Heart health and selenium: How this trace mineral supports heart (and why most people don't get enough)

If there’s one mineral that doesn’t get nearly enough attention in everyday health conversations, it’s selenium. It’s not as flashy as iron or calcium. It doesn’t trend like magnesium or zinc. But for your heart? Selenium might just be the quiet superhero keeping things running smoothly behind the scenes.

Most of us don’t think about our heart until something feels off. A racing pulse. A strange flutter. Or worse, a health scare that forces us to slow down. But long before those red flags pop up, your heart relies on a bunch of unsung nutrients to function properly—and selenium is one of them. So, what exactly is selenium? And how does it quietly protect your heart every single day?

So, what is selenium?
Selenium is a trace mineral, which means your body only needs tiny amounts of it—but those tiny amounts do huge jobs. Found in soil and absorbed by plants (and by extension, the animals that eat them), selenium plays a critical role in everything from thyroid function to immunity. But where it really shines is in its antioxidant powers—particularly its ability to fight oxidative stress.

Oxidative stress is basically what happens when there’s an imbalance between free radicals and antioxidants in your body. And when it comes to heart health, oxidative stress is one of the main culprits behind plaque buildup in arteries, inflammation, and even heart failure. Selenium helps by neutralizing those harmful free radicals and protecting your heart cells from damage.

The heart-selenium connection
So how exactly does selenium support heart health? For starters, selenium is a major player in the antioxidant defense system. It helps your body produce glutathione peroxidase, a powerful enzyme that protects your cells—including heart cells—from oxidative damage. Oxidative stress is one of the major culprits behind plaque buildup in arteries, inflammation, and eventual heart disease.

When your selenium levels are optimal, your cells are better equipped to fight inflammation and free radicals—those unstable molecules that cause damage at a cellular level. Think of selenium as a natural internal shield, buffering your cardiovascular system from daily wear and tear.

Inflammation and blood vessel health
Low selenium levels have been linked to increased markers of inflammation in the body. And chronic inflammation is now widely recognized as a root cause of atherosclerosis—the hardening and narrowing of arteries that can eventually lead to heart attacks or strokes. Selenium helps calm that inflammatory fire, making blood vessels more elastic and less prone to damage.

Some research even shows that selenium helps regulate levels of C-reactive protein (CRP), a biomarker doctors use to measure inflammation in the body. Lower CRP levels are associated with better heart health outcomes—and selenium may play a direct role in keeping that marker in check.

Cholesterol control and selenium’s indirect role
While selenium doesn’t directly lower your LDL (bad cholesterol) or raise your HDL (good cholesterol), it can influence how cholesterol behaves in your body. Oxidized LDL is especially dangerous because it’s more likely to stick to artery walls, forming the plaques that lead to blockages. Selenium’s antioxidant properties help prevent LDL from oxidizing, making it less likely to contribute to arterial damage.

Some studies also hint at selenium’s ability to support healthy lipid metabolism. That means it may help your body process fats more efficiently, though this research is still emerging and needs further backing before any bold claims are made.

What does the research say?
A large-scale review published in The American Journal of Clinical Nutrition looked at several studies and found that people with higher selenium levels had a lower risk of coronary heart disease.

But here’s the twist: more selenium doesn’t necessarily mean better health. Like many nutrients, it follows a U-shaped curve—too little is harmful, but so is too much. Very high selenium intake (especially from supplements) can lead to toxicity, with symptoms like nausea, hair loss, brittle nails, and even nervous system problems.

Why aren’t we getting enough?
Here’s the tricky part: selenium levels in food depend entirely on the soil where those foods are grown or raised. In countries where the soil is naturally rich in selenium—like parts of the U.S., Canada, or Venezuela—most people get enough from their diet without trying. But in areas where the soil is selenium-poor, like many regions in Europe, China, and even parts of India, dietary intake can quietly drop below the optimal range.

And it doesn’t help that modern diets are often overloaded with processed food, which has almost zero selenium. Add in digestive issues, certain medications, or restrictive eating patterns (like veganism without proper planning), and you’ve got a perfect storm for deficiency.

A lot of people are floating just under the radar—not severely deficient, but not optimal either. This low-grade deficiency might not trigger immediate symptoms, but over time, it puts subtle stress on the heart and increases long-term cardiovascular risk.

Can supplements help?
If you’re eating a varied diet that includes seafood, nuts, whole grains, and eggs, you’re probably getting enough selenium. A single Brazil nut, for instance, can contain more than 100% of your daily requirement—though the exact amount varies wildly depending on where the nut was grown.

That said, not everyone can rely on food alone, especially if you live in a region with selenium-depleted soil or have specific dietary restrictions. This is where a low-dose selenium supplement might help, but it’s crucial not to go overboard. The recommended daily intake for adults is around 55 micrograms per day, and going much above 400 micrograms regularly can lead to toxicity.

As always, it’s best to check with a healthcare provider before starting any supplement, especially since selenium can interact with certain medications and conditions.

Selenium might not be the flashiest nutrient in your pantry, but it plays a quietly powerful role in protecting your heart. From lowering inflammation and preventing oxidative stress to supporting healthy cholesterol behavior, selenium is a behind-the-scenes ally your cardiovascular system depends on more than you might realize.

But like many good things in life, balance is key. Getting too little selenium can leave your heart vulnerable, while getting too much can backfire. The smartest move? Focus on a whole-food, varied diet that includes natural sources of selenium—and pay attention to where your food comes from. A little awareness now can go a long way in keeping your heart beating strong for years to come.

If you’ve never had your selenium levels checked or you suspect your diet may be low in it, it might be worth a conversation with your doctor.

Disclaimer:
This article is for informational purposes only and is not intended as medical advice. Always consult with a qualified healthcare provider before starting any new supplement or making changes to your diet, especially if you have an existing medical condition or are taking medication. Individual nutrient needs vary, and what works for one person may not be suitable for another. The information provided here is based on general research and should not replace personalized professional guidance. Use supplements responsibly and within recommended limits.