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.
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, “low-fat” 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.
Source of
· Calcium
· Protein
· Vitamin B2 (riboflavin)
· Vitamin B12
· Potassium
· Phosphorus
· Vitamin A and Vitamin D (added during processing)
Milk and Health
The Dietary Guidelines 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.
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
Different forms of dairy foods, such as cheese, or yogurt, may have health effects different than milk.
Bottom line: The health benefits of dairy foods 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 regard 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
The 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.
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.
