How Much Dietary Fat Do We Need, Anyway?

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Hi All,

From

http://www.lef.org/news/nutrition/2001/04/03/eng-essentialfats/eng-essentialfats\

_140828_101_051412227098.html I

quote:

How Much Dietary Fat Do We Need, Anyway?

Essential Fats, E. Siguel, MD PhD April 03, 2001

BOSTON (www.essentialfats.com)-- The lower limit of dietary fat intake (the

smallest amount that humans should eat)

depends on three factors: (a) energy needs, which can in great part be met by

carbohydrates now that most humans lead

sedentary lives, ( the need for EFAs, and © the amount of fat necessary to

absorb fat-soluble vitamins. According to

Dr Jequier, writing in the European J of Clinical Nutrition, " fat intake should

not be below 10% of total energy intake

in order to ensure an unrestricted absorption of fat-soluble vitamins,

particularly vitamins A and E. " The essential

fats, which are critical to proper body function, are the two families of

polyunsaturated fatty acids known as the w3

and w6. The essential fats include the essential fatty acids ( EFAs ) and their

derivatives. There are two EFAs--

linoleic acid (LA) is the w6 EFA, and linolenic acid (ALA) is the w3 EFA. There

are many EFA derivatives, including ARA

(an w6) and DHA (an w3). The essential fats help form cell membranes and are

precursors of the eicosanoid hormones,

which regulate a wide range of body functions, including immunological and

inflammatory responses (see

www.essentialfats.com for definitions)

The usual lower limit of fat intake to meet the energy needs of adults is

assumed to be between 10% and 15% of dietary

energy. However, it could be much lower and people have been known to survive

for many years on diets with almost no

fat, provided that enough carbohydrates are available.

The requirement for EFAs for adults is disputed. Most authors believe that 3-5%

of calories from LA and 0.5-1.0% of

calories from ALA will provide enough EFAs. Dr. Siguel disagrees. He suggests an

intake based on the number of cells in

the body rather than on caloric intake. According to Dr. Siguel, the need for

EFAs is not reduced by dieting or

curtailing caloric intake. He believes that the usual recommendations do not

provide enough essential fats for many

people who eat < 2,000 calories/day, such as elderly people and slim women on

low calorie diets.

There is great uncertainty about the upper limit for fat intake for adults.

Contrary to popular beliefs, recent studies

have shown that isocaloric (same calories) substitution of carbohydrates by fat

reduces the risk factors for

cardiovascular disease. As long as people remain within their ideal weight,

there is not apparent upper limit for fat

intake; it could be as high as 60%, while eating fewer carbohydrates. Obviously,

this assumes that people eat enough

protein (15-20%) and all other nutrients.

However, from a practical perspective, individuals who exercise actively burn

many calories and can eat many foods rich

in fat, whereas individuals with sedentary lifestyles must eat few calories and

therefore should eat foods low in fat.

According to Dr. Simopoulos, author and researcher of dietary fat, " human beings

evolved consuming a diet that contained

about equal amounts of w 3 and w 6 EFAs. " Over the past 100 years, there has

been an increase in the consumption of w 6

fatty acids due to the increased intake of vegetable oils from corn, sunflower

seeds, safflower seeds, cottonseed, and

soybeans. Dr. Simopoulos calculates that Western diets today have a ratio of w 6

to w 3 fatty acids from approximately

20-30:1 instead of the historical range of 1-2:1. Dr. Simopoulos believes that

research has shown that a high intake of

w 6 fatty acids shifts the physiologic state to one that is prothrombotic and

proaggregatory, characterized by increases

in blood viscosity, vasospasm, vasoconstriction, and decreases in bleeding time.

However, according to Dr. Siguel, these

conditions may also be explained by an excess of saturated fats.

In general, w 3 fatty acids have antiinflammatory, antithrombotic (prevent

clots), antiarrhythmic (prevent heart

malfunction), hypolipidemic (lower lipids), and vasodilatory (dilate blood

vessels) properties. Because many researchers

believe that a substantial number of people on a western diet eat too many w 6s

and not enough w 3s, eating more w 3s

would correct this imbalance. Beneficial effects of w 3 fatty acids have been

shown in the " secondary " prevention

(reducing the worsening of the disease) of coronary heart disease, hypertension,

type 2 diabetes, renal disease,

rheumatoid arthritis, Ulcerative Colitis, Crohn's disease, chronic obstructive

pulmonary disease, dementia, circulatory

problems, and many other conditions.

Moral (essentialfats.com) . It is important to get enough essential fats in

one's diet, but this is not a blanket excuse

to eat fatty foods. Essential fats are found in foods with cell membranes,

particularly green, leafy vegetables,

soybeans, walnuts, and flax seeds. Sorry, they are not found in conventional

French fries or processed foods like

cereals, pastas, and cookies. Also, just because you need to eat essential fats

does not mean you can disregard

calories. You need to maintain an ideal weight to be healthy. This means you

must " spend " your calorie allotment

carefully on healthy foods--you need to get enough nutrients, protein, and

essential fats while not getting too many

calories and gaining weight. References Jequier E. Response to and range of

acceptable fat intake in adults. Eur J Clin

Nutr. 1999 Apr;53 Suppl 1:S84-8; discussion S88-93. Simopoulos AP. Essential

fatty acids in health and chronic disease.

Am J Clin Nutr. 1999 Sep;70(3 Suppl):560S-569S

This material is not medical care or advice and should not be used for diagnosis

or treatment. By reading or using the

information contained in or implied by this article, you agree that the content

provider shall not be liable for any

content errors, or for any actions taken in reliance thereon. Use of this

information is subject to the disclaimer and

the terms and conditions at http://www.essentialfats.com

========================

Good Health & Long Life,

Greg ,

http://www.ozemail.com.au/~gowatson

gowatson@...