Heart health is a hotly debated topic—and rightfully so. Heart disease is the leading cause of death in the United States.

The medical community remains committed to studying heart health, attempting to provide the public with analysis and solutions to some of their most pressing concerns. How much does family history play a part in heart health? How much exercise should I get? Can I really eat all those “healthy” fats?

There isn’t a single answer. And over time, even the gold standard proposed answer can change.

Remember when eating fat was the enemy? Counterintuitive as it may seem, we now know that eating more fat might lead to weight loss,Bueno2013 which can reduce risk for a number of heart-related illnesses. This is just a singular example of how we learn, how studies change, and how advice medical professionals may give based on those learnings will also, undoubtedly, change too.

Point is, the medical community has spent centuries studying heart health. Even still, if you’re looking for an answer to the question “What makes a healthy heart?” you’ll get a library’s worth of different answers.

Let’s look at some of the most common concerns about heart health, and use scientific studies to analyze their merit.

A Portrait of Heart Disease

Heart disease is a shapeshifter manifesting itself in various forms. It’s a catch-all phrase for numerous conditions.

Over 600,000 people every year die of heart disease in the US, with coronary heart disease the most common (killing 370,000 yearly).CDC2017

In men and women, about 40% of these deaths are related to what’s called “ischemic heart disease.”WorldHeartFederation2017 This occurs when the arteries of the heart cannot deliver enough oxygen-rich blood to the heart. Conditions caused by atherosclerosis (hardening and narrowing of the arteries) include coronary heart and artery diseases, leading to heart attacks and potentially sudden death.

About 35% of heart-related deaths in men and women are caused by brain-related cerebrovascular disease.WorldHeartFederation2017 These conditions are also caused by atherosclerosis, but instead the blockage of blood vessels flowing to the brain. This can lead to a stroke, in which the brain is deprived of oxygen and parts of the brain can become permanently damaged (or even results in a permanent disability / death).

Collectively, in men and women, inflammatory, rheumatic and hypertensive heart diseases account for less than 10% of heart-related deaths.WorldHeartFederation2017

Inflammatory heart disease can be caused by various infections, viruses, bacteria or other toxic material. Essentially, this is an infection of the heart, and sometimes, its origin isn’t found. Rheumatic heart disease relates to damage to heart valves, often a complication of rheumatic fever which is usually a condition suffered most commonly in children under 15. Hypertensive heart diseases are associated with high blood pressure, in which the heart works under increased pressure, leading to problems in the arteries and muscle.

The remaining ~15% of heart disease-related deaths are caused by various conditions like congenital heart disease, cardiac arrhythmias and heart failure.WorldHeartFederation2017

Dietary Fat

For years, fat was villainized. Low-fat-this and low-fat-that became popular dietary staples in fear a diet high in fat would be the culprit of an unhealthy heart. But now we better understand only certain types of fat can be dangerous, and a diet of healthy fats can foster a healthy heart. Increased fat consumption is not always associated with cardiovascular disease.Deghan2017

There are several different kinds of dietary fats.

Saturated fats are solid at room temperature, like in butter and coconut oil. Historically, it was recommended to limit dietary intake of saturated fats because it was thought to be associated with heart disease. But emerging research illustrates increased consumption of saturated fat can have beneficial effects on blood biomarkers, like increasing healthy HDL cholesterol levels.Mente2017

Unsaturated fats are liquid at room temp, like in vegetable-based fats such as olive oil. They’re typically thought of as the healthy fats, and increased consumption of mono and polyunsaturated fats have been linked to improved blood biomarkers like lower blood triglycerides.Volek2000 When people talk about “good fats,” they’re likely referring to monounsaturated and polyunsaturated fats. These have fewer hydrogen atoms than saturated fats, and can be found in vegetables, nuts, seeds and fish.

What you want to watch out for are trans-fats. These are produced artificially when hydrogen is added to unsaturated fatty acids in order to solidify them and increase shelf life. Associations with poor health outcomes forced the FDA to remove their GRAS (generally regarded as safe) status in 2015.Fda2015

How does fat help or hurt your heart? It has to do with lowering LDL (bad) cholesterol, which can line arteries and cause atherosclerosis, a blood vessel disease that can lead to heart attacks and strokes.

One review showed that reducing saturated fats, and replacing them with polyunsaturated fats, reduces coronary heart disease events.Mozaffarian2010 But another study showed inconclusive results when analyzing the effects of saturated fat consumption on vascular function, diabetes and stroke.Micha2010

While it seems fat isn’t the devil it was once cast, it’s still important to monitor dietary fat and focus on consuming unsaturated fats.

Exercise

Just like biceps or quads, the heart is a muscle. With regular exercise, it can become stronger, better able to pump blood throughout the body.

Before getting into all the positives about exercise for the heart, there are a few considerations.

Heart problems rarely occur due to physical activity; however, cardiac arrests and heart attacks are possible, but these usually occur in those who already have some type of heart condition, especially those with congenital heart problems (meaning, they’ve had these problems since birth).

Rarely, heart problems occur as a result of physical activity. Examples of these problems include arrhythmias, sudden cardiac arrest, and heart attack. These events generally happen to people who already have heart conditions. Fitness level can also play a role.

However, the benefits of exercise for the heart seems to far outweigh the risks.

Overall physical activity, including running, weight training, and walking are associated with reduced risk of coronary heart disease (CHD).Tanasescu2002 The opposite of a healthy, active lifestyle is a sedentary one (one many people live!). A sedentary lifestyle increases risks for death from CHD, according to a meta-analysis.Berlin1990 But there’s a “Goldilocks effect” when it comes to exercise—too little exercise is bad, and too much exercise can also be bad.

While it’s inconclusive the best type of exercise to promote heart health, there isn’t anything inconclusive about the efficacy of exercise. Anywhere from 60 minutes per week to 150 minutes per week (for those who are able) is prescribed by the National Heart, Lung, and Blood Institute.NationalHeartBloodandLungInstitute2018

Family History

Many people think they may be at risk of heart disease based on their family history. It’s even one of the boxes you may check when filling out a form in a new doctor’s office.

Family history is a complex risk factor for heart disease. There are many, many genes that control how your heart works, and small changes can have important effects on the function of the heart. Start by looking at your immediate family’s health, and go outward from there. Genes are, unfortunately, inescapable. But they don’t explicitly predict your bill of future health.

Part of the reason doctor’s ask about family history is to help them understand what you may be susceptible to. That way, you can focus on specific strategies to fight against your genetic hand.

Even though there isn’t one genetic fingerprint tightly linked to heart disease, some studies do show a strong correlation between family history and coronary heart disease.Nasir2004 Some point to an especially strong relationship between heart disease and first-degree family members.PohjolaSintonen1998 Others illustrate the problems with linking family history to heart disease, especially in relation to the number of family members with heart disease and an understanding of what, specifically, that heart disease was (leading to misunderstandings about how family history impacts CHD).Nasir2004 The conclusion? This study denotes how difficult it is to showcase the connection, suggesting that family history and CHD remain largely unexplained.Hawe2003

At its core, this one is difficult to unpack.

Other Risk Factors

Numerous other risk factors exist that may lead to heart disease. Many of these are related to the conditions above, but they warrant a bit of further exploration.

Diabetes

Diabetes occurs when blood glucose (or blood sugar) levels are too high. Insulin in the hormone that helps shuttle glucose into cells for energy. Type 1 diabetics don’t make insulin (assumed to be caused by genes, or environmental factors like viruses). Type 2 diabetics don’t respond to insulin (assumed to be caused mostly by lifestyle factors and genes).

Overtime, high blood glucose can damage blood vessels and nerves that control the heart.

The National Institute of Diabetes and Digestive and Kidney Diseases claims diabetics have a higher chance of developing heart disease, and have a greater chance of having a heart attack or stroke.Buse2017 It seems diabetes increases the risk of all clinical manifestations of CHD.Kannel1985

There doesn’t seem to be much debate here. The longer you have diabetes, the higher your chances of developing heart disease,CDC2017a and those with diabetes are almost twice as likely to die from heart disease or stroke.Huo2016 But it’s not clear what to do about this risk, as intense blood sugar control doesn’t appear to reduce the risk of heart disease in diabetics.Conget2009

Blood Pressure

When most people think of blood pressure, they think of high blood pressure. This means the force of the pumping blood in arteries is higher than it should be. But how’s this relate to heart disease?

Excess strain from high blood pressure narrows and weakens coronary arteries. Often this is because of plaque in the arteries, basically a buildup of fat and cholesterol (among other things), increasing the risk for a blood clot. When an artery is blocked, blood flow is compromised, and the heart becomes starved of oxygen, resulting in a heart attack.

High blood pressure increases risks of cardiovascular disease.Vasan2001 It may also cause a stroke (on conjunction with other factors).Collins1990 More exercise and changes to diet are often prescribed to help alleviate high blood pressure.

Cholesterol

We’d need a whole article to analyze how cholesterol affects heart disease.

Cholesterol is essential to healthy cells, making hormones, making vitamin D and supporting digestion—but having too much of the “wrong” type in your blood can increase risk of heart disease. Simply speaking, cholesterol, found in dietary fats like meats and dairy, has two types.

HDL is the “good cholesterol,” helping the body rid itself of excess cholesterol and ensure it doesn’t end up in the arteries. LDL is the “bad cholesterol,” collecting in the walls of arteries and leading to plaque. When too much cholesterol builds up in artery walls (a process called atherosclerosis), it can cause a heart attack.

Studies have shown total cholesterol / HDL ratio is better at predicting risk for CHD when compared to total cholesterol or LDL cholesterol levels.Kinosian1994 Furthermore, one study bucked the LDL trend but showing that high LDL cholesterol was inversely associated with mortality in most people over 60.Ravnskov2016 But other studies have shown lower HDL cholesterol levels were found in persons with CHD when compared to those without the disease.Castelli1977 And some studies have pointed to low LDL has being a strong indicator of CHD.Howard2000

Studies seem to show inconclusive results for LDL and HDL levels in heart disease. You can learn more here, on our recent episode of the H.V.M.N. Podcast with Dave Feldman (also known as Dave Keto).

Assessing Your Heart Health

There are many, many factors influencing heart health; lifestyle, diet, family history, all these things play a role in what’s a complex medical issue.

Start with consulting your doctor to understand risk factors. Since February is American Heart Health Month, there’s no time like the present.