They Are and Why You Need Them
By Denis Faye
In October we evaluated
vitamins. Now it's time to take on minerals.
The biggest difference
between vitamins and minerals is that minerals aren't organic.
Also, you can actually
absorb minerals through industrial contaminants in both the air and water, although
that's not something we recommend.
There are two types
of minerals: macro and trace. Macro minerals are required in quantities ranging
from 100 milligrams (mg) to 1 gram. This group includes calcium, phosphorus,
magnesium, sodium, potassium, chloride and sulfur. These are your body's major
electrolytes, or salts. Although they serve various functions, they all work
together to maintain and carry electricity across your body by way of your cells.
As the folks at Gatorade love to warn us, you lose electrolytes when you sweat,
so maintaining them is especially important for us exercise nuts. And this can
be a little hard to gauge because the scale slides greatly. For example, an
inactive person can live on 500 mg of sodium a day, but an athlete doing hard,
prolonged activity (running in the desert, for example) can lose 2000 mg an
The second group
of minerals is called trace minerals. There are quite a few of these, but the
ones we're going to deal with are copper, iodine, zinc, selenium, chromium and
manganese. As their heading would indicate, you don't need much of these bad
boys to get by. And like all minerals, too much can be toxic.
There's no recommended daily allowance (RDA) for magnesium, although roughly 400 mg is
a healthy intake for men, and 300 mg for women. But like all electrolytes, more
is needed when you exercise. Taking too much can lead to kidney problems, with
side effects including nausea, vomiting, diarrhea, dizziness and muscle weakness.
If you do ample exercise, this is generally not a problem.
Magnesium is the
cattle dog of electrolytes, as it herds other electrolytes into and out of cells.
This is why you'll so often see it mixed into various supplements. It also regulates
energy production in cells and is vital for proper muscle, nerve and enzyme
function. This makes it particularly important for exerciselow levels
can lead to problems such as cramping.
Mostly found inside
bones and cells, magnesium is plentiful in the body. It's absorbed through the
small intestines and can be found in nuts, green vegetables, whole grainsand
especially pumpkin seeds.
You don't need much zincthe RDA is only 15 mg. But those little milligrams go
a long way. Zinc supports your immune system and aids in healing. It's also important
for your digestion by stimulating approximately 100 enzymesprotein catalysts
that convert nutrients to energy and break down food.
If you take over
150 mg a day on a regular basis, you run the risk zinc toxicity, a nasty bit
of business involving reduced immune function and reduced levels of "good"
You'll find zinc
in liver, eggs, seafood, whole grains and oysters, which contain an impressive
11 mg per gram.
an RDA of 2 mg, you need just a hint of copper, but that hint is vital for forming
red blood cells and making sure your immune system, bones, blood vessels and
nerves stay healthy.
Too much copper,
however, can be trouble. For adults, taking more than 10 mg a day can lead to
toxic reactions including severe anemia, nausea, abdominal pain, diarrhea, coma
hard to overdose on copper through a healthy diet. Usually the way it happens
is through industrial contamination or overuse use of copper supplements.
Your best sources
of copper include oysters, nuts, organ meats and legumes.
no RDA for manganese, about roughly 2 mg is a good target.
form tendons and other connective tissue, fats, cholesterol, bones and proteins.
It also aids in the digestion of certain proteins, as well as transporting glucose
throughout the body.
It's not the most
exciting mineral, considering that deficiency in humans has never been reportednor
has manganese toxicity from dietary intake. However, inhaling manganese-laced
dust has been known to damage the central nervous systems of miners and steel
Just in case, the
Food and Nutrition Board of the Institute of Medicine says adults should keep
their manganese intake to below 11 mg daily.
You'll find manganese
in nuts, whole grains, vegetables, fruits and, apparently, mine shafts.
again, there's no RDA for chromium, but 35 micrograms (mcg) per day is suggested
for men, 25 mg for women.
with insulin to aid cells in taking in glucose and releasing energy. People
who primarily eat processed foods are strong candidates for chromium deficiency.
Also, chromium is passed through urine, sweat, bile and hair, so people who
do a lot of physical exercise need to keep an eye on their level. A deficiency
is characterized by insulin resistance, hyperglycemia and lipid abnormalities.
There have been
no known cases of chromium toxicitynot even in steel workers.
You'll find this
mineral in broccoli, turkey, corn oil, clams, brewer's yeast and whole grains.
So, if your kids resist eating broccoli, tell them it's okay, they can just
eat clams instead.
Checking in with an RDA of 150 mcg, iodine provides only one service for the human body, but that service is a doozy.�It helps in the formation
of the all-important thyroid hormone, which is crucial for human growth and development.
deficiency is rare nowadays, it can lead to goiter, a swelling of the thyroid
gland that shows up on the front of the neck. Ironically, too much iodine over
a long period of time can actually hinder thyroid function, which in turn leads
to hypothyroidism and, you guessed it, again with the goiter.
According to the
Food and Nutrition Board of the Institute of Medicine, iodine toxicity can be
a risk for an adult when the approximately 1100 mg daily limit is exceeded.
Although it would be hard to eat that much, our most common source of contact
with iodine is car exhaust.
While you'll want
to avoid sucking tail pipes, healthier sources of iodine are seafood and iodized
molybdenum has no RDA, the approximately 45 mcg you should be taking is needed
to convert something called purine into uric acid. And why is that important?
Because your body needs uric acid to take iron out of storage and put it in
a role in several other enzyme-related activities, but none of them are as sexy
as that uric acid conversion.
isn't really a concern nowadays and toxicity is extremely rare, although if
you do consume more than 2000 mcg a day it could interfere with your absorption
of copper, or lead to nausea, diarrhea, or joint pain and swelling.
You'll find it
in milk, dried beans, peas, nuts and seeds, eggs, liver, tomatoes, carrots and
There's no RDA for this mineral, but 55 mcg is a good number for most adults to shoot
for. It plays an important role in antioxidant enzymes and is crucial if you want
to keep your immune system and thyroid gland working properly.
Too much selenium,
as in 750 mcg on a daily basis, can lead to selenosis, a condition with symptoms
including nausea, vomiting, diarrhea, hair loss, white blotchy nails, and mild
nerve damage. Selenosis is rare in America, usually resulting from industrial
Given its role
in the immune system and as an antioxidant, researchers are currently investigating
the effect of selenium supplementation on HIV patients.
You'll find selenium
in seafood, organ meats, lean meats, grainsand huge doses in Brazil nuts,
as in a quarter cup containing 1036 mcg.
1000 mg RDA is an important one. When we hit 30, we start to lose bone mass.
Getting enough calcium, vitamin D and phosphorus helps slow that bone loss down.
It is also essential for preventing osteoporosis.
However, make sure
to keep it below 2500 mg a day. Any more could lead to constipation and interfere
with absorption of iron and magnesium.
Although it's widely
believed that dairy is the source of calcium, in fact there are quite
a few sourcesmany of which are more efficient than milkincluding
tofu and whole grains, cold-water fish, broccoli and spinach.
for iron is a paltry 18 mg, given that the adult body is pretty good at holding
on to this mineral. The exception to this is menstruation. Since the bulk of
your iron is stored in red blood cells, women with heavy periods experience
significant iron loss.
Iron is an important
component of two proteins, hemoglobin and myoglobin. Hemoglobin, found in red
blood cells, carries oxygen to your body's tissues. The lesser-known myoglobin
also helps provide oxygen to muscles.
Because we hold
on to iron, it's an easy one to get too much of. For adults, 45 mg is a good
number to keep below. Signs of iron toxicity include nausea, vomiting, constipation,
diarrhea, dark-colored stools and abdominal distress.
There are two kinds
of dietary iron: heme and nonheme. The body absorbs heme, which comes from meat,
quite efficiently. Nonheme, from lentils and legumes, has a tougher time getting
The RDA for phosphorus is 1000 mg. Although its main function is forming bones and
teeth, it also plays an important part in the body's use of protein, carbs and
fats for the growth and upkeep of cells.
The kidneys regulate
the body's phosphorus, so you pass what you don't need. People with kidney problems
need to limit phosphorus intake. Elevated phosphorus levels in the blood can
lead to hyperphosphatemia, which means blood calcium levels decrease and the
parathyroid gland overproduces parathyroid hormone, leading to bone loss.
But it's pretty
tough to totally knock phosphorus from your diet since most foods contain this
mineral, especially fish, meat, poultry, eggs and grains.
no RDA for potassium, but if you eat a healthy, balanced diet, you should get
plenty of it. Exercise can change this, as you lose it quickly when you sweat.
Since sweat is approximately 3 parts sodium to 1 part potassium, it's good to
keep that in mind when rehydrating during exercise.
You'll find potassium
inside every cell in your body, where it balances the sodium outside the cells.
The two maintain proper hydration. An imbalance can lead to pooling of water
As with phosphorus,
the kidneys regulate your potassium, so if you get too much, it comes out in
include lean meats, vegetables and fruit.
Many of us mistake this important electrolyte for a villain. Indeed, too much sodium
can lead to hypertension, edema and even osteoporosis. But don't blame this poor
mineral! Instead, blame our lousy eating habits. The RDA for sodium is less than
2400 mg a day. The average American diet provides twice that.
Like with potassium,
when we sweat, the amount of sodium we need changes rapidly. Your body only
needs around 500 mg a day to function properly, so the RDA is based on a ballpark
estimate. If you sit around all day, you need less. If you're a bike messenger
in the tropics, chances are you'll need a lot more. In an average hour of exercise,
like a session of Burn It Up!, you probably sweat out about 600 mg
of sodium, and this can double if it's hot outside.
Sodium is crucial
because it works with potassium to maintain the body's extracellular fluid levels
by pumping water into cells. It also plays an important role in several other
functions, including regulation of plasma volume, nerve impulses and muscle
Americans, the body can pass excess sodium through the kidneys. Also, as mentioned
earlier, we sweat out lots of the stuff during exercise, so it's important to
find a balance that's right for you.
The best way to
get sodium is through salt and all that is salty. Some healthier examples of
high-sodium foods are pickles, chicken soup and pretzels.