Cholesterol: What you’re doing may actually have the opposite effect

“You shouldn’t eat too many shrimp”… “limit egg yolks”… “eat low fat dairy” ….sound familiar? We’ve heard that high cholesterol levels lead to heart disease, stroke, weight gain  – so it’s no wonder we try to avoid cholesterol-rich foods like the plague. But did you know that cholesterol is critical for our body? And the foods we are made to fear are actually some of the healthiest? The guidelines now label cholesterol as “nutrient of no concern.” 

 

So why do we fear cholesterol? 

In 1968, the American Heart Association (AHA) started recommending limiting dietary cholesterol intake to 300 mg a day and restricting egg consumption to a maximum of three whole eggs per week. However, these recommendations did not align with the scientific research, which showed that increased intake of dietary cholesterol is actually associated with decreased synthesis of endogenous cholesterol. What does this mean? Basically, blood cholesterol comes from two sources: (1) exogenous, or dietary cholesterol, and (2) endogenous cholesterol, which is synthesized by the liver (endogenous means that it is produced in the body).  The body has a mechanism in place to maintain cholesterol balance: as dietary cholesterol is increased, the amount of cholesterol that the body makes actually decreases. So our body can maintain an internal balance. Meaning that the recommendation to avoid cholesterol did nothing to improve our cholesterol levels. And completely eliminating cholesterol isn’t wise. 

 

We NEED cholesterol. 

The body produces and uses cholesterol to make hormones like estrogen, testosterone, vitamin D, and other critical molecules that our body needs to function and thrive. Cholesterol is also important for cell membranes. This means that insufficient cholesterol can lead to hormonal imbalances (like mood changes, thinning of the hair, infertility), thinning of the blood vessels (aka increased risk for hemorrhagic stroke), and altered metabolism (aka unwelcome changes in weight). So as you can tell we NEED cholesterol. But not all cholesterol is created equal. 

 

Which foods alter our cholesterol levels? 

While it may seem intuitive to think that foods high in cholesterol and fat will increase our blood cholesterol levels, it’s actually not the case. The main culprits? Refined carbohydrates and trans fat – more below.

 

Culprit #1: Refined Carbohydrates:

High carbohydrate diets are linked with high TG and low HDL levels, which are associated with heart disease. This may be surprising for some of you, as  foods high in SFA and cholesterol were thought to be the culprit for heart disease. So dietary recommendations to prevent and treat heart disease started focusing on reducing SFA intake, primarily as a means of lowering LDL-cholesterol. Note: This reduction in LDL as a result of reducing SFA intake is actually more specific to the larger and more buoyant LDL particles, which are the non-atherogenic LDL particles; i.e. not the type of heart disease-causing LDL. 

 

So when one macronutrient is restricted in the diet, there’s an increased intake of another macronutrient, like carbohydrates. When we replace SFA with a higher carbohydrate intake, especially refined carbohydrates, we are actually increasing our TG and small dense LDL, and decreasing our HDL. This combination is what set us on the path to heart disease and weight gain. Note: the emphasis is on refined carbohydrates, or simple sugars like fructose found in sweetened beverages and snack foods – not the fructose found in fruit, and not the good complex carbs like starch in potatoes, fiber in vegetables, etc.  

 

Refined carbohydrates increase the number of small dense LDL particles, which is associated with a higher risk of developing heart disease. Unlike glucose, which is the other simple sugar, fructose has a higher potential to induce belly fat and insulin resistance because it increases endogenous lipogenesis, i.e. drives up the body’s production of fat, which results in the creation of palmitic acid (a driver of fatty plaque deposits in the arteries). 

 

Culprit #2: Trans fats:

 Trans fats are basically created in an industrial lab where the fat molecule gets many hydrogen atoms attached to it to make the fat more solid at room temperature. This is desirable from a food manufacturer’s perspective because it increases the food’s shelf life. But trans fats can also form in our own kitchen! Actually, more likely in a McDonald’s kitchen, because trans fats can form when the same oil is re-used to fry multiple batches of food. But we digress. So  back to the industrial trans fat that is solid at room temperature. Imagine having a block of fat that sits in your arteries instead of fluid fat that flows normally throughout the blood. That block of fat represents an increased amount of small dense LDL particles as a result of ingesting trans fats from deep-fried foods or ultra-processed foods from Dunkin Donuts. 

 

So what are some high cholesterol foods that you shouldn’t fear? 

Two of the biggest victims of this cholesterol myth are shrimp and egg yolks. Both are high in cholesterol and therefore have been demonized and linked to higher blood cholesterol levels. Now that we can safely say that high cholesterol foods will not increase our blood cholesterol levels, let’s not shy away from eggs and shrimp anymore. Eggs may actually help improve our lipoprotein profile, lowering our risk of heart disease. What!!? That’s right. When one study compared the effects of whole eggs and yolk-free egg substitutes on cholesterol levels, it was observed that those individuals who ate three whole eggs per day experienced a greater increase in HDL and a greater decrease in LDL than those who consumed an equivalent amount of egg substitute. This increase in HDL is desirable because HDL helps us get rid of excess cholesterol. A decrease in LDL is also desirable because it reduces risk of developing atherogenic plaques.  

 

What other foods shouldn’t I fear? 

 

• Full Fat Cheese: One study found that a high intake of 3 ounces of full-fat cheese per day did not raise LDL cholesterol compared to the same amount of low-fat cheese. Other studies support this finding when they showed dairy intake, especially fermented dairy foods like cheese and yogurt, to have neutral or beneficial effects on blood lipid profiles. So reach for the full fat instead of low fat options – you’ll be getting more nutrients, more satiety, and better flavor! 
• Shellfish (hello shrimp, scallops, mussels, oysters) are rich in protein, B vitamins, iron, selenium, and bioactive components like carotenoid antioxidant, lower LDL cholesterol. 
• Pasture-raised steak has a lower cholesterol content than feedlot beef and contains more anti-inflammatory omega-3 fatty acids. So instead of always getting chicken or low fat meat options, opt for a grass fed red meat option every once in a while! 

 

Your Main Takeaways?

 

Despite the longstanding myth that high cholesterol foods increase your cholesterol, science has shown us that it’s actually the refined carbs and trans fats that are to blame. We know that changing your relationship with high fat foods can be tough, but we give you scientific permission to enjoy full fat options and high cholesterol foods like shellfish and eggs with more liberty. When it comes to high fat foods, the key is sticking to the whole unprocessed food (aka full fat over low fat dairy, always). So if your doctor is telling you to avoid shrimp, eggs, or chose low fat dairy, it may be your job to catch them up on the current research!  

 

Co-written by Cristina Veltri Illien, MHS, RD