In a world as busy, chaotic, and expensive as ours is these days, it’s OK to pursue convenience whenever we get the chance. For instance, Costco is so popular in the United States because of its convenience—you can save time and money by buying things in bulk at a lower price, all in one trip to the store. You can purchase almost anything there, from food to cleaning products, and electronics to clothing items, they have it all. And one thing they have plenty of are vitamins and supplements. But what are some of the best Costco supplements to buy, and how can you know if you need to take a supplement?

“Do you need to take excessive vitamins, minerals, and supplements if you eat a balanced diet? Not usually. While there are a variety of vitamins and minerals that are essential for good health, many of them are needed in small quantities and consuming them in excess typically does not improve your health or performance,” says Amy Goodson, MS, RD, CSSD, LD author of The Sports Nutrition Playbook and member of our Expert Medical Board. “A good ‘rule of thumb’ for seeing if you need a supplement is to evaluate your diet and see if there are any foods or food groups you don’t eat, then evaluate what nutrients are the highest in that food or food group to see if you are getting enough. If not, then consider supplementing.”

People with really busy schedules who may struggle to eat a balanced diet, or those with specific health complications that may require higher levels of a certain vitamin may also benefit from taking supplements. But before you purchase any supplement to add to your daily routine, it’s important to talk with a health professional, first. “People should always check with their doctor before they decide to take any supplement every day, as each person has unique health needs and dietary habits,” says Lauren Manaker, MS, RDN, registered dietitian and author of The First Time Mom’s Pregnancy Cookbook and Fueling Male Fertility.

If you and your doctor decide that taking an extra supplement or vitamin may be beneficial to your unique health needs, you may want to check your local Costco to see if they have what you’re looking for. Below is a list of the best Costco supplements you can find, hand-picked by our expert dietitians.

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“This multivitamin has been third-party tested by consumer labs and it actually contains all the nutrients that are listed on the label (this is not true for every supplement),” says Sydney Greene MS, RDN. “In addition, it is free of heavy metals and it disintegrates properly. Whether or not you eat a robust diet, it can be beneficial to include a daily multivitamin to cover nutrient needs.”

The daily use of a multivitamin is helpful for those who may not be getting enough of their basic nutrients through their regular diet, according to the National Institutes of Health. And while some studies have found that there may be longer-term benefits of multivitamins on disease prevention, the American Journal of Clinical Nutrition warns that many of these studies are observational and may not take into account that most people who take daily vitamins also live a healthier all-around lifestyle than those who don’t. If you’re unsure as to whether or not a multivitamin could be helpful for you, talk with your doctor before buying one.

“Vitamin D is important for calcium absorption, bone health, and osteoporosis prevention,” explains Lisa Young, Ph.D., RDN, author of Finally Full, Finally Slim and member of our Medical Expert Board.

“Especially in the colder months when we aren’t being exposed to sunlight as much, many of us can become deficient in this vitamin,” adds Manaker.

A possible solution? Head to your local Costco and pick up the Kirkland D3 supplement.

“This vitamin D is USP-Certified and it is a great value,” Manaker continues.

For all of your future supplement shopping endeavors, if something is USP certified, it means that when it comes to potency and quantity, the supplement product contains what is listed on the label and is currently compliant with the FDA’s Good Manufacturing Process guidelines. Furthermore, this designation means the supplement will dissolve and break down in the body, and does not contain harmful levels of contaminants.

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If you’re vegan or just dairy-free, or are someone who only consumes dairy products from time to time, you may be missing out on some key vitamins and minerals. Thankfully, there are certain supplements that can help you out.

“Most people do not consume the recommended three servings of dairy a day, leaving many of them low on calcium intake. Plus, cow’s milk also provides vitamin D—a nutrient not found in most American’s diets,” says Goodson. “If this is you, consider taking Citracal Plus. It provides 50% of your daily calcium needs and is made with calcium citrate (absorbed better than calcium carbonate), and it also provides 1000 IU of vitamin D, which is 125% of the dietary recommendation.”

Trista Best, MPH, RD, LD at Balance One Supplements recommends picking up a CoQ10 supplement the next time you’re at Costco.

“Coenzyme Q10 (CoQ10), also known as ubiquinone, is an antioxidant created by the body that is located in every cell and used by the cells to produce energy for cell growth and maintenance. Its antioxidant properties help protect the cells and tissues from free radical and toxin damage, making it cardio-protective. It has been recommended to help in healing from heart failure and other cardiovascular diseases,” says Best.

There are many brands of CoQ10 out there, and even multiple brand options at Costco, but Best recommends Nature Made.

“Costco’s Nature Made CoQ10 comes in a convenient 140 softgel bottle with each one providing 200 milligrams of this important compound,” Best continues. “With a serving size of just 1 softgel, Nature’s Own makes it easy to add as part of your supplement regimen.”

For some people, taking a daily probiotic can help maintain a healthy gut—especially if you’re someone who is often stressed, busy, or just find it difficult to maintain a balanced diet.

“Probiotics are living microorganisms that are valuable for your gut health, providing benefits ranging from assisting with digestion to alleviating common gastrointestinal symptoms,” says Goodson. “Culturelle® Digestive Daily Probiotic capsules deliver the clinically proven effective amount of 10 billion CFUs for healthy digestion.”

CFUs are “colony forming units” that estimate how many live, active microorganisms can be found in a probiotic supplement.

“Specifically, Culturelle is a third party tested and approved supplement, and the type of probiotic in this product (Lactobacillus rhamnosus GG) is a clinically-studied probiotic known to reduce occasional digestive upset including gas, bloating and diarrhea,” Greene adds. “It also contains 200 milligrams of prebiotics in the form of inulin, which are the fibers that help feed the good bacteria or probiotics in your gut.”

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“The majority of Americans are not eating the recommended 8-10 ounces of seafood every week, which opens them up to missing out on important omega-3 fatty acids, particularly DHA and EPA,” says Manaker. According to the Cleveland Clinic, omega-3s may help lower triglycerides, raise HDL cholesterol (the “good” kind), lower your blood pressure, and protect against dementia and Alzheimer’s disease.

“While these supplements won’t be a substitute for eating fish, it can help fill the healthy fat gap that may develop. This supplement is third-party verified and they are manufactured in a way that attempts to preserve the integrity of these fats,” says Manaker.

A B-complex supplement contains all of the B vitamins, such as B12, B9 (folic acid), B3 (niacin), and B1 (thiamin).

“This B-complex has been approved and third party tested by consumer labs,” says Greene. “It is free of gluten, artificial colors, lactose, and preservatives. In addition the B vitamins, this supplement includes vitamin C, sodium, and potassium.”

B vitamins are often recommended for people who are pregnant, because they may need higher dosages of B12 and folate, as well as older adults who may have a deficiency in B6. Another subgroup that may benefit from a B-complex supplement are vegans or vegetarians because it is harder for them to get enough B12 through their diet.

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“Vitamin C is an antioxidant vitamin and helps keep inflammation at bay, as well as promote a healthy immune system,” says Young.

According to the National Institutes of Health, vitamin C inadequacy—which is when your intake is below the recommended dietary amount—is common among smokers, people with malabsorption or chronic disease, or those who don’t have a lot of diet variety. If you’re worried you may need a boost of this vitamin, talk with a doctor as soon as possible.

When it comes to some of the best Costco supplements, their brand of vitamin C is great.

“This chewable supplement can be consumed on the go and tastes great, too,” says Young.

“Most people are not consuming enough magnesium. This mineral can help support bone health, heart health, and may even support mood—although more data is needed to confirm the benefits on mood,” says Manaker. “Magnesium glycinate is a form of magnesium that is typically well-absorbed by the body, unlike magnesium oxide, which is found in many other supplements.” According to Mayo Clinic, magnesium can also support muscle and nerve function, but deficiency in magnesium over a long time can lead to an increased risk of heart disease or type 2 diabetes.

Dietitians swear by these vitamins and say that they are some of the best Costco supplements you can buy. While these provide many benefits and can add to a healthy, balanced lifestyle, it’s still important to speak with your dietitian or doctor before implementing any kind of supplement into your daily routine.