What is a healthy balanced diet? carbohydrates,
lipids, vegetable oils, animal fats, protein, mineral ions, vitamins, dietary
fibre (roughage), water
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of biology notes on diet and exercise
What is a healthy balanced diet?
You need to know the content of a healthy human
diet: carbohydrates, lipids (fats and oils), proteins, vitamins,
minerals, dietary fibre and water, and why each is needed
Know that a healthy diet contains the
right balance of the different foods you need and the right amount of
energy and the different food groups are ...
These are needed to provide energy
for your body chemistry to function correctly, and of course to keep you
warm at 37oC,
Carbohydrate sources include bread, potatoes and cereals,
all of which contain starch.
Carbohydrates are digested and broken down to give sugars
such as glucose that are needed for respiration in the mitochondria of cells
- powering much of a cell's, tissue or organs chemistry.
BUT, not too much, or excessive
fats or carbohydrates build up in your body which can lead to obesity.
Obesity is a common disorder in developed
countries eg in Europe and the US.
Obesity is defined as 'having a body mass
of at least 20% greater than the maximum recommended body mass.
Although the usual causes of obesity are
overeating, lack of sufficient exercise and bad diet, hormonal problems can
also help cause obesity.
Obesity can contribute to other medical
problems eg arthritis (joint inflammation), type 2 diabetes (failure to
control blood sugar levels), high blood pressure and heart disease and even
some types of cancer.
Lipids (e.g. animal fats and vegetable
Sources include butter, vegetable cooking oils and cream.
These can act as energy stores which your body can use if
insufficient carbohydrates are available.
They are also important molecules for the formation of cell
If you have too much saturated fat in
your diet, your blood cholesterol levels are raised above what is needed and
deposits form on the walls of your blood vessels leading to higher blood
See also medical issues mentioned under carbohydrates.
Sources include cheese, meat, eggs and fish.
Proteins are used by the body to build
cells - growth of new tissue, cell repair and cell replacement.
Proteins are important molecules for muscles, tissues and
In digestions, protein is broken down into much smaller
amino acid molecules, these are then combined in the ribosomes of cells to
synthesise the particular protein molecules are body needs.
A variety of mineral ions are needed in
varying amounts for healthy functioning of the body - organs, skin, bones
You do need mineral salts containing e.g.
sodium, calcium, potassium and chloride ions BUT too much salt (sodium
chloride) can cause high blood pressure and heart problems.
You need iron to make haemoglobin molecules that convey
oxygen from the lungs through the blood vessel systems to all the cells of
your body. Iron is found in red meat and some vegetables.
Calcium ions are an important component in bone structure -
skeleton and teeth.
Sodium ions are important for the functioning of the nervous
system, readily obtained from table salt.
Vitamins are needed in tiny amounts for
healthy functioning of the body - organs, skin, bones etc.
They are involved in many important chemical reactions in
the complex biochemistry of our body.
There are many vitamins important for good health e.g.
Vitamin C for healthy skin and avoiding scurvy.
Vitamin D helps the body absorb
and retain calcium and phosphorus; both are critical for building bone and
teeth structure and it also believed to reduce cancer cell growth, help
control infections and reduce inflammation..
The name 'vitamin' dates from the time early in the 20th
century when it was recognised that micro amounts of particular molecules
were need for important reactions in maintaining a healthy body.
They are mostly obtained from vegetables, fruit and cereals.
Dietary fibre keeps everything moving
smoothly through the lower part of your digestive system - from the small
intestine to the colon.
Fibre helps undigested food pass through the gut system.
Good sources of fibre include vegetables, fruit, nuts and
Highly processed food tend to be deficient in good quality
It improves the conditions for your gut bacteria and fungi
(microbes of the microbiome) to do their job in aiding digestion and
synthesising important molecules including some vitamins.
Potable water, fit for drinking and cooking.
Water is present in all drinks and you need a few litres per
day and water makes up ~75% of your body.
It is the great solvent of the body and provides the main
medium for transport and the chemical reactions in and out of cells.
In other words throughout your body including the contents
of cells, circulatory system of the blood and your digestion system.
Water is also a reactant molecules in the digesting of food
e.g. the hydrolysis of complex carbohydrates into smaller sugar molecules.
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