Supplements are often marketed as a quick and convenient way to boost health, improve energy, or address specific deficiencies. While many can provide real benefits, some come with hidden dangers that consumers may not be aware of. Certain supplements, especially when taken in excessive amounts or combined with other medications, can harm vital organs.

We checked in with Ramit Singh Sambyal, MD, Robert Iafelice , MS, RDN; Dr. Rimas Geiga , MD; and Robert Love, a neuroscientist who has over 2M followers on TikTok, to discover seven supplements that may pose “hidden dangers” to your overall health. Read on to get all their insights!

1. Fish oil without antioxidants

Fish oil is one of the more popular supplements due to its great benefits, such as reducing inflammation and lowering triglycerides. However, experts say that if you’re taking fish oil and it doesn’t contain antioxidants, it can be pretty risky for your cardiovascular health .

“While fish oil is very beneficial for cardiovascular health, it can be harmful,” Iafelice says. Fish oil that isn’t preserved with antioxidants like vitamin C, E, or astaxanthin poses a risk, as “fish oil is extremely susceptible to rancidity and the production of toxic byproducts.” Yikes!

For this reason, Iafelice says, you should “always be sure that your fish oil has antioxidants in it to protect it from rancidity.”

2. Ephedra

Ephedra has actually been banned in dietary supplements since 2004 by the FDA. This ingredient is known to increase your heart rate, blood pressure, and other cardiovascular complications.

But Dr. Sambyal warns, “Despite this ban, some products may still have ephedra or its derivatives, like ma-huang in traditional Chinese medicine.”

He further adds that “this stimulant can increase blood pressure, heart rate, and metabolism. Ephedra can interact with blood pressure medications and other drugs such as caffeine and decongestants.”

3. Green Tea Extract

Green tea extract is renowned for its antioxidant properties, primarily due to its high concentrations of catechins like epigallocatechin gallate (EGCG).

However, Dr. Geiga warns that, while there are many benefits to green tea , “high concentrations of catechins in green tea extract can induce oxidative stress in the liver, leading to hepatotoxicity.” This oxidative stress may manifest as elevated liver enzymes and, in severe cases, acute hepatitis.

To mitigate these risks, it is recommended to limit intake to no more than 300 mg per day and consider brewed green tea as a safer alternative.

4. Turmeric

A recent study that was published in JAMA Network Open has revealed that drug-induced liver injury is on the rise in the U.S., with supplements like turmeric being a few of the common culprits. The ease of accessing these supplements, either through a quick online purchase or over-the-counter availability, has significantly added to this increase.

Turmeric supplements are popular because of the active compound curcumin. Curcumin has strong anti-inflammatory and antioxidant properties. However, the study claimed that if taken in excessive amounts, it could put you at risk of liver damage, kidney stones, and even liver failure.

5. Iron

Love says that a lot of people take iron supplements, but the truth is they don’t really need it.

“High levels of iron can lead to memory loss as well as loss of cognition. And iron in excess actually increases aging,” he reveals.

Love says that unless you’ve undergone a blood test that shows significant low levels of iron in your body, “you probably don’t need iron supplements.” However, this supplement can benefit those who are on a vegan diet, he notes.

6. Copper

Taking copper supplements in excess can negatively affect your brain due to copper’s role in oxidative stress and its impact on brain health.

Love says that high levels of copper “actually increase free radicals, and this can cause oxidative stress and damage in your brain.”

Instead, he says to make sure you’re taking plenty of zinc, either in a supplement form or food. “Zinc counteracts the free radicals of copper, and that helps protect your brain,” he explains.

7. Calcium Carbonate

Another supplement to take cautiously is calcium supplements. Best known for its bone health benefits, they can also cause constipation, bloating, and gas, as they can slow down the digestive process.

McKinney elaborates on this and notes that “calcium is an essential element for the development of bones; however, calcium carbonate supplements produce a constipating effect and may be uncomfortable in the digestive system. This type of calcium is less soluble and may bring disturbances in the intestines, so it becomes difficult for the digestive tract to become healthy.”

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Losing weight is challenging, and many people turn to weight-loss supplements to help achieve their goals. Who doesn’t want a quick fix? Unfortunately, many supplements marketed for weight loss don’t do what they promise—and may even work against your goals. Not only are supplements expensive, but they are also unregulated, so you don’t always know what you’re getting. The best way to lose weight is to focus on a food-first approach, which means eating plenty of nutrient-dense foods and maintaining a slight calorie deficit over time. 

In this article, we get into some popular weight-loss supplements and why nutrition professionals don’t recommend them, plus helpful tips for healthy, sustainable weight loss. Knowing what to watch out for can help you make informed choices and prioritize strategies that actually support your health and weight-loss journey.

Green Coffee Bean Extract

If you’ve searched for supplements aiding weight loss, you’ve likely come across green coffee bean extract. Quite simply, this supplement is derived from the coffee plant’s seeds, which are green before roasting. “[Green coffee bean extract] has chlorogenic acid, a coffee compound that can supposedly decrease fat absorption and speed up metabolism,” says Danielle VenHuizen, M.S., RDN, a Seattle-based dietitian and owner of Food Sense Nutrition. She adds that these claims are mostly unwarranted. 

According to the National Institutes of Health (NIH), only a few human trials have examined the effectiveness of green coffee bean extract on weight loss. These trials had poor study design and showed mixed results. While a 2020 review in Complementary Therapies in Medicine found that green coffee extract may help reduce weight and body mass index, there wasn’t a significant effect on body fat percentage, meaning that the mass lost could come from water or muscle.

Body mass index (BMI) is a measure that’s often used in healthcare to determine a person’s body weight category such as overweight or obese, and therefore, chronic disease risk. However, it has limitations and does not account for individual factors that influence one’s health status, such as body composition, ethnicity, race, sex and age. This is why it shouldn’t be used as a comprehensive measure of someone’s health and can be a source of body size stigma and bias.

“Additionally, in my clinical experience, I have yet to meet a client who has lost weight by using green coffee bean extract,” says VenHuizen. Lastly, there isn’t much information on the safety of green coffee bean extract, so buyers beware. 

Garcinia Cambogia

Garcinia cambogia is a fruit with ​​hydroxycitric acid (HCA), a compound thought to reduce fat production in the body and suppress appetite. “Studies seem to indicate that some of these claims might be true, but unfortunately, the benefits are modest, and the research is conflicting,” says VenHuizen. A 2020 review in Diabetes, Obesity & Metabolism states that there are only a small number of studies on garcinia cambogia, and the methodology is poor, meaning that these results shouldn’t be trusted. 

Even more alarming, “several studies have reported liver issues with long-term use of this supplement,” says VenHuizen. One of those studies was published in 2022 in Clinical Gastroenterology and Hepatology. This is another pretty convincing reason to avoid adding this supplement to your weight-loss regimen. 

Raspberry Ketone

Raspberry ketone is a compound found in the raspberry fruit. Small test-tube and animal studies suggest it may suppress the buildup of fat in the body, but the results are extremely limited. According to the NIH, there has only been one human study on the effects of raspberry ketones on weight loss. The participants took the supplement for eight weeks while also following a calorie-restricted diet. The raspberry ketone supplement was combined with caffeine, bitter orange, ginger, garlic, cayenne, L-theanine, pepper extract, B vitamins and chromium. 

The 45 participants who finished the study lost weight, but it’s impossible to know if it was due to the raspberry ketone blend or the calorie deficit. In short, there isn’t enough evidence to support raspberry ketones for weight loss, so save your money. Instead, we recommend snacking on some raspberries, which have several health benefits, including filling fiber and inflammation-fighting anthocyanins.

Caffeine

The most recognizable supplement on this list, caffeine is a compound that stimulates the nervous system. It’s naturally present in tea, coffee and chocolate, as well as in herbal supplements like guarana. Caffeine increases thermogenesis, the body’s natural production of heat. During this process, the body burns extra calories. 

Research suggests caffeine can help with weight loss, but a large dose is necessary to create a response. A 2020 review in Nutrients found that more than 3 milligrams of caffeine per kilogram of body weight is necessary to stimulate the breakdown of fat. For a 150-pound person, that’s 200 mg of caffeine, or two cups of coffee. 

The Food and Drug Administration states that it’s safe to consume up to 400 mg of caffeine daily, but everyone has a different tolerance level. People sensitive to caffeine may experience symptoms like nervousness, jitters, heart racing and headaches, among others. 

Although caffeine may increase fat loss, it’s not the best way to lose weight, especially because supplements with caffeine may contain more than that, plus other stimulants. That said, caffeine from natural sources like coffee is the safest way to consume caffeine. So, feel free to include a cup of coffee or tea in your day for an energy boost, but don’t expect it to affect your weight too much. 

Tips for Healthy Weight Loss 

Although they may not be quick or flashy, the most effective tools for losing weight are good old-fashioned healthy eating and exercise. VenHuizen recommends increasing fiber-rich fruits and vegetables and healthy fats in the diet. “These foods naturally increase satiety and provide anti-inflammatory benefits that may aid in weight loss,” says VenHuizen. “And unlike supplements, studies on fruit and vegetable intake show that these foods improve weight-loss efforts,” she adds. 

In addition, “Trying to stay moderately active throughout the day, especially for people who work sedentary desk jobs, can help with weight loss,” says Madeleine Putzi, M.S., RDN, a Pittsburgh-based dietitian. She recommends getting up and walking around once per hour to increase your total amount of steps for the day, which is an easy and non-taxing way to increase your daily calorie burn. 

Putzi also suggests investing in a standing desk and/or a walking pad if possible. “If you walk for 10 minutes at 3 miles per hour, you will hit around 1,000 steps. Do that every hour, and that’s an easy 8,000 steps by the end of your workday,” says Putzi.

The Bottom Line

Weight-loss supplements are usually not worth the expensive price tag. If a supplement promises to “magically burn fat or flatten your belly,” chances are it’s not the miracle that’s promised on the bottle. A food and exercise approach to weight loss is the most effective way to reach your weight-loss goals in a sustainable way.