On a recent evening, I fixed my 87-year-old mom a glass of freshly blended broccoli, spinach and apple juice. Good for the heart; scrubs the blood clean. I was sure she’d like it, if only for the health benefits. To my surprise, she frowned at the taste and asked for a bowl of ice cream.

What was a concerned son to do?

I’ve spent the past few days with my parents at their home in Shreveport, La., mostly exploring ways to help meet their changing health needs. Some elder-care experts say that when aging parents stop acting in their own best interest, the grown children must “reverse roles” and simply make them do the right thing.

Good luck with that, fellow baby boomers.

“You think I should get this?” asked Dad, holding up a brochure for the 2014 Chevrolet Impala. His 89th birthday is next month. “Do I give myself one last spark?” he continued. “Or do I resign myself to the fact that I will never have anything more than what I have now?”

What was I supposed to say? No, Dad, no more for you?

I feel like a double agent during these visits — disguised as a son but operating as an inspector on assignment for my two younger sisters. Make sure to check the attic for wasps, they instructed me. And lay down a few mouse traps. Both sisters thought they had heard tiny rustlings in the night during their last visits.

“Dad,” I said, “your daughters think you might have mice.” I figured that putting it on the girls might stir his protective instincts.

Instead, he replied incredulously, “I just paid a pest control company $1,500.” Turned out that “just paid” was three years ago. And it was mostly for termite control.

I raised the ante by suggesting that his daughters might be reluctant to visit a house that has rustlings in the night. Sure enough, his resistance began to wane. “Well, I guess something could have slipped in,” he conceded.

Both of my parents were born in the rural South and grew up during the Depression. Along with their marriage vows was a pledge to never go broke. They have kept both promises now for 63 years. Trained as teachers, they worked at the same high school for more than 30 years and then started a printing and photography business.

They earned enough to build a house, pay off the mortgage, send three kids to college and save enough to keep themselves relatively secure in old age.

I couldn’t “reverse roles” with them if my life depended on it.

But according to a report released in January by the Pew Research Center, that’s what many baby boomers do. Among adults with at least one parent who is 65 or older, 30 percent said their parent or parents needed help to handle their affairs or care for themselves. Half of adults 60 or older with a living parent said the parent needs help with day-to-day living.

My parents aren’t there yet. But there have been changes.

A year ago, Mom was able to swim up to a mile every day. Then she caught pneumonia, and the lack of exercise caused her osteoarthritis to worsen. She had to give up swimming and eventually stop driving, too.

“I’m doing just fine,” Mom says whenever I call. Only during my visits can I see the melancholy in her eyes.

Dad is more outspoken about his concerns.

“Some children are devoted to their parents and will happily take them in when they get too old to take care of themselves,” he said. “But others will think nothing of putting their parents in a nursing home, and some of those places are just awful. They even make you sign over your house or your bank account.”

Two of us grown children live in the Washington area; one lives in Houston. Our parents have made it clear that they have no intention of moving out of their house. So everybody just keeps watch. A day at a time.

“I know you all are very busy and have lives of your own,” Dad told me.

To cheer up my parents, I recalled the many summers I came home for the annual “bloodwash.” Nine days spent on Mom’s “fat farm,” as she called it, eating nothing but raw fruits and vegetables, drinking a gallon of freshly blended juices and declaring just how good it all tasted.

Offering Mom that glass of broccoli, spinach and apple juice during this visit was meant to be a toast to the good old days. But she wanted ice cream.

“Not until you finish your veggie juice,” the concerned son insisted.

Mom smiled at the parody of herself telling me the same thing more than half a century ago. Then she held out her hand for me to hold. And when we finally let go, I fixed her that bowl of ice cream and made one for myself.

To read previous columns, go to washingtonpost.com/milloy.