Download Tamara Truax AGEC 352 Term Project December 7, 2007 Effects of

Tamara Truax
AGEC 352
Term Project
December 7, 2007
Effects of Food Group Serving Standards on a Minimum Cost Diet
I created a low cost diet by evaluating 20 different foods based on price and 10 nutrition
constraints. The nutrition constraints were based on a 2000 calorie diet as recommended for a
young female adult with average physical activity. The minimum cost diet of the twenty foods
came to $1.20 per day. This diet contained only 4 foods none of which were fruits or
vegetables. The USDA recommends a balanced diet to include foods from all five food groups
whereas my minimum cost diet only included food from three food groups. I added five
additional constraints forcing the model to use a minimum number of foods from each of the
five food groups. This second diet was of course more costly than the first at $2.85 per day.
The nutrition standards given cover many constraints however they do not require the
diet to be diverse in the five food groups. I was interested to see whether the minimum cost
diet would include foods from the five different food groups automatically or whether these
constraints would have to be added to the model. Growing up we have always heard to eat our
fruits and vegetables, but the question is can we get the nutrients and vitamins we need
without eating fruits and vegetables. If we can how much more will the diet cost to follow the
additional recommendations from the USDA on daily servings of the five food groups.
To create my model I choose twenty foods from our class list. When choosing the foods,
I tried to keep an even amount of breads and grains; fruits; vegetables; meat, eggs, and nuts;
and dairy. I knew the minimum cost diet might not include all of these categories, but when I
added the food group constraints I wanted the model to have more than one choice to use
from the different food groups.
When adding the additional food group constraints, I used the old USDA food group
serving standards. This added five additional constraints to my model. The new USDA
standards are in weight instead of servings. I was unable to use these new standards because
the weight of the servings was not included in the data, but I spoke to a dietician who told me
the old and new standards should be pretty close to one another. The USDA translated them
into weight to avoid the confusion of defining what a serving size is for each different food. I
gave each of the foods an objective value of 0, 1, or 2 for the food group serving constraints.
For example the jr. cheeseburger has 2 servings of grains because it has two slices of bread. It
also has 1 serving of dairy, 1 serving of meat, and 0 servings of fruits and vegetables. For the
right hand side of these constraints, I used the minimum daily serving recommendation for
each food group.
My minimum cost 2000 calorie diet used four foods and cost $1.20 per day. This diet
included 6.19 servings of peanut butter, 5.49 servings of multi-grain flakes, .78 servings of long
grain rice, and .34 servings of 2 percent milk. The calorie, sodium, fiber and calcium constraints
were all binding. The sensitivity report shows the most expensive foods which could be
included into the diet would be raisins, oats, and Wendy’s broccoli and cheese potato. Fiber is
the most expensive binding constraint. Each additional unit of fiber costs about $.013. Calcium
is the next most expensive; then calories and sodium.
I find it interesting you can obtain all the recommended vitamins without having to eat
the recommended number of servings from the different food groups. I think this is possible
because some foods are enriched or fortified with vitamins they would not normally have. This
diet is also very high in fat with 874.59 grams. This is mainly due to the 6 servings of peanut
butter which each contain 140 grams of fat. I am curious if requiring minimum servings from
each of the food groups will lower the fat content, mainly due to increased intake of fruits and
vegetables. I expect the use of peanut butter to lower, however peanut butter is important for
the binding constraints: fiber and sodium. Looking over the possible candidates for fruits and
vegetables, the lowest reduced cost on the sensitivity report would include green beans and
pineapple. However this does not take into account some of the other foods which contain
servings from more than one food group such as Campbell’s vegetable beef soup.
The minimum cost diet with the additional food group constraints came to $2.85 per
day; $1.65 more than the first solution. This diet included pineapple and green beans in
addition to the multi-grain flakes, rice, milk, and peanut butter. The servings of multi-grain
flakes increased from 5.49 to 6.28. Rice increased 2 servings making the final value 2.78. The
usage of milk also increased from a third of a serving to 2 servings. Peanut butter decreased
about 68% coming to 2 servings. The diet included 3 servings of green beans and 2 servings of
pineapple to fulfill the fruit and vegetable constraints.
The decrease in the servings of peanut butter decreased the amount of fat in the diet by
66%. The fat content was originally 874.59 grams and in the second solution it was 300.45
grams. In the second solution the sodium and calcium constraints are no longer binding. This is
largely because of the amount of sodium in the green beans and the increased servings of milk
which has the most calcium. Of the new constraints the vegetables; fruits; meat, eggs, and
nuts; and dairy constraints are all binding. The fruit constraint costs the most with a shadow
price of $0.32. Next most expensive are the vegetable and dairy constraints at $0.25 and $0.22
respectively. The meat, eggs, and nuts are the least expensive food group constraint at $0.02.
The shadow price of the calorie constraint decreased to $0.0001. While the cost of fiber in the
new diet increased from $0.01 to $0.03.
Looking at the allowable price increases, they are fairly high for milk, peanut butter, and
pineapple. For milk this is probably because there is not really another good dairy source on
the food list. It would be interesting to see if the price of the diet would change if cheese or
yogurt were added to the food list. The multi-grain flakes have an allowable increase of $0.01.
This means a one cent increase in the price would affect the usage of the multi-grain flakes.
Rice also has a low allowable increase of $0.02. If the prices of these two foods went up it
would probably dramatically change the diet.
In conclusion, all of our nutritional needs can be met without eating food from each of
the five food groups. However, including all five of the food groups helped to lower the fat
intake of the diet. A diet including food from all five food groups also had less binding
constraints on nutrients. At the same time, a minimum cost diet with all five food groups would
cost approximately $1040 per year; $602 more than the minimum cost diet without the food
group constraints. In the end the question is whether the lower fat content, larger variety, and
increased vitamins is worth the increased cost of a diet which meets the food group standards.