Preventive Medicine and
Nutrition
Essential
Fatty Acid Basics
The body can synthesize some of the fats it
needs from the foods you eat. However, two essential fatty acids
cannot be synthesized in the body and can be taken in the diet
from plant foods. Their names-linolenic and linoleic acid-are not
important. What is important is that these basic fats are used to
build specialized fats called omega-3 and omega-6 fatty acids.1
Omega-3 and omega-6 fatty acids are
important in the normal functioning of all tissues of the body.
Deficiencies are responsible for a host of symptoms and disorders
including abnormalities in the liver and kidney, changes in the
blood, reduced growth rates, decreased immune function,
depression, and skin changes, including dryness and scaliness.
Adequate intake of the essential fatty acids results in numerous
health benefits. Prevention of atherosclerosis, reduced incidence
of heart disease and stroke, and relief from the symptoms
associated with ulcerative colitis, menstrual pain, and joint pain
have also been documented. 2,3, 4
While supplements and added oils are not
typically necessary in the vegetarian diet, good sources of
omega-3 and omega-6 fats should be included daily. It is important
to take these two fats in the proper ratio as well. Omega-6 fatty
acids compete with omega-3 fatty acids for use in the body, and
therefore excessive intake of omega-6 fatty acids can be a
problem. The U.S. diet has become heavy in omega-6 fats and low in
omega-3 fats, secondary to a reliance on processed foods and oils.
It is necessary to balance this by eating a low-fat diet that is
low in processed foods and with fat mainly coming from omega-3
fatty acids.
Omega-6
Fatty Acids
Omega-6 fats are found in leafy vegetables,
seeds, nuts, grains, and vegetable oils (corn, safflower, soybean,
cottonseed, sesame, sunflower). Other omega-6 fatty acids, such as
gamma-linolenic acid (GLA), can be found in more rare oils,
including black currant, borage, evening primrose, and hemp oils.3
Most diets provide adequate amounts of omega-6 fatty acids.
| Plant Foods Rich in Omega-3 Fatty
Acids |
| Green leafy vegetables (lettuce, broccoli,
kale, purslane, spinach, etc.) |
| Legumes (mungo*, kidney, navy, pinto, or
lima beans, peas or split peas, etc.) |
| Citrus fruits, melons, cherries |
| Ground flaxseed |
| * Mungo beans are particularly high in
omega-3 fatty acids. They are sold in many Indian groceries
and may be found under the name "urid." |
Omega-3
Fatty Acids
It is important for vegetarians to include
foods that are rich in omega-3 fatty acids on a daily basis.
Alpha-linolenic acid, a common omega-3 fatty acid, is found in
many vegetables, beans, nuts, seeds, and fruits. The best source
of alpha-linolenic acid is flaxseeds or flaxseed oil. More
concentrated sources can be found in oils such as canola, soybean,
walnut, and wheat germ. Omega-3 fatty acids can be found in
smaller quantities in nuts, seeds, and soy products, as well as
beans, vegetables, and whole grains. Corn, safflower, sunflower,
and cottonseed oils are generally low in omega-3s.
| Omega-3 Content of Natural Oils5,6 |
| Flaxseed 53-62% |
| Linseed 53% |
| Canola 11% |
| Walnut 10% |
| Wheat germ 7% |
| Soybean 7% |
Flaxseeds
for Omega-3s
Flaxseed oil and ground flaxseeds are
particularly good choices to meet your needs for omega-3 fatty
acids. One teaspoonful of flaxseed oil or a tablespoonful of
ground flaxseed will supply the daily requirement of alpha-linolenic
acid. To protect it from oxygen damage, flaxseed oil or ground
flax seed must be stored in the refrigerator or the freezer. Use a
little in dressings for salads or baked potatoes. Don't try to
cook with this oil, however, as heat damages its omega-3s.For you
to absorb what you need from flaxseeds, theymust be ground. Simply
put fresh flaxseeds in a spice or coffee grinder for a few
seconds. Some people grind a cup every week or so and store it in
the freezer. A spoonful can be added to a smoothie or sprinkled on
breakfast cereal, a salad, or other dish.
Pregnancy
and Lactation
In pregnancy and lactation, it is especially
important to obtain adequate essential fatty acids from the diet.
Recent research suggests that pregnant women may have increased
needs for these fatty acids, as they are needed for fetal growth,
brain development, learning, and behavior. Essential fatty acids
are also important for the infant after birth for growth and
proper development, as well as the normal functioning of all
tissues of the body. Infants receive essential fatty acids through
breast milk, so it is important that the mother's diet contain a
good supply of omega-3s. Pregnant somen and lactating mothers may
also opt to take a DHA supplment (DHA, or docosahexaenoic acid, is
a form of omega-3 fatty acids). A DHA supplement based on cultured
microalgae, under the trademark Neuromins, is available in many
natural food stores.
Fish for
Essential Fatty Acids?
Some people may have heard that fish are
good sources of essential fatty acids. However, the high amounts
of fat and cholesterol and the lack of fiber make fish a poor
choice. Fish are also often high in mercury and other
environmental toxins that have no place in an optimal diet.
Fish oils have been popularized as an aid
against everything from heart problems to arthritis. The bad news
about fish oils is that omega-3s in fish oils are highly unstable
molecules that tend to decompose and, in the process, unleash
dangerous free radicals. Research has shown that omega-3s are
found in a more stable form in vegetables, fruits, and beans.7,
8
Whether you are interested in promoting
cardiovascular health, ensuring the proper growth and development
of your child, or relieving pain, a vegetarian diet rich in
fruits, vegetables, nuts, seeds, and legumes can help you achieve
adequate intake of the essential fatty acids.
References
1. Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human
Metabolism. West Publishing Company, New York, 1995.
2. Linscheer WG, Vergroesen AJ. Lipids. In: Modern Nutrition in
Health and Disease. Shils ME, Olson JA, Shike M, eds. Lea and
Febiger, Philadelphia, 1994.
3. Barnard N. Foods That Fight Pain. Harmony Books, New York,
1998.
4. Omega-3 fatty acids and depression: new data. Harv Ment Helath
Lett 2003 Jun;19(12):7.
5. Hunter JE. n-3 Fatty acids from vegetable oils. Am J Clin Nutr
1990;51:809-14.
6. Mantzioris E, James MJ, Gibson RA, Cleland LG. Dietary
substitution with an alpha-linolenic acid-rich vegetable oil
increases eicosapentaenoic acid concentrations in tissues. Am J
Clin Nutr 1994;59:1304-9.
7. Odeleye OE, Watson RR. Health implications of the n-3 fatty
acids. Am J Clin Nutr 1991;53:177-8.
8. Kinsella JE. Reply to O Odeleye and R Watson. Am J Clin Nutr
1991;53:178. |
