A Heart Healthy Low Carb High Fat Diet- Oxymoron or The New Truth?

What do you think of when you hear “heart healthy” food? Oatmeal? Cheerios? These may slightly lower your LDL cholesterol so have been awarded the “heart healthy” seal from the American Heart Association.

But what about a big spinach salad with avocado, hard boiled eggs, grass-fed beef and doused in olive oil? That sounds delicious to me, but is it “heart healthy? I encounter this question on a daily basis with my patients, and the answer surprises many of them!

Is Heart Health Defined by LDL Cholesterol?

Unfortunately, most of our current definitions of heart health center around LDL cholesterol concentration. While LDL cholesterol plays a role in heart health, it by no means defines heart health in totality.

It is true that observational data show an association between increasing LDL concentration and increasing risk of heart disease and death. What is frequently not discussed, however, is that other markers have a better predictive value. For instance, the PURE study investigated over 135,000 subjects from across the world and found that the ApoB/Apo A1 (essentially an LDL/HDL ratio) was a much better predictor of risk. Other studies have shown the triglyceride: HDL ratio has greater predictive value than LDL alone.

Why does this matter? Our healthcare system has simplified things too much, so as a result we focus on one bad guy, one demon to fight. In reality heart disease is caused, and made more likely to occur, by a constellation of contributing issues.

Can we then define something as heart healthy if it improves one risk factor but worsens others? For some, a low fat, high carbohydrate diet can do just that. It can lower the LDL but also lower HDL, increase triglycerides, and worsen insulin resistance and obesity. To me, that doesn’t fit a heart healthy definition.

Elevated blood sugar, elevated insulin levels, inflammation, high blood pressure, poor nutrition, and yes, lipids all contribute to heart health and all need to improve to truly call something heart healthy. It does us all an injustice to over simplify it to one single cause.

Are Whole Grains and PUFAs heart healthy?

Two of most common heart healthy food categories are whole grains and industrial seed oils containing polyunsaturated fatty acids (PUFAs).

Studies show that PUFAs can lower LDL. Amazingly, however, there are also studies showing they have no clinical benefit or even increase risk of dying. According to our simplified definitions, that doesn’t stop them from being defined as “heart healthy,” but I think we would all agree that deserves a closer look.

Same for blood sugar. If you have a diagnosis of Type 2 Diabetes (DM2) that is a risk for cardiovascular disease. If you don’t have the diagnosis, you are fine. That ignores the disease of insulin resistance that can predate diabetes for decades and increases the risk of heart disease and possibly even cancer and dementia.

Cereal can also be called “heart healthy” as they may minimally lower LDL. But is that a good thing if they contain grains that also worsen your insulin resistance and metabolic syndrome? I say definitely not. In fact, the Cochrane Reviews analyzed all of the randomized trials on whole grains and concluded there is insufficient evidence to support a beneficial heart health claim.

I urge all my patients to look beyond the basic, simplified evaluation and start looking at the whole picture.

A Heart Healthy, High Fat Diet Is NOT an Oxymoron

Consumption of fat has been wrongly vilified for decades based on poor quality science. Observational studies with small outcome differences that are complicated by numerous confounding variables were never designed to inform national guidelines! Yet that is exactly what happened with the research on fat consumption dating back to the 1960s.

The other part of wrongly demonizing fat is the company it keeps. A standard American high fat and high carb diet full of processed foods is clearly harmful. But we can’t blame it just on the fat. It is also the company it keeps.

On the other hand, real foods, low carb, high fat diets appear to improve the vast majority of cardiovascular risk markers. They can raise LDL in a minority of people, but the truth is that they can improve everything else! These diets reduce blood pressure, reduce inflammation, improve HDL and triglycerides, and they reverse diabetes and metabolic syndrome. Shouldn’t that be the definition of “heart healthy” we seek? Instead of focusing on one isolated marker, shouldn’t we define heart health by looking at the whole patient?

So, when you weigh your options for a heart healthy diet, remember to look beyond the simplistic definition. Remember to consider the effect different foods have on ALL of your risk markers. And focus on a real-foods based pattern that you can enjoy and sustain for the long run.

Thanks for reading,

Bret Scher, MD FACC

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