Lesson two: Malnutrition
Lesson 2 objectives: Consider four different types of malnutrition (deficiency, imbalance, excess of nutrients in diet, starvation). Consider ethical implications of malnutrition research
Ethical considerations of human experimentation
Vitamin C was investigated in the UK and US using volunteers, who were deprived of vitamin C until they developed symptoms of scurvy. Task: discuss what ethical guidelines should be used in human experimentation research?
Types of malnutrition
1) Deficiency: A diet that has a lack of sufficiency in a specific nutrient is called a deficiency eg. Scurvy results from a deficiency of Vitamin C
A) Scurvy: was the scourge of maritime adventures in the 18th century. Captain James Cook (a Scottish explorer) is widely credited with the discovery that citrus fruits would cure the symptoms:
- Bleeding gums
- Loss of teeth
- Wounds on skin fail to heal
- Pale skin
- Sunken eyes
B) Protein deficiency (Kwashiorkor): A diet that has a deficiency of protein.
- Little muscle development
- Stick like arms and legs
- Emaciation very little body fat
- Distended belly (caused by fluid retention)
This has been a major problem in areas of global conflict in the 21st century.
2) Imbalance of nutrients
A) Diabetes type 2. It is widely considered that type II diabetes is correlated with diets that are high in fatty acids, and sugars, and low in complex carbohydrates. Lack of sufficient exercise and some genetic factors are also correlated.
Diabetes type 11 victims suffer from:
- Hyperglycaemia: excess levels of glucose in the blood leading to nausea, fainting, thirst, headaches
- Hypoglycaemia: low levels of glucose in the blood leading to collapse, dizziness, confusion, trembling.
Unike diabetes type 1, patients diagnosed with diabetes type 11 tend to control their condition using carefully timed periods of exercise and feeding. Blood glucose levels are measured using a glycometer. A normal blood glucose level remains within 5.5-7mmol/L (source: leicesterdiabetes.org.uk)
B) Obesity: Obesity means having a body mass index which is high enough to cause harm to a person’s health. It is caused principally by having a higher calorific intake and calorific use. However diets containing high sugars, and high fats content have been correlated, as well as many other factors.
The hypothalamus in the brain contains an appetite control centre. It is responsive to the following hormones:
- leptin from the adipose tissue when it begins to accumulate
- PYY3-36 from the small intestine when it contains food
- Insulin from pancreas when blood glucose levels are high
All of these contribute to a suppression of the desire to eat by the appetite centre. Some research have suggested that abnormalities in the appetite control centre might be responsible for obesity