What's the latest on cholesterol, heart health, GLP-1 drugs, and more?

Among our coverage of peer-reviewed research and preliminary findings this week, a few studies and reviews have particularly stood out.

We’ve curated this roundup to give our readers a snippet of what’s happening in the health and wellness space, accompanied by expert commentary for those who want to learn more.

Here are this week’s picks and some further reading suggestions among the latest medical news.

Pick #1: Do eggs raise cholesterol?

The debate over whether eating eggs leads to high cholesterol and increases heart disease risk has been ongoing for decades.

According to the American Heart Association (AHA), for example, one large egg contains up to 186 milligrams of dietary cholesterol.

The now-outdated daily recommended limit was 300 milligrams, which fueled concerns. Now, however, according to current dietary guidelines, this daily intake is recommended to be kept “as low as possible” without compromising on nutritional needs.

However, a recent study showed that people still believe in outdated misconceptions about eggs, preventing them from including them in their daily diets. The study highlighted that eggs do not have a major impact on overall cholesterol levels.

Experts, including Kelsey Costa, MS, RDN, registered dietitian nutritionist and founder of Dietitian Insights, have noted that eggs are a great source of protein and various micronutrients.

“Eggs are a good source of lean protein and many essential micronutrients, including folate, vitamin A, B2 (riboflavin), B5, B12, phosphorus, and selenium,” Costa told Medical News Today.

She also underscored that how eggs are produced and cooked can affect the potential benefits or harm related to eating them.

Limiting eggs and monitoring cholesterol consumption was first promoted in 1968 by the AHA.

The whole discussion received renewed attention in 2015 when the Dietary Guidelines for Americans (DGA) removed the daily limit on egg consumption over cholesterol concerns.

“At the time, it was thought that dietary cholesterol (i.e. the cholesterol found in eggs) could raise levels of plasma cholesterol. This amount of dietary cholesterol that could be consumed per day was further reduced later on for those at high risk of heart disease. It was not until 2015 — and after a lot of research had been done — that these guidelines were abandoned,” Donna Kritz-Silverstein, PhD, said.

Speaking of cholesterol, another recent study found that there can be too much of a good thing. This study, which was published in the British Journal of Ophthalmology, indicated that older adults over the age of 55 may have a heightened risk of developing glaucoma if they had high levels of HDL cholesterol.

The findings were divisive with one expert, Yu-Ming Ni, MD, he would have expected higher “good” cholesterol (HDL-C) to be associated with lower rates of glaucoma, and higher “bad” cholesterol (LDL-C) associated with higher rates of glaucoma.

And if you are curious about why doctors refer to “good” and “bad” cholesterol, read this.

Pick #2: GLP-1 drugs and their health effects

Although GLP-1 medications have become synonymous with weight loss, despite their main objective to treat type 2 diabetes, research into the benefits and harms of this class of drugs is growing each day.

The latest addition to the evidence is a review of its effects on eye health, with a few cases leading to potentially blinding eye conditions.

As part of this review, researchers discovered that nine people taking semaglutide and tirzepatide, which is the active ingredient in Zepbound and Mounjaro, experienced vision problems, including an eye condition called nonarteritic anterior ischemic optic neuropathy (NAION) and two other potentially blinding eye conditions.

Study author Bradley Katz, MD, PhD told us that:

“Between 2-3% of the U.S. population received a prescription for one of these medications in 2023. Because so many people are using these medications, it’s critical to monitor any ill effects on the eye or other parts of the body.”

The researchers have hypothesized that rapid changes in blood sugar levels might contribute to these complications, although the exact reason is still unclear.

On a more positive note, new research also recently found a link between chronic obstructive pulmonary disease (COPD) symptoms and GLP-1 medications.

The study found people with type 2 diabetes who are receiving treatment with GLP-1 and SGLT-2 medications have a lower risk of having COPD symptom flare-ups compared to those taking DPP-4 drugs.

Pick #3: Ketone supplements for heart health

The ketogenic diet, characterized by low carbohydrates and high fat consumption, has become increasingly popular over the last decade or so. As a result, ketone drinks or supplements have boomed.

One recent study decided to investigate whether ketones could improve heart function.

The researchers observed that heart function was better after people drank the ketone drink than after the placebo in all the participants, both when resting and when undertaking moderate exercise.

The specific indicators of this improvement were: increased cardiac output, stroke volume, and peripheral muscle oxygenation.

Although, at first glance, it is easy to overestimate the findings and assume they apply to everyone, this study’s participants were a very specific group: older adults with type 2 diabetes. And there were only 13 people.

The study authors said they were exploring the dose-response relationship of a ketone drink and heart function in healthy individuals.

Although initially recommended for people with epilepsy, many researchers have also been looking into the keto diet’s potential to treat autoimmune diseases, such as lupus or arthritis. At MNT, we dedicated a podcast episode to this.

In this episode and the accompanying feature, we invited a patient with lived experience to see if this worked in real life while discussing the potential mechanisms with a researcher.