Following some great questions from City Survivor regulars, let's look at nutrient dosages in nutrition supplements.
“I was curious why you have included 300% NRV of vitamin C in each capsule” - Juliet, Immune Support
“I had a question about the B vitamin levels - in terms of NRV % to the untrained eye these look quite high (especially the B12), though I’m sure well within safe levels. Wondering if you could shed any more light on this”- Alex, Pollution Protection Daily Multi
Here I’ll explain what Nutrient Reference Values (NRVs) are, and why would supplements exceed 100%?
Is it safe to have more than 100% NRV?
It’s an EU labelling requirement to show what % of each NRV is provided in a supplement. The essential vitamins and minerals have NRVs, not other nutrients like amino acids, herbs, other antioxidants.
If you look at any supplement pot, you should see a nutrient table like this, from Pollution Protection Daily Multi showing how much of a nutrient is present (in micrograms/milligrams/international units) and what % of the NRV that provides:
The NRV is 200mcg
PP provides 400mcg i.e. 200% of the NRV
So why would we put more than the NRV in the supplement?
Simply put, NRV doesn’t refer to maximum safe intakes; it’s the estimated average amount a healthy adult would need to prevent deficiency.
If we look at optimal health rather than preventing harmful deficiency, we’d obviously want a lot more than the reference value.
That’s why you may see amounts exceeding 100% of an NRV in City Survivor's nutrition supplements.
When formulating a supplement, I would look not only at NRVs but at optimal intakes, and taking into consideration the increased demand for certain nutrients because of our lifestyle - pollution exposure, poor quality food, alcohol consumption, stress, common illnesses etc.
So while a capsule might appear to have a high dose based on NRV, we use sensible amounts in forms that are easily absorbed, and in their active forms so your body doesn’t have to put extra work into using them.
Be aware that you’ll see supplement tablets with mega doses and sometimes that’s a ‘throw a lot at the wall and see what sticks’ approach - if you have a poorly absorbed nutrient but put tons in, some amount will likely get absorbed.
But, much will be lost in urine. Or, in the case of magnesium, you might get an unpleasant upset tummy the next morning!
Nutritional Therapist and founder of City Survivor supplements