Milk

glass of milk against dark blue background

Milk is the liquid produced by the mammary glands of mammals, including humans. Breast milk is the preferred food for infants, as it is well-tolerated while their digestive tracts develop and mature. Dairy milk may be introduced at later ages if tolerated well. Although dairy milk may come from any mammal, cows, goats, buffalo, and sheep are common producers. This section will focus on dairy milk from cows, and briefly discuss non-dairy plant milk alternatives.

Whole cow’s milk contains about 87% water. The remaining 13% contains protein, fat, carbohydrates, vitamins, and minerals. Processing techniques remove fat to produce lower fat varieties: “reduced fat” contains 2% milkfat, “lowfat” contains 1% milkfat, and “nonfat” or “skim” has virtually no milkfat. Cows are often pregnant while they are milked, so dairy milk contains hormones like insulin-like growth factor-1 (IGF-1), estrogens, and progestins. Some cows are given additional hormones to increase milk production.

Rich In

Milk and Health

The Dietary Guidelines for Americans recommends including three 8-ounce servings of milk daily (or equal portions of other dairy foods like cheese or yogurt), which is justified to increase calcium intake and reduce the risk of osteoporosis and fractures. Marketing efforts such as the iconic “Got Milk?” campaign with celebrities donning milk mustaches spread this message as well. However, research has not shown a consistent benefit on bone health with high intakes of milk, and furthermore has suggested potential harm with certain conditions like prostate cancer. [1]

Research on milk often produces contrary findings. Some reasons may be the wide range of different nutritional qualities in milk and how milk intake is measured, as seen in the following factors:

  • The amount of milk that is considered a “high” or “low” intake can vary among populations studied. For example, people from Japan tend to drink about less than half of the milk consumed in Western countries [2]
  • Are different classifications of milk included, or just one type? Whole, reduced-fat, fat-free, or organic?
  • The composition of milk (fat, protein from varying amino acids) may differ depending on the breed and feed of the cows.
  • Are other factors in the diet considered, such as if the participants are eating plenty of fruits and vegetables, or large amounts of processed meat or refined carbohydrates, which can confound the true health effects of milk?
  • Different forms of dairy foods, such as cheese, or yogurt, may have health effects different than milk.

Bottom line: The health benefits of milk appear to be stronger for fermented types like yogurt, which play a role in the gut microbiome. Milk possesses several individual nutrients that can affect blood pressure and bone health, but some of their health-promoting effects may be weakened by whole milk’s high saturated fat content. Although popular media articles have speculated that whole milk is not less healthful than skim milk, research has not supported this statement in regards to diabetes and heart disease, and a high intake of any type of milk can lead to weight gain due to the extra calories.

For Your Health and the Planet’s Health

icon of a globe with a fork and spoon on the sides of itThe production of dairy foods places considerable demand on land, water, and other natural resources, and dairy-producing ruminant animals like cattle, sheep, and goats generate methane—a powerful greenhouse gas. In identifying a dietary pattern both healthy for people and sustainable for the planet, the “planetary health diet” sets the target for dairy foods at 250 grams per day (with a range of 0 to 500 grams per day), which is about one (8-ounce) cup of milk.

Purchase

Milk is often sold in cartons or opaque containers because too much exposure to light can cause a loss of vitamin A and B2. Choose a carton with the latest sell-by or use-by date (indicating it is the freshest). Most milk sold in supermarkets is pasteurized and homogenized, processing techniques that use heat to kill most of the bacteria present and break down fat molecules so that texture of milk remains smooth and creamy.

What about plant-based milk?

The FDA defines “milk” as the “lacteal secretion obtained from one or more healthy milk-producing animals, e.g., cows, goats, sheep, and water buffalo…” Because of the rise in popularity of plant-based non-dairy milks, the FDA has initiated plans to enforce a federal standard of identity defining milk that would exclude food products extracted from plants.

Plant-based milks contain no lactose so may be better tolerated than dairy milk in some people. Also, plant-based milk has no cholesterol, and most have little saturated fat. However the nutritional content varies widely, so be sure to read the food label to ensure you are getting the desired nutrients. This chart compares dairy milks to a sample of plant-based milks. As you will see, nutrients vary across types of plant-based milks, as well as among different brands selling similar options. Specific brands may contain more or less of the nutrients depending on if products are fortified, or if added flavors or sweeteners are included. Generally, plant-milks labeled “original” will include added sugars, so look for unsweetened options and be sure to check the Nutrition Facts label and ingredients list so you know what you’re buying.

Type of Milk
[all entries for 1 cup
(8 fluid oz/240 mL)]
Cal Prot.
(g)
Sugar (g) Fat (g) Calc. (mg) Pot.
(mg)
Fiber (mg)
Natural/
Added
Sat. Mono. Poly.
Cow Whole milk (3.5% fat) 149 7.5 12/0 4.5 2 0.5 276 322 0
Low fat milk (1% fat) 102 8 12.5/0 1.5 0.7 0.1 305 366 0
Soy Plain 80 7 1/0 0.5 1 2.5 300 350 2
Sweetened 110 8 1/5 0.5 1 2.5 450 380 2
Sweetened 140 10 3/7 0.5 N/A N/A 276 512 N/A
Almond Plain 35 1 0/0 0 N/A N/A 430 35 1
Sweetened 60 1 0/5 0 N/A N/A 429 40 1
Sweetened 60 1 0/7 0 1.5 0.5 450 170 1
Cashew Plain 50 1 0/0 0.5 N/A N/A 44 N/A N/A
Sweetened 80 1 1/5 0.5 N/A N/A 44 N/A N/A
Sweetened 130 4 1/1 1.5 N/A N/A 15 150 0
Coconut Plain 45 0 0/0 3.5 N/A N/A 130 40 1
Sweetened 70 0 0/7 4 N/A N/A 130 40 1
Sweetened 70 0 0/5 4 N/A N/A 460 170 0
Rice Plain 70 0 <1/0 0 1.5 0.5 325 N/A 0
Sweetened 120 1 <1/10 0 1.5 0.5 26 N/A 0
Hemp Plain 60 3 0/0 N/A 0.5 3.5 257 100 N/A
Sweetened 140 4 0/12 1 0.5 4 263 145 N/A
Sweetened 100 2 0/6 0.5 1 4.5 390 N/A 0
Oat Plain 60 1 0/0 0 N/A N/A 460 170 1
Sweetened 80 2 0/4* 0 N/A N/A 460 190 1
Sweetened 120 3 0/7* 0.5 N/A N/A 350 390 2

*Some sugars are created in the processing of oats to make oat milk, which are listed as “added sugars” even if no other sweeteners are added.

Storage

Milk requires refrigeration at a temperature below 40 F. If it has been stored at room temperature for two hours or longer, it is recommended to discard it. Although pasteurization kills much of the bacteria in milk, any remaining bacteria can grow quickly in milk at room temperature or warmer. Once milk is opened, it will last about 3-5 days after the sell-by date on the label. Spoiled milk has a strong, sour odor and lumpy texture caused by excess bacteria producing lactic acid, which curdles the protein in milk and produces off odors.

Store milk towards the rear of the refrigerator rather than the front or side shelf door, where the temperature varies the most. Don’t forget to close the carton or recap the bottle to prevent the milk from absorbing the odors and flavors of other foods in the refrigerator.

Lactose-free milk undergoes pasteurization and the addition of an enzyme lactase, which breaks down the milk sugar lactose, so it generally lasts longer than regular milk. If refrigerated properly, lactose-free milk can last about 7 days after the sell-by date once it is opened.

Serve

Milk is not just for drinking by the glass or splashing onto cold cereal. Adding milk to foods can boost one’s intake of calcium, vitamin D, protein, and other nutrients.

  • Blend 1 cup of milk, 1/2 cup of fresh or frozen berries, and 1 small banana for an easy breakfast drink or snack.
  • Overnight oats. In a mason jar (you can also reuse a clean jelly or salsa jar), add 1 cup of milk, 1/2 cup of rolled oats, 1 tablespoon chia seeds, 3 tablespoons of chopped nuts, ½ sliced banana, and ¼ cup fresh or frozen berries. Secure the lid and shake the jar well until all the ingredients are mixed. Refrigerate overnight.
  • Hot oatmeal. Cook old-fashioned rolled oats in milk (the ratio is generally ½ cup oats to 1 cup milk).

Did You Know?

Several other animals produce milk including sheep, goat, and yaks. These types of milk are more popular in European, Middle Eastern, and Asian countries than in the U.S. Sheep’s milk can be made into various cheeses like feta and ricotta, and goat’s milk produces a popular cheese called goat cheese or chevre.

How do they compare nutritionally? Sheep, goat, and yak milks contain about the same if not more calcium than cow’s milk. The amount of protein and carbohydrate are about the same. They all contain some lactose but less than found in cow’s milk, so they may be easier to digest for people with lactose sensitivity.

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