Well there was, but he may not have known about it...Dr Walter Kempner down at Duke had developed his Rice Diet, and it really does control hypertension. As well as some heart and kidney disease.
FDR either didn't know of it, or if he did know about it he didn't want to use it because it is a very restrictive diet.
Still a useful diet if you're dealing with these issues and have allergies to the usual drug treatment.
https://nutritionfacts.org/video/kempner-rice-diet-whipping-us-into-shape/
FDR smoked like a dragon and drank like a fish up to the end.
He'd start with mixing martinis before dinner and continue until after 10pm.