In health/medical writing, things sometimes follow a fashion. When the topic is new, there can be a kind of "if some is good, then a lot is even better". Over the years, its often turned out that "too little is bad, some is good, a lot is bad" (basic Goldilocks theory). Famously, this turned out to be true for:

1) Vitamin D

2) Folic Acid

The ironic and recurring theme is almost that "things that are good for you can be simultaneously bad for you"

1) Neutrophils-implicated in cancer metastases and heart disease, yet simultaneously help fight cancer and heart disease?

2) Cell senescence-implicated in higher inflammation, yet to some degree a cancer inhibitor.

One common thread in this may be a) Mitochondrial machinery enhancers may also abet cancer and b) Telomere lengthening may increase longevity, but enhance cancer.

My point about milk for seniors was that much of our necessary protein comes from milk, yet "too much" can be arteriosclerotic or hard on organs? Personally, I don't drink more than 1 cup of milk per day, nor exceed 1 lb/kg body wt of protein (to be safe). At age 69, I exercise 7 hrs/wk of low-impact, pull back when my body tells me to.

All in all...hurry up with those studies and clinical trials that show the upper limits!!!