A growing number of countries are developing and revising their dietary
guidelines, and food guide education materials.
We can think about our dietary guidelines in 2 major categories, Food-based and
Biochemical. Food-based guidelines talk about what
foods we need to eat to meet our nutritional needs, while the Biochemical
guidelines define a nutrient and nutrient requirement.
Both are estimations, and typically generalized to a population with some
consideration of age and gender. Dietary guidelines are derived from
research that's determining the nutritional needs of humans.
In determining biological requirements, we've also developed clinical measures of
status that can be used in medical and nutritional assessment.
Health care experts can then use these assessments to help prevent malnutrition
and disease. The guidelines, especially the food based
guidelines, are designed to inform the public about nutritional requirements.
In addition, they give information on nutrient content of foods, and are based
on population based measures. Countries having their own guidelines
face among many factors including scientific research, cultural and dietary
habits and agricultural industries. Since different cultures have different
food availabilities, food preferences, dietary patterns.
In cultural definitions of foods, it's clear a global food guidance system would
be inappropriate. In this lesson, you'll get a chance to
look up the dietary guidelines in your country, and share and contrast this
information with other students. To give you background and a starting
point, let's consider the development of the dietary guidelines in the US.
The US food guide system is based on the United States of Agriculture's research
on the types of foods Americans consume, the nutrient composition of these foods
and the relation to the individual's nutrient needs.
So let's see how it's changed over time. We'll start in 1894.
Here we can see somewhat of a generic message looking mainly at the American
male. The next message looks a little more at
keeping someone fit. Then we see the start of a number of food
groups, numbering them. Simplifying that number a little bit.
Making things even simpler by putting hassle-free in the title.
And in 1980, we saw the first. Example of the dietary guidelines for
Americans. And this is going to be revised every 5
years. so you will see how that changes too.
We see some reference to give you that we eat in some type of pattern.
And then we start to see these examples that show a pictorial image that's
supposed to guide us on how to eat. And here we have the good guide pyramid
that started. That pyramid was changed a bit to make it
more personable. And then we've gone back to an image that
everyone can recognize, the thing that you eat off of, whether it be paper or
plastic, ceramic or even a piece of bread, MyPlate.
So what does this look like in pictures? we have the details of the groups here.
Let's see what type of images were sent out to educate the public.
So here we have that generic making us healthy example.
If you notice, you'll show here pictures, of how much food someone should eat.
So, if you couldn't read for example, you might try to get an understanding of,
well that's what my food should look like, for an average family in a week.
We even see pictures of happy children eating, so, if you eat well you will be
happy, might have been the message they were trying Trying to convey.
As we go on we now see groupings of foods before everything was put together.
Here we see foods broken up into different sections.
Again, different sections and through nutrition research and understanding we
did, at different times, group different types of foods together.
As we went on, we saw simplification of the message.
Here are only 4 food groups are appearing.
Continuing again this idea of the hassle-free guide, this is an older
document, so it may get a little harder to read.
But we do see a vegetable and fruit group, a bread and cereal group, a milk
and cheese group and then the meat and poultry, fish and bean group.
As I mentioned, we then went to the idea of providing dietary guidelines for
Americans actually manuscripts giving more information, detailed education on
what we should eat. And again this is still based on
research. Continuing on with the Food Guidance
System, we saw a change in the shape so it's not just blocks of food, now we saw
some creativity coming in here, trying to make a Food wheel.
And then there's that Food Pyramid that started in 92'.
This was changed in 2005, and what you can see that's different here, is now
there's a person in it, so we considered that maybe we needed to make this more
individual, and also by having the person on the stairs, we see that activities
brought into play. Still people were challenged by
understanding how much they should eat, quantity wise.
So then we come to MyPlate, a more straightforward image.
Something you'd definitely recognise. It's a plate And as a nutrition educator
I like that the dairy is a round circle. To me that guides someone to think about
dairy as milk or yogurt, not just cheese which typically comes with more fat.
Which is now considered to be excess calories.
In addition to the food based guidelines research has also helped us understand
nutritional requirements on the biochemical level.
Measuring nutritional status either directly or indirectly within a study
population, and expanding scientific findings to make intake recommendation
based on age and gender. These dietary reference intakes tell us
just how much carbohydrates, lipids, protein, vitamins and minerals we need to
reach biological sufficiency. Keep in mind, recommendations are
population based and each individual may actually need more or less.
The recommendations are set to meet nutrient requirements, prevent disease
and deficiency and avoid excess intake. So they may not be perfect for everybody,
but we can use them to understand how we get these vitamins out of our food.
Food and how much we need. Since dietary reference intakes are based
primarily on deficiency we should first consider how nutritional deficiency
develops and how we can evaluate status at various stages.
For vitamin and mineral requirements the laboratory tests will give us the best
model for determining Requirement. Once we have a biological graph print, we
can scientifically determine the level of intake needed to obtain a given blood
value, and in some cases, we may measure actual plasma or serum concentrations,
and other cases we may measure enzyme activitiy.
We can see here the stages of deveolpment In the assessment methods.
So let's take a few minutes to consider some of the ways that we determine
requirements for a few vitamins. When reviewing these slides, the details
aren't as important. What I want you to get an idea of is how
varied that the determinations can be. Just starting with Vitamin A.
In determining Vitamin A status, numerous measures were brought together, to give
an idea of how much Vitamin A should be stored in the body, if we're consuming
enough. And the primary site where we store in
the body is the liver. So that gave us a key location to look
at, and a key thing to consider. So in this example we have a series of
tests. Brought together to determine Vitamin A
requirement. In the case of Vitamin B, we look more
directly at blood values, as well as some measure of vitamin B activity.
In the case of Folate, we have similar measures to vitamin B.
Both cases showing actual blood measures as well as some enzyme or activity
quotients or measure. In the case of Riboflavin, we consider not only the
blood but also the urine. Here, we see an abbreviation.
This stands for erythrocyte folate activity coefficient.
And the more direct measure, the nonactive measure, is Urinary Riboflavin.
But if you think about it. The Riboflavin that's made it to the
urine is Riboflavin that's been processed.
Thiamin again uses both blood and urine. Looking at direct measures and enzymatic
measure. Niacin only looks at urine output.
Once we scientifically derive the nutrient requirement, we can set an
estimated average requirement, or EAR. This amount of a given nutrient will
satisfy the needs of 50% of population. Then, by calculating 2 standard
deviations above and below the EAR, we get the Recommended Dietary Allowance or
RDA. This value, will be sufficient for 97 to
98% of the population. We do not have scientific data, to
support an EAR. We can extrapolate finding, and develop,
an adequate intake, or AI value. An adequate intake level, is adequate for
most people, and is often used, in recommendations for infants And children.
Finally, we can also establish tolerable upper intake levels for UL.
This is scientifically or clinically derived and prevents toxicity.
This is mostly concerned when dealing with supplementaton rather than from food
micro nutrients. Macro nutrient recommendations - first
step to prevent disease either by deficiency or excess Keep in mind DRI
values are set for population groups rather than individuals they can be used
to assess adequacy of intake, plan diets and set policy and guidelines.
Individuals should follow these recommendations with care, since we don't
know the actual individual requirements. Using the RDA's and AI's targets and
avoid exceeding the UL.