Milk consumption has diminished about 40 percent since 1975. In 2016, research was published that reviewed the majority of research on dairy milk. But how does food that used to be universally considered healthy become questioned by so many?

“Milk is an incredible source of protein, calcium, vitamin D, which are ‘nutrients of concern’ in the U.S. population,” meaning that many people don’t get enough, says Vasanti Malik, PhD, a research scientist in the department of nutrition at Harvard T.H. Chan School of Public Health. “It also contains magnesium, along with other minerals and nutrients.”

“If you don’t consume dairy, it’s really hard to get enough calcium,” which is crucial for strong bones, says Ali Webster, PhD, RD, Associate Director of Nutrition Communications for the International Food Information Council Foundation. The vitamin D and potassium in milk are also important for bone health.

The advantages of milk go beyond general health. Milk is one of the best muscle-building foods given its composition of protein. In fact, it’s the basis of both whey protein and casein protein. If you’re drinking either one of those protein shakes, each of those powders started as milk.

In adults, intake of dairy products was associated with a neutral or reduced risk of type 2 diabetes and a reduced risk of cardiovascular disease, particularly stroke, and was shown to improve body composition and facilitate weight loss during energy restriction. The evidence suggested a beneficial effect of milk and dairy intake on bone mineral density but no association with the risk of bone fracture. Among cancers, milk and dairy intake was inversely associated with colorectal cancer, bladder cancer, gastric cancer, and breast cancer, and not associated with risk of pancreatic cancer, ovarian cancer, or lung cancer, while the evidence for prostate cancer risk was inconsistent.

That doesn’t mean you need milk, but it does mean there are many benefits if you decide to drink it. Cow’s milk undeniably packed with many vitamins and minerals your body wants. You can’t rely solely on milk to fight osteoporosis. You also need magnesium (milk has some but isn’t a great source) and vitamin K (found in leafy greens, fish, meat, and eggs)—but it does help you check off a lot of these boxes at once.

A cup of spinach, for instance, has 350 mg calcium (slightly more than the 300 mg found in a cup of milk), and also provides fiber and folate. A 6-oz can of salmon with bones provides 380 mg of calcium, plus heart-healthy omega-3 fatty acids.