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Human nutrition and healthA3. Special issues in human nutrition

April 10, 20232

Breast 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

April 10, 20233

Human vs. Artificial milkComposition Human milk Artificial milk

Carbohydrate lactose Lactose or glucose polymers

Protein source 65% whey proteins, 35% casein

18% bovine whey and 82% bovine casein, or soya proteins

Fatty acids Human butter fat Palm, coconut, soy or safflower oils

antibodies Present mostly in the first milk (colostrum)

No antibodies present

Vitamins ans minerals

May be lower, but easier to absorb

Higher, but harder to absorb (bio-availability)

April 10, 20234

Type 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)

April 10, 20235

Type 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

April 10, 20236

Type II diabetes Incidence of 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.

April 10, 20237

Regulation of sugar levels in the 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)

April 10, 20238

Type 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)

April 10, 20239

Type II diabetes It can be controlled through careful diet

and healthy lifestyle

April 10, 202310

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.

April 10, 202311

Ethical 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.

April 10, 202312

Ethical 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)

April 10, 202313

Ethical 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)

April 10, 202314

Ethical 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.

April 10, 202315

Ethical 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.

April 10, 202316

Cholesterol It is 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.

April 10, 202317

Cholesterol 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.

April 10, 202318

Food 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?

April 10, 202319

Food 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.

April 10, 202320

Food 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 foodReduced food options

April 10, 202321

Food 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?