Relax guys, no Dr would suggest a meat free diet is necessary - all things in moderation is the key - and that includes virtually all substances we take in.
Ok, as medic I'll take a diabolical liberty here and chime in with a few suggestions.
Keeping the weight as close to ideal as possible, not smoking, (at all, I'm afraid), and not drinking to excess, ( = only 2-3 drinks per day really), are key prevention measures. Having regular health checks also wise. Then, as much as is feasible, try to plan for a worst case scenario, so hopefully, rather like carrying an EPIRB but hoping you won't have to use it, you won't have to do it.
For example, husband or wife, skipper or first mate, (and in no particular order), has a heart attack - or some other disabling medical misadventure at sea - what to do?
Well if heart attack/angina is suspected, giving a couple of soluble aspirin immediately is never going to hurt, as it does thin the blood and help maintain blood flow to tissue if it is being starved of blood and lessen further clot extension, as long as they are not allergic to it - worth checking.
Then see to keeping them fairly flat and comfortable while you summon help, which also could justify setting off your EPIRB if you could not raise someone on the radio, and depending on the severity of the emergency and how far from help you are..? If possible, as when on land, getting the rescue people to you is often better and quicker than you trying to get to them.
Defibrillators are not really feasible to carry unless one has a condition which justifies the expense and being trained to use it. Most in that category would have an implanted automatic defibrillator anyway.
The next most important question is are you BOTH capable of getting the boat home of to safe haven, just in case help can't reach you? So often the SO, (2iC) is a wife or female partner who has never mastered that function, being content to be driven and just do a bit of line-handling at the dock. Maybe time to do some role-swapping drills..?
Finally, CPR. Good news here. (Well good insofar as there can be anything good about having to do it).
There has been a recent breakthrough in the approach to carrying out CPR which makes it a lot easier to do, especially if alone, and a lot less distasteful if to a stranger. It is now official that it is no longer considered necessary to go digging fingers into the mouth to try and drag out stuff, unless you know they had something lodged there, because we now know if good and adequate compressions of the chest are carried out, not only will any stuff be expelled, but more importantly, the compression of the chest, because it is springy, drags in and forces out enough air to be adequate without trying to blow air in. So, amazing as this may sound, here in Australia anyway, and I understand this is now international advice, mouth to mouth breathing is out. Is that a huge sighs of relief I hear? Yes, and I agree. There is no way I would ever place my mouth to that of a stranger and do that. Fortunately I always had an ambu-bag when I needed it, but I always suspected breathing air in was superfluous from my anaesthetic days, when the best way to check the tube was in the right place was to give a couple of quite gentle downward pushes on the subject's chest, and felt the puff of air out the end of the E-T tube before we connected it up to the ventilator.
How to give good compressions...? Well, to quote the intensive care specialist who took the refresher course I was at when we were advised of this latest development, "make good and firm downward compressions of about 5cm excursions, over the middle of the chest - not the stomach - between the breasts is best, and do it to the rhythm of the BG's song "Stayin' Alive".
Good and easy to remember. It's quite fast, (~ 2/second), so you can't do it that long. Everyone knows that song I think. If not Google it. Best of luck, and hope you never have to...I still do...
Prevention and avoidance is better... have that checkup...