5 Fitness Supplements That Have Been Scientifically Proven to Work

It can be a challenge to determine which fitness supplements are worth spending your money on. The marketing on many of these products can convince you that you need to take preworkout supplements among other things to achieve your fitness goals. It can be confusing, so we’ve narrowed down the supplements that are worth buying based on expert recommendations.

There are plenty of supplements out there that don’t workbut there are some that have been thoroughly tested, studied and proven to work by scientists. Supplements aren’t necessary if you’re already getting all the┬ánutrients you need through food, but these are the ones you should opt for if you decide to take them. Read on to learn which supplements you should be investing in and how they work.

What to look for when shopping for supplements

When shopping for supplements, you may notice that many of them may have labels such as fat burners, BCAAs or other complicated names. Many of these labels are marketing tactics intended to draw you in, and they’re usually too good to be true. DJ Mazzoni, a registered dietitian and Medical Reviewer at Illuminate Labssays there are two important things to consider when shopping for supplements.

The first part is looking at the testing a supplement company has done with its products. “Ideally, the supplement company publishes test results proving their products are safe and accurately labeled.” Mazzoni says this is key because fitness supplements are more frequently contaminated with illicit substances than other products. Not to mention, the Food and Drug Administration doesn’t have the power to review dietary supplement products for safety or effectiveness.

As an alternative, it’s important to look for third-party testing programs that test for substances prohibited in sports. Mazzoni suggests looking for an NSF certification on the label to ensure the safety and efficacy of the product. The second thing to consider is that the dosage is based on published medical research. He explains, “Creatine, for example, is proven to be effective, but most medical research involves a daily dose around 5 grams with a higher loading dose for one to two weeks prior.” This means if a product contains creatine at 1 gram, it’s unlikely to provide any benefit, even if the brand provides test results.

Supplements worth your money

Now that you know how to spot if a brand is reputable, you’re probably wondering which supplements are worth investing in. This all comes down to your own fitness goals and needs. Please remember to consult with your doctor before taking any supplements.

Whey protein

Protein is a macronutrient required for everyone, no matter if they have a fitness goal or not. According to Mazzoni, protein is effective for muscle recovery and building muscle at a minimum of 20 grams post-workout. Although protein powder can contribute to supplementation, he recommends eating it as a whole food. However, if you go down the protein powder route, he suggests aiming for a whey protein-sourced protein powder coming from pastured animals. If you can’t stomach whey, there are plant-based alternatives to choose from. When picking a plant-based protein powder, you should verify that it’s free of added sugars, fillers, preservatives, and high in protein and amino acids. Also keep in mind that plant-based protein powders contain higher levels of heavy metals, such as lead.

Creatine monohydrate

Creatine is one of the few powdered supplements that have been thoroughly researched and proven to work. It’s been known to help improve strength, power, and muscle mass in health and exercise performance. Extensive studies have found that it is safe to consume and the International Society of Sports Nutrition has confirmed that there aren’t negative long-term effects, even at higher doses. Mazzoni recommends taking creatine daily, but people should consult their doctor about long-term daily use for over six months.

Typically it’s recommended to take 3 to 5 grams daily, and it’s important to make sure that the supplement has the word monohydrate in the name since there are other forms of creatine that haven’t been as well researched.

While taking creatine monohydrate you might also notice some weight gain, but this is due to water retention in the muscles. Adequate hydration while taking creatine supplementation can help to minimize other possible side effects such as digestive issues, muscle cramps, stiffness and heat intolerance.


Caffeine is found in coffee, some beverages and some supplements. Besides giving you an energy boost, caffeine also helps improve your workout performance. If you’re a healthy individual, 400 milligrams is the daily maximum limit you can have safely. “A typical caffeine dose is around 200 milligrams preworkout,” explains Mazzoni, adding that caffeine can also be found in dietary supplements, but he favors sticking to black coffee since there is no risk of overdosing and it provides other health benefits.

You’ve probably noticed preworkout supplements mention caffeine on their labels, but some people may not want the added ingredients such as the artificial sugars. If you’re looking to get the benefits of caffeine, you’re better off sipping a cup of coffee 45 minutes to an hour before your workout. An 8-ounce cup of coffee contains about 80 to 100 mg of caffeine.


Citrulline is a nonessential amino acid created by the body, obtained from dietary sources, and can also be found in two supplement forms: L-citrulline or citrulline malate. The difference between the two is that the former is purely citrulline, while the latter has origins of citrulline and is blended with malic acid, which helps provide energy. Although some evidence supports that L-citrulline has health benefits, citrulline malate hasn’t been studied enough to determine if it provides the same benefits. Foods that naturally produce citrulline include watermelon, cucumber, legumes, meats and nuts. L-citrulline has become more popular with athletes because it has been found to boost blood flow and protein synthesis, which stimulates the signals within the body involved in muscle building.

The supplement can help with recovery while also helping you train as intensely as you want. L-citrulline also provides other health benefits that are not related to exercise. “L-citrulline reduces blood pressure in hypertensive patients because it’s a nitric oxide precursor,” explains Mazzoni. You want more nitric oxide because the molecule is known to improve blood flow by widening your blood vessels and allowing for more blood circulation. If you decide to take L-citrulline, he recommends taking a maximum of 10 grams as a pre-workout supplement.


Beta-alanine is a nonessential amino acid produced by our bodies that also helps aid in the production of carnosine. Carnosine helps the muscles work harder and longer before they get fatigued. It does this by reducing the lactic acid that builds up in your muscles during exercise, which helps improve your endurance and athletic performance.

Research has shown evidence that supports the positive effects beta-alanine has on your muscles. In one instance, rowers were given beta-alanine for a series of seven weeks. Compared to those who didn’t take it, they saw an improvement in their speed and rowed 4.3 seconds faster. It’s even been found to help muscle endurance in older adultswhich is beneficial to preventing falls and maintaining a healthy life.

Beta-alanine is naturally found in poultry, meat and fish. But if you choose to take it as a supplement, it’s recommended that you take between 4 to 6 grams of beta-alanine to get maximum results.

Bottom line

Although these supplements are relatively safe, keep in mind side effects can still occur. Mazzoni warns that people with high blood pressure should avoid caffeinated supplements since they can raise blood pressure and increase heart rate. Additionally, if you’re pregnant or nursing, it’s important to consult with your doctor before taking any supplements, and if you have diabetes it’s best to avoid supplements with added sugar. Supplements can also interact with certain medications.

Mazzoni says, “Fitness supplements can be effective at improving workout performance, but I recommend working with a doctor who can help choose fitness supplements that meet a patient’s unique needs and who can help them assess effective dosage.” As with any supplement you choose to add to your diet, keep in mind that it isn’t meant to replace a whole food group or the nutrients you need. Instead, it’s intended to support a healthy and balanced diet, which will improve its efficacy.