You Are What You Eat
Topics covered:
The distinction between nutrients, food and diet
The major components of the diet
How the body maintains nutritional "status" and how this can be
measured
How a nutritional deficiency can arise
A textbook definition of nutrition would be – “The sum of the processes concerned with
growth, maintenance and repair of the living body as a whole, or its constituent parts”
This process is broken down into different stages: Ingestion, digestion, absorption,
transport, assimilation and excretion
This definition overlooks an important factor, that there are foods that have non-
nutritional value.
So a better definition would be nutrition is concerned with understanding the effects of
food on the human body in health and disease
Some definitions:
Diet – The sum of food consumed by a person
Foods – Substances that we take into the body
Nutrients – The components of food
Factors that influence our diet: Personal beliefs, physiological (e.g. age), economic,
education, food characteristics, advertised
Foods are classified into different groups based on the nutrients they contain, we
have the eat-well plate which tells us the foods that make up our diet and what
proportions they should be in. 1/3 starchy carb, 1/3 fruit and veg, Non-dairy sources of
protein, food high in fat/sugar and dairy
, Nutrients
Nutrients, the components of food, are divided into macronutrients and micronutrients
Macronutrients include: Fat, carbs, protein and alcohol <- these can be used for energy,
structural materials e.g. membranes, teeth, bones and can be used for hormone/enzyme
synthesis
-Most energy dense is fat (9kcal/g), then alcohol (7kcal/g), then protein and carbs/CHO
(4kcal/g)
Micronutrients include: Vitamins and trace minerals <- These are used as cofactors
in metabolism (e.g. thiamin/B1 in CHO and AA catabolism)
Food groups complement each other to give a balance of nutrients e.g. rice and peas.
There are 20 amino acids and of these we have some essential amino acids (Leucine,
Valine, Threonine, Methionine, Phenylalanine, Lysine).
Essential AAs cannot be made by the body and hence we must obtain them through our
diet.
A complete protein is a food that contains adequate amounts of all the essential
amino acids e.g. fish, chicken, eggs, cheese
An incomplete protein is deficient in one or more essential acids.
But vegetarians can still get all their amino acids by protein combining, this is where
they eat complementary proteins, these are two or more incomplete protein sources
that when combined provide adequate amounts of all the essential amino acids.
E.g. Rice is limited by its lysine content, beans are limited by methionine content, but
mixed together they are complete
Food composition and how we process them affects the way foods are handled in the
body. Food processing effects the palatability, digestability and metabolic response
Blood Glucose Regulation
When we intake carbs, glucose will enter into our blood. This glucose has three possible
fates, it can be used as an energy source through glycolysis, it can be stored as glycogen
or converted and stored as fat.
When we eat the meal our blood level rises and insulin is released from the pancreas.
Insulin tells liver and muscle cells to convert glucose to glycogen, it also tells them to
convert amino acids to protein and tells adipocytes/liver to convert glycerol and FA to
TAGs.
Obese people can develop insulin resistance, so they have to release more insulin to
control their blood levels.
Type 2 DM is in part due to insulin resistance (so linked to obesity).
Topics covered:
The distinction between nutrients, food and diet
The major components of the diet
How the body maintains nutritional "status" and how this can be
measured
How a nutritional deficiency can arise
A textbook definition of nutrition would be – “The sum of the processes concerned with
growth, maintenance and repair of the living body as a whole, or its constituent parts”
This process is broken down into different stages: Ingestion, digestion, absorption,
transport, assimilation and excretion
This definition overlooks an important factor, that there are foods that have non-
nutritional value.
So a better definition would be nutrition is concerned with understanding the effects of
food on the human body in health and disease
Some definitions:
Diet – The sum of food consumed by a person
Foods – Substances that we take into the body
Nutrients – The components of food
Factors that influence our diet: Personal beliefs, physiological (e.g. age), economic,
education, food characteristics, advertised
Foods are classified into different groups based on the nutrients they contain, we
have the eat-well plate which tells us the foods that make up our diet and what
proportions they should be in. 1/3 starchy carb, 1/3 fruit and veg, Non-dairy sources of
protein, food high in fat/sugar and dairy
, Nutrients
Nutrients, the components of food, are divided into macronutrients and micronutrients
Macronutrients include: Fat, carbs, protein and alcohol <- these can be used for energy,
structural materials e.g. membranes, teeth, bones and can be used for hormone/enzyme
synthesis
-Most energy dense is fat (9kcal/g), then alcohol (7kcal/g), then protein and carbs/CHO
(4kcal/g)
Micronutrients include: Vitamins and trace minerals <- These are used as cofactors
in metabolism (e.g. thiamin/B1 in CHO and AA catabolism)
Food groups complement each other to give a balance of nutrients e.g. rice and peas.
There are 20 amino acids and of these we have some essential amino acids (Leucine,
Valine, Threonine, Methionine, Phenylalanine, Lysine).
Essential AAs cannot be made by the body and hence we must obtain them through our
diet.
A complete protein is a food that contains adequate amounts of all the essential
amino acids e.g. fish, chicken, eggs, cheese
An incomplete protein is deficient in one or more essential acids.
But vegetarians can still get all their amino acids by protein combining, this is where
they eat complementary proteins, these are two or more incomplete protein sources
that when combined provide adequate amounts of all the essential amino acids.
E.g. Rice is limited by its lysine content, beans are limited by methionine content, but
mixed together they are complete
Food composition and how we process them affects the way foods are handled in the
body. Food processing effects the palatability, digestability and metabolic response
Blood Glucose Regulation
When we intake carbs, glucose will enter into our blood. This glucose has three possible
fates, it can be used as an energy source through glycolysis, it can be stored as glycogen
or converted and stored as fat.
When we eat the meal our blood level rises and insulin is released from the pancreas.
Insulin tells liver and muscle cells to convert glucose to glycogen, it also tells them to
convert amino acids to protein and tells adipocytes/liver to convert glycerol and FA to
TAGs.
Obese people can develop insulin resistance, so they have to release more insulin to
control their blood levels.
Type 2 DM is in part due to insulin resistance (so linked to obesity).
