Do people over 85 absorb multivitamin and mineral supplements well?

Honestly, it depends on to whom it is you are speaking. We had a family doctor (died suddenly, ten years after retiring, from a heart attack), a gem of a human being, who told my wife that our community, which is a retirement destination on the west coast of Canada, had some of the most expensive sewage in the world. His inference was that it was because people were plying themselves liberally with sometimes exotic and expensive supplements which their bodies either couldn't use or declined to use, and it went into their toilets and down the drains.
I have read that our aging bodies don't absorb nutrients as well as they did years earlier. That may be true, in which case some modest supplementation couldn't hurt, provided the money isn't wasted on expensive urine. But I feel that eating properly, meaning not too much, and eating nutritionally (very little package goods of any kind, whether fancy rice pilafs with flavouring packets included, or tins with their plastic linings and things added to the 'food' to make you want to ingest even more of it) should keep even feeble people from harm. Lots of vegetables, some fruit (careful, fructose is hard on the body!), especially blackberries and blueberries, and eating fresh flesh for protein and the full range of amino acids and such is the way to go.
However, that's just me. So far, so good. I do run a bit shy on potassium, apparently, so I add some of that shakeable powder (potassium salt available at your grocers) into my coffee each afternoon (I like my coffee less bitter, and salt helps). I have to take a statin, to my regret and annoyance, and the science says to supplement with coenzyme Q10, or CoQ10. I place one under-the-tongue B12 there about once a week...just 'cuz. But I take no other vitamins or supplements...oh, forgot the magnesium malate, 200 mg, that I take twice a week to help my heart stay in rhythm. But that's it. No daily, nothing prescribed, no anemia...nothing like that.

[Edit. added] Okay, I'm undoing my own position on this a bit, but I do also take D3. Accordingly to a lot of personal reasearch, the human body that lives above the 30th parallel gets about half of what it needs, and the further north you live, the worse it gets. And that starts in September for us up north because the sun gets low, the days shorter, and we're not out in shorts or lying by the pool. So, every second or third day I give myself and my wife two 2500 IU tablets. D3 is critical for body immune and transport functions. Most of us get much less than we could use if our bodies could speak...which they will in an unpleasant way if you short yourself.

Finally, your primary care provider is the person to discuss this with. They know you best professionally and scientifically.

Thank you for your comments. I have to smile though about your comment about the knowledge of primary care providers. They have limited knowledge about nutrition and vitamin supplements and other things as well. Research on google provided by AI is also a waste of time. I listen to my body tell me what it wants. I have lived a healthy life style all of my 86 years, no packaged foods, only good stuff, consumed lots of vitamins and red wine. Now I find myself getting tired more often and my energy level is not the same. It is hard for an A personality to accept. I know I have autoimmune disorders that doctors know very little about. I deal with it on my own terms. I am healthy, no morbidity, annual blood tests are good. Except for a daily low dose aspirin, I take no meds. I'll keep up with my multi vitamins and minerals even if my organs don't get the full benefit.
Wishing you the best of life.

I can't disagree with you, botswana. I had to have multiple diagnostics to see if I have ischemia before an electrophysiologist would agree to treat my heart arrhythmia. None of them showed ischemia, nor did they show atherosclerosis. I even had a Doppler ultrasound of my carotid arteries at my request, but they are/were clear. I still developed an arrhythmia, and it turns out that it was almost certainly due to what was ultimately diagnosed as severe sleep apnea. This in a fit man, a runner and cyclist, always healthy and engaged in many things, etc.

I went back to my cardiologist and asked him why I should be on a statin at my age with apparently clear arteries. He actually laughed and said that I most assuredly DO HAVE heart disease, it's just not the cause of my arrhythmia. So, I stay on a statin, and stay on CoQ10. They never tell you that you do not produce much, if any, of your own CoQ10 if you take a statin.

Honestly, it depends on to whom it is you are speaking. We had a family doctor (died suddenly, ten years after retiring, from a heart attack), a gem of a human being, who told my wife that our community, which is a retirement destination on the west coast of Canada, had some of the most expensive sewage in the world. His inference was that it was because people were plying themselves liberally with sometimes exotic and expensive supplements which their bodies either couldn't use or declined to use, and it went into their toilets and down the drains.
I have read that our aging bodies don't absorb nutrients as well as they did years earlier. That may be true, in which case some modest supplementation couldn't hurt, provided the money isn't wasted on expensive urine. But I feel that eating properly, meaning not too much, and eating nutritionally (very little package goods of any kind, whether fancy rice pilafs with flavouring packets included, or tins with their plastic linings and things added to the 'food' to make you want to ingest even more of it) should keep even feeble people from harm. Lots of vegetables, some fruit (careful, fructose is hard on the body!), especially blackberries and blueberries, and eating fresh flesh for protein and the full range of amino acids and such is the way to go.
However, that's just me. So far, so good. I do run a bit shy on potassium, apparently, so I add some of that shakeable powder (potassium salt available at your grocers) into my coffee each afternoon (I like my coffee less bitter, and salt helps). I have to take a statin, to my regret and annoyance, and the science says to supplement with coenzyme Q10, or CoQ10. I place one under-the-tongue B12 there about once a week...just 'cuz. But I take no other vitamins or supplements...oh, forgot the magnesium malate, 200 mg, that I take twice a week to help my heart stay in rhythm. But that's it. No daily, nothing prescribed, no anemia...nothing like that.

[Edit. added] Okay, I'm undoing my own position on this a bit, but I do also take D3. Accordingly to a lot of personal reasearch, the human body that lives above the 30th parallel gets about half of what it needs, and the further north you live, the worse it gets. And that starts in September for us up north because the sun gets low, the days shorter, and we're not out in shorts or lying by the pool. So, every second or third day I give myself and my wife two 2500 IU tablets. D3 is critical for body immune and transport functions. Most of us get much less than we could use if our bodies could speak...which they will in an unpleasant way if you short yourself.

Finally, your primary care provider is the person to discuss this with. They know you best professionally and scientifically.

Honestly, it depends on to whom it is you are speaking. We had a family doctor (died suddenly, ten years after retiring, from a heart attack), a gem of a human being, who told my wife that our community, which is a retirement destination on the west coast of Canada, had some of the most expensive sewage in the world. His inference was that it was because people were plying themselves liberally with sometimes exotic and expensive supplements which their bodies either couldn't use or declined to use, and it went into their toilets and down the drains.
I have read that our aging bodies don't absorb nutrients as well as they did years earlier. That may be true, in which case some modest supplementation couldn't hurt, provided the money isn't wasted on expensive urine. But I feel that eating properly, meaning not too much, and eating nutritionally (very little package goods of any kind, whether fancy rice pilafs with flavouring packets included, or tins with their plastic linings and things added to the 'food' to make you want to ingest even more of it) should keep even feeble people from harm. Lots of vegetables, some fruit (careful, fructose is hard on the body!), especially blackberries and blueberries, and eating fresh flesh for protein and the full range of amino acids and such is the way to go.
However, that's just me. So far, so good. I do run a bit shy on potassium, apparently, so I add some of that shakeable powder (potassium salt available at your grocers) into my coffee each afternoon (I like my coffee less bitter, and salt helps). I have to take a statin, to my regret and annoyance, and the science says to supplement with coenzyme Q10, or CoQ10. I place one under-the-tongue B12 there about once a week...just 'cuz. But I take no other vitamins or supplements...oh, forgot the magnesium malate, 200 mg, that I take twice a week to help my heart stay in rhythm. But that's it. No daily, nothing prescribed, no anemia...nothing like that.

[Edit. added] Okay, I'm undoing my own position on this a bit, but I do also take D3. Accordingly to a lot of personal reasearch, the human body that lives above the 30th parallel gets about half of what it needs, and the further north you live, the worse it gets. And that starts in September for us up north because the sun gets low, the days shorter, and we're not out in shorts or lying by the pool. So, every second or third day I give myself and my wife two 2500 IU tablets. D3 is critical for body immune and transport functions. Most of us get much less than we could use if our bodies could speak...which they will in an unpleasant way if you short yourself.

Finally, your primary care provider is the person to discuss this with. They know you best professionally and scientifically.

I noted your comment about potassium. Back in 2011 I got C-diff due to antibiotics my dentist gave me and was in the hospital. I had very low potassium. So I started to track and I just don't have enough potassium. Potassium is important for your muscles, and of course the heart is a muscle.
My Primary put me on prescription potassium and I take 10mg twice a day and I just manage to stay in range. I have read that older people tend to be lower in Potassium. I now check out the medications I am prescribed because some will raise your potassium and some will lower it. I adjust accordingly then to stay in range

I noted your comment about potassium. Back in 2011 I got C-diff due to antibiotics my dentist gave me and was in the hospital. I had very low potassium. So I started to track and I just don't have enough potassium. Potassium is important for your muscles, and of course the heart is a muscle.
My Primary put me on prescription potassium and I take 10mg twice a day and I just manage to stay in range. I have read that older people tend to be lower in Potassium. I now check out the medications I am prescribed because some will raise your potassium and some will lower it. I adjust accordingly then to stay in range

@vic83 Sorry if I sound like a know it all but c-diff is a pathogen usually acquired in hospital. But vitamins don’t cause it. I am a retired RN.