Human nutrition and health A3. Special issues in human nutrition1
2 November 1, 2011Breast feeding babies Advantages of breast feeding: Promotes bonding between mother and baby Acts as a natural birth-control method, reducing the chance of conception while the mother is lactating Helps mother loose weight after pregnancy, helps prevent breast cancer and post partum depression Avoids the allergies to proteins in cow’s milk that can develop when babies receive formula. Colostrum and early breast milk contain high concentrations of antibodies, helping protect baby from infections Breast milk is free and available as long as mother remains healthy
3 November 1, 2011 Human vs. Artificial milkComposition Human milk Artificial milkCarbohydrate lactose Lactose or glucose polymersProtein source 65% whey proteins, 18% bovine whey and 35% casein 82% bovine casein, or soya proteinsFatty acids Human butter fat Palm, coconut, soy or safflower oilsantibodies Present mostly in the No antibodies present first milk (colostrum)Vitamins ans minerals May be lower, but Higher, but harder to easier to absorb absorb (bio- availability)
4 November 1, 2011Type II diabetes Several forms of diabetes. Diabetes mellitus is the most common. Type I diabetes: auto-immune destruction of insulin-secretin cells in the pancreas (not enough cells that make insulin) Type II diabetes: decreased responsiveness of body cells to insulin (not enough insulin receptors on target cells)
5 November 1, 2011Type II diabetes After many years, diabetes can lead to serious problems with your eyes, kidneys, nerves, and gums and teeth. But the most serious problem caused by diabetes is heart disease. When you have diabetes, you are more than twice as likely as people without diabetes to have heart disease or a stroke. Other related health problems related to the cardiovascular system: Atherosclerosis, hypertension, CHD
6 November 1, 2011Type II diabetes Incidenceof type II diabetes is increasing in many countries that show risk factors: Diets rich in fat and low in fiber Obesity due to overeating and lack of exercise (the receptors in the liver ‘wear out’ or become resistant to insulin) Genetic factors which affect fat metabolism.
7 November 1, 2011Regulation of sugar levels inthe blood a) Low glucose concentration is detected by the pancreas. b) Alpha cells in the pancreatic islets secret glucagon. c)Glucagon flows through the blood to receptors on liver cells. d)Liver responds by adding glucose to blood stream. h) High blood glucose levels stimulate the beta pancreatic cells a) Beta pancreatic cells secrete insulin. f)Insulin flows through the blood to the receptors on liver cells. g)Insulin stimulates the liver to remove blood glucose and store this as glycogen (insoluble)
8 November 1, 2011Type II diabetes The main symptoms are: being very thirsty and/or urinating often feeling very hungry or tired losing weight without trying having sores (injuries) that heal slowly having dry, itchy skin losing the feeling in your feet or having tingling in your feet having blurry eyesight elevated levels of blood glucose or glucose in the urine (detected in lab tests)
9 November 1, 2011Type II diabetes It can be controlled through careful diet and healthy lifestyle
10 November 1, 2011 Ethical issues in human diets Discuss the ethical issues concerning the of eating of animal food products, including honey, eggs, milk and meat. Beliefs: It is wrong to eat food if its production involves animal suffering. Vegetarians do not eat meat because an animal must be slaughtered, however they are willing to drink milk and eat eggs because animals do not need to die to produce them. Vegans do not eat meat, eggs nor drink milk or even honey.
11 November 1, 2011Ethical issues in human diets Meat Advantages: source of proteins, some vitamins and minerals. Ethical concerns: animal welfare, pain and suffering Use of growth hormones affects humans, growth of antibiotic-resistant strains of bacteria Huge demand for land and water for feeding animals. Methane production contributes to global warming.
12 November 1, 2011Ethical issues in human diets Fish: Advantages: source of proteins and healthy fatty acids Concerns: Overfishing Biomagnification of pollutants and toxins can be harmful to humans (mercury)
13 November 1, 2011Ethical issues in human diets Milk Advantages: source of proteins, calcium and energy Concerns: Animal welfare. Cows need to give birth to calves to produce milk. Few are needed for replacement, most are grown for meat or sacrificed soon after birth. Increase in antibiotic-resistant bacteria Huge demand for water and soil (deforestation)
14 November 1, 2011Ethical issues in human diets Eggs Advantages: source of proteins and fat Concerns: Male chicks are often sacrificed since they cannot produce eggs. Animal welfare and living conditions can propagate illnesses High egg yolk consumption associated to high cholesterol levels and poor health.
15 November 1, 2011Ethical issues in human diets Honey Advantages: natural sweetener, provides energy. Bees pollinate many flowers. Concerns: Farmed bees compete with wild local insects and bees for nectar. Artificial selection of bees will result in genetic shift in bee populations.
16 November 1, 2011Cholesterol Itis a normal component of plasma membranes in human dells. LDL – low density lipoprotein HDL – high density lipoprotein Positive correlation between high levels of cholesterol in blood plasma and an increased risk of coronary heart disease (CHD). However, this is being challenged.
17 November 1, 2011Cholesterol Only LDL is implicated in CHD, but studies focus on total blood cholesterol levels. Reducing dietary intake of cholesterol often has a very small effect on blood cholesterol levels. The liver can synthesize cholesterol Genetic factors: some families have high cholesterol levels even with a low dietary intake. It has been suggested that the link between dietary cholesterol intake and CHD is not logical, and that the more likely cause of CHD is a diet high in saturated fats, that also tend to be high in cholesterol, so there is a correlation without necessarily causation.
18 November 1, 2011Food miles Where does your food come from? How distant is the place of origin of the food you eat? How much energy has been spent to transport your food? How much fuel has been burned, and therefore how much CO2 has been released into the atmosphere?
19 November 1, 2011Food miles Food miles are a measure of the distance a food product travels from ’plough to plate’ It is an indicator of the environmental impact of the foods we eat Environmentalists campaign for less transport of food and more consumption of locally produced food.
20 November 1, 2011Food miles Advantages: Local foods are cheaper and fresher Less wrapping and packaging Boost of local economy and farmers Less imported goods Disadvantages: Seasonal availability of food Reduced food options
21 November 1, 2011Food miles Can consumers affect the environment by the choices they make in buying food? Should we consider ethical issues when we buy food, or should we leave it up to governments? Is it right that buying locally produced food is a form of protectionism, which can harm farmers in the developing world? Evaluate the claim that internet shopping and home delivery of food reduce the use of energy in food transport Referring to the precautionary principle, should we wait until more research has been done before changing our pattern of consumption?