Toxins in Sprouted Seeds: Separating Myth from Reality
Warren Peary and William Peavy, Ph.D.
toxins in food has become a hot and controversial subject recently.
the last few years, some popular writers have attacked sprouts (particularly alfalfa
and legume sprouts) as containing natural toxins. These writers may have heard
something about a lathyrogen toxin, saponins, canavanine, and maybe other nasty-sounding
toxins, and concluded that the sprouts of legumes are toxic in the raw state and
so should not be eaten. These statements are taken out of context.
One of the natural toxins that has been mentioned comes from peas
of the genus Lathyrus. It is blamed for causing a disease known as lathyrism.
Lathyrism causes paralysis in the legs in susceptible individuals and is believed
to be caused by a toxic amino acid. This sounds scary, but it's not, because peas
of the genus Lathyrus are NOT edible peas. The toxin is found only in the seeds
of certain Lathyrus species (L. sativus, L. cicera, L. clymenum). Edible peas
and beans are of the genera Cicer, Glycine, Phaseolus, Pisum, and Vigna. They
DO NOT contain any such toxin.
peas of the genus Lathyrus include sweet peas, which are ornamentals grown for
their scented flowers. In India, where food is often scarce, some people have
resorted to eating a non-edible pea known as Lathyrus sativus. It is often called
"chickpea" but is NOT the same chickpea eaten in this country or any
other developed country. The edible chickpea is of the genus Cicer and in botany
is known as Cicer arieti-num.
of lathyrism in India have been blamed on eating large amounts of the non-edible
chickpea without proper cooking. Well-cooked, it is safe to eat. But it shouldn't
matter to us at all because it is considered an inedible species.
are at least 1,500 species of legumes within one of three subfamilies of the family
Leguminosae (Latin for legume). Of these 1,500 species, only a few dozen are regularly
used as human food. Of course there are toxins in many of the raw legumes not
usually used for human food; that's why humans have learned not to eat them. This
is the first mistake sometimes made in warning about natural toxins - talking
about a toxin that's found in some non-edible species people don't or shouldn't
eat to begin with!
The second mistake often made in talking about natural toxins is to call something
toxic that, in the body, is not toxic at all but rather, is beneficial. Such is
the case with saponins.
are a compound found in legumes and legume sprouts. They are toxic to red blood
cells only in vitro (outside of the body in a test tube) but harmless when ingested.
Saponins appear to be beneficial, being responsible for a major part of the cholesterol-
lowering effect of legumes. Perhaps it is more than coincidence that the increase
in the incidence of heart disease in the 20th century in the Western countries
coincides with a decline in the consumption of saponin-rich legumes. Saponins
also seem to be anticarcinogens; in one study they inhibited colon cancer.
some of the most beneficial nutrients, such as vitamin C, can be shown to be toxic
under certain laboratory conditions. Vitamin C is considered an important antioxidant,
and substantial evidence shows that it is involved in cancer prevention.
under the right experimental conditions, in the presence of iron (Fe III) or copper
(Cu II) ions, ascorbic acid can actually cause the formation of harmful free radicals.6
Does this mean you should try to avoid vitamin C? Absolutely not! These experimental
conditions do not appear to be relevant to what goes on in our bodies.
The third mistake made in warning about some natural toxins is failing to say
that the amount encountered in a food is so minuscule that it is completely insignificant.
Such is the case with a toxin called canavanine, which is found in alfalfa seeds.
While some writers may make canavanine sound like a dangerous carcinogen - it
isn't. Canavanine is a non-protein amino acid that's toxic in high amounts. In
the dry seed it serves as a storage protein, a growth inhibitor, and a defense
against natural predators. As you might guess, as the sprout grows, canavanine
falls rapidly to insignificant levels. The text, Seed Physiology, clearly states
that "Canavanine... is non-toxic to mammals at low concentration."
is so irrelevant that the 1980 text, Toxic Constituents of Plant Foodstuffs, doesn't
even mention it. A 150-pound human would have to consume 14,000 milligrams of
canavanine all at once for it to be toxic at the same level it is toxic in mice.
This is an incredible amount! It is doubtful that with a generous helping of alfalfa
sprouts, you would get more than a few milligrams. There is NO canavanine at all
in other legumes that are commonly used as human food.
in toxic amounts, canavanine has nothing to do with cancer. In very high, toxic
amounts it can cause a lupus-like anemia in susceptible animals due to an alteration
in the red blood cells. These studies are not relevant to the human diet. The
minute doses found in the diet are completely irrelevant and harmless.
remember that most substances can show some kind of toxic effect at a high enough
dose. Vitamin A, selenium, copper, zinc, and iron will all kill you at a high
enough dose. So don't stop eating alfalfa sprouts any more than you would any
other food because of some minute toxin that may be present. They are a good source
of vitamin C, folic acid, and other protective compounds.
IN SPROUTED LEGUMES
As far as the sprouts of other edible legumes go,
the only other toxins for which any concern has been raised is for a class known
as anti- nutrients. These are sub-stances that bind enzymes or nutrients and inhibit
the absorption of the nutrients. The commonly alleged anti- nutrients are protease
inhibitors, amylase inhibitors- , phytic acid, and polyphenolic compounds such
as tannins. With proper soaking and germination, none of these is anything to
the world, studies have been and are being conducted on the use of germinated
seeds as a low-cost, highly nutritive source of human food. It is well-established
that when legumes are properly soaked and germinated, their nutritive value increases
greatly, usually to levels equal to or exceeding those of the cooked bean. (Nutritive
value is the ability of food to provide a usable form of nutrients: protein, carbohydrates,
vitamins and minerals). This has been shown for mung bean, lentil, chickpea (garbanzo
bean), cowpea (blackeye pea), pigeon pea, fava bean, fenugreek seeds (a member
of the pea family), green And black gram, kidney bean, moth bean, rice bean,
soybean, and legumes in general.
increase in nutritive value in the raw sprouted seed is due to an explosion of
enzyme activity, which breaks down the storage-protein and starch in the seed
into amino acids, peptides, and simpler carbohydrates needed for the seed to grow.
The seed is literally digesting its own protein and starch and creating amino
acids in the process. Because of this process, sprouted seeds are essentially
a predigested food. At the same time, the anti-nutritional factors such as enzyme
inhibitors and other anti-nutrients are greatly decreased to insignificant levels
or to nothing.
alone causes a significant decrease in anti-nutrients, as the antinutrients are
leached into the soak water. Soaking for 18 hours removed 65% of hemag-glutinin
activity in peas.66 Soaking for 24 hours at room temperature removed 66% of the
trypsin (protease) inhibitor activity in mung bean, 93% in lentil, 59% in chickpea,
and 100% in broad bean. Then as germination proceeds, anti-nutrients are degraded
further to lower levels or nothing. Soaking for 12 hours and 3-4 days of germination
completely removed all hemagglutinating activity in mung bean and lentil. Soaking
for 10 hours and germination for 3 days completely eliminated amylase inhibitor
in lentils. Normal cooking removes most or all of the anti-nutrients.
Some of the substances commonly referred to as anti-nutrients
are actually powerful cancer-protecting phyto-chemicals. These include protease
inhibitors and tannins. The problem in most diets is that we don't get enough
of these substances.
research shows that protease inhibitors are one of the most powerful anti-carcinogens
we have in our arsenal. They have proven to be particularly protective against
cancer of the colon, breast, and prostate.
have also been shown to give substantial protection against cancer (including
cancer of the stomach and lungs) when ingested orally. Tannins and other polyphenols
may play a role in fighting tooth decay. Evidence shows that some tannins inhibit
the growth of bacteria that cause tooth decay. Phytates, like tannins, may also
interact with digestive processes in a beneficial way. Small amounts in food slow
down the absorption of sugars and regulate insulin levels. This is beneficial
in the prevention and treatment of diabetes and hyperlipidemia (high blood fats).
Small amounts of protease inhibitors, tannins, and phytates are beneficial and
can be considered to be a normal part of our nutritional ecology.
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