| It’s
important to realize that the adverse effects of excessive fat are
consistently linked with animal fats and processed fats and
oils containing trans fatty acids. The unprocessed fats and
oils of whole plant foods have quite a different effect on health.
Many studies have demonstrated that the fat in nuts, seeds, avocados,
olives and other plant foods is actually protective. When people get
most of their fat from these sources, they can consume relatively
high amounts without adverse effects. In contrast, people who get
most of their fat from animal foods and processed products tend to
be at risk even at moderate fat intakes. They really do need to cut
down on these potentially damaging fats and oils.
For healthy
vegetarians, cutting down too much on wholesome, high-fat plant
foods poses several problems:
- Very low-fat
diets may provide excessive bulk and insufficient calories, particularly
for infants, children, and people with very high energy requirements,
like athletes or labourers.
- Very low
fat diets often contain inadequate amounts of essential fatty
acids, especially the omega-3 fatty acids (discussed below).
- Insufficient
fat can compromise absorption of fat-soluble vitamins (A, D, E,
and K), minerals (including iron, zinc, manganese, and calcium),
and healthful phytochemicals (like the lycopene in tomato products).
- People on
very low fat diets often become “fat phobic.” They assume all
high fat foods are bad and that all low fat foods are good. This
often leads them to choose foods that are actually “nutritional
washouts” (packaged fat-free cookies, cakes, and chips, for example)
while obsessively avoiding higher-fat plant foods that are very
nutritious, like avocados, olives, nuts, seeds, and tofu.
Very low fat diets can cause a drop in HDL-cholesterol (“good
cholesterol”) and a rise in triglycerides (another potentially
damaging blood fat, like LDL-cholesterol), actually increasing
your risk for cardiovascular disease. However, this is not normally
a problem unless you replace the fat with refined carbohydrates,
like sugar and white flour products.
So, how much fat
should you eat?
I’d suggest
something in the range of 15 to 30 percent of calories. But remember,
the quality of the fat is at least as important as the quantity.
That brings
us to part two of your question:
What are
the best fats and oils for vegetarians?
Without a doubt
the answer is whole plant foods, like nuts, seeds, avocados,
olives, and soybeans. These foods are packaged by nature to protect
their fats and oils from damaging light, heat, and oxygen. They
also carry valuable vitamins, minerals, phytochemicals, plant sterols,
essential fatty acids, and fibre.
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Many studies have demonstrated that the fat in nuts, seeds,
avocados, olives and other plant foods is actually protective.
When people get most of their fat from these sources, they
can consume relatively high amounts without adverse effects.
Becoming
Vegan
By
Brenda Davis and Vesanto Melina
Lacto-
and lacto-ovo vegetarian diets have the potential to be high
in saturated fat and cholesterol if you eat a lot of eggs
or full-fat dairy products.
Becoming
Vegetarian
By
Vesanto Melina, Brenda Davis, and Victoria Harrison
Most
people get too much of the omega-6 fatty acids in their diet
and not enough of the omega-3s. This imbalance may result
in poor brain development and reduced visual acuity in infants.
In people of any age, it may also contribute to chronic diseases,
immune/inflammatory disorders, and psychological disorders
too.
Dairy-Free
& Delicious
By
Brenda Davis, Bryanna Clark Grogan, and Joanne Stepaniak
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As I’ve already
suggested, the fats in these foods are actually good for us.
That’s right:
we need fat. It provides energy, insulation, and “padding,”
not just for our posteriors but to protect internal organs. We need
fat to absorb many vitamins, minerals and phytochemicals. Certain
fats are required for healthy cell membranes and to maintain cell
integrity, permeability, shape, and flexibility. These fats also
are critical for the development and functioning of the brain and
nervous system. Finally, they are the building blocks for hormone-like
substances called eicosanoids that regulate many organ systems.
These special
fats are known as essential fatty acids (EFA), because they
are as essential for our survival as vitamins and oxygen.
How do we
ensure that we eat good fats?
Begin by reducing
your intake of foods rich in saturated fats, cholesterol, and trans
fatty acids.
Unless you use
large amounts of tropical plant oils (coconut, palm, and palm kernel
oil), vegan diets are generally low in saturated fat. They’re always
free of cholesterol.
On the other
hand, lacto- and lacto-ovo vegetarian diets have the potential to
be high in saturated fat and cholesterol if you eat a lot of eggs
or full-fat dairy products.
There is considerable
controversy about tropical oils. In less affluent parts of the world
where the indigenous diet is plant-based and coconuts and other
high saturated-fat plant foods are staples, the rates of chronic
disease are relatively low. By contrast, tropical oils are scarce
in most North American diets, yet chronic disease rates are high.
Research suggests that – when consumed in moderation as part of
a high fibre, cholesterol-free, plant-based diet – coconut and other
saturated fat-rich plant foods do not increase cholesterol levels
or heart attacks.
So it’s unnecessary
for vegans or vegetarians to completely eliminate these foods from
their diets. The small amount of saturated fat coming from whole
plant foods may in fact be of benefit for vegans. These are very
stable fats with a low risk of being damaged and made dangerous
to your health by oxidation, in contrast to the unstable polyunsaturated
fats that are generally very high in vegan diets.
What about
cholesterol? Since it’s found only in animal foods, this potential
artery clogger is rarely a problem in vegetarian diets, unless you
eat a lot of eggs and high fat dairy products.
Trans fatty
acids are another story. The product primarily of hydrogenation
(the food technology process of changing liquid oils into solid
fats), the main sources of these harmful fats are:
shortening
hydrogenated
commercially prepared foods, like crackers, cookies, cakes, pastries,
potato chips, frozen convenience foods (just about any commercial
snack food)
and, of course,
any food that lists “hydrogenated” or “partially-hydrogenated”
vegetable oil on the label.
Also, beware of
fast food establishments: they generally use hydrogenated oils for
deep-frying.
Because trans
fatty acids increase the risk of degenerative diseases, they should
be avoided.
Now for the
healthy fats.
One of the biggest
problems with fat in the vegetarian diet (and many nonvegetarian
diets too) is that we get a poor balance of essential fatty acids.
There are two
essential fatty acids:
Linoleic
acid, from the omega-6 family, which can be converted
and elongated in our bodies to two very important long-chain fatty
acids named GLA (gamma-linolenic acid) and AA (arachidonic acid).
Similarly,
alpha-linolenic acid, from the omega-3 family, which
can be converted and elongated to two other very important long-chain
fatty acids: DHA (docosahexaenoic acid) and EPA (eicosapentaenoic
acid).
Most people get
too much of the omega-6 fatty acids in their diet and not enough of
the omega-3s. This imbalance may result in poor brain development
and reduced visual acuity in infants. In people of any age, it may
also contribute to chronic diseases, immune/inflammatory disorders,
and psychological disorders too.
Linoleic acid
is found mainly in seed oils (like sunflower, safflower, sesame,
and grape), corn oil, soy, and grains. Alpha-linolenic acid is found
mainly in flax seeds, hemp seeds, greens, canola oil, walnuts, and
soy.
Few plant foods
contain the long-chain fatty acids, which are most commonly found
in fish (omega-3s – namely EPA and DHA) and meat (omega-6s – namely
AA). Algae and seaweed are the only exception. They contain long-chain
omega-3s, but generally in very small amounts.
Thus, vegans
(but not necessarilly vegetarians, see below) get almost all their
long-chain fatty acids from internal conversion of the short-chain
EFA. Unfortunately, this conversion is very limited for omega-3
fatty acids: only about 4-10% of alpha-linolenic acid is converted
into EPA, and just 2-5% becomes DHA. Worse, high intakes of omega-6
fatty acids can competitively block this conversion by up to 50%.
Fortunately,
to optimize your essential fatty acid balance there are several
things you can do:
- Limit your
use of linoleic-acid-rich oils (see above).
- Select foods
rich in monounsaturated fat as your primary fat source: nuts and
nut oils, olives and olive oil (extra virgin is best), canola
oil (preferably organic), and avocados.
- Include a
good source of alpha-linolenic acid in your diet every day. We
need about 2 to 3 grams. You can get this much from:
1 tsp. flax
oil
1/4 cup
walnuts
2 Tbsp.
soy oil
1 Tbsp.
hemp oil
20 cups
dark greens
1 cup soybeans
1 Tbsp.
ground flaxseeds
4 tsp. canola
oil
12 ounces
firm tofu
- Consider
getting a direct source of EPA and DHA, especially if you’re pregnant
or lactating.
- For lacto-ovo
vegetarians, omega-3 rich eggs are a reasonable source of
DHA.
- For vegans,
microalgae-based supplements are the best option. While seaweeds
themselves contain some EPA, they are so low in fat you’d
have to eat enormous (and potentially unhealthful) amounts
to make any significant contribution to omega-3 intake.
- There
are two companies that market vegetarian DHA. NuTru sells
“O-Mega-Zen3” with 300 mg of DHA per capsule, and Seroyal
of Toronto sells a 100 mg capsule, but only through licensed
health practitioners. Martek and OmegaTech also sell microalgae-based
DHA, but their capsules are made of nonvegetarian gelatin.
A reasonable daily intake of DHA would be 100-300 mg. Use
200-300 mg during pregnancy and lactation.
To ensure the highest
quality of fat in your diet, remember to use fresh, whole
plant foods.
Whenever possible,
choose mechanically-pressed, unrefined oils.
Store nuts,
seeds and oils in a cool, dry place in airtight containers away
from direct sunlight. When properly stored, unshelled nuts and whole
seeds last up to a year. Shelled nuts and ground seeds can be stored
in the refrigerator for up to four months or in an airtight container
in the freezer for up to one year. Ground flaxseeds are more unstable
due to their high omega-3 content. They are best stored in the freezer
after grinding. Nut halves keep better than pieces as they are less
exposed to light and oxygen.
While refined
oils last many months in the pantry, fresh-pressed oils (other than
olive oil) go rancid much more quickly and need to be refrigerated
and used within two months (flax oil is best used up within six
weeks). Olive oil lasts longer than other fresh-pressed oils and
can be stored in the pantry for up to three to four months.
Finally,
oils are easily damaged by heat, especially those containing omega-3
fatty acids. But those like olive oil, organic canola oil, and high
oleic sunflower or safflower oil that contain mostly monounsaturated
fats are more stable when heated and are your best choice for cooking
and baking. So is nonhydrogenated margarine (casein-free, if you’re
vegan).
With just a little
bit of care, a vegetarian diet can be a source of fats and oils that
add savour to your meals and health to your years.
Brenda
Davis, R. D.
One of the world’s most respected vegan
dietitans, Brenda Davis is co-author of the acclaimed Becoming Vegetarian
and Becoming
Vegan. Her latest book is Dairy-Free
& Delicious.
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