I have a link you could check out.
https://www.healthline.com/nutrition/heart-healthy-foods#TOC_TITLE_HDR_13

I have been told that a small piece of dark chocolate a day is good for the heart.

Mediterranean diet seems to be the one. Lots of vegetables, olive oil, sardines…

Vegetables. Low fat. Legumes.

He should see a registered dietitian.

^^^ Doctor speaking ^^^

Anyway @KRD sorry about that diversion. Not sure what brought that on. Like I said a registered dietitian is the best person to talk to about heart healthy diets.

My heart healthy dinner tonight was grilled turkey breast with grilled asparagus and grilled broccoli.

My cardiologist had me go through a “course” on heart healthy eating as part of a cardiac rehab program in Berkeley CA. For the most part, it was not anything new, but I did learn about some “healthy fats” that are not at all good for heart patients, like coconut oil

Coconut oil is a current trendy thing that for 30 years I have considered a bad oil along with palm oil. Coconut oil is extremely high in saturated fat, palm oil not quite as bad, but much worse than some others.

Just read the labels or look up the nutrition.

Heart conditions can be for many reasons. We don’t really know what the condition is for the OP’s grandpa. He could have damage to the heart not related to cholesterol and fats. I suggested low cholesterol and low fat foods myself, but if his arteries are clear and cholesterol is low and his heart damage is unrelated to those things, maybe it’s not so urgent he be extremely strict, except to say good overall health is always better

Most primary docs will give you a diet plan, I’d ask for one. From everything I’ve read, less red meat, more fish, beans and grains. Limited sugar.

Just go ahead and aim for lean meats, green vegetables, and if you must use oil make it olive or peanut. Add some grains like rice and barley. Almonds are a good snack. Fruits are generally good too. A few eggs a week are fine. I don’t know if sugar is bad for heart health but I eliminated it to reduce inflammation. There are plenty of good sweet treats available that have no sugar content.

People with reasonably good health can safely experiment with lots of different diets like Flexitarian, DASH, Keto, or the Mediterranean diet already mentioned.

But for anyone who’s been diagnosed with a serious cardiac condition, your probably better off taking advice from @Caravanfan.

See a qualified dietician.

Keto diet is mostly bunk. You will lose weight, but it’s not heart healthy. DASH is good for hypertension but is almost unpalatable. There was some inital data that showed Mediterranean diet was good but that has been mostly retracted. I’ve never heard of flexitarian before right now but in a quick google it seems fine.

Basically the best diet (as much as I hate to paraphrase Michael Pollan because he drives me a little nuts) is to don’t eat too much, and eat mostly plants, and don’t eat too much processed food.

But I will add never, ever feel guilty about eating something you enjoy.

As stated in Relax and Enjoy Your Food, “What you eat today doesn’t matter. What you eat this month does.”

^^I don’t know, it seems like the same difference. A day becomes a week becomes a month and then becomes a year. The only way I maintain myself at a lower weight and/or reasonable cholesterol is to be good 99% of the time, but I have crappy genes.

Ice cream sundae today = not a big deal. Ice cream sundae every day for a month = problem.

@RocketGuy I just mean people who don’t control themselves well cheat more than once a month. I’ve become one of those people in the last 20 years.

Nuts.

I echo @Caravanfan‘s echo of Michael Pollan. Can’t go wrong with that.

“Eat food, not too much, mostly plants”