Agricultural Literacy Curriculum Matrix
Stacking Up Milk and Milk Substitutes
Students will compare and contrast milk and plant-based milk substitutes by learning their source from farm-to-table and discovering how they "stack-up" in nutritional value. Students will also explore food package labeling laws and consumer trends in milk consumption to think critically about the impact of labels in marketing and consumer perceptions of food. Grades 9-12
- 1 container of dairy, soy, almond, coconut, and rice milk
- When choosing milk substitutes for sampling, try to select unsweetened and unflavored varieties if available to allow students to taste the beverage in raw form. Purchase enough milk for each student to sample in Activity 1.
- 5 small cups for taste testing
- Stacking Up Milk Information Cards, 1 classroom set divided by milk type (3 sheets per milk type)
- Stacking Up Milk Comparison Notes, 1 per student
- Milk for student sampling (use leftover milk from the Interest Approach)
- Small cups for sampling, 1 per student
- Stacking Up Milk and Milk Substitutes PowerPoint slides
Essential Files (maps, charts, pictures, or documents)
Food and Drug Administration (FDA): a federal agency in the United States responsible for protecting the public health by ensuring the safety, efficacy, and security of human and veterinary drugs, biological products, medical devices, and the safety of our nation's food supply
fortify: to increase the nutritive value of food, usually with vitamins or minerals
lactase: an enzyme produced by the large intestine which breaks down lactose
lactase persistence: the ability to continue to produce lactase into adulthood
lactose: a disaccharide sugar present in milk which contains glucose and galactose units
milk: an opaque white fluid rich in fat and protein, secreted by female mammals for the nourishment of their young
United States Department of Agriculture (USDA): a federal agency responsible for developing and executing federal laws related to farming, forestry, and food
Did You Know? (Ag Facts)
- Worldwide sales of non-dairy milk alternatives more than doubled between 2009 and 2015, reaching $21 billion.1
- In 2019, there was 42.3 billion pounds of fluid milk sold in the United States.2
- In 2017, the top five milk producing states were California (18.5%), Wisconsin (14.1%), New York (6.9%), Idaho (6.8%), and Texas (5.6%), which in total makes up 51.9% of the total production in the United States.3
Background Agricultural Connections
Milk is defined by the Food and Drug Administration (FDA) as the lacteal secretion from a mammal.4 In order to properly digest milk, the body needs to have an enzyme called lactase to digest the sugar, lactose, found in milk. Babies are born with this enzyme allowing them to digest their mother’s milk. Today approximately 35% of adults across the world still produce lactase allowing the digestion of milk. Although this varies largely based on cultural descent. For example, 95% of northern Europeans are lactose tolerant, while only 10% of adults of east Asian descent still produce the lactase enzyme.11 Historical evidence suggests that the lactase enzyme turned off at the time of weaning for our ancient ancestors.5 The use of milk beyond childhood didn’t begin until about 10,000 BC when humans started to switch from hunter gatherers, to those that farmed and settled in communities. As animals became domesticated, people began using their milk by-products. First, they fermented milk to make cheese and yogurt, which was digestible without their body’s production of lactase. As milk, and milk by-products, started to become part of their diet, lactase persistence, or the ability to continue to produce lactase into adulthood, became more widespread. There was a strong selective advantage for individuals to be able to digest milk and benefit from its nutrition beyond the intake of their mother’s milk, especially in times of crop failure, drought, or famine.6 For more details, see Archaeology: The Milk Revolution.
The nutritional benefits of dairy products have been outlined by the United States Department of Agriculture (USDA) and Department of Health and Human Services (DHHS) 2015 dietary guidelines. These organizations include fat-free and low-fat (1%) dairy, including milk, yogurt, and cheese as part of a healthy diet. Recommended intake is based on age rather than calorie level and are 2 cup-equivalents per day for children ages 2 to 3 years, 2½ cup-equivalents per day for children ages 4 to 8 years, and 3 cup-equivalents per day for adolescents ages 9 to 18 years and for adults. The dairy group contributes many essential nutrients including: calcium, phosphorus, vitamin A, vitamin D (in products fortified with vitamin D), riboflavin, vitamin B12, protein, potassium, zinc, choline, magnesium, and selenium. Switching to dairy products that are fat-free or low-fat can reduce the amount of saturated fat in the diet without changing the nutrient content.
Dairy milk alternatives for individuals with milk allergy, or those that choose not to consume dairy products come in a wide range of plant sources with soy, almond, rice, and coconut being the most common. Soy beverage that is fortified with calcium, vitamin A, and vitamin D is the only plant-based “milk” included in the dairy food group because it is the most nutritionally similar to milk after it is fortified.7 Those who choose not to eat dairy products should make sure they consume a diet which is rich in the nutrients commonly provided by dairy (protein, calcium, potassium, magnesium, vitamin D, and vitamin A).7
Milk and milk substitutes (soy, coconut, almond, rice, etc) often carry the same "milk" name, but they vary greatly in nutrition, source, and processing. Dairy milk has the greatest number of naturally occurring nutrients. It is most often produced by cattle in the United States, but can also be produced by goats, sheep, or other mammals. The processing of dairy milk includes pasteurization, homogenization, and standardization to determine the correct percentage of milk fat (whole, 2%, 1%, or skim). Dairy milk substitutes are processed using various methods, but all share similarities in that the plant material is broken down, extracted in water, and further strained or homogenized producing a milk-like substance. Eventually it undergoes further processing to improve shelf stability, remove off-flavor, and add other flavors to promote acceptability and further imitate the appearance of dairy milk.8 Soy beverages are the only milk substitutes comparable in protein content to dairy milk. Even with these differences and the fact that milk, as defined, comes from mammals, all of these beverages carry the same label of 'milk' on the store shelves. This has led to a vast debate amongst industries as to whether this is misleading to consumers. While they can all be poured on cereal, do they stack up equally in nutrition? The dairy industry and other plant-based milk industries have discussed the matter. In 2017 the Dairy Pride Act was introduced to require the FDA to intervene and enforce labeling laws for plant-based milk substitutes.12 However, at this time, no verdict has been made on the debate to require action for the FDA to change or enforce labeling practices. This makes it even more important for consumers to learn about the products so they can make the best decision in choosing milk or plant-based alternatives.
Interest Approach - Engagement
- To stimulate thinking, discuss the following questions:
- Where does milk come from?
- What is milk?
- What products are made from milk?
- What kinds of milk can we choose from at the grocery store?
- Ask for 5 volunteers who would be willing to taste a sample of milk and try to identify what type of milk it is. Once the volunteers have been chosen, clarify that they do not have any food allergies and give each of them an unlabeled sample of milk. As they drink it, have them describe to the class what it tastes like (flavor, thickness, texture, etc.)
- When the student identifies the correct milk, reveal the package. If a student cannot identify the milk correctly, move on to the next student and then come back to them as the options are narrowed down.
- Once all of the milks have been revealed, inform students that each of them can be found in the dairy section of their local grocery store.
- Inform the students that they will be discovering the answers to the following questions:
- Are all of these milks equivalent in the nutrition they provide?
- Can each of these milks be used interchangeably in cooking and baking?
Activity 1: Stacking Up Nutrition in Milk and Milk Substitutes
- Give each student one copy of the Stacking Up Milk Comparison Notes and one small cup for sampling.
- Divide the class into five groups and set up a station for each milk type. Give each group one copy of the Stacking Up Milk Information Cards (3 sheets per milk type) and the remaining milk from the Interest Approach for sampling.
- Instruct students to read the information found on the cards, fill out the corresponding section of their notes, and sample the milk. Set a countdown clock for five minutes. After five minutes, allow students to rotate to the next station. Reset the clock and continue until each group has been to each station.
- Alternate Approach: Separate the class into 5 different groups (milk, soy, almond, rice, coconut). Give each group the corresponding Stacking Up Milk Information Cards. Assign the students to become experts on their milk type and prepare a 5 minute presentation answering the questions outlined in the Stacking Up Milk comparison notes. Remaining students will complete their notes as other groups present. Provide an opportunity for students to sample each milk.
- Once students have completed each rotation and their Stacking Up Milk Comparison Notes are complete, bring the class back together to synthesize what they have learned.
- Project the Stacking Up Milk and Milk Substitutes PowerPoint on your whiteboard. Choose 5 volunteers to come to the front and assign each of them a milk or milk substitute (milk, soy, almond, rice, and coconut). Give the volunteers instructions that they will use their notes to draw a line on their cup (projected on the board) to represent the amount of each nutrient in their "glass" of milk. Use the following notes for clarification and guided discussion:
- (Slide 2) Fat: Point out that the fat content in these milks are fairly similar with soy having the most. The type of fat is really the difference between these beverages. The plant-based milks contain more unsaturated fats, while milk and coconut milk contain saturated fats. Your body needs both of these fats in order to function at its best.
- (Slide 3) Carbohydrates: Point out that these beverages have similar carbohydrate content. Ask, "Which milk has the highest content of carbohydrates." (rice)
- (Slide 4) Protein: Ask students, "Which beverage has the most protein?" (milk and soy) "Which has the least?" (coconut) "If you are trying to build muscle or recover from a workout, which would be the best option?" (Chocolate milk is known as a recovery drink because it is a good source of protein and carbohydrates which replenish the body after a workout.) "If you are looking for a good protein source as a vegetarian which beverage would be the best?" (soy)
- (Slide 5) Calcium: Ask students, "Which milk contains calcium naturally?" (milk) "Do you think it is better to have naturally occurring calcium or fortified?" (Natural. Just as with any other vitamin and mineral, it is best to obtain it naturally from an original food source rather than a fortified one for optimal nutrient absorption and utilization by the body. However, fortified foods are still valuable in preventing nutrient deficiencies and their associated diseases. It is important to get adequate calcium to maintain bone health and growth.)
- (Slide 6) Vitamins & Minerals: Inform students that exact nutrient content in plant-based milk changes slightly from brand to brand since they are all fortified vitamins and minerals. The vitamins and minerals noted on this slide came from the ingredient labels of the most popular brands. Dairy milk will be consistent from brand to brand.
- (Slide 7) Lactose Intolerance: Individuals with lactose intolerance or a milk protein allergy may choose not to consume milk. However, accommodations do exist in the form of dairy products that have had lactase added to them in processing to make them lactose free (for example, Lactaid®). Alternatively, some may choose plant-based milk substitutes instead.
- (Slides 8 and 9) Allergies: Note that the occurrence of allergies will eliminate milk options, but others can be chosen.
- Conclude by discussing with students that milk and plant-based milk substitutes can all fit into a healthy diet. Although milk and milk substitutes do not stack up equally in nutritional content for every stage of life, an overall diet can be balanced to meet nutritional needs according to an individual's choice in milk.
Activity 2: The "Milk" Debate and the Impacts of Labeling
- Now that students have compared the nutritional aspects of milk and milk substitutes, complete a deeper investigation of milk and plant-based milk substitutes by examining the impacts of marketing, consumer perceptions, and food package labeling.
- Ask students what the dictionary definition of the word milk is. Ask one or two students to find the definition and share with the class.
- Explain that the FDA (Food and Drug Administration) in the United States is responsible for regulating food labels. For example, the Nutrition Facts label, ingredients, allergens, etc. to help ensure that the labels on our food packages accurately communicate to consumers what is contained. The FDA defines milk as, "...the lacteal secretion, practically free from colostrum, obtained by the complete milking of one or more healthy cows."4
- Draw on students' knowledge of milk and milk substitutes and ask which of the five milks they've learned about are actually milk (dairy milk).
- Listen to the NPR broadcast (2:18), Soy, Almond, Coconut: If It's Not From a Cow, Can You Legally Call it Milk?
- Note: This a 2016 NPR broadcast. This labeling issue is current and on-going. For more information, see the timeline for Dairy Foods Standards and Labeling.
- Discuss students' thoughts and opinions on the subject. Use the following questions to guide discussion and thought:
- Does the word milk mislead a consumer about the nutrient content of plant-based milk substitutes?
- If alternative terms were created for the plant-based milks, what could they be? (Brainstorm ideas. Examples include water, juice, or beverage).
- What if the package label were to say soy beverage, almond juice, or rice water? (Use the terms your students came up with.) Would you view the drink differently? Would you perceive it's healthfulness differently?
- Should the FDA enforce that the use of the word milk on food labels be restricted except from that produced by mammals?
- Consumer trends show increased sales of plant-based milk substitutes between 2009 and 2015. Could the labeling and associated consumer perceptions impact this trend? What other factors may impact this trend?
Concept Elaboration and Evaluation
After completing these activities, review and summarize the following key concepts.
- Dairy milk and plant-based milk substitutes (if fortified) can help provide essential nutrients as part of a balanced diet.
- Fortification is a step in food processing where nutrients are added to a food to increase the nutritional value of the final food product.
- Without fortification, dairy milk provides the most comprehensive nutrition from a natural source compared to plant-based substitutes.
- A variety of plant-based milk substitutes provide nutritious options for individuals with allergies or other health concerns.
Make homemade almond, soy, or rice milk.
View the video, Is Dairy Bad for You? The Truth About Milk. As a class discuss why milk is promoted as part of a healthy diet as well as viewpoints where it is discouraged in various diets or marketing.
For a science lesson illustrating the effect of the enzyme lactase, see Lactose Lab: Some Don't Like it Sweet.
Read the Forbes article, The Dairy Pride Act's Beef With Plant-Based Milk.
Suggested Companion Resources
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