The five supplements you should always AVOID 


Last year, around 75 percent of Americans took dietary supplements. That’s great news—especially considering the backslide in wellness care that occurred in 2020.  

But even though smart supplementation can enhance a healthy lifestyle, you MUST be careful.  

There’s a lot of JUNK on the market. And there’s a lot of MISINFORMATION about which supplements help support your overall health and well-being. There are also medical myths about supplements that remain common among doctors, who don’t know or understand the real science.  

So, today, let’s go over five supplements you should always AVOID. Then, I’ll tell you about four science-backed supplements that BELONG on your “starting line-up”…

Five supplements to AVOID at all costs

In 2020, the U.S. dietary supplement industry raked in nearly $50 billion. That’s a staggering amount of money, by anyone’s standards. This success, however, tends to attract manufacturers who are looking to make an easy buck producing low-quality, underperforming, or even harmful products.  

So, here are five supplements you should AVOID at all costs—for various reasons… 

1.) Multivitamins. As I often report, avoid spending your hard-earned money on expensive, over-hyped, underperforming multivitamins. After all, it’s physically IMPOSSIBLE to get all the minerals, micronutrients, and vitamins that you should take daily—in all the right doses, in all the right forms—into a single, little, one-a-day pill.

It just doesn’t add up. And any brand-name formula that promises otherwise is stretching the truth. Pure and simple.

2.) Iron (in any form). Unless you’ve been diagnosed by a physician, through blood testing, with iron-deficiency anemia, you should avoid taking iron supplements. (That includes any one-a-day multivitamin that contains iron, too!)  

For one, a recent study found that iron can damage your DNA in as little as 10 MINUTES! Plus, other research links excess iron to an increased risk of cancer, organ failure, heart disease, infections, and glaucoma. 

The fact is, your body naturally accumulates and contains just about all the iron it needs (about 4 grams). It’s stored inside hemoglobin in your red blood cells and gets recycled by your body. So, for most people, there’s NEVER any need to supplement with iron in any form or fashion. You get enough from a healthy, balanced diet. 

3.) Fiber. Here is another example of a nutrient that NEEDS to come from your diet and not from supplements. You should ALWAYS get your fiber from eating whole foods. In fact, if you consume your recommended five fruits and vegetables daily, you take in plenty of both soluble and insoluble fiber. So, there’s never any need to supplement with a fiber pill—or to reach for artificial fiber supplements or fake food items with added fiber. 

4.) Vitamin A. I don’t recommend taking a vitamin A supplement—unless it’s part of a specific treatment (usually combined with vitamin E), under direct supervision of a physician.  

That’s because you can safely get all the vitamin A you need from a healthy, balanced diet. In fact, green, leafy vegetables and yellow-orange-red vegetables, in particular, contain colorful carotenoids, which your body naturally and safely converts into all the active vitamin A it needs. 

5.) Calcium. I know many doctors recommend their older female patients take calcium to support strong bones and prevent osteoporosis. But following that misguided recommendation can actually cause FAR more harm than good…for five big reasons. 

For one, high calcium intake from supplements increases the risk of dementia, kidney stones, and prostate cancer. Second, calcium supplements may affect your thyroid’s hormone production. Third, calcium can interfere with certain antibiotics. (Although I also generally advise against taking these drugs in most instances.) Fourth, excess calcium can interfere with absorption of other minerals taken at the same time. 

Fifth, and perhaps most importantly, research links calcium supplementation with cardiovascular disease, the No. 1 killer in the U.S. 

Now, let’s move on to the four supplements that BELONG in everyone’s daily regimen… 

Your “starting line-up” of science-backed supplements 

Of course, before I get into the supplements that EVERYONE should take daily, please make note of this key point… 

Nutritional supplements are meant to supplement (NOT replace) a healthy, balanced diet—like the Mediterranean diet. (On this type of diet, you can enjoy: free-range, grass-fed and -finished meats; wild-caught fish and seafood; organic fruits and vegetables; full-fat, whole-milk dairy [including milk, yogurts, and cheese]; seeds and nuts; and alcohol in moderation.) 

Then, these basic nutrients can support all of the health benefits of following a proper diet and make sure you’re not missing anything: 

  • Vitamin C—250 mg twice per day, for a total of 500 mg daily (if you sometimes have difficulty getting your full five daily servings of fruits and vegetables). 
  • Vitamin D3—250 mcg (10,000 IU) per day. 
  • Vitamin B complex—with at least 5 mg of B6. 
  • Fish oil—dosage depends entirely on your weekly fish consumption, as I often report. 

From there, you can add certain supplements to target specific areas of concern. For example, I highly recommend my ABCs of joint health (ashwagandha, boswellia, and curcumin) for anyone experiencing joint pain and inflammation. And tomorrow, I’ll tell you about a natural berry extract that shows promise for boosting metabolism. 

Now, before I go, here’s one last tip… 

Be choosey about WHERE you get your supplements 

I recommend against buying supplements (or anything else, for that matter) from big retail outlets. Scientific studies, and even consumer legal actions, show time and again they can’t be trusted. Instead, I urge you to do your research and purchase high-quality supplements. 

You’ll want to choose a company that bases each and every formula on the most up-to-date scientific research available. One that looks to human control studies first to help them build products that deliver real, life-changing results. 

And one of the simplest ways to spot a high-quality brand is by looking at their refund policy. Do they offer a 100% Money-Back Lifetime Guarantee—so that if any specific formula doesn’t meet your expectations, you can return it for a full refund? By doing so, the company is basically putting their full trust within a product. 

So, in 2021, make this positive change for yourself: Choose high-quality supplements. And leave the unnecessary junk, often peddled by deceptive retailers, out to dry. 

Always on the side of science, 

Marc S. Micozzi, M.D., Ph.D. 

P.S. I’m always working diligently to bring you the latest science on nutritional supplements. And that includes which dietary supplements I believe are—and aren’t—the best for your health. In fact, I spell it all out for you in the January 2018 issue of my monthly newsletter, Insiders’ Cures (“Ring in the New Year with the right supplements”). So if you haven’t already, consider signing up today. Click here now! 



“CRN Consumer Surveys Find Changes in Supplement Use in 2020.” American Botanical Council, accessed 9/28/21. (