We all see the RDA amounts listed on the side panel of almost every packaged food. We also see on our supplements that they contain XXX% of the RDA. This is important information, but what is that RDA amount and how is it determined?
The RDA was developed by the US Army during World War II. The Army wanted to know what the MINIMUM amount of vitamins and minerals the troops needed to avoid diseases of deficiency such as Beri Beri, Rickets, Pellagra, scurvy, etc. So if you get 100% of the RDA of all the essential vitamins and minerals you should be just above the level of deficiency. Lets put this in another term we can all relate to. We all know in school that an “F” grade is failing, but a “D-” is passing, just barely. Well the RDA is the “D-” amount that just keeps you from developing the diseases of deficiency.
Unfortunately many people and even many doctors believe the RDA is all you need or a maximum. I even heard a pediatrician on a morning talk show talking about kids nutrition. She said that you do not want to exceed the RDA, so if your child takes supplements make sure that the amount of say Vitamin A they get in their diet plus the amount in the supplement doesn’t exceed the RDA!! This is insane, that is like telling parents to not let their kids do better than a “D-” in school!
For example if you look at the RDA (or now the RDI) for Vitamin C for an adult man it is 90mg (link to USDA RDA tables) but the nutritional experts recommend 1,500-2,000 mg of Vitamin C a day. So 90 mg will prevent you from having scurvy, but to benefit form the potent antioxidant properties of Vitamin C to protect you from the environmental toxins and protect your cells it takes 2000% of the RDA. So back to the classroom analogy, 90mg gets you a “D-” 2,000mg gets you an “A+”
Similar for Vitamin E. The RDA is 15 IU, but the optimal amount is 400 IU. Can you get these amounts from your diet alone? Well the RDA probably yes, but to consume the optimal amount you’d need to eat:
- 3.5 pounds of wheat germ (vitamin E fortified) daily, or
- 2.3 pounds of almonds daily, or
- 28.8 pounds of spinach daily, or
- 3.6 cups of safflower oil daily.