Besides humans (and companion animals who are fed by humans), no species drinks milk beyond infancy or drinks the milk of another species. Cow’s milk is suited to the nutritional needs of calves, who have four stomachs and gain hundreds of pounds in a matter of months, sometimes weighing more than 1,000 pounds before they are 2 years old.
Cow’s milk is the number one cause of food allergies among infants and children, according to the American Gastroenterological Association.Most people begin to produce less lactase, the enzyme that helps with the digestion of milk, when they are as young as 2 years old. This reduction can lead to lactose intolerance.(30) Millions of Americans are lactose intolerant, and an estimated 90 percent of Asian-Americans and 75 percent of Native- and African-Americans suffer from the condition, which can cause bloating, gas, cramps, vomiting, headaches, rashes, and asthma.(31) A U.K. study showed that people who suffered from irregular heartbeats, asthma, headaches, fatigue, and digestive problems “showed marked and often complete improvements in their health after cutting milk from their diets.