The benefits of vitamin D3 are extraordinary because this nutrient actually acts as a hormone in the body. It plays a major role in reducing autoimmune disease risk, mood disorders, and chronic pain — beyond its well-known role in bone health.

Chrissy Carroll, RDN notes that even healthy athletes are routinely low in vitamin D, especially those who train indoors or live in northern climates. Many experts recommend checking vitamin D blood levels at least twice a year.

Vitamin D3 works best when paired with the lesser-known vitamin K2 (as MK-7). K2 acts as a traffic director: it guides calcium into bones and teeth — away from arteries, where it can cause harm. This combination is especially important for heart health and digestive health. Even children are surprisingly low in this newly recognized essential nutrient.

Magnesium participates in over 300 enzymatic reactions and 80% of our metabolic functions, yet over half of Americans get less than the recommended amount. Modern farming depletes soil magnesium, many medications cause losses, and exercise accelerates depletion further.

Magnesium is helpful for IBS and constipation, and it may reduce hot flash severity and improve sleep quality. Research also shows supplementation can lower blood pressure and improve blood sugar in people with diabetes.

Not all forms are equal. Magnesium glycinate is best absorbed and easiest on digestion. Magnesium citrate works well for constipation. Avoid magnesium oxide — it has poor bioavailability and mostly just acts as a laxative.

Fish oil, found primarily in oily fish, is rich in EPA and DHA — essential omega-3 fatty acids most Americans don’t get enough of. Registered Dietitian Moushumi Mukherjee, MS, RDN recommends fish oil supplementation to help reduce cholesterol and triglycerides.

Omega-3s support joint, heart, brain, skin, dental, and immune health. Research links higher fish oil intake to significant reductions in healthcare costs and improved cognitive development in children.

Quality matters enormously: most commercial fish oils are in ethyl ester form, which is poorly absorbed. Cod liver oil is naturally in triglyceride form — the best-absorbed option — and may also improve bone density. See the best cod liver oil supplements for top picks.

Registered Dietitian Doug Cook, RDN champions vitamin C for optimal health. This essential antioxidant reduces the risk of respiratory infections, lowers inflammation, and supports anti-aging by helping the body synthesize collagen. It also reduces histamine release from mast cells, making it valuable for allergy sufferers.

The best supplemental form is liposomal vitamin C, which encases vitamin C in a fat-soluble membrane for dramatically improved absorption compared to standard ascorbic acid. This can be especially valuable during illness or times of high physical stress.

Probiotics have become mainstream for very good reasons — as beneficial bacteria, they influence systems far beyond the gut. From reducing the risk of candida and UTIs to easing menstrual symptoms, the evidence base is broad and growing.

Research shows probiotics reduce symptoms of anxiety and stress. According to dietitian Anne Marie Berggren of Root Deep Nutrition, probiotics can be a simple step toward better mood and reduced depression symptoms. They also address IBS and SIBO and reduce acid reflux symptoms.

Children benefit significantly from probiotics too — from better immunity to reduced colic and ear infections, according to Registered Dietitian Danielle Omar, RDN.

B vitamins are actually eight distinct nutrients, each with unique functions. Together they help convert food into usable energy and support nerve, brain, and cardiovascular health. Here’s a quick overview:

• B1 (Thiamine) — Converts glucose to energy. Depleted by sugar, processed foods, alcohol, and many medications. Learn more about thiamine benefits.
• B2 (Riboflavin) — Acts as an antioxidant and helps convert tryptophan to niacin. Responsible for the yellow color in urine after taking B-complex supplements.
• B3 (Niacin / NAD) — Deficiency is far more common than recognized. Supports protein and carbohydrate metabolism. Learn about NAD supplement benefits.
• B6 (P5P / Pyridoxal-5-Phosphate) — Critical for protein metabolism, mood, stress reduction, and reducing kidney stone risk.
• B9 (Folate) — Essential for reproduction and reducing inflammation. Choose methylfolate over synthetic folic acid for better utilization — especially important for people with MTHFR gene variants.
• B12 (Cobalamin) — Deficiency linked to nerve damage and anemia. Restrictive diets and low stomach acid are the most common causes of B12 deficiency.

For a whole-food source of all B vitamins, the best option is grass-fed beef liver. When supplementing, choose a methylated B-complex with natural, bioavailable forms.

As a critical antioxidant found in every cell, coenzyme Q10 (CoQ10) has few downsides and significant benefits for most people. It plays a central role in mitochondrial energy production and reduces oxidative damage throughout the body.

CoQ10 is especially important for people taking statin medications or blood pressure drugs, as these commonly deplete CoQ10. People with fibromyalgia, migraines, neurological diseases, and chronic fatigue often see meaningful improvements when supplementing. Drug interactions are rare.

You can get a flu shot, but are you getting enough zinc? According to Registered Dietitian Doug Cook, RDN, low zinc levels significantly increase susceptibility to infections including colds and influenza. Low zinc also contributes to sexual dysfunction, acne, allergies, and diarrhea.

Many common medications deplete zinc — including proton pump inhibitors (PPIs), ibuprofen, and blood pressure medications. The typical American diet is also consistently low in zinc, making modest supplementation reasonable for many people.

Choline may be the most overlooked essential nutrient in America. It’s a critical building block for virtually every cell — yet research shows over 90% of Americans don’t eat adequate amounts, including pregnant and breastfeeding women.

Health writer and dietitian Elizabeth Ward, MS, RD identifies choline as a very common deficiency. Registered Dietitian Brittany Poulson advocates for higher choline in prenatal vitamins — since most prenatal vitamins don’t contain it at all.

Low choline is linked to increased risk of liver disease, heart disease, and neurological conditions. It may also help gallbladder health. The best dietary source is eggs — and liver, which can meet nearly 100% of daily needs in a single serving.

If you avoid or limit animal foods, a choline supplement is advisable. Supplemental doses around 250 mg/day are generally well tolerated. Regarding TMAO concerns: research shows choline supplementation does not reliably raise TMAO, and choline-rich eggs do not raise cholesterol, contrary to earlier fears.

Turmeric has been used medicinally for thousands of years, and modern science is validating its value. Research confirms curcumin — turmeric’s active compound — reduces inflammatory markers and can ease joint pain in people with rheumatoid arthritis. Other studies suggest benefits for reducing depression symptoms.

The main challenge with turmeric is absorption. Standard curcumin powder has very poor bioavailability. According to dietitian Anne Marie Berggren, RDN, CurcuRouge® (found in Curalieve by Integrative Therapeutics) is among the most bioavailable forms. Thorne Curcumin Phytosome is another well-researched highly bioavailable option.

For those seeking broad anti-inflammatory benefits, black seed oil is another excellent natural option to consider alongside turmeric.