A Segula is like turning your radio to get better reception. It doesn’t help if nothing is being broadcast or if the plug is out.
Eating healthy helps you to be healthy. It doesn’t mean Hashem can’t do what He wants. Many people with healthy lifestyles died of heart attacks and strokes. A Segula is not more foolproof. You try it. If it helped, good; if not, you got to say Perek Shira. Don’t think there is any trick out there that can force Hashem into doing things your way.