Chances are you've heard it before: High blood cholesterol levels are linked to an increased risk of health issues like high blood pressure, stroke and heart disease. Taking steps to lower your cholesterol may sound daunting, but one of the first changes to make is actually simpler than you may think: Eat more fiber.
"Most Americans don't eat enough fiber-rich plant foods," says Sharon Palmer, RDN, a Los Angeles-based nutritionist and founder of The Plant-Powered Dietitian. "We don't eat enough whole grains, vegetables, beans, fruits, nuts and seeds, all of which are key sources of fiber in the diet."
That's a real shame, especially because fiber has been shown to deliver some pretty impressive health benefits. An October 2018 meta-analysis published in The American Journal of Cardiology, for example, reported that people who were given psyllium fiber supplements in addition to a statin experienced reductions in their LDL cholesterol levels that were equivalent to doubling their statin dosage. So, that's nice.
How Does Fiber Lower Cholesterol?
A quick recap on cholesterol: The fat-like molecule is naturally made in the body; in fact, the most significant source of cholesterol is what the body makes. Though it gets a bad rap, cholesterol is actually essential to our health: It aids in digestion and also helps to produce hormones like estrogen and testosterone, as well as vitamin D, according to Harvard Health Publishing.
Dietary cholesterol is found in foods like meat, dairy and eggs. In the body, cholesterol circulates with other fats and protein in complexes called lipoproteins. If you've ever heard of LDL or HDL cholesterol, that second "L" stands for "lipoprotein." LDL stands for low-density lipoprotein while HDL stands for high-density lipoprotein.
LDL is considered the "bad" type of cholesterol since it contributes to plaque accumulation in the arteries (which can raise your risk of cardiovascular disease and stroke). HDL is considered "good" because it scoops up cholesterol that's hanging out in the body and shuttles it back to the liver for excretion.
OK, now back to the fiber.
The nutrient does wonders for the body. The non-digestible carbohydrate helps to stabilize blood sugar levels, increase feelings of fullness, aid weight loss and boost gut health. Fiber is also your best friend when it comes to heart health.
"Soluble fiber can trap bile (which is largely made of cholesterol) so that it is eliminated and less of it is reabsorbed by the body."
"Fiber lowers serum cholesterol by trapping and removing bile via the stool," explains Elise Brett, MD, a New York City-based endocrinologist and associate clinical professor at the Icahn School of Medicine at Mount Sinai. Bile gets released from the gallbladder into the small intestine to help the body digest dietary fats.
There are two types of fiber: soluble and insoluble. Only soluble fiber, the more viscous gel-forming type, can lower blood cholesterol levels, according to the U.S. National Library of Medicine. "Soluble fiber can trap bile (which contains a large amount of cholesterol) so that it is eliminated and less of it is reabsorbed by the body," adds Dr. Brett. The result: More cholesterol is removed from the circulation. Bingo!
"Examples of soluble fiber include beta-glucan, psyllium and raw guar gum." Beta-glucan is naturally found in oat bran cereals while wheat bran contains insoluble fiber and has no effect on cholesterol. "Heat and pressure processing in food preparation can also reduce the cholesterol-lowering effect of natural fiber," Dr. Brett says.
So, How Do We Get More Fiber?
Women and men should get 25 and 38 grams of dietary fiber per day, respectively, per the Academy of Nutrition and Dietetics.
It only takes 5 to 10 grams of soluble fiber per day to help lower LDL cholesterol levels, according to the National Lipid Association. Not sure what that looks like? A cup of cooked oatmeal topped with two tablespoons of flaxseeds and berries can provide 3 grams of soluble fiber. Snack on a small orange and a banana, and you're already at at least 5 grams of soluble fiber by lunchtime.
Fiber is present in all plant foods, but some sources offer up more of the good-for-you roughage than others. Here are some great sources of soluble fiber:
- Oat bran
- Nuts and seeds
- Jerusalem artichokes
- Brussels sprouts
And if you're struggling with high cholesterol, note these foods to eat sparingly:
- Fatty cuts of meat
- Processed meats
- Full-fat dairy products (including yogurt, butter, cheese and milk)
- Processed foods (such as baked goods and microwavable popcorn) containing trans-fatty acids aka partially hydrogenated oils
Fiber-Rich Plant Foods Also Contain Other Cholesterol-Lowering Compounds
Besides fiber, plants are rich in two other compounds that are linked to lowering your cholesterol levels. "Plant sterols and stanols are naturally occurring compounds found in plants and are particularly high in foods such as vegetable oils, seeds, nuts and cereals," explains Dr. Brett.
Research suggests that diets high in plant sterols can help reduce serum cholesterol levels. One small October 2018 study published in the journal Food & Function even found that post-menopausal women who drank beverages containing 2 grams of plant sterols daily experienced significant decreases in total and LDL cholesterol levels, as well as reduced pro-inflammatory biomarkers, compared to those who didn't sip.
So, how exactly do these compounds work? "Among other mechanisms, phytosterols lower serum cholesterol by competing with dietary and biliary cholesterol for absorption in the intestinal lumen (aka the inside of your intestines), thus blocking intestinal cholesterol absorption," explains Dr. Brett.
Though plant sterols and stanols are naturally present in plant foods, they don't occur in concentrations high enough to have a major effect on serum cholesterol levels, per the Cleveland Clinic. You need at least 2 grams of plant sterols and stanols per day to help lower cholesterol, Dr. Brett tells us, and opting for a supplement can help you achieve that goal.
What If You're Genetically Predisposed to Having High Cholesterol Levels?
“You can have a predisposition to higher cholesterol levels through genetic influences, but research shows that lifestyle choices such as diet and exercise can actually down-regulate, or ‘turn off,' genes that are linked with disease,” Palmer notes. “If you have a family history of high cholesterol levels (aka familial hypercholesterolemia), it doesn’t mean that diet and exercise are of no use to you. Even if you are taking medications, both should still be part of your lifestyle plan.”
A healthy diet is critical for heart health — and soluble fiber, in particular, is essential for reducing those harmful LDL cholesterol levels. Limiting animal products, especially full-fat ones, can also help reduce serum cholesterol levels.
Just remember: If you suffer from elevated cholesterol due to a genetic condition such as familial hypercholesterolemia, dietary choices alone may not be able to lower your serum cholesterol levels too much — but they're still good to incorporate into your diet. Speak with your doctor about additional ways to lower your cholesterol if diet and exercise aren't effective.
- The American Journal of Cardiology: “Meta-Analysis of Usefulness of Psyllium Fiber as Adjuvant Antilipid Therapy to Enhance Cholesterol Lowering Efficacy of Statins”
- Harvard Health Publishing: “How It’s Made: Cholesterol Production in Your Body”
- Academy of Nutrition & Dietetics: “Easy Ways to Boost Fiber in Your Daily Diet”
- Food & Function: “A Positive Impact on the Serum Lipid Profile and Cytokines After the Consumption of a Plant Sterol-Enriched Beverage With a Milk Fat Globule Membrane: A Clinical Study.”
- U.S. National Library of Medicine: “Soluble vs. Insoluble Fiber”
- National Lipid Association: "Adding Soluble Fiber to Lower Your Cholesterol"