Heart attack survivors with the healthiest diets had death rates 23% to 34% lower over an average 16 years

Advice about food after a heart attack is mostly borrowed. It comes from studies of people who have never had one, on the assumption that what protects a healthy heart will also protect a damaged one. A study published in Circulation in August looks at that assumption directly, in nearly 6,000 survivors followed for an average of almost 16 years.

Those with the best diets had the lowest death rates, by a wide margin, and it made little difference which definition of eating well was used. The result fits what trials and other cohorts have found. It is also the kind of result most open to the influence of everything else that healthy eaters do.

Why diet after a heart attack has been hard to study

The authors start from the gap. Current dietary guidelines are largely based on evidence from the general population, and data on dietary patterns and survival after myocardial infarction (MI) remain limited. Myocardial infarction means a heart attack.

A survivor is not in the same position as someone trying to prevent a first event. Most are taking several drugs that lower cholesterol and blood pressure, which could leave less for food to do. Their time horizon is shorter and their risk is far higher.

The best evidence would come from trials that assign survivors to different diets, and a few exist. Their limits are practical. People cannot be blinded to what they eat, and few will stay on an assigned diet for a decade. So most of what is known comes from observing what people choose to eat and what happens to them.

Modern guidance also thinks in whole diets. The American Heart Association’s statement on the subject emphasizes the importance of dietary patterns beyond individual foods or nutrients. Its list is familiar: plenty of fruit and vegetables, whole grains, protein mostly from plants and fish, liquid plant oils, and little processed food, added sugar or salt.

How the study scored the diets of heart attack survivors

The data come from two of the longest-running health studies in the United States, both made up of health workers who fill in detailed questionnaires every few years. The research team, with Le Ma as first author, picked out the participants who had a heart attack along the way and lived. That gave 3,277 women from the Nurses’ Health Study and 2,618 men from the Health Professionals Follow-Up Study who survived a nonfatal MI. The mean age at MI diagnosis was 68.2.

Diet was assessed using validated food frequency questionnaires and updated every 2 to 4 years. Because the questionnaires had been running for decades, the researchers knew what people ate before the heart attack as well as after.

Each person’s diet after the heart attack was then scored eight ways. Five of the scores measure how closely a diet follows a named pattern:

Score	What it rewards
Alternate Healthy Eating Index	Foods and nutrients linked to lower risk of chronic disease
Healthy Eating Index-2015	Agreement with the US government’s dietary guidelines
Alternate Mediterranean Diet Score	Vegetables, fruit, nuts, whole grains, legumes, fish and olive oil
Dietary Approaches to Stop Hypertension	The diet designed to lower blood pressure
Healthful Plant-Based Diet Index	Healthy plant foods over animal foods and refined starches

The other three were built differently, from the foods that track with blood markers of inflammation and of insulin, and were reversed so that a higher score is better.

The main outcome was total mortality, with cardiovascular disease mortality and recurrent nonfatal MI as secondary outcomes.

Lower death rates with every healthy diet score

Heart attack survivors in their late sixties are at high risk, and the follow-up was long. During 15.7 years of follow-up after MI, 3858 deaths (65.4%) were documented, about four in ten of them from cardiovascular disease.

Against that background, the differences by diet were plain. On every one of the eight measures, higher post-MI dietary scores were consistently associated with lower total mortality.

Score	Death rate, top fifth compared with bottom fifth	Plausible range
Alternate Mediterranean Diet Score	34% lower	25% to 41%
Alternate Healthy Eating Index	33% lower	26% to 40%
Insulin-related food score (hyperinsulinemia)	29% lower	20% to 36%
Healthy Eating Index-2015	27% lower	19% to 35%
Insulin-related food score (insulin resistance)	27% lower	17% to 35%
Healthful Plant-Based Diet Index	26% lower	17% to 34%
Dietary Approaches to Stop Hypertension	23% lower	14% to 31%
Inflammation-related food score	23% lower	14% to 32%

The spread between the scores is smaller than the uncertainty around each one. The study gives no grounds for ranking a Mediterranean diet above a plant-based one. That is unsurprising, because the scores overlap heavily. A person who eats many vegetables, whole grains, nuts and fish, and little processed meat and sugar, will do well on nearly all of them.

The pattern extended beyond deaths from any cause. Similar inverse associations were observed for cardiovascular disease mortality and recurrent nonfatal MI, inverse meaning that as the score went up the risk went down.

These are relative differences between the best and worst fifths. They say how much lower the rate of death was in one group than in the other, and they do not translate directly into years of life gained.

Changing diet after a heart attack

The question most survivors would ask is whether changing matters, and the study has something to say because it had diet records from both sides of the event.

People whose score on the Alternate Healthy Eating Index improved from before the heart attack to after had a death rate 14% lower, with a plausible range of 3% to 24%. Movement in the other direction went with worse outcomes. In the authors’ words, decreased adherence to most patterns was associated with higher mortality.

The same research group reported something similar in 2013, in a smaller analysis that used one diet score. Among 4,098 survivors it found a death rate 24% lower in the top fifth for diet quality after the heart attack, and 29% lower among those who had improved the most. That analysis divided people differently from the new one, so its 29% and the new 14% are not directly comparable. It adjusted for medication use, medical history, and lifestyle risk factors. Its conclusion was that survivors who consume a higher-quality diet, which has been associated with a lower risk of coronary heart disease in primary prevention, have lower subsequent all-cause mortality. Primary prevention means preventing a first event, and secondary prevention means preventing another. The 2013 analysis recorded 1,133 deaths. The new study has more participants, a longer follow-up and more than three times as many deaths, and extends the result to seven more definitions of a good diet.

What trials and other cohorts say about diet after a heart attack

An independent cohort in the Netherlands has found an association in the same direction, and a smaller one. Researchers there followed 4,365 heart attack patients and scored their diets against Dutch guidelines for people with cardiovascular disease. During a median follow-up of 14.6 years, cardiovascular deaths were 22% less frequent among patients with high-quality diets than among those with low-quality diets, and deaths from any cause 16% less frequent.

That study also offered an absolute figure, which it called the number needed to eat. Over ten years, it estimated, 77 patients would have to eat a high-quality diet instead of a low-quality one for there to be one fewer death from any cause, and 13 for one fewer cardiovascular death.

Randomized evidence exists for one pattern. The Lyon Diet Heart Study was, in its authors’ description, a randomized secondary prevention trial aimed at testing whether a Mediterranean-type diet may reduce the rate of recurrence after a first myocardial infarction. After an average of 46 months, cardiac deaths and nonfatal heart attacks numbered 14 in the Mediterranean diet group and 44 in the comparison group.

A more recent Spanish trial assigned 1,002 patients with coronary heart disease to a Mediterranean diet or a low-fat diet for seven years. Major cardiovascular events occurred in 87 of the 502 people in the Mediterranean group and 111 of the 500 in the low-fat group. The authors concluded that in secondary prevention, the Mediterranean diet was superior to the low-fat diet in preventing major cardiovascular events. The difference appeared in men, who made up most of the trial, and not in the 175 women.

So a randomized signal exists for the Mediterranean pattern specifically, and observational support now exists for healthy eating defined in many ways.

Why better diets may not fully explain the lower death rates

People who eat well differ. They are more likely to exercise, less likely to smoke, and more likely to take their medicines and keep appointments. No statistical adjustment captures all of that, and some part of a quarter-to-a-third difference in death rates could be explained this way.

Illness changes eating. A survivor whose heart is failing may lose appetite, cook less and eat worse. In that case poor diet would be a sign of poor health as much as a cause of it.

The participants were health professionals. Nurses and other health professionals who volunteer for decades of questionnaires are not typical. Their diets, incomes and access to care differ from those of most heart attack survivors.

Diet was self-reported. Food questionnaires are imprecise, though repeating them every few years reduces the error.

Eight scores are not eight confirmations. They were calculated from the same questionnaires in the same people, and reward much the same foods.

The era. The cohorts began decades ago, and treatment after a heart attack has changed over that time.

The authors’ own conclusion is carefully worded. Among survivors, adherence to post-MI dietary patterns emphasizing higher diet quality was associated with better long-term survival.

What a person eats after a heart attack is one part of their care, alongside medicines and rehabilitation, which is assessed by their doctor.

Among 5,895 American health professionals followed for an average of 15.7 years after a heart attack, those with the healthiest diets on any of eight scores had death rates 23% to 34% lower than those with the least healthy, in an observational study that could not fully separate diet from the other habits of people who eat well.