One-third fewer fractures in the higher-dairy group
At the study start, residents in both groups had similar vitamin D levels (72 nmol/L) and bone morphology. They were consuming two servings of dairy food and drink a day, where a serving was 250 mL of milk (including lactose-free milk) or 200 g of yogurt or 40 g of cheese.
Their initial daily calcium intake was 650 mg, which stayed the same in the control group, but increased to >1100 mg in the intervention group.
Their initial daily protein intake was around 59 g, which remained the same in the control group, but increased to about 72 grams (1.1 g/kg body weight) in the intervention group.
At 2 years, the 1.5 servings/day increase in dairy intake in the control versus intervention group was associated with an 11% reduction in falls (62% vs. 57%), a 33% reduction in fractures (5.2% vs. 3.7%), a 46% reduction in hip fractures (2.4% vs. 1.3%), and no difference in mortality (28% in both groups).
The intervention was also associated with a slowing in bone loss and an increase in insulinlike growth factor–1.
Four dairy servings a day “is high”
Dr. Willett said that “it is reasonable for seniors to take one or two servings of dairy per day, but four servings per day, as in this study, is probably not necessary.”
Moreover, “dairy production has a major impact on greenhouse gas emissions, and even two servings per day would not be environmentally sustainable if everyone were to consume this amount,” he observed.
“Because the world is facing an existential threat from climate change, general advice to consume high amounts of dairy products would be irresponsible as we can get all essential nutrients from other sources,” he added. “That said, modest amounts of dairy foods, such as one to two servings per day could be reasonable. There is some suggestive evidence that dairy in the form of yogurt may have particular benefits.”
The study was funded by Melbourne University and various dietary councils. Dr. Iuliano reported receiving lecture fees from Abbott. Dr. Rosen and Dr. Willett reported no relevant financial relationships.
A version of this article originally appeared on Medscape.com.