Should You Say No to Paleo?

A new Australian study found people who followed the so-called “caveman diet” had twice the amount of a key biomarker linked to heart disease. Here’s what you need to know.

by Lara DeSanto Health Writer

The Paleo diet (short for Paleolithic) is based on the diets of prehistoric humans, who loaded their plates with lean meats, fish, veggies, fruit, nuts, and seeds. Basically, paleo dieters eat only foods you could hunt and gather more than 10,000 years ago—that means no grains, legumes, dairy, salt, refined sugar, or processed oils. And while this diet has grown in popularity in today’s world, experts have raised concerns about whether it’s appropriate for modern humans, especially in regards to whether it to leads to deficiencies in important nutrients like vitamin D and calcium. And now there’s another issue to add to the list.

New research from Edith Cowan University in Australia found that people on the Paleo diet have two times the amount of a blood biomarker that is clearly linked to heart disease. The study, published in the European Journal of Nutrition, found double the amount of trimethylamine-n-oxide (TMAO) in the blood of 44 Paleo dieters compared with 47 dieters following a traditional Australian diet.

"Many Paleo diet proponents claim the diet is beneficial to gut health, but this research suggests that when it comes to the production of TMAO in the gut, the Paleo diet could be having an adverse impact in terms of heart health," said lead researcher Angela Genoni, Ph.D., a nutrition and dietetics lecturer at the university.

How Paleo Dieters May Endanger Their Heart Health

While the Paleo diet isn’t all bad—there’s nothing wrong with a heavy emphasis on fruits and veggies, for example—there are some major food groups missing. For example, the lack of whole grains is a huge concern, says Dr. Genoni.

In fact, most experts recommend people eat a plant-based diet (Mediterranean diet) for optimal health, and a key component of plant-based diets? Whole grains. Whole grains provide essential nutrients, according to the Mayo Clinic, like fiber, B vitamins, and iron.

"We found the lack of whole grains were associated with TMAO levels, which may provide a link between the reduced risks of cardiovascular disease we see in populations with high intakes of whole grains," says Dr. Genoni. Basically, the research explains, people who don’t eat whole grains have higher levels of the gut bacteria that produces the TMAO biomarker linked to heart disease.

"The Paleo diet excludes all grains and we know that whole grains are a fantastic source of resistant starch and many other fermentable fibers that are vital to the health of your gut microbiome," says Dr. Genoni. "Because TMAO is produced in the gut, a lack of whole grains might change the populations of bacteria enough to enable higher production of this compound.”

Another potentially dangerous aspect of the Paleo diet is the increased amount of red meat and saturated fats, which has been linked to heart disease as well. In fact, Paleo followers in the study ate twice the amount of saturated fats that experts recommend for adults.

What’s in a Heart-Healthy Diet?

While you may be tempted by fad diets like Paleo, again, a Mediterranean plant-based diet remains experts’ favorite when it comes to your overall health—including your heart health.

But what exactly goes into a healthy plant-based diet? According to Harvard Health, you should fill up on the following plant foods:

  • Whole grains, like brown rice and steel-cut oats

  • Fruits and veggies

  • Legumes, like dried beans and peanuts

  • Nuts

You can also eat limited amounts of lean meats and fish and low-fat or fat-free dairy products.

Here are some more tips from Harvard Health on how to start eating a heart-healthy, plant-based diet:

  • Get the right grains. So now you know that whole grains are important. But what does that mean for your shopping cart, exactly? Look for labels that say “whole grain,” and opt for whole wheat bread instead of white, brown instead of white rice, and other similar swaps.

  • Load up on color. When it comes to fruits and veggies, go for a variety of colors (that means potatoes and French fries aren’t going to cut it). Think colorful berries, avocado, broccoli, kale, red and yellow peppers, and more.

  • Use oils wisely. When cooking or dressing up your salad, go for healthy oils, like olive oil and canola oil. Skip the butter whenever possible.

  • Say no to sugary drinks. Skip the soda and sugary coffee concoctions and opt for tea, juice (no more than one glass per day), or plain old water. Spice things up with sparking water for that fizzy flavor.

  • Pick healthy proteins. Fish has plenty of benefits, so why not add salmon to your salad once or twice a week? Other smart protein choices are beans, nuts, and poultry. And we know bacon is tasty, but your heart will thank you for opting for a turkey bacon option instead.

Lara DeSanto
Meet Our Writer
Lara DeSanto

Lara is a former digital editor for HealthCentral, covering Sexual Health, Digestive Health, Head and Neck Cancer, and Gynecologic Cancers. She continues to contribute to HealthCentral while she works towards her masters in marriage and family therapy and art therapy. In a past life, she worked as the patient education editor at the American College of OB-GYNs and as a news writer/editor at