6 Best Supplements to Boost Your Health and Immunity

Tiffany Ayuda
Medically Reviewed
January 3, 2020

With so many supplements on the market these days, determining which are actually high quality, safe, and effective can be a challenge. Here are our tips and tricks for choosing the best supplements.

When it comes to supplements , let’s just say it’s complicated. Consuming nutrient-dense whole foods is always better for your body than pills and powders, but there is a proper place for supplements in your routine. Even the healthiest eaters don’t get enough of certain nutrients in their diets because of the way our society has evolved, according to Zandra Palma, MD, a former Parsley clinician in New York City.

“The soil quality is different today than what it was for our ancestors. The way we eat and move is different. We had a more diverse diet back then with plenty of vegetables and fruits. We didn’t use antibiotics, birth control , and other drugs. We had less chronic stress , and our exposures to environmental toxins are completely different,” Palma explains.

These environmental and societal factors play a large role in how much nutrients we’re actually getting in our diets. So while it’s always best to get nutrients from real food, Palma says that the reality is you’re not necessarily going to get adequate amounts. But taking supplements can ensure you’re getting a full spectrum of vitamins and minerals for optimal health.

How to shop for the best supplements

Given the number of products out there and limited government regulations over labeling and manufacturing processes for supplements, finding a high-quality product can be challenging and overwhelming. The Food and Drug Administration (FDA) isn’t authorized to review dietary supplements for safety and effectiveness before they’re marketed so it’s important to do a little digging yourself.

That said, you should always consult your doctor before introducing a supplement into your regimen. Taking supplements may impact the effectiveness of the medications you’re already taking. Plus, your doctor can prescribe blood tests to find out your specific nutrient deficiencies and can recommend the best supplement and dose for you.

Here are some of Palma’s tips for finding safe and effective supplements.

Choose pharmaceutical-grade supplements.

Palma recommends looking for pharmaceutical-grade vitamins, which have the purest form of the nutrient and can therefore be readily absorbed by the body. You can get medical-grade supplements from a licensed health practitioner, like your doctor or a nurse practitioner. Parsley Health also offers a variety of pharmaceutical-grade supplements .

Seek supplements that are third-party tested.

Many of the best supplement brands will be certified GMP (good manufacturing practice) . These supplements have been reviewed by independent, not-for-profit organizations, like NSF International , USP , and Consumer Lab for their composition, quality, and purity. Supplements credited with these labels have undergone rigorous testing and auditing to ensure that all ingredients listed on the label are, in fact, in the product and that they don’t contain harmful levels of contaminants.

Search NSF’s database of supplements to see if the vitamins you’re taking or considering purchasing have been reviewed, or check out a full list of USP-verified products . Consumer Lab also has an archive of helpful product reviews for supplements and health products.

Scan the ingredients label for processed forms of nutrients.

Palma notes that some supplements have processed forms of nutrients, which can actually mask deficiencies, so you want to read ingredient labels carefully. For example, you should never see folic acid in a supplement.

“Look for folate instead. Folic acid is a synthetic form of folate and can cause health problems and prenatal complications for pregnant women,” Palma says. In the same vein, Palma says you should avoid high doses of supplemental calcium, which can be found in many multi-vitamins.

“We want calcium in our bones and teeth—not in our hearts. Studies have shown that high doses of calcium are associated with an increased risk of cardiac events,” Palma says. For example, a 2016 study from the Journal of the American Heart Association surveyed more than 5,000 adults and found that those who took calcium supplements were associated with an increased risk for coronary artery calcification, a marker for cardiovascular disease.

Avoid gummy vitamins.

There’s no point in having sugar with your supplements, since you’re trying to reverse many of the negative effects of the sweet stuff. Ingredient labels that have dextrose, glucose, sucrose, and syrup all indicate that they contain sugar.

The best supplements to add to your regimen

Now that you know what to look for in high-quality supplements, here are some vitamins you want to consider adding to your regimen.

Vitamin D

Also known as the sunshine vitamin, this elusive nutrient is not found in many food sources. While salmon, grass-fed beef, eggs (with the yolks), mushrooms, and dairy have good amounts of vitamin D , you need at least 600 IU of vitamin D daily, and you probably won’t get that amount from food alone. It can also be difficult to get adequate sun exposure, especially if you wear sunscreen and stay indoors often. At Parsley Health, more than 90 percent of patients have a vitamin D deficiency .

“I recommend vitamin D for everyone. Our immune system uses it and we need it to build neurotransmitters and regulate hormones. Our brains also need it to create serotonin , which helps our mood,” Palma says.

Vitamin D supplements are available in D2 (ergocalciferol) and D3 (cholecalciferol). Most research has indicated that D3 is the best vitamin d supplement form because it has been shown to be the most effective in raising and maintaining vitamin D blood levels. However, recent research in the Proceedings of the Nutrition Society demonstrated that D2 and D3 supplements are equally beneficial. One thing to note is that D3 supplements are not vegan so those following a strict vegan diet may want to opt for D2, which the body will later convert to D3.

“You can get a full week’s dose once a week, but your dosage depends on your levels. I advise patients to get tested for their vitamin D levels because very high levels can cause toxicity,” Palma says.

Cod Liver Oil

Cod liver oil supplies omega-3 fatty acids , vitamin A, and vitamin D, making it one of the best dietary supplements you can take. “We all need anti-inflammatory lipids for cell membrane fluidity, and cod liver oil supplements offer this,” Palma says. And because vitamin A is fat-soluble, cod liver oil supplements allow your body to fully absorb it. “We don’t get enough of the main sources of vitamin A, like organ meat and pasture-raised eggs. Beta carotene is found in many orange veggies and fruits, but the problem with beta carotene is that not enough of it is converted into fat-soluble retinol,” Palma explains. She also says that beta carotene in supplement form isn’t good for your health and is actually linked to some cancers . So by incorporating cod liver oil supplements in your diet, you can help your body absorb more vitamin A in foods.

Studies also show the vitamin D in cod liver oil can help safeguard bone health and prevent osteoporosis . However, the jury is still out on the omega-3 fatty acids in supplements. While there’s plenty of scientific evidence that omega-3 fatty acids from food is beneficial for the heart, recent studies suggests that EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)—the main types of omega-3 fatty acids—in supplement form—have little to no cardiovascular benefits.


This mighty mineral is important for neurological and metabolic function, as well as sleep , muscle repair, anxiety , and heart health. But “because our soil is depleted of magnesium due to the way we farm things now, everybody doesn’t get enough of this nutrient,” Palma says. Research has even shown that 48 percent of the U.S. population consumes less than the recommended amount of magnesium from food. Palma recommends magnesium glycinate as one of the best magnesium supplements for most people because it helps with muscle relaxation and sleep and is more easily absorbed by the body than other forms of magnesium. Another reason to add this supplement to your routine? A 2018 study in The Journal of the American Osteopathic Association shows that low magnesium levels can make vitamin D ineffective.


Our farming practices have evolved so much throughout time that we aren’t exposed to as much good bacteria we used to get from our soil, Palma says. As a result, our guts are depleted of adequate amounts of the good bacteria it needs to boost immunity and perform normal digestive functions. Even if you’re eating plenty of fermented foods in your diet, like sauerkraut, kimchi, and yogurt, Palma recommends taking a broad-spectrum, medical-grade probiotic to help restore the good bacteria you might be missing after battling an infection and taking antibiotics.

While there are different strains of probiotics that address certain IBS issues, like diarrhea and constipation , Palma says transient commensals, when taken regularly, is one of the best probiotic supplements for any situation. “Transient commensals don’t stay in the gut. They live for only about three weeks, but they improve the quality of the bacteria that lives there and discourage bad strains,” Palma says.

Vitamin K

If foods high in vitamin K—like spinach, kale, broccoli, and carrot juice—are mainstays in your diet, you might be thinking that you’re getting plenty of this mineral. But there are actually two different types of vitamin K : K1 (phylloquinones) and K2 (menaquinones). K1 is primarily found in plants while K2 is in fermented foods and animal products. Your body also produces some K2 on its own but not enough of it. “You can get K2 from foods like grass-fed dairy and natto, but if you’re not eating a lot of these foods, I recommend a K2 supplement . K2 is the trafficker for calcium and delivers it to your bones and teeth where you need it—not your heart. For this reason, I recommend vitamin K2 for people with heart disease too,” Palma says.


Not everyone needs a multivitamin, but for some people they can help to fill any remaining nutritional gaps. “But the problem with most over-the-counter multivitamins is that there’s not enough of the stuff you need in them. There are many multivitamins that also contain toxic nutrients, like supplemental calcium, iron, and folic and acid,” Palma says. High doses of these supplemental vitamins can be toxic and lead to heart issues and pregnancy complications. If your doctor suggests a multi, Palma recommends opting for a food-based multivitamin that allows you to address a variety of nutrient deficiencies with one supplement. Food-based multis, in comparison to synthetically derived multis, contain nutrients extracted from vegetables, fruits, and medicinal plants that your body easily recognizes and absorbs as whole-food complexes. The bottom line is if your doctor doesn’t think you need a multivitamin, then it’s best to avoid taking one.

Tiffany Ayuda

Tiffany Ayuda is a New York City-based editor and writer passionate about fitness, nutrition, health, and wellness. She has held previous editorial roles at Prevention, Eat This, Not That, Daily Burn, and Everyday Health. Tiffany is also a certified personal trainer through the American Council on Exercise. When she's not writing or breaking up a sweat, Tiffany enjoys cooking up healthy meals in her Brooklyn kitchen.

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