Dear Dr. Watts,
Recently, I see that many processed foods contain
soy, sometimes in large amounts. I don’t eat a lot of
processed foods, but cold cereals are still on my menu.
However, I do make my own granola. Can you address
the nutritional issues of foods with soy?

Debra, your question is an
important one that many
people struggle to understand.
While we don’t have space here for
an exhaustive study, this is at least a
place to start. “The Whole Soy Story,”
by Kaayla T Daniel, PhD, CCN is a
great next read.

To start off, soy is very difficult to
digest unless enzymes and bacteria
have worked on it first to break down
complex proteins, fats and starches
into digestible amino acids; and fatty
acids and sugars-this is the process
of fermentation. Fermentation also
breaks down protease and trypsin
inhibitors found in soy. These
molecules were thought to protect
the plant from predation in the
wild. Animals that fed on soy would
eventually experience slowed growth
and diminished reproductive activity.

These anecdotal tales of adverse
effects are the basis for potential
concern today. There has been
increasing interest in soy since the
U.S. Food and Drug Administration
approved a 1999 health claim that
a diet low in saturated fat and
cholesterol and containing 25 grams
of soy protein, may reduce
the risk of heart disease.
However, soy contains other
molecules besides beneficial
protein and dietary fiber.

Soybeans are unique
among legumes because
they are a concentrated
source of isoflavones, or
phytoestrogens-molecules
that are close enough in
structure to act like human
hormones and sometimes bind with
estrogen receptor sites throughout
the body. Despite their relatively
low potency, it has been shown that
people who consume lots of soy
foods can have blood isoflavone
concentrations high enough to
produce estrogenic effects and
lower testosterone levels. This can
be a very real concern, especially for
people dealing with infertility, low
sexual function and cancers of the
reproductive systems.

They also contain several components
considered to be antinutrients, which
can interfere with protein digestion
and mineral absorption. These have
been linked to malnutrition, pancreatic
disease, anemia and even cancer.

Manganese, an essential mineral
nutrient, is found in high levels in
soy plants. But too much is a bad
thing. Infants who drink soy-based
formulas can be exposed to excessive
manganese levels and increase their
risk of adverse neurological effects.
Overexposure has been linked to
learning disabilities, soft teeth and
brittle bones.

Many Americans began eating and
drinking soy as an alternative to
meat and dairy products. But what is
happening now is that the soy most
Americans consume is not the most
easily digestible fermented form
of soy. The research and marketing
that boasts the wonders of soy
are not incorrect. There are many
valuable components to fermented
soy, including high levels of vitamin
K and fatty acids for healthy
bones and cells, digestive aid,
hormone replacement and strong
antioxidants, but these health claims
are often portrayed across all soy
products. Fermented soy versus
other soy products is like comparing
apples to oranges. So as a rule of
thumb, limit your nonfermented
soy foods intake to a level that is
appropriate with your specific body
needs (i.e. food sensitivities)
or a recommended daily
allowance of 2.5%-7% of
your daily caloric intake,
and when it comes to soy in
general, less is more.

FERMENTED SOY FOODS:

• Tempeh
• Miso
• Traditional soy sauce
• Fermented soymilk

NONFERMENTED SOY FOODS:

• Soymilk
• Tofu
• Soy nuts
• Soy protein isolates

Do you have a
question that
needs answering?
Get in touch with
Dr. Kristen Watts
to start the
conversation:nutrition@wedge.
coop