top of page



The problem with discussing vitamins is that the scope is extremely large.  Which vitamins?  There are so many.  Defining a vitamin versus a supplement?   What are we using the vitamins for?  To prevent illness, cancer, heart disease?  To promote mental health, prostate health, or even prevent dementia?


Another issue is that people are extremely invested in their vitamins…literally.  There is variation but the most widely quoted statistics come from the National Health Interview Survey (NHIS) conducted yearly by the CDC.   There is further variation defining vitamin and supplement and powder versus complementary medicine practitioners.  But the following is a decent breakdown from the NHIS from 2022:


“About 59 million Americans spend money on out-of-pocket complementary medical services and this adds up to about $30.2 billion per year.”


“About $14.7 billion on complementary health practitioners; almost 30% of what is spent on traditional physicians.”


“About $12.8 billion on vitamins and supplements; about 25% of what is spent on prescription drugs.”


On average, per American, that’s about $65 per month. 


And, I would finally like to add, most Americans typically don’t get their information from physicians.  There are two likely reasons for this:

  1. Vitamins are really not discussed at all in Medical school nor residency and so physicians are not well versed.

  2. The general consensus is that Vitamins are not typically necessary for those with good diets and good health.




Perhaps you recall Airborne.   This was touted for years as something to help prevent getting the common cold.  You probably do remember it because everyone recommended it.  So much so that the company got sued for false advertising in 2008 and had to pay out $23 million dollars.  Airborne is simply a collection of several vitamins and no study ever found that it actually worked to prevent colds. 



Prevagen.  This is the supplement being marketed against memory loss.  The main ingredient in Prevagen is Apoaequorin, a protein originally derived from the luminescent proteins of jellyfish.  And it is a big seller.  I simply couldn’t find recent results, but as of 2015 it had sold $165 million dollars’ worth of the product without a single study showing efficacy.  In fact, there has only been ONE study that I could find.  It is from Quincy Bioscience—the company that makes Prevagen.  And their results: “No statistically significant results were observed over the entire study population.”   Though they did do a post study analysis to find a few subsets of patients who gained some benefit, it’s hard to get behind this drug with not a single peer reviewed study showing improvement.   Lastly, I tried to find any mention of this drug on the peer reviewed website Up to Date—not a single reference.



VITAMIN D—So much has been discussed about this vitamin.  One thing I personally found very curious was the change to the ‘normal’ level from 20 to 30 about ten years ago.  Almost everyone had normal Vitamin D levels when 20 ng/mL was the standard.  Suddenly after raising to 30, there was a huge number who were suddenly ‘abnormal.’   According to the National Academy of Medicine, approximately 97.5% of people have their vitamin D needs met at > 20 ng/mL. 

The conclusion from the United States Preventative Service Task Force is that “The evidence is insufficient to assess the balance of benefits and risks of screening for Vitamin deficiency in asymptomatic adults.”

Below is a list of studies which led them to this conclusion.


  1. Eight randomized controlled studies (RCT’s) reporting on ‘all-cause mortality’.No difference was found for those getting Vitamin D than those without.This included a study from the Women’s Health Initiative.

  2. Six RCT’s showing no difference in the incidence of fractures.

  3. Five RCT’s showing no difference in the incidence of diabetes.

  4. Two trials regarding cardiovascular events showed no statistical difference

  5. Two trials regarding incidence of cancer found no difference.

  6. Nine trials reported on falls in community-dwelling adults.Roughly half of the trials found no statistical difference, the other half showed about 25% fewer falls.(though I must admit, I don’t understand the proposed mechanism between Vit D and falls)

  7. Three trials discussed depression and, again, no difference was found.


Harms of Vitamin D supplementation.  There really aren’t any that have been found. 


More on Vitamin D.  There are two types: 

Vitamin D2 (ergocalciferol) typically found in plant sources

Vitamin D3 (cholecalciferol) only found in animal sources


What test to run?   This is a little complicated but to summarize, the best blood test to run to evaluate is the 25 hydroxy (OH) vitamin D level known also as Calcidiol or Calcifediol.


What is the optimal level?  No one can agree.  Some say > 20 ng/mL. The majority currently say > 30 ng/ mL. 


Greatest consensus on when to supplement?

--Older adults with osteoporosis

--Breast cancer and Colon cancer.  There is evidence that higher levels of Vitamin D are beneficial for both of these cancers.  Further, treatment of breast cancer (blocking estrogens) can increase risk of Osteoporosis and for this reason is typically recommended. 


How much to take?  There really is no consensus here either.   Recommended daily allowance is 600 international units/ day (15 mcg).  Supplementation is often in the 600-800 IU/ day. 


Final thoughts on Vitamin D. 


Why is there more discussion now about Vitamin D deficiency?  It’s likely because there IS more deficiency than before.  It is a fat-soluble vitamin.  As the population has gained weight, there is more in fat cells and less available in the blood.  AND…we are trying to avoid skin cancer.  Staying indoors, wearing sun screen and more clothes lowers risk of skin cancer but decreases the amount of Vitamin D we produce. 



Perhaps the biggest proponent was Linus Pauling—a true genius who is one of only a handful of people to have won two Nobel Prizes.  I met him while I was in medical school.  At that time, in his 90’s, he continued to believe that mega doses of Vitamin C (he took 6 grams/ day) prevented the Common Cold and could lower risk of cancer. 


Vitamin C first gained notoriety as the cure for Scurvy.  In fact, this was really the first time that there was an association between specific foods and health.  As opposed to the idea of just getting enough calories.  Think of the pirate who didn’t have access to fruits and vegetables.  Yes, he may get enough calories from bread, but without specific Vitamins, health would suffer.  Symptoms of scurvy  can begin as early as three months but worsened as time goes on.

--small bruises around hair follicles, twisted/ coiled hairs

--gingivitis with bleeding gums and cavities

--severe musculoskeletal pain, so bad that children would often limp or refuse to walk

--weakness, shortness of breath, low blood pressure

--death was often from poor wound healing and then infection


Amazing bit of trivia, “Far more sailors died from the ‘plague of the sea’ (2 million) than all other disease combined including combat, storms, disasters and shipwrecks.” And it wasn’t until the mid-1700’s that Captain James Cook prevented scurvy by making his sailors take citrus and eat sauerkraut. 


So, how much do we need?   It’s dependent primarily on weight (children needing less) but the recommended daily allowance is from 15 to 90 mg / day.   Again, recall that Linus Pauling recommended 6,000 mg / day.  What is proposed that we gain from taking ‘extra’



--In the Physicians’ Health Study 2, over 14,000 males age > 50 were randomly assigned to receive Vitamin C 500 mg daily or placebo.  After eight years of treatment, there was no difference in the incidence of cancers, and during an additional three years of post-trial follow-up, there was no difference in the risk of all cancers and prostate cancers between the two groups.


--In an analysis of the Women’s Antioxidant Cardiovascular Study including almost 8,000 females, vitamin C 500 mg daily for 9.4 years had no effect on the incidence of cancers


Cardiovascular disease--Randomized trials have shown no benefit of Vitamin C for primary or secondary prevention of Cardiac disease.


Infection—Vitamin C may have a minor role in reducing the duration of cold symptoms in adults, although the clinical importance of this is likely small.  Further, there is no evidence that regular Vitamin C supplementation reduces the incidence of the common cold.


Kidney stones—Vitamin C increases urinary oxalate excretion and may increase the risk of kidney stones.


Cataracts and macular degeneration—In randomized trials, there was no benefit of Vitamin C supplementation in the primary prevention of cataracts or macular degeneration.


I’ll conclude the Vitamin C part with more controversy—Intravenous therapy.  IV therapy is used not only for Vitamin C but other vitamins as well.  Part of the debate is that when given intravenously, it bypasses the bodies normal mechanisms of absorption and excretion leading to perhaps toxic doses.  An example would be the Sepsis (overwhelming infection) study from June 23, 2022 in the New England Journal of Medicine.  In this study of over 800 patients, half got about 4,000 mg. of Vitamin C via IV for 28 days, the other half got nothing.  Vitamin C group 35% died

                                                   Placebo group    31% died


Regarding cancers.  An excellent discussion from the National Institute of Health can be found from the following webpage:

One thing fascinating it brings up is that the two studies from the Mayo clinic that refute the benefit of Vitamin C to improve longevity and quality of life with those who have cancer used the oral route.  The study that Linus Pauling did to reduce cancer mortality used the intravenous route. 




PROSTATE HEALTH—There are two major players in the market for prostate health:  Saw Palmetto and Beta-sitosterol (Beta prostate).


Saw Palmetto

--1998 there was a systematic review from 18 European countries which concluded there was ‘promising evidence’ of its benefits.

--2012 a larger systematic review from 32 randomized trials found no benefit

--2021 another meta-analysis with 27 different trials concluded, “with high certainty that the use of Saw Palmetto resulted in little or no short or long-term benefits in lower urinary tract symptoms nor quality of life.”



--a meta-analysis showed improvement in urine flow rates and symptoms scores, the problem of study design precluded strong inferences.


In 2011, the American Urological Society recommended against both of these agents.





There are too many choices and brands to discuss specifics.  But, the two largest trials that I could find were as follows:


In a trial conducted among 21,442 older adults in the United States, a daily multivitamin and cocoa extract supplement did not reduce the incidence of invasive cancer compared with placebo.


In a 2021 evidence review for the US Preventive Services Task Force including 84 trials (739,803 people included), vitamin and mineral supplantation was associated with little or no benefit in preventing cancer, cardiovascular disease, and death with the exception of a small benefit for cancer incidence with multivitamin use.  (I delved into this part further.  The benefit for “any” cancer was an odds ratio of 0.93.  But if you took beta carotene it increased your risk of lung cancer to an odds ratio of 1.20).


It was for these reasons that the USPSTF and the NIH (National Institute of Health) stated in 2021 that they don’t recommend supplementation for those in good health with normal diets. 



CONCLUSION:  A fair statement to say is that most studies on vitamins and supplements are not good studies.  The reason is there isn’t the money to study them.  Why would a company study Vitamin C and spend millions of dollars when you could get the benefits (if found) from Minute Maid orange juice for five bucks? 

There is also a definite concern with the ‘purity’ of the products out there.   Studies like those from ConsumerLab in 2020 are not unique.  This study found that 44% (12 out of 27 brands evaluated) had either too much, or too little of the products claimed on the label.  


At the end of the day, it is often remarked, “consult your physician.”  I will gladly continue to research and discuss any specific supplement you are interested in learning more about.  And though I will keep an open mind, I feel that Vitamins are a lot like politics, we focus on the studies that are consistent with our beliefs. 

bottom of page