The human body requires seven major types of nutrients
A nutrient is a source of nourishment, an ingredient in a food, e.g.
protein, carbohydrate, fat, vitamin, mineral, fiber and water.
Macronutrients are nutrients we need in relatively large quantities.
Micronutrients are nutrients we need in relatively small quantities.
Energy macronutrients - these provide energy, which is measured either
in kilocalories (kcal) or Joules. 1 kcal = 4185.8 joules.
■Carbohydrates - 4 kcal per gram
Molecules consist of carbon, hydrogen and oxygen atoms. Carbohydrates
include monosaccharides (glucose, fructose, glactose), sisaccharides,
and polysaccharides (starch).
Nutritionally, polysaccharides are
more favored for humans because they are more complex molecular sugar
chains and take longer to break down - the more complex a sugar molecule
is the longer it takes to break down and absorb into the bloodstream,
and the less it spikes blood sugar levels. Spikes in blood sugar levels
are linked to heart and vascular diseases.
■Proteins - 4 kcal per gram
Molecules contain nitrogen, carbon, hydrogen and oxygen. Simple
proteins, called monomers, are used to create complicated proteins,
called polymers, which build and repair tissue. When used as a fuel the
protein needs to break down, as it breaks down it gets rid of nitrogen,
which has to be eliminated by the kidneys.
■Fats - 9 kcal per gram
Molecules consist of carbon, hydrogen, and oxygen atoms. Fats are
triglycerides - three molecules of fatty acid combined with a molecule
of the alcohol glycerol. Fatty acids are simple compounds (monomers)
while triglycerides are complex molecules (polymers). For more details
on dietary fat, go to "What is fat? How much fat should I eat?"
Other macronutrients. These do not provide energy
■Fiber
Fiber consists mostly of carbohydrates. However because of its limited
absorption by the body, not much of the sugars and starches get into the
blood stream. Fiber is a crucial part of essential human nutrition. For
more details go to "What is fiber? What is dietary fiber?"
■Water
About 70% of the non-fat mass of the human body is water. Nobody is
completely sure how much water the human body needs - claims vary from
between one to seven liters per day to avoid dehydration. We do know
that water requirements are very closely linked to body size, age,
environmental temperatures, physical activity, different states of
health, and dietary habits.
Somebody who consumes a lot of salt
will require more water than another person of the same height, age and
weight, exposed to the same levels of outside temperatures, and similar
levels of physical exertion who consumes less salt. Most blanket claims
that 'the more water you drink the healthier your are' are not backed
with scientific evidence. The variables that influence water
requirements are so vast that accurate advice on water intake would only
be valid after evaluating each person individually.
Micronutrients - nutrients required in small quantities throughout a person's life
Minerals
Dietary minerals are the other chemical elements our bodies need, apart
from carbon, hydrogen, oxygen and nitrogen. The term "minerals" is
misleading, and would be more relevant if called "ions" or "dietary
ions" (it is a pity they are not called so). People whose intake of
foods is varied and well thought out - those with a well balanced diet -
will in most cases obtain all their minerals from what they eat.
Minerals are often artificially added to some foods to make up for
potential dietary shortages and subsequent health problems. The best
example of this is iodized salt - iodine is added to prevent iodine
deficiency, which even today affects about two billion people and causes
mental retardation and thyroid gland problems. Iodine deficiency
remains a serious public health problem in over half the planet.
Experts at the University of Florida5 say that 16 key minerals are
essential for human biochemical processes by serving structural and
functional roles, as well as electrolytes:
■Potassium
What it
does - a systemic (affects entire body) electrolyte, essential in
co-regulating ATP (an important carrier of energy in cells in the body,
also key in making RNA) with sodium.
Deficiency - hypokalemia (can profoundly affect the nervous system and heart).
Excess - hyperkalemia (can also profoundly affect the nervous system and heart).
■Chloride
What it does - key for hydrochloric acid production in the stomach, also important for cellular pump functions.
Deficiency - hypochleremia (low salt levels, which if severe can be very dangerous for health).
Excess - hyperchloremia (usually no symptoms, linked to excessive fluid loss).
■Sodium
What it does - a systemic electrolyte, and essential in regulating ATP with potassium.
Deficiency - hyponatremia (cause cells to malfunction; extremely low sodium can be fatal).
Excess - hypernatremia (can also cause cells to malfunction, extremely high levels can be fatal).
The American Heart Association (AHA) announced on November 5, 20126
that sodium consumption should be limited to 1,500 milligrams per day,
and that includes everybody, even healthy people without high blood
pressure, diabetes or cardiovascular diseases. AHA's chief executive
officer, Nancy Brown said "Our recommendation is simple in the sense
that it applies to the entire U.S population, not just at-risk groups.
Americans of all ages, regardless of individual risk factors, can
improve the heart health and reduce their risk of cardiovascular disease
by restricting their daily consumption of sodium to less that 1,500
milligrams."
■Calcium
What it does - important for muscle,
heart and digestive health. Builds bone, assists in the synthesis and
function of blood cells.
Deficiency - hypocalcaemia (muscle cramps, abdominal cramps, spasms, and hyperactive deep tendon reflexes).
Excess - hypercalcaemia (muscle weakness, constipation, undermined
conduction of electrical impulses in the heart, calcium stones in
urinary tract, impaired kidney function, and impaired absorption of iron
leading to iron deficiency).
■Phosphorus
What it does - component of bones and energy processing.
Deficiency - hypophosphatemia, an example is rickets.
Excess - hyperphosphatemia, often a result of kidney failure.
■Magnesium
What it does - processes ATP and required for good bones.
Deficiency - hypomagnesemia (irritability of the nervous system with
spasms of the hands and feet, muscular twitching and cramps, and larynx
spasms).
Excess - hypermagnesemia (nausea, vomiting, impaired
breathing, low blood pressure). Very rare, and may occur if patient has
renal problems.
■Zinc
What it does - required by several enzymes.
Deficiency - short stature, anemia, increased pigmentation of skin,
enlarged liver and spleen, impaired gonadal function, impaired wound
healing, and immune deficiency.
Excess - suppresses copper and iron absorption.
■Iron
What it does - required for proteins and enzymes, especially hemoglobin.
Deficiency - anemia.
Excess - iron overload disorder; iron deposits can form in organs, particularly the heart.
■Manganese
What it does - a cofactor in enzyme functions.
Deficiency - wobbliness, fainting, hearing loss, weak tendons and ligaments. Less commonly, can be cause of diabetes.
Excess - interferes with the absorption of dietary iron.
■Copper
What it does - component of many redox (reduction and oxidation) enzymes.
Deficiency - anemia or pancytopenia (reduction in the number of red and
white blood cells, as well as platelets) and a neurodegeneration.
Excess - can interfere with body's formation of blood cellular
components; in severe cases convulsions, palsy, and insensibility and
eventually death (similar to arsenic poisoning).
■Iodine
What it does - required for the biosynthesis of thyroxine (a form of thyroid hormone).
Deficiency - developmental delays, among other problems.
Excess - can affect functioning of thyroid gland.
■Selenium
What it does - cofactor essential to activity of antioxidant enzymes.
Deficiency - Keshan disease (myocardial necrosis leading to weakening
of the heart), Kashing-Beck disease (atrophy degeneration and necrosis
of cartilage tissue).
Excess - garlic-smelling breath,
gastrointestinal disorders, hair loss, sloughing of nails, fatigue,
irritability, and neurological damage.
■Molybdenum
What it does
- vital part of three important enzyme systems, xanthine oxidase,
aldehyde oxidase, and sulfite oxidase. It has a vital role in uric acid
formation and iron utilization, in carbohydrate metabolism, and sulfite
detoxification.
Deficiency - may affect metabolism and blood counts,
but as this deficiency is often alongside other mineral deficiencies,
such as copper, it is hard to say which one was the cause of the health
problem.
Excess - there is very little data on toxicity, therefore excess is probably not an issue.
Vitamins
These are organic compounds we require in tiny amounts. An organic
compound is any molecule that contains carbon. It is called a vitamin
when our bodies cannot synthesize (produce) enough or any of it. So we
have to obtain it from our food. Vitamins are classified by what they do
biologically - their biological and chemical activity - and not their
structure.
Vitamins are classified as water soluble (they can
dissolve in water) or fat soluble (they can dissolve in fat). For humans
there are 4 fat-soluble (A, D, E, and K) and 9 water-soluble (8 B
vitamins and vitamin C) vitamins - a total of 13.
Water soluble
vitamins need to be consumed more regularly because they are eliminated
faster and are not readily stored. Urinary output is a good predictor of
water soluble vitamin consumption. Several water-soluble vitamins are
manufactured by bacteria.
Fat soluble vitamins are absorbed
through the intestines with the help of fats (lipids). They are more
likely to accumulate in the body because they are harder to eliminate
quickly. Excess levels of fat soluble vitamins are more likely than with
water-soluble vitamins - this condition is called hypervitaminosis.
Patients with cystic fibrosis need to have their levels of fat-soluble
vitamins closely monitored.
We know that most vitamins have many
different reactions, which means they have several different functions.
Below is a list of vitamins, and some details we know about them:
■Vitamin A
chemical names - retinol, retinoids and carotenoids.
Solubility - fat.
Deficiency disease - Night-blindness.
Overdose disease - Keratomalacia (degeneration of the cornea).
■Vitamin B1
chemical name - thiamine.
Solubility - water.
Deficiency disease - beriberi, Wernicke-Korsakoff syndrome.
Overdose disease - rare hypersensitive reactions resembling anaphylactic shock when overdose is due to injection. Drowsiness.
■Vitamin B2
chemical name - riboflavin
Solubility - water
Deficiency disease - ariboflanisosis (mouth lesions, seborrhea, and vascularization of the cornea).
Overdose disease - no known complications. Excess is excreted in urine.
■Vitamin B3
chemical name - niacin.
Solubility - water.
Deficiency disease - pellagra.
Overdose disease - liver damage, skin problems, and gastrointestinal complaints, plus other problems.
■Vitamin B5
chemical name -pantothenic acid.
Solubility - water.
Deficiency disease - paresthesia (tingling, pricking, or numbness of the skin with no apparent long-term physical effect).
Overdose disease - none reported.
■Vitamin B6
chemical name - pyridoxamine, pyridoxal.
Solubility - water.
Deficiency disease - anemia, peripheral neuropathy.
Overdose disease - nerve damage, proprioception is impaired (ability to sense stimuli within your own body is undermined).
■Vitamin B7
chemical name - biotin.
Solubility - water.
Deficiency disease - dermatitis, enteritis.
Overdose disease - none reported.
■Vitamin B9
chemical name - folinic acid.
Solubility - water.
Deficiency disease - birth defects during pregnancy, such as neural tube.
Overdose disease - seizure threshold possibly diminished.
■Vitamin B12
chemical name - cyanocobalamin, hydroxycobalamin, methylcobalamin.
Solubility - water.
Deficiency disease - megaloblastic anemia (red blood cells without nucleus).
Overdose disease - none reported.
■Vitamin C
chemical name - ascorbic acid.
Solubility - water.
Deficiency disease - scurvy, which can lead to a large number of complications.
Overdose disease - vitamin C megadosage - diarrhea, nausea, skin
irritation, burning upon urination, depletion of the mineral copper, and
higher risk of kidney stones.
■Vitamin D
chemical name - ergocalciferol, cholecalciferol.
Solubility - fat.
Deficiency disease - rickets, osteomalacia (softening of bone), recent studies indicate higher risk of some cancers.
Overdose disease - hypervitaminosis D (headache, weakness, disturbed
digestion, increased blood pressure, and tissue calcification).
■Vitamin E
chemical name - tocotrienols.
Solubility - fat.
Deficiency disease - very rare, may include hemolytic anemia in newborn babies.
Overdose disease - one study reported higher risk of congestive heart failure.
■Vitamin K
chemical name - phylloquinone, menaquinones.
Solubility - fat.
Deficiency disease - greater tendency to bleed.
Overdose disease - may undermine effects of warfarin.
