Vitamin Brands to Avoid – What to Watch Out For

author avatar Dr. Eric Berg 04/22/2024

Not all vitamin supplements are created equal. While some vitamin and mineral supplements use natural ingredients, others are made with synthetic nutrients that are poorly absorbed and may increase the risk of adverse health effects.

Here are the red flags to look for when choosing a dietary supplement and the vitamin brands to avoid. 

Selection of dietary supplements

Synthetic vs. natural

Natural vitamin and supplement brands contain essential vitamins, minerals, antioxidants, or other health-promoting nutrients naturally occurring in whole foods. 

They’re typically extracted from food sources such as plants or herbs by grinding or juicing, followed by dehydration to form a powdered substance that can be incorporated into pills or capsules.

In contrast, synthetic nutrients are created in laboratories using chemical processes to produce artificial compounds that mimic the chemical composition of naturally occurring nutrients.

Not only are synthetic vitamins less potent and not as well absorbed as their natural counterparts, but they may also pose potential health risks if taken for prolonged periods. 

“Although synthetic vitamins are structurally similar to natural ones, they typically lack the cofactors and co-nutrients present in natural sources, which are important for optimal nutrient absorption and utilization,” explains Dr. Berg. 

Artificial nutrients are cheap to produce, and almost all multivitamin and mineral supplements available in drug stores and supermarkets are made with synthetic ingredients.

In contrast, extracting vitamins from natural food sources is a laborious and expensive process, which is why supplement brands containing natural ingredients are often considerably more expensive. 


Watch the video below to discover why you should avoid multivitamin brands containing synthetic nutrients.

8 vitamin brand red flags

It’s estimated that more than 50 percent of adults in the U.S. take at least one dietary supplement to prevent nutrient deficiencies and promote optimal health.

While dietary supplements can provide health benefits when combined with a healthy lifestyle, it’s crucial to choose high-quality products containing natural nutrients.   

Here are eight red flags to watch out for when selecting supplements. 

1. Vitamin D3 supplements without vitamin K2

It’s well known that vitamin D plays a crucial role in bone health, immune system function, and overall well-being.  

A lesser-known fact is that vitamin D3, the natural form of this fat-soluble vitamin, should always be combined with vitamin K2.  

Vitamin D3 stimulates intestinal calcium absorption and raises blood calcium concentrations. This can increase the risk of calcium deposits in arteries and soft tissues, which is linked to poor cardiovascular health and joint issues.  

Vitamin K2 directs calcium from the blood into the bones. This not only promotes skeletal health but also prevents soft tissue calcification, which explains why it’s crucial always to take vitamin D3 with vitamin K2

Research published in BMJ Open investigated the combined effects of vitamin D3 and K2 and concluded, “The combination of vitamin D and vitamin K showed a lower increase in carotid intima-media thickness, a marker of arterial calcification, compared with vitamin D alone.”

2. Products made with synthetic vitamins 

Because synthetic vitamins are easy and cheap to produce, many supplement manufacturers opt for artificial forms over natural ones. 

However, synthetic nutrients are less effective than natural vitamins and often are produced using harsh chemicals deemed unsafe for human consumption.  

According to a study published in Free Radical Research, certain synthetic supplement brands contain residues of pesticides, heavy metals, hexane, petroleum, and pharmacologically active ingredients. 

Prolonged low-dose exposure to such contaminants has been connected to various health issues, including neurological and hormonal issues, liver problems, and an increased risk of cancer.  

It’s best to avoid supplement brands containing synthetic vitamins, such as:

  • Retinol palmitate, a synthetic form of vitamin A

  • Vitamin D2 or ergocalciferol, a synthetic form of vitamin D

  • Dl-alpha-tocopherol, a synthetic form of vitamin E

  • Vitamin K3, also known as menadione, a synthetic form of vitamin K

  • Pyridoxine hydrochloride, a synthetic form of vitamin B6

  • Cyanocobalamin, a synthetic form of vitamin B12

  • Ascorbic acid, the synthetic form of vitamin C

It’s especially important to avoid prenatal vitamins containing ingredients such as retinol palmitate, the synthetic form of vitamin A, which has been linked to a higher risk of congenital disabilities. 

In addition, pregnant women shouldn’t take a daily multivitamin with Dl-alpha-tocopherol and ascorbic acid, as these artificial nutrients can lead to blood clotting issues and other pregnancy-related complications.  

Gummy vitamins

3. Gummy vitamins 

Many gummy vitamins are designed to appeal to children with their fruity flavors and chewable texture. However, these supplements are often laden with sugar, which can promote weight gain and dental decay

These products also are typically made with synthetic vitamins, which are poorly absorbed and less effective than natural ones. Relying on gummy multivitamins to obtain essential nutrients may increase the risk of nutritional deficiencies. 

In addition, some gummy vitamin brands are inaccurately labeled, and false claims about the nutrient dosages have been made.   

Research published in the Journal of the American Medical Association found that the majority of melatonin gummy products tested contained between 17 and 470 percent of the melatonin dosage stated on the product label.  

4. Supplements containing megadoses  

Synthetic vitamins tend to have lower absorption rates than naturally occurring vitamins. As a result, synthetic supplements are often formulated with extremely high nutrient concentrations of up to 400 percent of the recommended daily allowance (RDA) to compensate for a lower absorption rate. 

However, nutrient absorption varies among individuals, and synthetic supplements can lead to excessive vitamin levels, a condition known as hypervitaminosis, linked to various health issues.  

People with liver or kidney disease often experience impaired detoxification and elimination processes, leaving them at an increased risk of hypervitaminosis when taking synthetic supplements.

It’s essential to check the labels of the supplement you plan to use and avoid vitamin brands that contain megadoses of synthetic vitamins to minimize the risk of vitamin toxicity and associated health consequences.

Fish oil capsule

5. Unpurified omega-3 fish oils 

Adequate intake of omega-3 fish oils has been linked to better cardiovascular health, and fish oil supplements are among the most popular dietary supplements in the United States. 

However, the quality of fish oil supplements can vary significantly, and it's essential to choose high-quality products to ensure safety and effectiveness.

Large predatory species of oily fish can accumulate mercury, lead, and other toxins, such as dioxins, via the food chain, which increases the risk of contaminated omega-3 fish oil. 

A study published in Environmental Science and Pollution Research found that certain fish oil supplements regularly exceed safe limits of harmful pollutants, including lead.    

Long-term heavy metal exposure is associated with serious neurological issues, and it’s crucial to choose products that underwent purification processes and third-party testing to ensure purity and the absence of contaminants. 

6. Mineral complexes with inorganic chelators 

Essential minerals such as iron, calcium, magnesium, manganese, and copper must be bound to an organic compound known as a chelator to be absorbed into the body.  

Unfortunately, many cheap mineral supplements use inorganic chelators to bind minerals, including oxides, hydroxides, and phosphates. These chelators aren’t well absorbed and are more likely to cause digestive issues and side effects. 

In contrast, certain amino acids are natural chelators that enhance mineral absorption and are less likely to cause digestive discomfort or irritation than inorganic minerals.

Avoid supplements containing inorganic mineral complexes such as:

  • Magnesium oxide

  • Magnesium hydroxide

  • Magnesium sulfate

  • Iron oxide

  • Zinc sulfate

  • Calcium carbonate  

  • Chromium picolinate 

  • Sodium selenite 

Instead, opt for a mineral supplement that contains minerals bound to natural chelators, including glycine, histidine, cysteine, and glutamic acid.

Pills filled into a container

7. Products with unnecessary fillers 

Many supplement manufacturers use fillers, preservatives, flavorings, and dyes to enhance the appearance, taste, and shelf life of their products. 

However, these ingredients may pose risks, including allergic reactions, gastrointestinal issues, and long-term health effects. 

In addition, certain fillers are derived from genetically modified organisms (GMOs), which have been connected to fertility problems, neurological issues, and poor liver function.

Check supplement labels and avoid products made with unnecessary fillers, such as:

  • Cornstarch

  • Hydrogenated palm oil

  • Soybean oil

  • High-fructose corn syrup  

  • Artificial sweeteners 

  • Artificial food dye

  • Magnesium stearate 

  • Sodium benzoate

  • Titanium dioxide  

8. Low-potency probiotics 

Low-potency probiotic products may not deliver enough live bacteria into the intestinal tract to provide significant health benefits. 

The harsh acidic conditions in the stomach typically lead to lower survival rates of probiotic bacteria, limiting their effectiveness in supporting gut health, immune function, and overall well-being.   

It’s generally recommended to take probiotics with at least 60 billion colony-forming units (CFUs), a measure of how many viable microorganisms are present in a probiotic supplement.  

Woman reading a supplement label

Key takeaways

Vitamin and mineral supplements can play a crucial role in maintaining optimal nutrient stores. However, the quality of dietary supplements varies widely, and it’s important to know which vitamin brands to avoid.

To minimize the risk of adverse health effects, hypervitaminosis, and heavy metal exposure, it’s crucial to check labels and avoid products made with synthetic nutrients, supplements containing unnecessary fillers, unpurified omega-3 fish oils, and gummy vitamins.   


1. What are the top vitamin brands to avoid?

It’s recommended to avoid vitamin brands containing synthetic nutrients, inorganic mineral complexes, and potentially harmful fillers such as hydrogenated oils, preservatives, artificial sweeteners, and flavorings.

In addition, unpurified omega-3 fish oils, vitamin D3 supplements without vitamin K2, and low-potency probiotics may not offer significant health benefits and can increase the risk of health issues.

2. What should I look for in a supplement brand?

To maximize health benefits and reduce the risk of adverse side effects, it’s best to opt for supplements made with natural vitamins and organically chelated minerals without unnecessary fillers and preservatives.

In addition, choose products with transparent labeling, third-party testing, and good manufacturing practices (GMP) certification.

3. What supplements should I avoid?

It’s best to avoid supplements made with synthetic vitamins and minerals bound to inorganic compounds. These artificial nutrients aren’t as well absorbed as natural vitamins and are associated with an increased risk of side effects. 

It’s also important to avoid unpurified omega-3 fish oils, probiotic supplements containing less than 60 billion colony-forming units, and vitamin D3 supplements without vitamin K2. 

4. Are natural vitamins better than synthetic ones?

Yes, natural vitamins are better than synthetic ones. While natural vitamins are derived from whole foods, synthetic supplements are manufactured in laboratories.

Natural vitamins are typically more readily absorbed and potent than synthetic nutrients. In addition, synthetic vitamins carry a higher risk of side effects and may contain harmful chemical residues due to their manufacturing methods.






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