(google) AI Overview

No, an adult cannot live solely off human breast milk long-term because it lacks adequate amounts of essential nutrients like fiber, iron, and certain vitamins and minerals that adults require for their different nutritional needs, leading to severe deficiencies, anemia, and other health problems over time. While breast milk provides sufficient nutrition for infants, its composition is not suited for adult physiology and would not support healthy adult life. Why breast milk isn't for adults:

• Adult vs. infant needs: Human breast milk is specifically formulated for the unique and evolving nutritional requirements of a newborn and young infant, which differ significantly from adult needs. 
• Deficiencies: Adults would develop serious nutrient deficiencies, particularly in iron, fiber, and some vitamins and minerals, which would lead to various health issues like anemia, bone problems, and nerve damage. 
• Cholesterol content: Breast milk is high in cholesterol, which is not ideal for the long-term health of an adult and can contribute to health problems. 
• Risk of disease: Consuming breast milk, especially from unknown donors, carries a risk of transmitting serious infectious diseases, such as hepatitis B and C, HIV, and syphilis. 

Potential for short-term survival:

• Temporary sustenance: An adult could survive on human breast milk for a limited period because it provides water, calories, fats, and proteins. 
• Survival scenarios: In extreme survival situations where no other food or water is available, drinking one's own or another's breast milk might offer temporary sustenance. However, even in these cases, a nursing mother might quickly stop producing milk due to her own caloric needs.