Introduction to Nuitrition, Health, and Fitness

Our meal contains various nutrients that are required to build, replace or provide energy to survive and maintain life.   Nutrition is the study of food, how the body uses nutrients in each meal, and the overall relationship between diet, health, and disease.

A nutrient is a source of food, a component of nourishment, for instance, protein, carbohydrate, fat, vitamin, mineral, fibre, and water.  Similarly, nutrition involves identifying how certain diseases and conditions may be caused by dietary factors, such as poor diet (malnutrition), food allergies, and food intolerances and excessive high-density food (calories) intake that could lead to obesity and other health issues in the future.

Therefore, nutrition focuses on how diseases, conditions, and how problems can be prevented or reduced with a healthy meal.

Macronutrients are nutrients we need in relatively large quantities.

1. Macronutrients can be further split into (a) energy macronutrients (that provide energy), and (b) macronutrients that do not provide energy.
2. ​Micronutrients are nutrients we need in relatively small quantities.

1a. Energy macronutrients

Energy macronutrients provide energy, which is measured either in kilocalories (kcal or calories) or Joules. 1 kilocalorie (calorie) = 4185.8 joules. Energy macronutrients include:

Carbohydrates - 4 kcal per gram

Carbohydrate molecules include monosaccharides (glucose, fructose, galactose), disaccharides, and polysaccharides (starch).  Nutritionally, polysaccharides are favoured over monosaccharides because they are more complex and therefore take longer to break down and be absorbed into the bloodstream; this means that they do not cause major spikes in blood sugar levels, which are linked to heart and vascular diseases.

Proteins - 4 kcal per gram

There are 20 amino acids - organic compounds found in nature that combine to form proteins. Some amino acids are essential, meaning they need to be consumed. Other amino acids are non-essential because the body can make them.

Fats - 9 kcal per gram

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).

Fats are required in the diet for health as they serve many functions, including lubricating joints, helping organs produce hormones, assisting in absorption of certain vitamins, reducing inflammation, and preserving brain health.

1.b Macronutrients that do not provide energy

These do not provide energy, but are still important:

Fibre (UK) Fiber (USA)

Dietary fibre is vegetable or animal tissue that is eaten as part of food. Fibre consists mostly of carbohydrates. However, because it is not easily absorbed by the body, not much of the sugars and starches get into the blood stream. Fibre is a crucial part of nutrition, health, and fuel for gut bacteria.

The term fibre refers to carbohydrates that cannot be digested. fibre is found in the plants we eat for food — fruits, vegetables, grains, and legumes.

Sometimes, a distinction is made between soluble fibre and insoluble fibre:

• Soluble fibre partially dissolves in water and has been shown to lower cholesterol.
• Insoluble fibre does not dissolve in water, but that's why it helps with constipation.

It's important to include both kinds of fibre  as part of a healthy diet.

A diet that includes foods that are rich in fibre can help lower blood cholesterol and prevent diabetes and heart disease. When carbohydrates are combined with fibre , it slows the absorption of sugar and regulates insulin response.

And food with fibre make us feel full, which discourages overeating.

Also, fibre itself has no calories, and adequate amounts of fiber help move food through the digestive system, promoting healthy bowel function and protecting against constipation.

Figuring Out fibre 

Great sources of fibre include:

• whole-grain breads and cereals
• fruits like apples, oranges, bananas, berries, prunes, and pears
• vegetables like green peas, broccoli, spinach, and artichokes
• legumes (split peas, soy, lentils, etc.)
• almonds

Look for the fiber content of foods on the nutrition labels — it's listed as part of the information given for "total carbohydrates." A high-fibre food has 5 grams or more of fiber per serving and a good source of fibre is one that provides 2.5 to 4.9 grams per serving.

Water

About 70 percent of the non-fat mass of the human body is water. It is vital for many processes in the human body.

Nobody is completely sure how much water the human body needs - claims vary from 1-7 litres 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; for instance, somebody who consumes a lot of salt will require more water than another similar person.

Claims that 'the more water you drink, the healthier you 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.

2. Micronutrients

Micronutrients are required in smaller quantities:

Minerals

There are two kinds of minerals: macrominerals and trace minerals. Macro means "large" in Greek (and your body needs larger amounts of macrominerals than trace minerals). The macromineral group is made up of calcium, phosphorus, magnesium, sodium, potassium, chloride, and sulfur. Minerals are found in a range of food types.

Dietary minerals are the other chemical elements our bodies need, other than carbon, hydrogen, oxygen, and nitrogen.  People with a well-balanced diet will, in most cases, obtain all the minerals they need from what they eat.

A trace of something means that there is only a little of it. So even though your body needs trace minerals, it needs just a tiny bit of each one. Trace minerals includes iron, manganese, copper, iodine, zinc, cobalt, fluoride, and selenium.

Minerals are sometimes added to certain foods to make up for any shortages.

The best example of this is iodized salt - iodine is added to prevent iodine deficiency, which affects about 2 billion people, globally; it 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 Florida say that 16 key minerals are essential for human biochemical processes:

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.

keeps your muscles and nervous system working properly.

Which foods are rich in potassium?

• bananas
• tomatoes
• potatoes and sweet potatoes, with skins
• green vegetables, such as spinach and broccoli
• citrus fruits, like oranges
• low-fat milk and yogurt
• legumes, such as beans, split peas, and lentils

Deficiency - hypokalaemia - can profoundly affect the nervous system and heart.

Excess - hyperkalaemia - can also profoundly affect the nervous system and heart.

Chloride

What it does - key for producing stomach acid, important in the transport of molecules between cells, and vital for the proper functioning of nerves.

Deficiency - hypochloraemia - low salt levels, which, if severe, can be very dangerous.

Excess - hyperchloremia - usually no symptoms, linked with excessive fluid loss.

Sodium

What it does - a systemic electrolyte, and essential in regulating ATP with potassium. Important for nerve function and regulating body fluid levels.

Deficiency - hyponatremia - causes cells to malfunction; extremely low sodium can be fatal.

Excess - hypernatremia - can also cause cells to malfunction, extremely high levels can be fatal.

Calcium

What it does - important for muscle, heart, and digestive health. Builds bone, assists in the synthesis and function of blood cells.

Calcium is the top macromineral when it comes to your bones. This mineral helps build strong bones, so you can do everything from standing up straight to scoring that winning goal. It also helps build strong, healthy teeth, for chomping on tasty food.

Which foods are rich in calcium?

• dairy products, such as milk, cheese, and yogurt
• canned salmon and sardines with bones
• leafy green vegetables, such as broccoli
• calcium-fortified foods — from orange juice to cereals and crackers

Deficiency - hypocalcaemia - muscle cramps, abdominal cramps, spasms, and hyperactive deep tendon reflexes.

Excess - hypercalcemia - muscle weakness, constipation, undermined conduction of electrical impulses in the heart, calcium stones in the urinary tract, impaired kidney function, and impaired absorption of iron, leading to iron deficiency.

Phosphorus

What it does - important for the structure of DNA, transporter of energy (ATP), component of cellular membrane, helps strengthen bones.

Deficiency - hypophosphatemia, an example is rickets.

Excess - hyperphosphatemia, often a result of kidney failure.

Magnesium

What it does - processes ATP; required for good bones and management of proper muscle movement. Hundreds of enzymes rely on magnesium to work properly.

Deficiency - hypomagnesemia - irritability of the nervous system with spasms of the hands and feet, muscular twitching and cramps, constipation, and larynx spasms.

Excess - hypermagnesemia - nausea, vomiting, impaired breathing, low blood pressure. Very rare but may occur if patient has renal problems.

Zinc

What it does - required by many enzymes. Important for reproductive organ growth. Also important in gene expression and regulating the nervous and immune systems.

Zinc helps your immune system, which is your body's system for fighting off illnesses and infections. It also helps with cell growth and helps heal wounds, such as cuts.

Which foods are rich in zinc?

• beef, pork, and dark meat chicken
• nuts, such as cashews, almonds, and peanuts
• legumes, such as beans, split peas, and lentils

Deficiency - short stature, anaemia, increased pigmentation of skin, enlarged liver and spleen, impaired reproductive function, impaired wound healing, and immune deficiency.

Excess - suppresses copper and iron absorption.

Iron

What it does - required for proteins and enzymes, especially haemoglobin, the oxygen-carrying compound in blood.

The body needs iron to transport oxygen from your lungs to the rest of your body. Your entire body needs oxygen to stay healthy and alive. Iron helps because it's important in the formation of hemoglobin, which is the part of your red blood cells that carries oxygen throughout the body.

Which foods are rich in iron?

• meat, especially red meat, such as beef
• tuna and salmon
• eggs
• beans
• baked potato with skins
• dried fruits, like raisins
• leafy green vegetables, such as broccoli
• whole and enriched grains, like wheat or oats

Deficiency - anaemia.

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 a cause of diabetes.

Excess - interferes with the absorption of dietary iron.

Copper

What it does - component of many enzymes.

Deficiency - anaemia or pancytopenia (reduction in the number of red and white blood cells, as well as platelets) and neurodegeneration.

Excess - can interfere with body's formation of blood cellular components; in severe cases, convulsions, palsy, and eventually death (like arsenic poisoning).

Iodine

What it does - required for the biosynthesis of thyroxine (one type of thyroid hormone).

Deficiency - developmental delays, enlarged thyroid gland (in the neck), and fatigue.

Excess - can affect the function of the thyroid gland.

Selenium

What it does - essential cofactor for antioxidant enzymes.

Deficiency - Kashan disease - myocardial necrosis (tissue death in the heart) leading to weakening of the heart; Kashan-Beck disease - break down of cartilage.

Excess - garlic-smelling breath, gastrointestinal disorders, hair loss, sloughing of nails, fatigue, irritability, and neurological damage.

Molybdenum

What it does - In humans, molybdenum's main function is to serve as a catalyst for enzymes and to help break down amino acids in the body. It is vital part within  three important enzyme systems, xanthine oxidase, aldehyde oxidase, and sulphite oxidase. It has a vital role in uric acid formation, in carbohydrate metabolism, and sulphite detoxification.

Deficiency - may affect metabolism and blood counts, but as this deficiency often occurs at the same time as other mineral deficiencies, it is hard to say which deficiency caused which health problem.

Excess - Molybdenum is a micronutrient essential for life, but too much of it is toxic. There is very little data on toxicity.

Vitamins

Our bodies cannot synthesize vitamins, so we must consume them.

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 need to get it from our food.

Vitamins are classified as water soluble (they can be dissolved in water) or fat soluble (they can be dissolved in fat). For humans, there are four fat-soluble vitamins (A, D, E, and K) and nine water-soluble vitamins (eight B vitamins and vitamin C).

Water-soluble vitamins need to be consumed more regularly because they are eliminated faster (in urine) and are not easily stored.

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 get rid of quickly. If too many vitamins build up, it is called hypervitaminosis. A very low-fat diet can affect the absorption of fat-soluble vitamins.

We know that most vitamins have many different functions.

Below is a list of vitamins, and some of their roles. Note that most often vitamin overdose symptoms are related to supplementation or impaired metabolism or excretion, not vitamin intake from foods.

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 an overdose is due to injection.

Vitamin B2

Chemical name - riboflavin.

Solubility - water.

Deficiency disease - ariboflavinosis (mouth lesions, seborrhoea, 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 - paraesthesia (tingling, pricking, or numbness of the skin with no apparent long-term physical effect).

Overdose disease - none reported.

Vitamin B6

Chemical names - pyridoxamine, pyridoxal.

Solubility - water.

Deficiency disease - anaemia, peripheral neuropathy.

Overdose disease - nerve damage, proprioception is impaired (the ability to sense where parts of the body are in space).

Vitamin B7

Chemical name - biotin.

Solubility - water.

Deficiency disease - dermatitis, enteritis.

Overdose disease - none reported.

Vitamin B9

Chemical name - folate or folic acid.

Solubility - water.

Deficiency disease - birth defects.

Overdose disease - increased risk of seizures.

Vitamin B12

Chemical names - cyanocobalamin, hydroxocobalamin, methyl cobalamin.

Solubility - water.

Deficiency disease - megaloblastic anaemia (a defect in the production of red blood cells).

Overdose disease - none reported.

Vitamin C

Chemical name - ascorbic acid.

Solubility - water.

Deficiency disease - scurvy, which can lead to many complications.

Overdose disease - vitamin C megadose - diarrhoea, nausea, skin irritation, burning upon urination, depletion of copper in the body, and higher risk of kidney stones.

Vitamin D

Chemical names - ergocalciferol, cholecalciferol.

Solubility - fat.

Deficiency disease - rickets, osteomalacia (softening of bone), recent studies indicate higher risk of some cancers, autoimmune disorders, and chronic diseases

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 haemolytic anaemia in new-born babies.

Overdose disease - dehydration, vomiting, irritability, constipation, build-up of excess calcium.

Vitamin K

Chemical names - phylloquinone, menaquinones.

Solubility - fat.

Deficiency disease - greater tendency to bleed and bruise.

Overdose disease - may undermine effects of warfarin.