When people have weight loss surgery, their bodies struggle to absorb important nutrients like selenium, which helps protect against disease and muscle loss. Researchers studied 100 older adults to see how selenium levels changed after surgery and whether taking supplements helped. They found that people who took selenium supplements after surgery had much better selenium levels than those who didn’t. However, some people taking supplements had too much selenium in their bodies, which might not be healthy. The study suggests that people who have weight loss surgery may need special selenium supplements, but doctors need more research to figure out the right amount.

The Quick Take

  • What they studied: Whether people who have weight loss surgery need selenium supplements and what happens to their selenium levels when they take them
  • Who participated: 100 adults over age 65 (50 who had weight loss surgery and 50 who didn’t), roughly split between men and women
  • Key finding: People who had weight loss surgery and took selenium supplements had much better selenium levels (93% had healthy levels) compared to those who didn’t take supplements (only 57% had healthy levels). However, 28% of people taking supplements had too much selenium, which could be a problem.
  • What it means for you: If you’ve had weight loss surgery, you might benefit from selenium supplements to prevent muscle loss and disease, but you should talk to your doctor about the right dose since taking too much might not be safe.

The Research Details

Researchers compared two groups of older adults: 50 people who had weight loss surgery in the past and 50 people who never had the surgery. They measured three things in everyone’s blood: a special protein called selenoprotein P (which shows how much selenium your body is using), regular selenium levels, and how much selenium people ate in their diet. They also looked at whether people were taking selenium supplements or not. This type of study is called a “snapshot” study because it looks at everyone at one point in time, rather than following them over months or years.

Weight loss surgery works by making your stomach smaller or changing how your intestines absorb food. This means your body can’t absorb nutrients as well as before. Selenium is especially important for older adults because it helps prevent muscle loss and serious diseases. By measuring selenoprotein P (the most accurate way to check selenium status), researchers could see exactly how much selenium people’s bodies were actually using, not just what they ate.

This study is reliable because it measured selenium in multiple ways and used the best marker available (selenoprotein P). However, because it’s a snapshot study rather than following people over time, we can’t be completely sure that supplements caused the higher selenium levels—other factors might be involved. The groups were fairly similar in size and age, which is good. The study was registered before it started, which shows the researchers were being transparent about their work.

What the Results Show

People who had weight loss surgery and took selenium supplements had significantly higher selenium levels than everyone else. Specifically, 93% of the surgery group taking supplements had healthy selenium levels, compared to only 57% of the surgery group not taking supplements and 100% of people without surgery who didn’t take supplements (who had adequate but not high levels). The surgery group taking supplements had the highest selenoprotein P levels of all groups studied.

Interestingly, the surgery group taking supplements had a concerning finding: 28% of them had “supersaturated” levels, meaning they had too much selenium in their bodies. None of the other groups had this problem. This suggests that some people taking supplements might be getting more selenium than their bodies need.

The researchers found that three things predicted how much selenoprotein P people had: whether they took supplements, how much selenium they ate, and how much weight they had lost during surgery. Weight loss was particularly important—people who lost more weight tended to have different selenium levels than those who lost less weight.

The study found that people who had weight loss surgery were slightly younger (average age about 2 years younger) and had less diabetes than the control group. This is important because it means the surgery group was actually in slightly better health overall, which makes the selenium deficiency problem even more notable. The fact that weight loss amount predicted selenium levels suggests that the surgery itself—and how much weight people lost—directly affects how their bodies handle selenium.

This is the first study to look at selenoprotein P (the best measure of selenium status) in people after weight loss surgery. Previous research showed that weight loss surgery causes many nutrient deficiencies, but selenium was often overlooked in supplement recommendations. This study confirms that selenium deficiency is a real problem after surgery, similar to other nutrients like iron and vitamin B12. However, unlike those nutrients, selenium can be harmful in excess, which makes finding the right supplement dose more complicated.

This study is a snapshot in time, so we can’t prove that supplements caused the higher selenium levels—only that people taking supplements had higher levels. The study only looked at older adults (over 65), so results might be different for younger people who have weight loss surgery. The researchers didn’t know what type of surgery each person had or exactly how much supplement they were taking, which could affect the results. The study was relatively small (100 people total), so larger studies are needed to confirm these findings. Finally, we still don’t know if having too much selenium (supersaturation) actually causes health problems, so we can’t say for sure whether the high levels in supplement-takers are dangerous.

The Bottom Line

If you’ve had weight loss surgery, ask your doctor about selenium testing and whether you need supplements. Current guidelines don’t recommend selenium supplements after surgery, but this research suggests they may be helpful. However, because too much selenium might be harmful, work with your doctor to find the right dose rather than taking supplements on your own. The evidence is moderate—this is one good study, but more research is needed before we can be completely confident.

This research is most relevant for people over 65 who have had weight loss surgery. It may also apply to younger people who’ve had surgery, though more research is needed. People who haven’t had weight loss surgery don’t need to worry about this—they can usually get enough selenium from food. People with certain health conditions that affect selenium absorption should definitely talk to their doctor about this research.

If you start taking selenium supplements after weight loss surgery, it may take several weeks to months to see your selenium levels improve. The benefits for muscle and disease prevention would develop over months to years of maintaining healthy selenium levels. You should have your selenium levels checked a few months after starting supplements to make sure you’re in the healthy range, not too high or too low.

Want to Apply This Research?

  • Track daily selenium intake in micrograms (target: 55 micrograms per day for adults) and log any selenium supplements taken, including dose and time. Set reminders for supplement timing if taking them with meals for better absorption.
  • If you’ve had weight loss surgery, add selenium-rich foods to your daily meals (like Brazil nuts, fish, eggs, and whole grains) and discuss supplement options with your healthcare provider. Use the app to log these foods and track whether you’re meeting your selenium needs through diet alone before starting supplements.
  • Set quarterly reminders to check in with your doctor about selenium levels through blood tests. Track any symptoms of selenium deficiency (muscle weakness, fatigue) or excess (nausea, hair loss, brittle nails) in the app’s symptom log. Monitor weight changes, as the study showed weight loss affects selenium status.

This research is for educational purposes and should not replace professional medical advice. If you have had weight loss surgery or are considering it, consult with your doctor or a registered dietitian before starting any selenium supplements. This study was conducted in older adults (65+) and results may not apply to younger populations. Do not self-diagnose or self-treat based on this information. Blood tests are needed to determine your actual selenium status, as symptoms of deficiency and excess can be similar to other conditions. Always work with your healthcare provider to determine appropriate supplementation for your individual needs.