Understanding Cholesterol

Understanding Cholesterol

Even those of us with only the fuzziest understanding of nutritional science have managed to grasp this basic fact: cholesterol bad. More specifically, we’ve been told for decades to avoid eating foods, like eggs, that are high in cholesterol, because they’re terrible for our heart health — but that advice could soon be changing.

Every five years, officials from the USDA and the U.S. Department of Health and Human Services meet to review and revise national dietary guidelines; before they do so, an advisory panel made up of some of the nation’s top nutrition scientists recommend changes to the officials — recommendations which are sometimes ignored, and sometimes enacted. This year, that panel is expected to recommend softening long-standing restrictions on the consumption of high-cholesterol foods.

The recommendations are expected later this month, and while we don’t yet know exactly what they’ll say, notes from a December meeting give us a hint: the advisory panel stated that ”cholesterol is not considered a nutrient of concern for overconsumption.” So … that means what, exactly, in practical terms? Science of Us recently contacted nutrition experts to understand more about the new science of cholesterol. Here’s what they had to say.

First — what was the old, now-outdated way of thinking about cholesterol, again?
According to Walter Willett, a nutrition scientist at Harvard School of Public Health, since the 1960s, public-health experts have advised people to keep their cholesterol consumption very low — about 300 milligrams a day, and no more than two eggs per week. The thinking was that eating a lot of cholesterol-laden foods would increase the cholesterol in your bloodstream, clogging up your arteries and leading to heart disease.

Two eggs a week is not a lot of eggs! But researchers are backing off from this line of thinking?
Right. More recent research shows that consuming cholesterol does not actually seem to have much, if any, impact on the amount of cholesterol found in the blood. According to Willett, the link between dietary cholesterol and cholesterol in the bloodstream has always been weak, “and, actually, there’s never been a single study that showed higher egg consumption is related to higher risk of heart disease,” he said. The latest research suggests that if you even can drive up your cholesterol levels by consuming lots of foods that are high in cholesterol, the effect is likely very modest. “If we double our cholesterol intake, we don’t double our blood cholesterol level — we may increase it 5 percent,” Willett said.

This is part of a broader shift away from the idea of a tight connection between diet and cholesterol levels in the bloodstream. Your genes, as it turns out, are a much bigger factor in determining whether you’ll have lots of cholesterol in your bloodstream.”Basically, our bodies make a lot of cholesterol,” Willett said. “So, really, we are our own most important source of cholesterol.” Cholesterol is a key building block of many essential hormones, including sex hormones, and dietary cholesterol doesn’t appear to affect those functions, either.

So what caused this shift in thinking? 
There does appear to be a small number of people who are sensitive to dietary cholesterol, in that consuming it greatly increases the amount found in their bloodstream. “So this has been debated for more than 40 years now,” said David Klurfeld, a nutrition scientist at the USDA. To complicate matters, Klurfeld said, there’s not a good way of testing which people will respond to dietary cholesterol this way. But, Klurfeld said, “the reason this has been such a source of controversy among scientists is that the dietary guidelines are supposed to be for the whole country,” not a small number of individuals.

But the way scientists study the effect of cholesterol in the diet has also changed, Klurfeld said. “Part of the problem is we don’t study humans nearly as much as we study experimental animals,” he said. For many years, the rabbit was the standard test subject for studies on cholesterol consumption. Cholesterol is only found in animal products, and rabbits are herbivores, “so they don’t handle cholesterol at all,” he said. In other words, you can’t directly extrapolate results from rabbit studies to (mostly) omnivorous humans. Long-term, well-controlled studies in humans helped to change experts’ understanding of dietary cholesterol, and these findings are expected to be reflected in the advisory panel’s recommendations.

What are the new standards?
Again, we don’t know yet. The advisory panel is expected to complete its report early this year, likely by the end of the month. These are recommendations that the USDA and Health and Human Services (HHS) will consider when revising the dietary guidelines later this year — they don’t have to follow the panel’s suggestions.

What’s some practical advice to take away here? (In other words, is it cool if I eat eggs every day now?)
It’s probably just fine to eat a couple of eggs a day instead of a couple of eggs a week, as was previously recommended, the experts said. “It looks like eggs are more or less neutral when it comes to heart disease risk,” said Willett. Sure, there are better things you could be eating for breakfast — he suggested some combination of whole grains, berries, nuts, and yogurt — but an omelette a day is very unlikely to harm you, even if our outdated nutritional guidelines say otherwise.

The nation’s top nutrition advisory panel has decided to drop its caution about eating cholesterol-laden food. It’s a move that could undo almost 40 years of government warnings about its consumption.

In December, the Dietary Guidelines Advisory Committee issued a report suggesting that cholesterol found in foods such as egg yolks should no longer be listed as a “nutrient of concern.”

What that means for you, is if you’ve been avoiding that omelette with the yolks or certain meats, you may be able to enjoy them in moderation again.
Researchers have found that about 20% of a person’s blood cholesterol comes from food, the rest is from your genes.
Local dietician, Stephanie Wharton said this may be a good chance for people to start getting certain nutrients they’ve been missing out on.

“Some of the foods that contain cholesterol also have a lot of good nutrients, like good proteins, good vitamins, good immune system enhancing vitamins. If you are avoiding those things, then it can be something that your body is lacking by focusing so much on cholesterol.”

How Cholesterol and High Blood Pressure Affect Your Heart

When it comes to heart health, your cholesterol and blood pressure numbers count. High cholesterol, especially when combined with high blood pressure, is a major risk factor for coronary heart disease, heart attacks, and stroke. It is important to note that not all cholesterol is bad cholesterol. Learning more about how your numbers affect your heart is one of the best ways to lower your risk for heart disease.

What is cholesterol?

Cholesterol is a waxy, fat-like substance that comes naturally from your liver and from the food you eat. Cholesterol helps your body perform important functions that are necessary for daily life. When you eat foods that are high in saturated and trans fats, such as meat and full-fat dairy products, your liver produces more cholesterol. Excess cholesterol traveling through the bloodstream can form plaque in your artery walls. Over time, the plaque in the arteries can harden and restrict oxygen-rich blood to the heart. If the plaque happens to break open, blood clots can form, which can then lead to a blocked artery that supplies blood to the heart.

The higher the levels of bad cholesterol (LDL) in your blood, the greater the chances of developing heart disease.

What numbers should you look for in cholesterol?

  • Total cholesterol level
  • LDL (“bad” cholesterol)
  • HDL (“good” cholesterol)
  • Trigycerides

How to lower cholesterol and blood pressure

  • Eat a well-balanced diet low in saturated fats and trans fats
  • Choose lean cuts of meat or go meatless a few times per week
  • Use minimal amounts of fat and oils
  • Keep sodium levels to 1500mg/day or less
  • Limit alcohol consumption
  • Start an exercise plan
  • Quit smoking


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