Figure 1.4: Sources of Vitamins  
Functions of Vitamins  
(i) They promote the functions of immune enzymes and nervous system.  
(ii) They are important in the formation of bone tissue and red blood cells.  
Sources, Functions and Deficiency Symptoms of Vitamins  
Vitamin A.  
Sources  
Liver, milk, eggs, oranges, carrots and pumpkins.  
Formation of membranes of the eyes and respiratory tract.  
(i) Night blindness (poor night vision).  
Function  
Deficiency  
symptoms  
(ii) Increased risk of infection.  
Vitamin B1  
Sources  
Lean meat, liver, eggs, mushroom, brown rice and whole grain cereals.  
(i) It assists in carbohydrate metabolism.  
(ii) It helps in muscle contraction.  
Functions  
Deficiency Beriberi, a disease characterized by loss of appetite, retarded growth,  
symptom  
muscle cramps, nerve disorder and heart failure.  
Vitamin B2  
Sources  
Liver, meat, mushroom and whole grain cereals.  
Metabolism of all foods and the release of energy to the cells.  
(i) Cracks and sores around the mouth and nose  
(ii) Visual problems  
Function  
Deficiency  
symptoms  
Vitamin B3  
Sources  
Nuts, fish, meat, mushroom, brown rice and whole grain cereals.  
(i) It is needed by many enzymes that convert food to energy.  
(ii) It keeps the skin healthy.  
Functions  
Deficiency Pellagra, a disease characterized by skin lesions, loss of appetite, diarrhoea  
symptom and muscle weakness.  
Vitamin B6  
Meat, vegetables, mushroom and whole grain cereals.  
Protein metabolism.  
Sources  
Function  
Deficiency Nerve irritability, Soreness in the mouth and eyes, Anaemia  
symptoms  
Vitamin B9  
Sources  
Liver, fish, green leafy vegetables, legumes and folate fortified foods.  
(i) Synthesis of new cells  
Functions  
(ii) Metabolism of carbohydrates  
Deficiency Birth defects, Anaemia and Frequent infections  
symptoms  
Vitamin B12  
Sources  
Liver, meat, eggs, milk and fish.  
(i) It helps in making genetic materials (DNA and RNA).  
(ii) It helps to form red blood cells.  
Functions  
Deficiency Anaemia, Nerve damage and Weight loss  
symptoms  
Vitamin C (Ascorbic Acid)  
Sources  
Tomatoes, fresh green vegetables and citrus fruits like oranges and lemons  
(i) It is used as antioxidant  
Functions  
(ii) It improves absorption of iron  
(iii) It is used in synthesis of collagen in the bones and gums  
Deficiency (i) Scurvy (bleeding gums)  
symptoms (ii) Muscles weakness  
(iii) Easy bruising  
(iv) Joint pains  
(v) Poor healing of wounds  
(vi) Frequent infections  
Vitamin D (Calciferol)  
Sources  
Egg yolk, milk, oily fish, sunlight and liver  
It helps to build and maintain teeth and bones.  
(i) Rickets in children.  
Functions  
Deficiency  
symptoms  
(ii) Osteoporosis (soft bones) in adults.  
Vitamin E (Tocopherol)  
Corn or sunflower oil, butter, brown rice and peanuts  
(i) It is used as antioxidant  
Sources  
Functions  
Deficiency  
(ii) It prevents damage of cell membranes.  
(i) Nerve abnormalities  
symptoms (ii) Infertility  
Vitamin K  
Sources  
Green vegetables and liver.  
Functions  
It is needed for normal blood clotting.  
Deficiency Defective blood clotting resulting in excessive bleeding in case of injury.  
symptoms  
5. MINERAL SALTS  
Minerals are inorganic elements that come from the soil and water and are absorbed and  
used by living organisms. They are needed by the body for growth, repair and protection  
against diseases. Examples of essential minerals needed by the body include; sodium,  
chlorine, potassium, calcium, phosphorous, magnesium, sulphur, zinc, iodine, copper,  
manganese and fluoride.  
Functions of Minerals  
(i) They are needed for the formation of pigments. For example; iron is needed in  
formation of haemoglobin, magnesium and iron are needed in formation of  
chlorophyll.  
(ii) They are important for activation of enzyme.  
(iii) They are essential for development of bone tissue and teeth.  
(iv) They are needed in formation of hormones.  
(v) They are used in transmission of nerve impulse.  
(vi) They are used in muscle actions, that is, contraction and relaxation of muscles.  
(vii) They essential for maintaining balance of body fluids.  
Sources, Functions and Deficiency Symptoms of Minerals  
Potassium  
Sources  
Peanuts, bananas, orange juice, meat and green beans.  
It helps in regular fluid balance needed for nerve and muscle function.  
(i) Poor muscle contraction  
Functions  
Deficiency  
symptoms (ii) Impaired nerve activity  
(iii) Retarded growth.  
Calcium  
Sources  
Milk, yoghurt, cheese, sardines and green vegetables.  
(i) It helps to build strong bones and teeth  
(ii) It promotes nerve transmission.  
Functions  
(iii) It helps in muscle contractions.  
(iv) It is important in blood clotting.  
Deficiency (i) Weak bones and bleeding easily.  
symptoms (ii) Impaired nerve activity.  
Phosphorus  
Sources  
Meat, milk, fish, eggs and nut.  
(i) It builds bones and teeth  
Functions  
(ii) It helps to maintain acid-base balance.  
(iii) It aids formation of genetic materials.  
Deficiency Poor bone and teeth formation.  
symptoms  
Sodium  
Sources  
Table salt, milk, bread, vegetables and processed foods.  
(i) Necessary for nerve transmission  
(ii) Needed for muscle contraction  
Functions  
(iii) Necessary for protein making  
(iv) Needed for proper fluid balance.  
Deficiency Muscle crumps and poor nerve transmission.  
symptoms  
Chloride  
Sources  
Table salt, eggs, milk, meat, sea foods and whole grain foods.  
Maintenance of water and ionic balance in the body and formation of  
hydrochloric acid in the stomach.  
Function  
Deficiency Poor digestion of proteins  
symptoms  
Magnesium  
Sources  
Spinach, pumpkin seeds, beans, nuts, sea foods and magnesium.  
(i) Maintaining a healthy immune system.  
(ii) Making proteins.  
Functions  
(iii) Contraction of muscles.  
(iv) Transmission of nerve impulse.  
(v) Strengthening of the bones.  
Deficiency Muscle weakness, irregular heartbeats and weak bones.  
symptoms  
Iodine  
Sources  
Sea foods, dairy products and iodized table salt.  
Production of thyroid hormone which regulates growth, development and  
metabolism.  
Functions  
Deficiency (i) Goiter (enlarged thyroid gland)  
symptoms (ii) Growth retardation  
(iii) Mental retardation  
(iv) Still birth  
Fluoride  
Sources  
Fish, fluorinated water or water naturally containing fluorine and most  
varieties of tea such as green tea.  
(i) Development of teeth and bones  
(ii) It helps to prevent tooth decay.  
Functions  
Deficiency (i) Poor development of bones and teeth.  
symptoms (ii) Tooth decay.  
Manganese  
Sources  
Plant foods, kidneys, liver, tea, coffee, nuts and fruits.  
(i) It helps in the formation of bones  
(ii) Activation of enzymes.  
Functions  
Deficiency Nausea, dizziness, loss of hearing and loss of bone mass.  
symptoms  
Copper  
Sources  
Whole grains, meat, drinking water, fish, liver, legumes, nuts and other  
seeds.  
(i) Synthesis of bones and haemoglobin  
(ii) Activation of enzymes.  
Functions  
Deficiency (i) Bleeding under the skin.  
symptoms (ii) Easy rupturing of blood vessels.  
(iii) Bones and joints problems.  
(iv) Anaemia.  
Iron  
Sources  
Liver, lean meat, fish, chicken, egg yolk, beans and green vegetables.  
(i) Essential for making red pigment in blood (haemoglobin).  
(ii) Essential for energy production.  
Functions  
Deficiency Anaemia.  
symptoms  
Zinc  
Sources  
Meat, fish, chicken, whole grains, shrimp, crab, oysters and vegetables.  
(i) Necessary for a healthy immune system.  
(ii) It controls normal growth and sexual maturation.  
(iii) Activation of enzymes.  
Functions  
(iv) It helps in wound healing.  
(v) It helps in taste detection.  
(vi) It promotes protein synthesis and DNA production.  
Deficiency (i) Impaired taste.  
symptoms (ii) Poor immune response.  
(iii) Skin problems.  
6. ROUGHAGE  
Roughage is dietary fiber that is obtained from the indigestible part of plants. Roughage  
does not have any nutritional value as it is not digested and absorbed in the body. Sources  
of dietary fibre include; cassava, potatoes, beans, fruits, cabbage, spinach and whole grain  
cereals.  
Functions of Roughage  
(i) It promotes peristalsis. It speeds up the passage of food and faeces through the gut  
by aiding contraction and relaxation of muscles (peristaltic movement).  
(ii) It helps to control body weight. Therefore, it protects the body from diseases such  
as heart diseases.  
(iii) It reduces the chances of constipation.  
(iv) It reduces the chances of developing gallstones and cancer of the colon.  
(v) Roughage adds bulk to food because it is indigestible.  
7. WATER  
Water is an essential nutrient for the human body as it is a major component of body  
fluids such as blood, tears and saliva. It constitutes about 90% of the total body weight.  
The water found in human bodies comes from the following sources; juice, soda, tea,  
porridge, alcohol, milk, water melon, cucumber, pineapples, pumpkins, pawpaw, oranges.  
river, dams, wells, lakes, sea, oceans and rains.  
Functions of water  
(i) It helps to maintain the shape of cell, tissues and organs.  
(ii) It helps in the process of breaking down food during digestion.  
(iii) It lubricates moving parts of the body and prevents friction.  
(iv) It helps in regulation of body temperature through sweating and evaporation.  
(v) It is used as solvent to dissolve different chemical substances in the body.  
(vi) It helps to excrete harmful by product of metabolic process. Example; urine, sweat.  
(vii) It is used in the manufacture of different secretions such as tears and saliva.  
(viii) It is used as a medium through which materials are transported in the body. For  
example; food and hormones.  
(ix) It is used as a medium through which chemical reactions of the body take place.  
NOTE: It is important to drink enough safe water and eat raw vegetables and fruits to  
maintain water content in the body. Lack of adequate water in the body leads to  
thirst, dehydration and constipation.  
BALANCED DIET  
Diet is the sum total of all foods for example carbohydrates, lipids, proteins and vitamins  
one takes in a meal.  
Balanced diet is a meal that contains all types of food in the right proportions. Components  
of balanced diet include:  
(a) Carbohydrates (about 60% of daily diet).  
(b) Proteins (10-35% depending on physiological needs).  
(c) Fats (about 15%)  
(d) Vitamins and minerals  
(e) Water  
FACTORS FOR A LACK OF A BALANCED DIET  
(i) Lack of knowledge/nutritional education. Insufficient understanding about which  
foods provide essential nutrients and how to prepare balanced meals can lead to  
unbalanced food choices.  
(ii) Poor dietary choices. High consumption of highly processed food often in a diet that  
is low in essential nutrients.  
(iii) Poverty and low income (economic constraints). This limits the ability to buy healthy  
foods leading to imbalanced diet.  
(iv) Limited access to nutritious foods. People living in food deserts or areas with  
inadequate availability of food may struggle to get a balanced diet.  
(v) Cultural and social influences. Cooking traditions influenced by cultural preferences  
or social norms may not always include a correct proportion of nutrients.  
(vi) Health conditions. Dietary restrictions due to health conditions or allergies can  
complicate maintaining a balanced diet.  
(vii) Psychological factors. Emotional eating or eating disorders can disrupt balanced  
eating pattern and lead to unhealthy food choices.  
(viii) Limited time/time pressure. Busy life styles and competing responsibilities can limit  
the time available for meal planning mad preparation.  
NOTE: The components of balanced diet should not necessarily be eaten in a single meal,  
but there should be a regular supply to the body of each of the food types. The  
following should be done in order to maintain a healthy lifestyle.  
(i)  
Take recommended amounts of protein, fats or oils, sugars and salts.  
Take recommended amounts of fruits and vegetables in the diet.  
(ii)  
(iii) Eat variety of foods including whole grains, fruits, vegetables and foods with  
roughage to provide the body with the required energy and nutrients.  
(iv) Maintain appropriate body weight to height ratio as recommended by the World  
Health Organization (WHO).  
(v)  
Do physical activities daily for 30 to 40 minutes.  
(vi) Replace red meat with fish, poultry or lean meat in your diet.  
(vii) Minimize your intake of fats or oils and salts. This will reduce your risk of heart  
attacks and high blood pressure respectively.  
(viii) Limit consumption of sugary drinks and all sweets to reduce your risk of tooth  
decay.  
(ix) Avoid processed and baked foods particularly those high in sugars, unhealthy fats  
and additives.  
(x)  
More importantly you should take in large amounts of water.  
Importance of Balanced diet  
(i)  
(ii)  
It supplies enough energy to the body. Example; carbohydrates and fats.  
It is used in body growth and repair. Example; proteins.  
(iii) It used in the formation of muscles, enzymes, hormones, bones and red blood cells.  
Example; proteins and minerals.  
(iv) Used in strengthening of bones and teeth. Example; minerals and vitamin D.  
(v)  
It helps peristalsis movement in alimentary canal. Example; roughage.  
(vi) Water is used for transporting materials and provision of a medium in which they  
react.  
(vii) It protects the body against diseases and infections.  
(viii) It helps to control body weight.  
(ix) It helps to promote mental health.  
NUTRITIONAL REQUIREMENTS FOR DIFFERENT GROUPS OF PEOPLE  
1. Pregnant/Expecting and lactating mothers.  
Pregnant and lactating (breast feeding) mother need to get enough nutrients and a  
balanced diet for themselves and their growing babies.  
(i)  
Pregnant and lactating mothers need food rich in protein. Protein helps to build  
muscles, breasts, uterus, blood supply and proper functioning of tissues and  
organs of the foetus and baby.  
(ii) Pregnant women should eat food rich in folic acid and vitamin B. This helps to  
lower the risk of birth defects such as spina bifidia. Spina bifidia is hole in the  
spine due to incomplete formation of spinal cord and bones of the spine.  
(iii) Pregnant and lactating women require calcium for the development of the foetus’  
and baby’s bones.  
(iv) Pregnant and lactating women require zinc. Zinc is important for proper  
progression of labour during delivery and for proper growth and development of  
the baby.  
(v) Pregnant women require iron. It is necessary for her blood supply needs. The  
foetus also needs to store iron for use during the first few months after birth.  
(vi) Pregnant women require dietary fibre. This helps to reduce the likelihood of  
constipation.  
(vii) Pregnant and lactating women should drink plenty of water. Water is the major  
component of breast milk. Also, some hormones produced during pregnancy  
increase thirst.  
(viii) Pregnant and lactating women should avoid drinking alcohol. Alcohol can pass  
from their bodies to the foetus and babies during pregnancy and breastfeeding  
and affect their development.  
(ix) Pregnant and lactating women should avoid smoking. The harmful constituents  
of tobacco smoke such as carbon monoxide and nicotine can pass from their  
bodies to the foetus and babies during pregnancy and breastfeeding and affect  
their development.  
2. Children  
This group ranges from the ages of 5-10 years. At this stage, the rate of growth is very  
high. So, there is a higher demand for energy rich foods, protein, minerals and  
vitamins.  
(i)  
Children require enough proteins for the growth and development of body tissues.  
(ii) They require minerals like calcium necessary for the formation of strong bones  
and teeth.  
(iii) They require Zinc which is important for body growth. The zinc plays a role in cell  
growth, differentiation and metabolism. Deficiency in zinc limits childhood growth  
and decreases resistance to diseases.  
(iv) They require vitamin B12 brain development as well as nervous and cognitive  
functions.  
(v) They require iron for the formation of red blood cells. Because a growing baby  
needs more oxygen and more blood) for growth.  
(vi) They require vitamin C which helps them to build their immunity. It also functions  
as antioxidant. Antioxidant is a substance which removes toxins from the body.  
(vii) They require enough carbohydrates and lipids for energy production because they  
are active than adult.  
3. Sedentary workers.  
These are individuals who stay in one place for a long time while performing their daily  
occupational activities. They include office secretaries, tailors, clerks, receptionists and  
doctors. Due to their lifestyle and occupation, obesity is increasingly becoming  
common among them. They are at risk of developing non-communicable diseases such  
as diabetes and disorders of the muscles and skeleton. Therefore:  
(i)  
(ii) They are recommended to limit the intake of foods rich in carbohydrates and lipids  
because they do not require much energy  
4. The elderly  
They are encouraged to balance their diets with physical exercise.  
.
Elderly people are less active, therefore requires less energy than other groups. This  
group loses appetite and grow thin than other groups. They required balanced diet with  
food rich in vitamins, proteins, roughages and some minerals such as iron, zinc,  
calcium and phosphorous to maintain their health.  
(i)  
They require iron necessary for making red blood cell which carry oxygen around  
the body.  
(ii) They need Zinc for a healthy immune system and regulating the healing of  
wounds.  
(iii) They require adequate amounts of calcium to strengthen their bones. This is  
because, old age comes with the loss of calcium leading to soft and weak bones  
that can break easily.  
(iv) They require vitamin D which is needed to improve their mental health and  
overcome depression.  
(v) They need foods that are easy to chew and swallow. They have problems of chewing  
tough foods because of weakened teeth and decreased production of saliva. For  
example; they can get protein from eggs or liver instead of meat.  
5. The sick  
Sick people need a balanced diet with plenty of nutrients for quick recovery.  
(i)  
They require foods rich in proteins, vitamins to enable their bodies repair damaged  
cells and fight infections.  
(ii)  
They need proper diet and exercise. This helps to combat symptoms such as  
fatigue, nausea, diarrhea and high blood sugar.  
(iii) They should avoid excess caffeine sugar, dried foods, spicy foods and alcohol  
because they are harmful to a body whose immune system is already weak.  
(iv) They require increased intake of fruits. Fruits provide vitamins that are required  
to fight diseases.  
(v)  
They require increased intake of vegetables. Vegetables provide necessary  
minerals for proper functioning of many body systems.  
(vi) They require increased intake of water. Water replaces the amount of water lost  
during sickness for example through diarrhoea or vomiting.  
THE FOOD GUIDE PYRAMID  
The food guide pyramid is a chart showing the recommended amounts of different food  
types that dieticians consider as healthy for eating. It is advisable to use food guide  
pyramid to know what to eat.  
NOTE: The food guide pyramid is not a fixed rule of what to eat each day, but just a  
general guide that helps to choose the right healthy diet. It is not used for all groups of  
people, it depends on the needs and health status of a person.