“I will see foods, and especially supplements that have more than 100% of the RDA of a certain nutrient, sometimes even in the thousands (Vitamin B12 – 1,000mcg = 41,667% of RDA!), is this safe?“
Yes! For most nutrients…
The RDA, Recommended Daily Allowance, which also directly compares to the DV %, Daily Value, is defined as the average amount of a certain nutrient a person should get each day… to prevent disease or illness.
Read the last part again…”to prevent disease/illness”. This translates to, the minimal amount of that particular nutrient you need to prevent a disease which has been shown with a deficiency.
The amounts are intended to prevent disease, not promote optimal health.
In fact, the Food and Nutrition Board (FNB), who establishes the RDA/%DV, refers specifically to nutritional amounts necessary to avoid scurvy, a condition cause by too little Vitamin C, or rickets, caused by too little Vitamin D.
Scurvy and Rickets?!? Goodness, there is way too much significant, credible research on Vitamin C and D that it does and supports MUCH more!
RDA’s also do not account for active/stressful lifestyles, different age groups, gender, or medical conditions. They are blanket recommendations that were originally set using data from adult men in the 1940’s.
But more, doesn’t mean better.
Typically you’ll see higher DV% for water soluble vitamin (Vitamin C and B’s), and those that have been very well studied (Vitamin A, D, E, and certain minerals – Selenium, Chromium), and in formulations that are for specific populations or conditions (anemic, geriatric, performance).
For other nutrients and general health conditions, 100% or less of the RDA may be acceptable.
To really understand how much “fortification” (the term used in foods) or your supplement should have, you should access your health condition, your goals, and your diet (i.e. do you eat a diet rich in nutrients)
Most credible products do not achieve even close to the upper tolerability levels (UTL) of nutrients, most of the time your body will let you know you’ve taken too much – sweating, diarrhea, vomiting (the main ways out!), but you should also be careful and check with your health care provider when taking higher dosages.
BTW – this is one of the more important reasons that PRoZE uses over 90 different plant based medicinals and nutrients – from essential oils, plant extracts, spices, sea-based minerals, etc.. in our formula so we don’t have to use too much of one nutrient or another!