Shopping for nutritional supplements is inherently complicated—on several levels.
First, there’s the question of what you actually need. For example, magnesium supplements are all the rage on social media, but you’re probably already getting enough through your diet and anything supplemental would be a waste of money. Then there’s the issue of what actually works. You would be surprised by how many popular supplement companies rely on influencer marketing to distract from massive gaps in supporting research. (Colostrum, anyone?) And, finally, there’s the very real possibility that what you’re paying for is not, in fact, what you’re actually getting. Overall, there’s good reason why experts call the nutritional supplement industry a Wild West.
“Dietary supplements are not evaluated by the FDA for effectiveness before they reach the market, so quality and transparency really matter,” says registered dietician Jennifer Scherer, BS, ACE-CPT, MES, RDN. Fortunately, there are a couple of ways to ensure that you’re getting your money’s worth—like this handy guide, for instance, where we’ve cross-referenced expert insights with peer-reviewed research. Moreover, all the product recommendations you’ll find below hold third-party certifications for both effectiveness and purity.
Whether you’re looking to build muscle, burn fat, banish brain fog, or just feel your best year-round, here are the nutritional supplements that are scientifically proven to get the job done.
Muscle Building
If you’re on a mission to build muscle, well-researched supplements like creatine and protein powder can help. Just don’t expect them to do the heavy lifting for you. “There is no magic pill for muscle building,” says Dana White, MS, RDN, ATC, a registered dietitian and clinical professor of health and exercise science at Quinnipiac University. “If you’re not eating enough or training appropriately, don’t even bother.” (We told you this was going to be a no-BS guide.)
Protein powder
Depending on your diet, protein powder is either going to be the most important supplement in your stack or the biggest waste of money. Protein is essential for building muscle, and countless studies, including a 2014 meta-analysis published in the Journal of the American College of Nutrition, have found protein supplementation to support muscle growth when paired with resistance training. But the supplemental stuff isn’t any better than the protein you get from food. “It’s more about the convenience of it,” says White. Experts recommend a daily intake of 1.6 to 2.2 grams per kilogram of body weight for anyone looking to gain muscle. If that sounds doable with your diet, delete the pricey powder from your cart.
Expert’s pick: Optimum Nutrition Gold Standard 100% Isolate Whey Protein Powder
Creatine
Creatine—specifically, creatine monohydrate—is one of the most well-researched supplements in existence. At this point, it is a well-established fact that creatine can boost muscle and strength gains (again, when used as part of a strength training regimen), as seen in this 2014 meta-analysis published in the journal Medicine and Science in Sports and Exercise. “What’s so special about creatine is its ability to provide muscle energy,” says White. “When taken at the proper dose, creatine can be very, very effective.” Similar to protein, creatine is available through certain foods, however not in meaningful enough amounts. (You’d have to eat 1–2 pounds of red meat per day to hit the daily recommended dose of five grams.)
Expert’s pick: Momentous Creatine
Beta Alanine
For years, beta alanine was thought of as an endurance supplement to help delay the onset of fatigue, but recent research, including a 2025 systematic review published in the Journal of the International Society of Sports Nutrition, has found it to be most effective during shorter, more intense efforts—like strength training. Similar to creatine, beta alanine supports muscle growth indirectly. “Beta alanine is a precursor carnosine, which helps to delay fatigue by buffering the increase in pH that you’ll really see as you’re getting into those final reps,” says White. “One of them is giving you more energy to do the work, while the other one’s making the work a little easier to do.”
Expert’s pick: Thorne Beta Alanine-SR
Weight Loss
Weight loss is a simple equation: Burn more calories than you consume. The more valuable, albeit slightly tricker goal, however, is to burn fat without eroding your hard-earned muscle—and that’s where supplements can help. “You can be thin and still have a high percentage of body fat,” says Lindsay Malone, MS, RDN, LD, instructor and clinical dietitian at Case Western Reserve University’s School of Medicine. “Preserving muscle while reducing excess body fat is far more meaningful than simply making the number on the scale go down.”
Green Tea Extract
A 2022 review published in the journal Nutrients compared the fat-burning potential of several popular weight loss ingredients and concluded that green tea extract had “the most plentiful and consistent clinical evidence,” citing reductions in body weight, BMI, and waist circumference. “Green tea contains caffeine and polyphenols called catechins—particularly epigallocatechin gallate, or EGCG—which may increase energy expenditure and fat oxidation, also known as fat burning,” says Malone. But here’s a tip: Regular green tea works, too. “I generally prefer brewed green tea over a concentrated extract,” Malone says. “It contributes polyphenols—and fluid—and avoids some of the risks associated with high-dose extracts.”
Editors’ pick: Renue By Science EGCG
Berberine
Berberine, sometimes referred to as “nature’s Ozempic,” is a bioactive compound found in several plants, and a 2022 systematic review published in the journal Frontiers in Nutrition found that berberine may, in fact, significantly reduce weight, BMI, and waist circumference. That said, it’s worth noting that while berberine supplements may be effective for weight loss, they’re no substitute for medications like Wegovy or Zepbound that mimic the GLP-1 hormone to regulate appetite. Instead, berberine triggers an enzyme called AMPK, which plays an important role in the metabolism and storage of fat. “It appears to influence sugar and fat metabolism, insulin sensitivity, and cellular energy regulation, which may help support fat loss indirectly,” says Malone.
Editors’ pick: Thorne Berberine
Spirulina
Spirulina is a blue-green algae that’s become a cornerstone ingredient of many greens powders due to its superfood qualities. “It provides protein, phytonutrients, and several antioxidants,” says Malone. It’s also a potentially powerful supplement for weight loss. A 2020 review published in the journal Open Heart highlighted several clinical trials that found spirulina to significantly reduce body fat, waist circumference, and BMI, while also curbing appetite and improving cholesterol levels. “Its value may be less about directly burning fat and more about adding nutrient-dense, phytonutrient-rich food components to an otherwise sound dietary pattern,” says Malone. “Just keep in mind that quality is especially important with algae-based supplements, as poorly controlled products may contain contaminants.”
Editors’ pick: KOS Organic Spirulina Powder
Immunity
The idea that you can “boost” your immune system is one of the most enduring (and misleading) health myths of all time. But that doesn’t mean immunity supplements aren’t worth it. Rather than supercharge your immune system, topping up on certain vitamins and minerals can ensure your body’s defenses are running optimally when you need them most.
Zinc
You probably don’t need a year’s supply of zinc, but we’d suggest keeping some on hand. “The evidence suggests that zinc is more useful for shortening an existing respiratory infection than for preventing one,” says registered dietician Jennifer Pallian, BSc, RD. A 2024 Cochrane review found zinc to make little or no difference to the number of colds people experienced. That said, the people taking zinc had colds that were about 2.4 days shorter on average. “Zinc supports immunity at several levels, from maintaining protective barriers to supporting the immune cells that respond once pathogens enter the body,” Pallian says. “These effects may help explain why zinc shows more promise for shortening an existing infection than preventing one in the first place.”
Editors’ pick: Momentous Zinc
Vitamin D
Generally speaking, vitamin D is one of the best supplements you could take, with research linking the vitamin to improvements in everything from mood to bone density. It’s also particularly adept at fending off respiratory infections, by way of its influence on three different kinds of white blood cells—macrophages, dendritic cells, and T cells—that play different but interconnected roles, Pallian says. “Macrophages are involved in recognizing and responding to pathogens, dendritic cells activate lymphocytes—the white blood cells that help fight infection—and T cells help direct the body’s more targeted immune response.” A 2021 meta-analysis published in the journal The Lancet reported a significant reduction in acute respiratory infections when people supplemented with vitamin D.
Editors’ pick: Transparent Labs Vitamin D3 and K2
Vitamin C
If there’s one supplement that people associate with immunity, it’s vitamin C—and for good reason. While zinc and vitamin D do well to shorten and prevent colds, respectively, vitamin C actually does both. A 2021 research review published in the journal BMJ Global Health found that vitamin C supplementation reduced the risk of acute respiratory infections by about four percent and shortened the duration of symptoms by almost 10 percent. “The research suggests that vitamin C may provide a small reduction in the likelihood of respiratory infections and may modestly shorten their duration, potentially through its antioxidant, anti-inflammatory, and tissue-repair functions,” Pallian says.
Editors’ pick: Solaray Liposomal Vitamin C
Cognitive Function
We may not have a Limitless pill just yet (no, for real, don’t click on that ad), but there’s a range of research-backed supplements proven to help your brain run on all cylinders. “My biggest advice to consumers is to be skeptical of proprietary ‘brain-boosting’ blends,” says Scherer. “The evidence is much stronger for supporting normal cognitive function or addressing a nutritional deficiency than it is for dramatically improving cognition in an otherwise healthy person.”
Fish Oil
Fish oil is the most researched and widely available supplement containing the omega-3 fatty acids EPA, DHA, and ALA, which can be massively beneficial to cognitive function. A 2022 review published in the journal Cureus found that supplementing with omega-3 fatty acids can improve learning, memory, cognitive well-being, and blood flow in the brain. “DHA is an important structural component of the brain, which makes omega-3 intake particularly relevant to brain health,” Scherer says. And the benefits don’t stop there. “Correcting Omega-3 deficiencies can help fight inflammation, enhance immunity, improve sleep, and have a positive impact on both strength and endurance straining,” says White.
Expert’s pick: Nordic Naturals Ultimate Omega
Multivitamin
Including a multivitamin in a list of cognitive supplements might seem like a cop-out, but you’d be surprised by how much you can improve brain function by simply covering your nutritional bases. “Vitamins and minerals interact with multiple biological pathways that support cognitive health,” says Pallian. A 2023 clinical trial published in The American Journal of Clinical Nutrition found that multivitamin supplementation can markedly protect cognitive function with age. “The researchers estimated that the difference between the multivitamin and placebo groups was equivalent to approximately 3.1 years of age-related memory change,” Pallian says. “More importantly, these potential benefits have been demonstrated in several randomized trials.”
Editors’ pick: Klean Athlete Klean Multivitamin
Curcumin
Research has shown curcumin supplementation to be effective in improving memory, learning, focus, and mood—but pay attention to the label. “One important issue is bioavailability, or how much curcumin becomes available for the body to use,” says Pallian. Curcumin on its own has low bioavailability, and therefore won’t do much for you. “Consequently, approaches such as modifying curcumin with lipids have been used to improve its bioavailability,” she says. In a 2020 study published in the journal Nutrients, supplementing with lipidated curcumin—the same kind used in the product recommendation below—yielded significant improvements to working memory and reductions in mental fatigue after just four weeks.
Editors’ pick: NOW Foods CurcuBrain
Gut Health
Commonly referred to as our “second brain,” the gut is inextricably involved in your physical and mental well-being. “A well-fortified microbiome is linked to better immune function, optimal nutrient absorption, and more regular digestion,” says White. “Use of these supplements may also help support athletic performance and reduce incidences of GI upset.” While diet remains the ultimate way to maintain a healthy gut, supplements can help fill the gaps.
Probiotic
Your gut is populated by trillions of microorganisms that influence just about every aspect of your health—for better or worse. Basically, your microbiome is a constant battle of good versus evil, and probiotics are the good guys. “Supplementing them can help support increased strains of healthy bacteria in the gut,” says White. Probiotics may also be a low-key performance enhancer, according to a 2023 review published in the International Journal of Environmental Research and Public Health. Athletes across a range of disciplines including rugby, baseball, badminton, and endurance sports saw improvements in performance, cardiorespiratory fitness, and even body composition while supplementing with probiotics.
Expert’s pick: Florastor Dual Action Probiotic Supplement
Prebiotic
Think of prebiotics as the “food” that sustains the healthy strains of bacteria in your gut. “Prebiotics are essentially fuel for beneficial microorganisms already living in the gastrointestinal tract,” says Scherer. Whereas probiotics introduce healthy bacteria to your gut, prebiotics help them thrive. A 2024 review published in the International Journal of Molecular Sciences found that supplementing with prebiotics has been shown to improve everything from inflammation to mental health. “I generally encourage people to think ‘food first’ with prebiotics,” Scherer says. “But a prebiotic supplement can be helpful when someone isn’t consistently getting enough through foods like onions, garlic, asparagus, oats, legumes, and bananas.”
Editors’ pick: Transparent Labs Greens
Fiber
“Of these gut supplements, fiber is probably the one I most frequently find useful, because so many people simply aren’t consuming enough fiber through their diet,” says Scherer. A 2016 paper published in the American Journal of Lifestyle Medicine reported an estimate that only about five percent of Americans meet the recommended daily fiber intake. In addition to improving bowel regularity, a 2025 trial published in the journal Microorganisms found that dietary fiber supplements helped regulate gut microbiota in healthy adults. “Again, food comes first,” Scherer says. “I want people eating vegetables, fruits, legumes, whole grains, nuts, and seeds rather than relying on a powder as their primary fiber source. But when someone consistently falls short, supplementation can be a very practical way to close the gap.”
Editors’ pick: Momentous Fiber+
