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Biology and Nutrition

In Biology class, youve learned about biomolecules, or organic molecules that make up living organisms

such as ourselves. When we eat food, we consume biomolecules and other nutrients that we then use as

energy and as the building blocks for our own bodies. There are six main classes of nutrients: water,

carbohydrates, fats, proteins, vitamins and minerals.

Table 1: Nutrients, their functions, and food sources

Nutrient Examples Functions in living things Food Sources

Water water fluid balance, nutrient

transport, gas exchange,nerve impulse transmission,

waste excretion, and manymore

Water, juices,

soup, fruits andvegetables

Carbohydrates Sugars, starch, glycogen fuel, broken down for

energy

Grains (rice,

wheat), bread,

sugars

Lipids Fats, cholesterol,phospholipids (cell

membrane component)

energy storage, can bebroken down for energy,

structural (in the cellmembrane), hormone

component

Butter, oils,animal products,

nuts and seeds

Proteins movement (actin and

myosin are involved inmuscle contraction),

enzymes, hormones, storage

of energy (proteins in eggwhites for chicken embryo)

enzymes (chemical

catalysts), structuralproteins, can be broken

down for energy

Beans and soy

products, animalproducts, nuts

and seeds

Vitamins Vitamins A, E, K (fatsoluble)

Vitamins B, C, D (watersoluble)

co-enzymes, necessary formetabolic processes

fruits,vegetables,

animal sources,sunlight

Minerals Calcium, iron, magnesium,etc.

fluid balance, structural(calcium), nerve impulse

regulation, hormone

regulation, many others

fruits,vegetables,

animal sources

As you can see, biomolecules play important roles in the body, and we need to consume most of them in

our daily diets in order to ensure good health. Unfortunately, many people in the U.S. and other developed

countries consume too many calories and too few nutrients. Many processed foods contain large amounts

of fat and empty calories, as well as added chemicals. Fortunately, the U.S. Food and Drug Administration

(FDA) mandates that companies must include ingredients and nutrition information on their foods

packaging. Understanding how to read ingredient lists and nutrition labels will allow you to understand the

nutrient content of that food, and how it should (or shouldnt!) fit into your diet.


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Figure 1. Cola Nutrition Label on a 12 ounce can

Nutrition Facts

Serving Size 8 fl oz

Servings Per Container 1.5

-------

Amount Per Serving

-------

Calories 100 -------

%Daily Value

Total Fat 0g 0%

Sodium 70mg 3%

Total Carb. 31g 10%

Sugars 39g ------

Protein 0g 0%

Vitamin A 0% Vitamin C 0% -------

Calcium 0% Iron 0% -------

Ingredients:

Carbonated water, high fructose corn syrup, sugar, phosphoric acid, caffeine, citric acid, natural flavor

Questions

How many calories does the can of cola contain?

What class of nutrient do these calories come from?

What vitamins and minerals does this cola contain?


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As you can see in the example above, one serving of cola contains 100 calories, but the can contains 1.5

servings, so one can actually contains 150 calories. Below is a simple equation to calculate the total

number of calories in a package of food.

Total calories in package=calories per serving x number of servings per package

You can also see that all of the calories come from carbohydrate, and based on the ingredients, the source

of that carbohydrate is high fructose corn syrup and sugar. The cola also contains no vitamins or minerals.

The ONLY thing a can of cola provides is calories.

Now, lets look at two more nutrition labels, one from a container of milk, and another from a container of

orange juice.

Figure 2: Nutrition Label for a container of 1% milk

Nutrition Facts


Servings Per Container 1

Amount Per Serving

-----

Calories 102 -----

%Daily Value

Total Fat 3g 4%

Saturated Fat 2g 8%

Cholesterol 10mg 3%

Sodium 124mg 5%

Total Carb. 12g 4%

Sugars 12g -----

Protein 8g -----

Vitamin A 10% Vitamin C 4% -----

Calcium 30% Iron 1% -----


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Figure 3: Nutrition Label from a container of 100% orange juice

Nutrition Facts


Servings Per Container

-----

Amount Per Serving

-----

Calories 110 -----

%Daily Value

Total Fat 0g 0%

Sodium 0mg 0%

Total Carb. 26g 9%

Sugars 22g -----

Protein 2g -----

Vitamin C 120% Vitamin B6 6%

Niacin 4% Magnesium 6%

-----

Folate 15% Thiamin 10% Calcium 2% -----

Questions

How does the nutrient content of milk and orange juice differ from cola? What do milk and oj have that

cola does not?

What do you think would be on the ingredient list for these two beverages?

Your Nutrition Label

Answer the following questions about the food label you brought in. Attach the label to this

worksheet before handing it in.


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What is the name of the food product?

How many calories are there per serving?

How many calories are there in the entire package?

Does the product contain any vitamins or minerals? If so, which ones?

Overall, would you classify this food product as a healthy or unhealthy choice? Explain why or why not.

Calories per Gram

The three types of biomolecules or nutrients that we use for energy are carbohydrates, fats, and proteins.

Each of these has a different caloric content. Each nutrients caloric content is listed below.

Carbohydrate: 4 calories/gram

Protein: 4 calories/gram

Fat: 9 calories/gram

(Alcohol, although not considered a nutrient, can also be broken down to produce energy. It contains 7calories per gram.)

Questions

Lets say you eat a hamburger for lunch. It contains 28 grams of protein, 37 grams of carbohydrate, and

18 grams of fat. How many calories did you just consume?

What if you also drink 8 ounces of soda, which have 31 grams of carbohydrate? How many additional

calories will you have consumed?

Now lets say your mom had the same meal with you, but she had a glass of red wine, which has 12 grams

of alcohol. How many calories did she consume?


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Body Mass Index

Body Mass Index (BMI) is a number calculated using a persons height and weight. For many people, BMI

is a reliable indicator of weight status, and can help predict a persons likelihood for developing major

weight-related diseases.

BMI=weight in lbs/(height)2 x 703

It is useful because it is easy to calculate, and it is a good indicator of weight status for most people. Howev

does not actually measure fat or muscle content. In fact, when one calculates the BMI of a body builder, fo

example, it would indicate that the body builder has a BMI in the overweight or even obese range. Addition

women tend to have more body fat than men and older adults tend to have more than younger adults.

Calculate your BMI (if you are not sure of your specific height or weight, use your best guess):

BMI= ________ lbs./(____________in.)2

x 703=

Now, use the table below to find your weight status.

Table 2: BMI and Weight Status

BMI Weight Status

Below 18.5 underweight

18.5 to 24.9 normal

25 to 29.9 overweight

30 and above obese

Remember, BMI is a very vague measurement. A person in the normal weight range can still be out of

shape and unhealthy. For example, a heavy smoker whose appetite is suppressed by nicotine might be in

the healthy weight range, but still at risk for major diseases. A very muscular person, like a body builder,

might appear overweight according to this measurement. Also, the above ranges are for adults. There is a

slightly different scale used for children and teenagers, which takes into account how body fat changes with

age.However, an adult with a BMI in the underweight range, overweight, or obese range, might want to

examine his or her diet and lifestyle and make changes accordingly. Being underweight may be an

indicator of an underlying disease, an eating disorder, or a metabolic imbalance. People who are

underweight because they are not consuming enough food may be at risk for malnutrition, bone disease,

anemia, and fertility problems. People who are overweight or obese have increased chances of developing

diabetes, heart disease, and most cancers, and being overweight during pregnancy can lead to complications

for both the mother and the baby.


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Here are some general guidelines to follow when choosing foods:

Choose whole grains instead of processed grains. For example, eat whole grain bread instead ofwhite bread, eat brown or wild rice instead of white rice, eat whole wheat pasta instead of regular

pasta.

Choose lean meats, fish, and vegetable proteins instead of red meat. Choose vegetables and fruits all the time, and eat a wide variety of them. Try to eat as many

different colored fruits and vegetables as you can every day!

Choose low fat dairy products. For example, drink skim milk and eat low fat yogurt. Eat nuts and seeds. They contain essential nutrients that are hard to find in many foods. Dont go

overboard, though, nuts and seeds can also be high in fat, so eat them in moderation.

Choose healthy oils, like olive oil, canola oil, and vegetable oils instead of butter and lard. Limit your intake of processed foods. In general, the fewer ingredients the product has, the better. Limit your intake of saturated fat, sugary sweets and sodas. Learn to cook! You can make dishes exactly how you like them, and you will know exactly what

went in them. Cooking can also be fun to do with family and friends.

Clearly, understanding nutrition is essential to maintaining a healthy weight and getting the nutrients your

body needs to live a full and healthy life. If you want to know more about food and nutrition, check out

some of the web sites listed below:

http://www.mypyramid.gov/

This web site, published by the United States Department of Agriculture (USDA), lets you analyze your

own diet, learn about different food groups, and look up the nutrient content of different foods.

http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/pyramid/

This is a web site published by the Harvard School of Public Health. On it, Dr. Walter Willett presents a

slightly different food pyramid than the one put out by the government, one that may be less biased byinput from special interest groups.

http://www.cdc.gov/HealthyLiving/

This is the web site on healthy living put out by the Centers for Disease Control (CDC).

http://www.eatright.org/Public/

This is the web site of the American Dietetic Association.