Poslao mi zabrinuti brat podugački tekst o vege mitovima tj. zašto je dobro jesti mesoPisao mrdrsci neki s hrpu radova... Ja sam uredno pročitala i prosljeđujem...da vas čujem, vegosi :D Tekst je prilično dugačak, ali nemam mogućnosti staviti ga nekam na net, a ne znam od kuda je izvorno pa ga eto tu.
MYTH #3: Our needs for vitamin D can be met by sunlight.
Though not really a vegetarian myth per se, it is widely believed that
one's vitamin D needs can be met simply by exposing one's skin to the
sun's rays for 15-20 minutes a few times a week. Concerns about vitamin
D deficiencies in vegetarians and vegans always exist as this nutrient,
in its full-complex form, is only found in animal fats (18) which vegans
do not consume and more moderate vegetarians only consume in limited
quantities due to their meatless diets.
It is true that a limited number of plant foods such as alfalfa,
sunflower seeds, and avocado, contain the plant form of vitamin D
(ergocalciferol, or vitamin D2). Although D2 can be used to prevent and
treat the vitamin D deficiency disease, rickets, in humans, it is
questionable, though, whether this form is as effective as
animal-derived vitamin D3 (cholecalciferol). Some studies have shown
that D2 is not utilized as well as D3 in animals (19) and clinicians
have reported disappointing results using vitamin D2 to treat vitamin
D-related conditions (20).
Although vitamin D can be created by our bodies by the action of
sunlight on our skin, it is very difficult to obtain an optimal amount
of vitamin D by a brief foray into the sun. There are three ultraviolet
bands of radiation that come from sunlight named A, B, and C. Only the
"B" form is capable of catalyzing the conversion of cholesterol to
vitamin D in our bodies (21) and UV-B rays are only present at certain
times of day, at certain latitudes, and at certain times of the year
(22). Furthermore, depending on one's skin color, obtaining 200-400 IUs
of vitamin D from the sun can take as long as two full hours of
continual sunning (23). A dark-skinned vegan, therefore, will find it
impossible to obtain optimal vitamin D intake by sunning himself for 20
minutes a few times a week, even if sunning occurs during those limited
times of the day and year when UV-B rays are available.
The current RDA for vitamin D is 400 IUs, but Dr. Weston Price's seminal
research into healthy native adult people's diets showed that their
daily intake of vitamin D (from animal foods) was about 10 times that
amount, or 4,000 IUs (24). Accordingly, Dr. Price placed a great
emphasis on vitamin D in the diet. Without vitamin D, for example, it is
impossible to utilize minerals like calcium, phosphorous, and magnesium.
Recent research has confirmed Dr. Price's higher recommendations for
vitamin D for adults (24).
Since rickets and/or low vitamin D levels has been well-documented in
many vegetarians and vegans (26), since animal fats are either lacking
or deficient in vegetarian diets (as well as those of the general
Western public who routinely try to cut their animal fat intake), since
sunlight is only a source of vitamin D at certain times and at certain
latitudes, and since current dietary recommendations for vitamin D are
too low, this emphasizes the need to have reliable and abundant sources
of this nutrient in our daily diets. Good sources include cod liver oil,
lard from pigs that were exposed to sunlight, shrimp, wild salmon,
sardines, butter, full-fat dairy products, and eggs from properly fed
chickens.
<MYTH #4: The body's needs for vitamin A can be entirely obtained from
plant foods.
True vitamin A, or retinol and its associated esters, is only found in
animal fats and organs like liver (27). Plants do contain beta-carotene,
a substance that the body can convert into vitamin A if certain
conditions are present (see below). Beta-carotene, however, is not
vitamin A. It is typical for vegans and vegetarians (as well as most
popular nutrition writers) to say that plant foods like carrots and
spinach contain vitamin A and that beta-carotene is just as good as
vitamin A. These things are not true even though beta-carotene is an
important nutritional factor for humans.
The conversion from carotene to vitamin A in the intestines can only
take place in the presence of bile salts. This means that fat must be
eaten with the carotenes to stimulate bile secretion. Additionally,
infants and people with hypothyroidism, gall bladder problems or
diabetes (altogether, a significant portion of the population) either
cannot make the conversion, or do so very poorly. Lastly, the body's
conversion from carotene to vitamin A is not very efficient: it takes
roughly 6 units of carotene to make one unit of vitamin A. What this
means is that a sweet potato (containing about 25,000 units of
beta-carotene) will only convert into about 4,000 units of vitamin A
(assuming you ate it with fat, are not diabetic, are not an infant, and
do not have a thyroid or gall bladder problem) [28].
Relying on plant sources for vitamin A, then, is not a very wise idea.
This provides yet another reason to include animal foods and fats in our
diets. Butter and full-fat dairy foods, especially from pastured cows,
are good vitamin A sources, as is cod liver oil. Vitamin A is
all-important in our diets, for it enables the body to use proteins and
minerals, insures proper vision, enhances the immune system, enables
reproduction, and fights infections (29). As with vitamin D, Dr. Price
found that the diets of healthy primitive peoples supplied substantial
amounts of vitamin A, again emphasizing the great need humans have for
this nutrient in maintaining optimal health now and for future
generations.