The need for Food
Humans and animals alike need food to survive because food
contains several life-supporting substances that are necessary
for them to survive and sustain their bodies. Some of these
life-supporting substances include proteins, fats, vitamins,
minerals and carbohydrates. We need a variety of nutrients
to survive in addition to calories, sunshine, and water. In
order to get these nutrients we need food. Eating healthy
whole foods is the best way to deliver nutrients to your body.
nutrient is a chemical that an organism needs to live and grow or a substance used in an
organism's metabolism which must be taken in from its
environment. Nutrients are the substances that enrich the body.
They are used to build and repair tissues, regulate body
processes and converted to and used as energy. Methods for
nutrient intake vary, with animals and protists consuming foods
that are digested by an internal digestive system, but most
plants ingest nutrients directly from the soil through their roots
or from the atmosphere.
Organic nutrients include carbohydrates, fats, proteins (or their
building blocks, amino acids), and vitamins. Inorganic chemical
compounds such as dietary minerals, water, and oxygen may
also be considered nutrients. A nutrient is said to be "essential" if it must be obtained from
an external source, ether because the organism cannot synthesized it or produces
insufficient quantities. Nutrients needed in very small amounts are micronutrients and
those that are needed in larger quantities are called macronutrients. The effects of
nutrients are dose-dependent and shortages are called deficiencies.
Most foods contain carbohydrates, which the body breaks down into simple sugars — the
major source of energy for the body.
Two Types of Carbohydrates
There are two major types of carbohydrates (or carbs) in foods: simple and complex.
Simple carbohydrates : These are also called simple sugars. Simple sugars are found in refined
sugars, like the white sugar you'd find in a sugar bowl. If you have a lollipop, you're eating
simple carbs. But you'll also find simple sugars in more nutritious foods, such as fruit and
milk. It's better to get your simple sugars from food like fruit and milk. Why? Because sugar
isn't added to these foods and they also contain vitamins, fiber, and important nutrients
Glucose is the only sugar used by the body to provide energy for its tissues. Therefore, all
digestible polysaccharides, disaccharides, and monosaccharide must eventually be
converted into glucose or a metabolite of glucose by various liver enzymes. Because of its
significant importance to proper cellular function, blood glucose levels must be kept
Complex carbohydrates: : These are also called starches. Starches include grain products, such
as bread, crackers, pasta, and rice. As with simple sugars, some complex carbohydrate
foods are better choices than others. Refined (say: ree-find) grains, such as white flour and
white rice, have been processed, which removes nutrients and fiber. But unrefined grains
still contain these vitamins and minerals. Unrefined grains also are rich in fiber, which
helps your digestive system work well. Fiber helps you feel full, so you are less likely to
overeat these foods. That explains why a bowl of oatmeal fills you up better than sugary
candy with the same amount of calories as the oatmeal.
Function of Carbohydrates
Carbohydrates have six major functions within the body:
Providing energy and regulation of blood glucose
Sparing the use of proteins for energy
Breakdown of fatty acids and preventing ketosis
Biological recognition processes
Flavor and Sweeteners
Types of polysaccharide
A polysaccharide is made of many monosaccharide molecules joined together. The process
of condensing many similar molecules to form a large molecule is called polymerization .
Starch , cellulose and glycogen are polysaccharides formed from the condensation of many
Starches are glucose polymers in which glucopyranose units are bonded by alpha-linkages.
It is made up of a mixture of amylose (15–20%) and amylopectin (80–85%). Amylose
consists of a linear chain of several hundred glucose molecules and Amylopectin is a
branched molecule made of several thousand glucose units (every chain of 24–30 glucose
units is one unit of Amylopectin). Starches are insoluble in water. They can be digested by
hydrolysis, catalyzed by enzymes called amylases, which can break the alpha-linkages
(glycosidic bonds). Humans and other animals have amylases, so they can digest starches.
Potato, rice, wheat, and maize are major sources of starch in the human diet. The
formations of starches are the ways that plants store glucose.
Glycogen is a polysaccharide that is the principal storage form of glucose (Glc) in animal
and human cells. Glycogen is found in the form of granules in the cytosol in many cell types
Glycogen plays an important role in the glucose cycle.
The structural component of plants are formed primarily from cellulose. Wood is largely
cellulose and lignin, while paper and cotton are nearly pure cellulose. Cellulose is a
polymer made with repeated glucose units bonded together by beta-linkages. Humans
and many other animals lack an enzyme to break the beta-linkages, so they do not digest
cellulose. Certain animals such as termites can digest cellulose, because bacteria
possessing the enzyme are present in their gut. Cellulose is insoluble in water. It does not
change color when mixed with iodine. On hydrolysis, it yields glucose. It is the most
abundant carbohydrate in nature.
Fats consist of a wide group of compounds that are generally soluble in organic solvents
and generally insoluble in water. Chemically, fats are triglycerides: triesters of glycerol
and any of several fatty acids. Fats may be either solid or liquid at room temperature,
depending on their structure and composition. Although the words "oils", "fats", and
"lipids" are all used to refer to fats, in reality, fat is a subset of lipid. "Oils" is usually used
to refer to fats that are liquids at normal room temperature, while "fats" is usually used to
refer to fats that are solids at normal room temperature. "Lipids" is used to refer to both
liquid and solid fats, along with other related substances, usually in a medical or
biochemical context, which are not soluble in water. The word "oil" is also used for any
substance that does not mix with water and has a greasy feel, such as petroleum (or crude
oil), heating oil, and essential oils, regardless of its chemical structure.
Function of Fats
1. The main function of fats in the body is to provide energy: By supplying energy, fats save
proteins from being used for energy and allow them to perform their more important role of
building and repairing tissues. Fats on oxidation provide almost twice as much energy as that
given by carbohydrates.
The fats provide on oxidation about 37 kJ of energy per gram as compared to 17kj of energy
per gram of carbohydrates. Fats yield more energy than carbohydrates because fats contain
less percentage of oxygen and higher percentage of carbon and hydrogen as compared with
Fats can also be stored in body for subsequent use. When we consume food which has more
energy than is required by the body for performing various functions, the excess food is
deposited under our skin in the from of subcutaneous fat.
2. In addition to supplying energy, fats also help in forming structural material of cells and
tissues such as the cell membrane.
3. Fats also carry the fats soluble vitamins A, D, E and K into the body and help in the
absorption of these vitamins in the intestines.
4. Some fats supply essential fatty acids.
The word protein comes from the Greek work proteios, meaning “primary.” Proteins are large
organic compounds essential to life. They are made up of complex combinations of amino
acids and are the most common macromolecules found in cells.
Protein is an essential nutrient which helps form the structural component of body tissues and
is used within many biological processes, for example protein is used to make enzymes,
antibodies to help us fight infection as well as DNA the building blocks to life. It’s also needed
to make up muscle tissue which in turn helps to keep our bodies active, strong, and healthy.
Most protein is stored in the body as muscle, generally accounting for around 40-45% of our
body’s total pool, so it makes sense that if you increase activity, perhaps to improve health
and fitness or body composition, you also need to consider protein as an important food group
in your diet.
Protein is found in dairy, meat, eggs, fish, beans and nuts, as well as in our protein shakes and
bars. A sensible approach to meeting your daily protein requirements is to include a
combination of these foods within your diet every day.
Effects of Protein Deficiency
Protein is a macronutrient that is essential for the construction, maintenance and repair of all
your body’s cells. Your body cannot survive without this nutrient. Failing to consume enough
can have a number of negative side effects and ultimately leads to death.
Protein deficiency normally affects people in developing countries who cannot get enough of
this nutrient as a result of famine. It can also affect people in developed countries who make
poor dietary choices (usually as a result of fad diets or poverty). Vegetarians and vegans are
also more susceptible to protein deficiency because they eat little or no meats and dairy
products (two food groups that are rich sources of protein). Here is one of the side effect of
1) KWASHIORKOR:- Kwashiorkor is a type of protein deficiency that affects children. It has
a number of symptoms which include an enlarged liver, a swollen abdomen, pedal oedema
(swollen feet), skin depigmentation, skin inflammation, thinning hair and tooth loss.
Kwashiorkor can also affect the immune system and inhibit the production of antibodies
(proteins that are used by the immune system to identify and neutralize foreign objects).
Finally, it can inhibit a child’s mental and physical development.
Function of Protein
Here are 5 major Function of Protein:
Repair and Maintenance
Protein is termed the building block of the body. It is called this because protein is vital in
the maintenance of body tissue, including development and repair. Hair, skin, eyes,
muscles and organs are all made from protein. This is why children need more protein per
pound of body weight than adults; they are growing and developing new protein tissue.
Protein is a major source of energy. If you consume more protein than you need for body
tissue maintenance and other necessary functions, your body will use it for energy. If it is
not needed due to sufficient intake of other energy sources such as carbohydrates, the
protein will be used to create fat and becomes part of fat cells.
Enzymes are proteins that increase the rate of chemical reactions in the body. In fact,
most of the necessary chemical reactions in the body would not efficiently proceed
without enzymes. For example, one type of enzyme functions as an aid in digesting large
protein, carbohydrate and fat molecules into smaller molecules, while another assists the
creation of DNA.
Transportation and Storage of Molecules
Protein is a major element in transportation of certain molecules. For example,
hemoglobin is a protein that transports oxygen throughout the body. Protein is also
sometimes used to store certain molecules. Ferritin is an example of a protein that
combines with iron for storage in the liver.
Protein forms antibodies that help prevent infection, illness and disease. These proteins
identify and assist in destroying antigens such as bacteria and viruses. They often work in
conjunction with the other immune system cells. For example, these antibodies identify
and then surround antigens in order to keep them contained until they can be destroyed
by white blood cells.
What are Vitamins?
A vitamin is one of a group of organic substances, present in minute amounts in natural
foodstuffs, that are essential to normal metabolism; insufficient amounts in the diet may
cause deficiency diseases.
Put simply, a vitamin is both:
An organic compound (contains carbon).
An essential nutrient the body cannot produce enough of on its own, so it has to get it
(tiny amounts) from food.
There are currently 13 recognized vitamins.
Vitamins are organic compounds which are needed in small quantities to sustain life. We get
vitamins from food, because the human body either does not produce enough of them, or
none at all.
An organic compound contains carbon. When an organism (living thing) cannot produce
enough of an organic chemical compound that it needs in tiny amounts, and has to get it from
food, it is called a vitamin.
Sometimes the compound is a vitamin for a human but not for some other animals. For
example, vitamin C (ascorbic acid) is a vitamin for humans but not for dogs, because dogs can
produce (synthesize) enough for their own needs, while humans cannot.
This Medical News Today information article provides details on what vitamins are, the
different types of vitamins (fat soluble and water soluble vitamins), and a list of different
Fat soluble and water soluble vitamins
There are fat-soluble and water-soluble vitamins.
Fat-soluble vitamins are stored in the fat tissues of our bodies, as well as the liver. Fat-soluble
vitamins are easier to store than water-soluble ones, and can stay in the body as reserves for
days, some of them for months.1
Fat-soluble vitamins are absorbed through the intestinal tract with the help of fats (lipids).
Water-soluble vitamins do not get stored in the body for long - they soon get expelled through
Water-soluble vitamins need to be replaced more often than fat-soluble ones.
Vitamins A, D, E and K are fat-soluble.
Vitamins C and all the B vitamins are water-soluble.
List of some vitamins
Vitamin A is a fat-soluble vitamin, also known as retinol because it produces pigments
in the eye's retina. The eye needs a specific metabolite - retinal - a light-absorbing
substance that is crucial for scotopic vision (low-light vision). Vitamin A is also important
for healthy teeth, skeletal tissue, soft tissue, the skin, and mucous membranes.
Vitamin B complex includes a bunch of water soluble vitamins that share
common characteristics and hence grouped under one name. All B vitamins
are extremely, important and considered essential micronutrients that must
be obtained to ensure optimal health and well- being. Vitamin B complex can
be consumed in moderate concentration via diet and nutritional
supplements with minimal risk of toxicity since excessive doses are excreted
Vitamin C is one of the safest and most effective nutrients, experts say. It may not be
the cure for the common cold (though it's thought to help prevent more serious
complications). But the benefits of vitamin C may include protection against immune
system deficiencies, cardiovascular disease, prenatal health problems, eye disease, and
even skin wrinkling.
If you shun the sun, suffer from milk allergies, or adhere to a strict vegetarian diet, you
may be at risk for vitamin D deficiency. Known as the sunshine vitamin, vitamin D is
produced by the body in response to sunlight. It is also occurs naturally in a few foods -including some fish, fish liver oils, and egg yolks -- and in fortified dairy and grain
Vitamin D is essential for strong bones because it helps the body use calcium from the
diet. Traditionally, vitamin D deficiency has been associated with rickets, a disease in
which the bone tissue doesn't properly mineralize, leading to soft bones and skeletal
deformities. But increasingly, research is revealing the importance of vitamin D in
protecting against a host of health problems.
We need water to survive because we depend on it to keep our bodies hydrated. Our bodies
are made up of between 50% to 70% of water and amazingly our brains comprise over 80%
water. It is therefore obvious that we need to take water to keep our bodies functioning.
The reason we need water to survive is because without it, everything around us including our
own bodies would dry up and die without it . human body can live without water for about 8 14 days. The body will not function properly after just a couple of days.
The 5 functions of water in our body
Chemical and metabolic reactions
Transport of nutrients
Body temperature regulation
5. Elimination of waste
The Functions of Water
Water is involved in many of our body’s vital functions
1. Cell life
Water is a carrier, distributing essential nutrients to cells, such as minerals, vitamins and
2. Chemical and metabolic reactions
Water removes waste products including toxins that the organs’ cells reject, and
removes them through urines and faeces.
3. Transport of nutrients
Water participates in the biochemical break-down of what we eat.
4. Body temperature regulation
Water has a large heat capacity which helps limit changes in body temperature in a
warm or a cold environment. Water allows the body to release heat when ambient
temperature is higher than body temperature (1). The body begins to sweat, and the
evaporation of water from the skin surface very efficiently cools the body.
5. Elimination of water
Water is an effective lubricant around joints. It also acts as a shock absorber for eyes,
brain, spinal cord and even for the foetus through amniotic fluid.
Water is at the center of life. This is why nobody can live more than 3 to 5 days
without any water intake.
Just like vitamins, minerals help your body grow, develop, and stay healthy. The body uses
minerals to perform many different functions — from building strong bones to transmitting
nerve impulses. Some minerals are even used to make hormones or maintain a normal
The two kinds of minerals are: 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.
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. Scientists aren't even sure how much of
these minerals you need each day. Trace minerals includes iron, manganese, copper, iodine,
zinc, cobalt, fluoride, and selenium.
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.
Following 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
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.
Following foods are rich in iron:
meat, especially red meat, such as beef
tuna and salmon
baked potato with skins
dried fruits, like raisins
leafy green vegetables, such as broccoli
whole and enriched grains, like wheat or oats