Chapter 12: Human Nutrition and Health Fifteen Summary Facts

Worksheet 12.1

Chapter 12: Human nutrition and health – fifteen summary facts

1The types of nutrient which are essential for the human diet are amino acids, fatty acids, minerals, vitamins and water. The sources of these have different amounts of energy: carbohydrates and proteins are similar (1760 and 1720 kJ per 100g, respectively) whereas lipids contain more than twice those levels (4000 kJ per 100g).

2Deficiency diseases such as kwashiorkor (lack of protein), goitre (lack of iodine), scurvy (lack of vitamin C), or rickets (lack of vitamin D) are all threatening to good health. So too is malnutrition caused by overeating – obesity can lead to high risk of a wide range of health problems such as heart disease and type II diabetes.

3Phenylketonuria (PKU) is a genetic disease in which it is impossible for a person to convert the amino acid phenylalanine into tyrosine. This means that toxic levels of phenylalanine accumulate, and this is detrimental to brain development in children.

4Dietary fats can be broken up into categories: unsaturated (includes monounsaturated, polyunsaturated and cis-fats), saturated, and trans-fats. The latter have been transformed from unsaturated to saturated by chemical processes (these include partially hydrogenated and fully hydrogenated fats).

5The shape of fatty acids is important to people who suffer from cardiovascular disease because the flatter (saturated) molecules tend to stick to the sides of arteries along with cholesterol to form plaque deposits that reduce or block the flow of blood. The more curved shaped (polyunsaturated) fatty acids tend to contribute to a healthy cardiovascular system free of plaque.

6Vitamins are organic compounds made of carbon, hydrogen and oxygen; minerals are inorganic compounds in the form of ions.

7It is difficult to determine how much vitamin C a person needs because everyone is different – researchers have given various doses to both human and animal subjects to seek the minimum amount necessary to avoid scurvy and the amount at which undesirable side-effects appear.

8Vitamin D can be obtained from eggs, liver or breakfast cereals but it can also be obtained by exposing the skin to sunlight. However, over-exposure of skin to sunlight can result in the development of melanoma (a type of cancer) brought on by damage from the UV waves in sunlight. Thus, the risks of vitamin D deficiency must be balanced with the risk of skin cancer.

9Different cultures and ethnic groups around the world get their energy from different types of food (wheat, rice, corn, fish or meat). As a result, different populations suffer from different health problems (e.g. obesity, cardiovascular disease, liver conditions, cancer). Some of these problems could be reduced in some instances by increasing the consumption of dietary fibre.

10A person’s BMI (body mass index) is calculated as: body mass in kilograms divided by height in metres squared. It should not be the only number used to determine if someone is obese or underweight.

11Anorexia nervosa is a psychological condition in which the patient (often a young female) is convinced that they are overweight even when their BMI indicates that they are of normal body mass or underweight. The consequences to the person’s physical and emotional health can be very serious and some are irreversible.

12Human breast milk is the most nutritional food for a growing human baby but is sometimes replaced by powdered baby formula. Reasons for this might include: medical concerns (e.g. reducing the risk of passing on an infectious disease to the child), cultural conflicts (it is not considered appropriate for women to breastfeed in public in some cultures), professional reasons (it is sometimes difficult to maintain a successful career and take sufficient time out of a work day to breastfeed).

13Type II diabetes is the result of the body developing an insensitivity to insulin over many years – although there are genetic factors, this condition often develops in people who are obese. An important part of keeping the disease under control is to change to a more healthy diet.

14People have many reasons for choosing to become vegetarians or vegans. They might consider that killing animals for food is wrong in and of itself; they might consider that the meat industry is wasteful and cruel and misuses valuable resources such as water and land.

15The term ‘food miles’ refers to the distance food travels from the place where it was produced to the place where it is consumed. The debate here is: Should humans reduce transportation pollution by eating only foods produced near their homes or should they continue to contribute to a world economy and keep a high variety of foods in their diets by continuing to have their food shipped in from all over the planet?