Episode 53 – Should You Take A Multivitamin?

Key Topics Covered

Reasons to take a multivitamin 

  • It can cover a lot of gaps in your diet – the average person has ~33% of calories coming from “discretionary” food. So, what if you have a below-average diet? It is very likely there is a sub-optimal intake of a lot of nutrients. 

Examples:

  • Low socioeconomics – struggle to consume enough food.
  • Picky eaters, range of allergies/intolerance, food aversions, disordered eating, large calorie deficit 
  • Bariatric surgery – especially in the first 12 months post-surgery  
  • Being in a large calorie deficit.

On average, it takes around 80% of your diet to reach 100% of your nutrient intake. So what if you go into a calorie deficit? You’d need 100% of your diet coming from nutrient-dense foods. Therefore, taking a multivitamin will help bridge this gap when in an extreme calorie deficit.

Reasons not to take a multivitamin  

  1. If you have a great diet, you could already have an appropriate amount of each micronutrient 
  2. Cost-to-benefit ratio 
  3. Potential for excessive supplementing of any individual nutrient – particularly if you take other supplements 
  4. Nutrient interactions – competing for absorption – even though it covers gaps, it can’t have enough iron or calcium for example, since they compete for absorption 
  5. It also cannot cover EVERYTHING. There are a whole bunch of other things we care about in food. For example, there are ~8000 types of polyphenols. We can’t include everything in a man-made product the way it is included naturally in the food matrix.  

Effects on longevity 

  • Iowa Women’s Health Study – this is the most commonly cited study on the topic 
  • Included almost 40,000 women >55 years old  
  • Vitamin and mineral supplementation INCREASED mortality.  
  • The issue though is that this is like a food frequency questionnaire.  
    • It’s just asking what people have and then measuring outcomes. Rather than randomising people into groups and controlling variables. 
    • SO PEOPLE THAT TOOK MULTIVITAMINS MAY ALSO BE MORE LIKELY TO DO OTHER THINGS THAT INCREASE MORTALITY RISK  
    • The trial did not exclude people with illnesses from being included. What if those who had more issues were more likely to supplement with vitamins and minerals? Therefore this could literally just be identifying that those who were sicker had higher mortality rates, for example.  
  • A review from 2019 covered 277 studies on the topic and identified that vitamin and mineral supplementation was not linked with reduced mortality. Folate had a small link, but that link was found most strongly in China where the authors highlighted that folate deficiency is far more common.  
  • The current consensus is that multivitamins do not increase longevity on average.  

An alternative supplementing each thing you need individually 

  • Arguably it makes sense to identify which nutrients you have a sub-optimal intake of. Then supplement those individually  
  • But obviously, this is not practical for everybody, since you need to know how to identify sub-optimal intake. 

Practical takeaway 

  • If there are a lot of inadequacies in your diet, a multivitamin could be a great option to help address these gaps. 
  • Otherwise, it could be best to either just focus on the overall diet OR cover easily identifiable gaps individually.  

Relevant Links/Resources: 

Studies Mentioned:

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