Stacking Up Milk and Milk Substitutes

Lesson Plan

Grade Level

9 - 12

Purpose

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

Estimated Time

60-90 minutes

Materials Needed

Engage:

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

Activity 1: Stacking Up Nutrition in Milk and Milk Substitutes

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

Activity 2: The "Milk" Debate and the Impacts of Labeling

NPR broadcast: Soy, Almond, Coconut: If It's Not From a Cow, Can You Legally Call it Milk?

Vocabulary

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?

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.⁸Soy 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.

Engage

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?

Explore and Explain