This is an overview of the five essential nutritional components of a healthy diet. It gives the daily requirements and the problems associated to taking insufficient or excessive amounts. If you are looking for a more detailed account I would recommend The Merck Manuals - Online Medical Library - nutritional pages.

Carbohydrates

 

These are the basic energy requirements. There are about 4 kilocalories in every gram of carbohydrate. Your daily requirement of carbohydrate is dependent upon your age, size, gender and activity levels.

As a general rule use the following formula:

Multiply your weight in pounds by 10 or your weight in Kilogrammes by 22.

If you weigh 135 pounds then you need (135x10) = 1,350 kcalories If you weigh 60Kg then you need (60x22) = 1320 kcalories

Any sustained period below this level could activate your body's fat storing mode as it prepares for a potential famine.

If you do not receive enough carbohydrate to properly maintain your body, it will break down and use its own proteins in order to maintain a healthy blood chemistry. Basically, it destroys muscle tissue in preference to fat.

Proteins

 

There are 9 essential amino acids that your body needs to build proteins which it cannot make itself.

Histidine

Isoleucine

Leucine

Lysine

Methionine (and cysteine)

Phenylalanine (and tyrosine)

Threonine

Tryptophan

Valine

Lysine and tryptophan are not common in vegetables so strict vegetarians should ensure that their diet contains sufficient amounts of these.

Overall Daily Protein Requirements

Activity level	Protein kg/day
Sedentary to low levels of activity	0.75
Regular activity > 1 hour per day	1.0 - 1.2
Endurance athletes	1.2 - 1.4
Strength athletes	1.6 - 1.7

Fatty acids

 

The body can make nearly all fats it needs from carbohydrates. However, there are 3 essential fatty acids that the body cannot make itself and so they are important in your diet. They are all unsaturated fats.

Linoleic acid

Linolenic acid

Arachidonic acid

Fats are the best form of energy which is why the body stores it. However, a diet high in fat is harmful but unsaturated and polyunsaturated fats are less harmful than saturated fats.

Omega-3 unsaturated fats are thought to be highly beneficial, especially to brain and nervous function and in eleviating heart disease. The recommended daily allowance (RDA) is 1.1 gm per day for women and 1.6 gm per day for men.

Improvements in nervous function have been shown with high levels of Omega-3, around 1000mg per day, over several months.

Minerals

 

There are about 18 principle minerals but only very small amounts are needed of most of them. The major nutritional minerals are:

 

Calcium is a major constituent of bones (30%), but calcium is also found in cells (particularly muscle cells) and in the blood. Calcium is essential to muscle contraction and to the normal functioning of many enzymes. It is necessary for the formation of bone and teeth, for blood clotting, and for normal heart rhythm.

 

Iron is an important component of haemoglobin (carries oxygen in red blood cells) and muscle cells. Iron is also necessary for the formation of many enzymes in the body.

 

Zinc is a component of more than a hundred enzymes, including those involved in the formation of DNA. It is also essential for healthy skin, healing of wounds, and growth. Much of the zinc consumed in the diet is not absorbed.

 

Magnesium is necessary for the formation of bone and teeth and for normal nerve and muscle function. Many enzymes in the body depend on magnesium to function normally.

 

Mineral	Benefits	Recommended Daily Allowance	Food Sources	Deficiency Symptoms
Calcium	Builds and maintains bone strength, which prevents stress fractures, Builds and maintains teeth, Helps regulate heart function, Assists in muscle growth and contraction.	Adults 1200 mg Children 800 mg Infants 500 mg Pregnant & Lactating Women 1200 mg	Milk & milk products, Calcium fortified juices, Beans, Oranges, Broccoli	Spontaneous nerve discharge and tetany (cramps)
Chlorine	Maintains nerve impulses that control the muscles, Maintains water balance and distribution, Needed for the production of stomach acid.	Adults 750 mg Children 600 mg	Table salt (sodium chloride)	Acid-based imbalance
Magnesium	Aids in the body's enery production, Combats stress, Assists in bone growth, Helps regulate body temperature.	Men 350 mg Women 300 mg Children 150-200 mg Infants 40-60 mg	Bananas, Green vegetables, Corn, Apples, Whole wheat bread	Increased nervous system irritability, vasodilation, and arrhythmias
Phosphorus	Helps in almost every chemical reaction in the body, assists in the use of carbohydrates, fats, and proteins for energy, Stimulates heart and muscle contractions, Prevents tooth decay.	Adults 1200 mg Children 800 mg	Meats, Fish, Chicken, Eggs, Whole grains, Chocolate!	Loss of energy and cellular function
Pottasium	Aids in the conversion of glucose to glycogen, Nourishes the muscles, Stimulates the kidney to get rid of body wastes.	Adults 2000 mg Children 1500 mg	Bananas, Green leafy vegetables, Oranges, Potatoes, Raisins, Dried beans	Muscle weakness, abnormal electrocardiogram, and alkaline urine
Sodium	With water, helps retain fluids that counteract dehydration, Helps our bodies produce a thirst sensation so we'll drink more fluids.	Adults 500 mg Children 400 mg	Seafood, Poultry, Carrots, Beets	Nausea, vomiting, exhaustion, and dizziness
Iron	Along with protein, helps form hemoglobin, which carries oxygen from the lungs through the blood to the body tissues, which includes the muscles.	Men 10-12 mg Women 15 mg Children 10 mg Pregnant Women 30 mg	Beef, Lamb, Pork, Leafy green vegetables, Iron fortified cereals, Breads	Anaemia, decreased oxygen transport, and energy loss
Selenium	Boosts your immune system and helps protect your body from cancer.	Men 70 mcg Women 55 mcg Children 20 - 30 mcg Infants 10 - 15 mcg Pregnant Women 65 mcg Lactating Women 75 mcg	Seafood, liver, lean meats, grains	No specific symptoms
Zinc	Helps remove carbon dioxide from excercising muscles, Aids in healing, Boost the immune system, Protects against pollution.	Men 15 mg Women 12 mg Children 10 mg Infants 5 mg	Lean meats, liver, eggs, seafood, whole grains, dairy products	May be cause of anaemia, retardation in growth, and delayed genital maturation

Vitamins

 

There are basically twelve vitamins that are esential to our nutritional needs. They are organic compounds that the body cannot produce itself but which are essential to its proper function. Failure to digest enough can produce specific deficiency diseases:

Scurvy from the lack of vitamin C (ascorbic acid)

Beriberi from the lack of vitamin B1 (thiamine)

Pellagra from the lack of lack of vitamin B3 (niacin)

However, deficiencies in any of the vitamins will cause problems and there are also dangers from overdosing, as the table below shows:

 

Vitamin	What it does	Food	Deficiency	Overdose	RDA
A (Retinol)	Healthy skin, lung linings, intestines, and urinary tract. Protects against infections.  The light-absorbing pigments in the eye.  Regulating gene expression essential for the health of epithelia.	Dark green leafy vegetables, yellow vegetables and fruits, and red palm oil as beta carotene that is converted to vitamin A.  Cream, butter, fish liver oils, egg yolk, beef.	Night-blindness.	More than 3mg.  Stored in the liver, toxic in large doses, especially in children. Amounts not much greater than the recommended dietary allowance lead to an increase in bone fractures later in life. High doses taken early in pregnancy have been linked to a greater risk of birth defects.	0.7 - 0.9 mg
B1(Thiamine)	Used in cell energy production to metabolize carbohydrates.	Eat, yeast, unpolished cereal grains, enriched bread and breakfast cereals.	Beriberi. Rarely found in developed countries except among alcoholics.	Water soluble and any excess easily excreted.	1.1 mg women 1.2 mg men
B2 (Riboflavin)	Prosthetic group of flavoprotein enzymes used in energy production in cells	Liver, eggs, cheese, milk, enriched bread and breakfast cereals	Tissue damage especially to the eyes, mouth, and genitals.	Water soluble and any excess easily excreted.	1.1 mg women 1.3 mg men
B3 (Niacin)	Used in cell energy production to metabolize many compounds including carbohydrates and fats.	Meat, yeast, milk, enriched bread and breakfast cereals	Pellagra (producing skin lesions); a risk where corn is the staple carbohydrate.	>35mg. Accidental ingestion of very high doses produces a brief illness, but niacin is water soluble and any excess is quickly excreted	14 mg women 16 mg men
B6 (Pyridoxine)	Used in cell nerve functions to metabolize fatty acids and amino acids. The creation of red blood cells. Skin production.	Legumes, wholegrain cereals, fish, liver, organs.		>100mg	5 mg (estimate)
B12 ()	Needed for DNA synthesis	Liver, beef, pork, organs, eggs, milk, cheese, cream.	Pernicious anaemia; caused by lack of intrinsic factor or a vegan diet	No ill effects	0.0024 mg
Pantothenic Acid	Used in cell energy production to metabolize carbohydrates and fats.	Vegetables, liver, meat, egg yolk.			5 mg (estimate)
Biotin	Metabolism of fatty acids and carbohydrates.	Legumes, nuts, cauliflower, fish, yeast, liver, kidneys, egg yolk, milk.			0.03 mg (estimate)
C (Ascorbic Acid)	Coenzyme in the synthesis of collagen	Citrus fruits, green peppers, tomatoes; destroyed by cooking.	Scurvy	No ill effects	75mg women 90 mg men
D	Absorption of calcium from the intestine and bone formation	Synthesized when ultraviolet light strikes the skin (forms vitamin D) Present in fish liver oils, butter, and steroid-containing foods irradiated with ultraviolet light.	Rickets in children; the inadequate conversion of cartilage to bone. Osteomalacia in adults; the softening of the bones.	> 2000 IU.  It is dangerous in very high doses, especially in young children, causing excessive calcium deposits and mental retardation. Pediatricians will not prescribe this now.	200 IU < 50 years old 400 IU 50-70 years old 600 IU > 70 years old
E (Tocopherol)	Antioxidant agent in cells.  protects cells from free radicals.	Vegetable oils, nuts, spinach	Anaemia, damage to the retinas	> 1500 IU High doses may be toxic.	15 mg
F (Folic Acid)	Synthesis of purines and pyrimidines.	Green leafy vegetables, asparagus, broccoli, tomatoes, fruits (especially citrus), liver and other organ meats, dried yeast, and enriched breads, pastas, and cereals, but destroyed by cooking.	Anaemia, birth defects. Women anticipating pregnancy should be extra careful that they receive adequate amounts (400 µg/day). Linked to Alzheimer's disease.	Water soluble and any excess easily excreted.	0.4 mg
K	Essential for normal blood clotting.	Spinach and other green leafy vegetables; synthesized by intestinal bacteria	Slow clotting of blood	High doses may be toxic to children	0.065 mg women 0.08 mg men