.

 

The researchers found that when the diet was increased with either of

these fats there was an increased risk of developing cataracts.

 

American Journal of Clinical Nutrition April 2005;81(4):773-779

 

Dr. Mercola's Comment:

 

The results of this study provide more compelling evidence that a high

intake of polyunsaturated fats, like the ones found in vegetable oils,

can be damaging to your health.

 

What may be surprising to some of you is that linolenic acid was also

shown to cause damage in this study. A vegetable source of the

well-known omega-3 fatty acids, linolenic acid (specifically

alpha-linolenic acid) is found in highest amounts in flax oil.

 

Flax oil has already been shown to be less effective in regard to

treating inflammation than fish oil is, and this study provides

further evidence why you should choose the latter for your source of

omega-3 fats.

 

The study did not examine whether fish oil had this effect. However,

previous studies have shown that fish oil -- specifically DHA, a type

of fatty acid unique to fish and some forms of algae -- has been found

to provide protection from macular degeneration, another common eye

disorder, while saturated fats, along with polyunsaturated fats from

vegetable oils, do not.

 

The results of this study provide yet another example of why we need

to make sure we eat a healthy balance of fats. Currently, Americans

consume omega-6 and omega-3 fats at a ratio anywhere from 20:1 to as

high as 50:1!

 

At the end of the 19th century, Americans consumed less than one pound

of liquid vegetable oil a year. At the turn of the 20th century, that

amount had increased to 75 pounds per year. Nearly all vegetable oils

are loaded with omega-6 fats. We were simply never designed to eat so

many processed vegetable oil fats. When one combines this with a

decline in the intake of fish and fish oils we have a prescription for

disaster.

 

During Paleolithic times, when humans ate a diet that was most natural

for their bodies, the ratio of fatty acids they consumed was anywhere

from 3:1 to 1:1. This is a tremendous difference.

 

Another key point to keep in mind is that their main sources of

omega-3 fats were seafood and wild game. They had absolutely zero

access to the liquid vegetable oils that Americans are eating today.

These oils are produced with machines that are able to squeeze out

every last drop of oil from different sources like corn and soy.

 

Not only did early humans not consume corn or soy, the only vegetable,

nut or seed oils they did eat were in a whole-food form, providing

only a fraction of the amount of oil you can find in a tablespoon of

such oils today.

 

The other primary issue that likely contributed to the incidence of

cataracts in the study was the level of antioxidants in the diet. The

antioxidants prevent the highly perishable PUFAs from being oxidized

and going rancid. If this happens to the PUFAs once they are part of

the lens of your eye you will develop cataracts.

 

So eating a diet rich in raw vegetables is likely to provide the most

comprehensive source of antioxidants to keep you healthy overall and

avoid the common causes of blindness, cataracts and age-related

macular degeneration. Dark colored fruits, like berries, are also high

in these beneficial antioxidants.

 

Some tips to assure yourself a balanced intake of fats in your diet

include:

 

* Eat small to moderate amounts of raw nuts and seeds.

* Eat plenty of raw vegetables and dark colored fruits, like

berries, to increase your antioxidant levels.

* Avoid liquid vegetable oils of any kind.

 

Related Articles:

 

Four Tips to Protect Your Eyesight as You Age

 

Are You at Risk for Cataracts?

 

Vitamins Protect Against Cataracts