Many vitamins and minerals are proven to slow aging, but one in particular wipes the floor with all the rest – selenium.  

Not only that, selenium plays a key role in keeping your immune system in check, helps your body recover faster, and is vital in all kinds of enzyme and hormone processes. So why is it that very few people ever heard about this essential trace mineral? 

Everyone has heard about the importance of magnesium or copper, but the fact is selenium is just as crucial, if not more! 

If you’re new to the topic of selenium benefits and how it can help you slow aging and stay healthy, here’s all you need to know.   

Health and anti-aging benefits of selenium

It’s fascinating how such a small thing like a trace mineral can have a profound influence on our bodies. Knowing about these minerals is especially crucial now when the world is filled with processed “food” that literally shortens our lives.

Yeah, I’m not a fan of processed sh*t that market shelves are filled with… but I digress. 

Let’s leave this topic for now and focus on what exactly can selenium do for your health. And there’s plenty of good stuff.

1. Boosts immunity

A strong and healthy immune system has never been more needed than in recent times, the COVID times. What you eat can pretty much make or break your immune response to all kinds of viral infections, including the one running rampant through the world right now (I’m writing this in December 2020).

Selenium is needed for the proper functioning of all kinds of immune mechanisms, like NK cells or macrophages. These mechanisms are the key in keeping us healthy throughout these harsh flu seasons, and now the new COVID season as well. 

2. Keeps your thyroid healthy

A healthy thyroid is the key to a healthy life. And selenium will help you keep this precious organ that way. Out of all organs in our body thyroid contains the biggest amount of selenium per gram of tissue. It’s no surprise then that people who suffer from hypothyroidism have very low serum levels of this mineral. 

If you find yourself fatigued more often or having a hard time falling asleep, thyroid issues might be the reason. With low selenium levels, it’s difficult for your thyroid to convert the T4 hormone into the more active T3. This may lead to a slower metabolism and is the reason why people with hypothyroidism can find it difficult to lose weight. 

Selenium seems to be especially helpful for people suffering from Hashimoto’s disease. This meta-analysis showed a significant improvement in thyroid function and overall well-being after just 3 months of supplementing with selenium. If you’re someone who’s dealing with this disease, adding selenium to your diet will surely be beneficial. 

3. Selenium slows down the aging 

You might hear me talk all the time about the power of antioxidants, and for good reason. These anti-aging compounds are your best ally in staying healthy, and selenium is part of the solution. 

The formation of enzymes called selenoproteins is the key here. These proteins are vital in not just fighting oxidative stress, but in DNA synthesis hormone production as well. And from just looking at the name of this enzyme we can see that selenium plays a critical role here. 

Selenoproteins act as a first-line defense against free radicals trying to damage our cells. These molecules play an important role in our health, that’s true. The problem arises when the number of free radicals goes out of control due to an unhealthy lifestyle, leading to all kinds of issues – the main one being faster aging.

Have you ever left a sliced apple for a while just to come back and see it turn brown? That’s oxidation – the same process that happens in our bodies all the time. The key, however, is to keep this process under control, and antioxidants are perfect for that. 

Aging signs from free radicals damage are best seen in the form of wrinkles. This is a good moment to mention that most face creams claiming to “reduce wrinkles with antioxidant formula” are pretty much worthless. Your skin simply doesn’t want to absorb them when applied via a face cream. That’s why having an antioxidant-rich diet is the best thing you can do to slow the aging process – our bodies are WAY more efficient in absorbing them from food rather than through creams.  

4. Keeps your brain young 

If there’s one condition that scares the sh*t out of me the most, it’s without a doubt Alzheimer’s disease. The worst part? The number of people who suffer from it grows with each year. Losing the memory of your family and life is a nightmare. Trust me, I’ve seen it first hand with my grandma. I would not wish this on my worst enemy. 

Luckily, there’s a light in a tunnel. It turns out Alzheimer’s disease can be treated and even prevented with lifestyle changes. One of the ways you can combat this aging disease is by adding selenium to your diet. It turns out people who suffer from Alzheimer’s are deficient in selenium, as well as zinc and manganese.

Another big issue seems to be oxidative stress, according to this study from NCBI. That’s why it’s so important to have as many high-quality antioxidant sources in your diet. Stuff like sea buckthorn or curcumin are just a few examples, there’s plenty of great choices. 

5. Protects against heart disease

While Alzheimer’s disease is on the rise all around the world, heart disease is no different. As it turns out, selenium is the key in the fight against both these conditions.

The main reason why selenium is so powerful against heart disease is its anti-inflammatory and anti-oxidative properties. These two are closely linked to atherosclerosis, which is the buildup of plaque in arteries. This buildup can be extremely dangerous, leading to strokes and heart attacks, something no one would really want to experience. 

Selenium also increases levels of HDL cholesterol (the good one) at the same time lowering its LDL (the bad one) counterpart. Great news for anyone having cholesterol issues, which is a lot of people, unfortunately. 

How to know if you’re deficient in selenium

The content of selenium in food is dependant on the soil in which it grew. The countries more prone to deficiencies are China, and Eastern Europe, so unless you live in one of these regions, you’re less likely to experience these signs. 

Nonetheless, even if you’re someone who’s low on selenium, chances are you won’t experience these symptoms unless you’re deficient in other essential nutrients

Here are the most common selenium deficiency symptoms:

  • Mental fog
  • Overall fatigue
  • Hair loss
  • Weakened immune system
  • Infertility
  • Muscle weakness

How can you know if these symptoms are caused by selenium deficiency? Well, it can be quite tricky. That’s because there’s no easy way to diagnose it via a test or something similar. The most common way to find out is by testing your levels of glutathione peroxidase, which is an enzyme that requires selenium to function. 

Severe selenium deficiency is very rare, though, so I wouldn’t sweat over it. By adding some of the selenium sources mentioned later in this article you will surely have nothing to worry about. 

Too much selenium is bad as well

Like with many healthy foods, the saying “the dose makes the poison” is right in this case as well. While selenium is pretty much crucial for good health, it’s still possible to overdose it. Fatal? Probably not, but definitely harmful to some extent. 

The daily recommended amount (RDA) of selenium is 55mcg, which isn’t a lot considering a single brazil nut contains around 100 mcg.

The upper tolerable limit, however, is considered to be 400 mcg a day. This means you’re more than fine if you end up eating a few brazil nuts too many. No one is judging, they are actually super tasty.

Let’s suppose, though, that you ended up eating an entire pack of brazil nuts. And not just once, every day for a week! What now?

Here’s the list of potential selenium side effects, according to

  • Diarrhea
  • Weakened fingernails
  • Breath and sweat smell like garlic (interesting)
  • Hair loss
  • Irritability
  • Itching of skin
  • Vomiting and nausea
  • Overall weakness and tiredness

Although these side effects might sound scary, overdosing on selenium is still rare. I wouldn’t sweat over it unless you REALLY end up eating a pack a day for the next week. Which would be impressive but not recommended!

Best sources of selenium 

If I’ve convinced you of adding more selenium to your diet, great! Now the next obvious would be – what foods are good selenium sources in the first place?

Below you can see the table of the best selenium sources out there, according to the National Institute of Health

(mcg) per
Brazil nuts, 1 ounce (6–8 nuts)544989
Tuna, yellowfin, cooked, dry heat, 3 ounces92167
Halibut, cooked, dry heat, 3 ounces4785
Sardines, canned in oil, drained solids with bone, 3 ounces4582
Ham, roasted, 3 ounces4276
Shrimp, canned, 3 ounces4073
Macaroni, enriched, cooked, 1 cup3767
Beef steak, bottom round, roasted, 3 ounces3360
Turkey, boneless, roasted, 3 ounces3156
Beef liver, pan fried, 3 ounces2851
Chicken, light meat, roasted, 3 ounces2240
Cottage cheese, 1% milkfat, 1 cup2036
Rice, brown, long-grain, cooked, 1 cup1935

Clearly, there’s no competition – brazil nuts are sweeping the floor with all other sources when it comes to selenium. Adding just one brazil nut will get you the recommended amount plus more! It’s also the cheapest way since a pack of brazil nuts will easily last you like a month or more. 

Eggs are also a good source if you eat a few of them a day. Before I get lynched by some people, I just want to say this. Yes – I’m one of the people who eat 10 eggs a day. No, cholesterol in eggs is not bad for you. Yes, I’m very healthy and never had an issue with cholesterol, even when eating this many eggs a day. People give them a bad rap because of false claims, that’s all. 

Selenium supplements over natural sources – worth it?

This is a question that’s asked with pretty much every vitamin out there. Is it worth taking supplements over natural sources for convenience’s sake?

Well, in the case of selenium, getting your RDA is quite easy. Simply eating one brazil nut is enough for the day, unlike some other vitamins that require you to eat a ton of fruits or veggies. For instance, if you’re not a fan of leafy greens, supplementing with a high-quality vitamin K supplement is great and even recommended. 

Of course, if you’re someone who’s not really into brazil nuts or eggs and still want to reap the anti-aging benefits of selenium, supplements will do the job. Here are some of the best selenium supplements on Amazon:

Life Extension Super Selenium Complex Capsules – $11.99

Nature’s Bounty Selenium Tablets – $25.99

Nature’s Way Selenium – $11.52

Bottom line

As you can see, adding selenium to your diet can make a ton of difference if your goal is to slow down body and brain aging. It’s one of those minerals that don’t often get mentioned, yet can keep you healthy for years to come. Simply add one brazil nut a day for the next 30 days and see the results for yourself. I promise you won’t regret it. 

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I'm Lucas, a 30-year-old guy from Poland who's passionate about natural ways to fight aging and staying healthy for as long as possible.