Have never heard of Niagen.. My losing 15 pounds since prior 6 month visit, was very likely the reason for much lower B P. When I first got there, was 112/61- like a teenager.
Weight loss is VERY important for keeping B P down.
Food choice not nearly important as quantity, you need to eat less to keep your body mass index (BMI) under control. Get your BMI below 30, and preferably below 25 You can buy an OMRON BMI meter on ebay for about $28
Food choices are important for keeping your arteries unclogged.