I started drinking green smoothies based on the recommendations i saw over here (+ reading Dr Greger). However, my wife claims that drinking one in proximity to my morning coffee minimizes the nutritional benefits from the smoothie.
I don't see any mention of that in Dr Greger book or website, and when i google "coffee green smoothies" or any other related term, well... i get recipes for green smoothies with coffee
The only thing I can think of is that the coffee is acidic in PH. One of the benefits of a green smoothie is that it's alkaline, so the coffee would counteract that to some extent.
Blocking the absorption of iron isn't that bad for a male. Men are rarely low on iron because we don't bleed once a month. Too much iron on the other hand causes oxidative stress. Also iron from veggies are poorly absorbed anyway unlike from animal sources.
I've read some papers that coffee helps lengthen telomeres. Telomeres is what keeps cell replication from straying off course and it shortens every time a cell divides. Once the telomeres are too short, cell replication stops and the cell dies - it's one of the many factors in aging.
So the question is: Can the coffee to iron absorption be compensated for later in the day or do you want longer telomeres to help stave off aging by drinking coffee?
Coffee is a diuretic, and I imagine at least some of the vitamins and minerals (water soluble ones at least) from your smoothie are being literally flushed down the toilet afterwards (through urination). I'm not sure if that's what she was thinking about, but it's what I'd be thinking about.
The habitual coffee drinker won't have a lot of problems with mineral or vitamin absorption. I don't stop coffee in my patients nor tell them to adjust their routine adjacent to their smoothies etc. If you're a green smoothie drinker you're likely the type who is getting far more than your fair share of the goodies so we don't worry about ya.
If you have Crohn's or UC or had terminal ileum resection or have some other autoimmune disease or drink more than 4-5 cups a day or are blatant end-stage vegan then a discussion of adjusting your coffee might be in order.
