I was reading about RDAs of certain vitamins and things like Proteins, Iron, Pottasium, Sodium, that it’s almost impossible to get those unless I eat like a whale.

So what gives?

  • Strayce@lemmy.sdf.orgEnglish
    0·
    19 days ago

    There’s a couple things at play here.

    Firstly, the math. Nutrient requirements in a given population tend to be normally distributed (there are a couple that aren’t). RDA is considered enough to meet the requirements of 98% of people. EAR (estimated average requirement) is the middle of the bell curve, so most people’s actual requirement will be closer to that. RDIs are used for diet planning in individuals though, so as to minimise the risk of deficiency. There’s a huge margin of safety between EAR and anything that would cause problems from excess (e.g. Vitamin A toxicity) so using RDI won’t cause issues there. Actually working out an individual person’s requirement for a specific nutrient is a bunch of really complicated biochem, so it’s better to just aim for the RDI.

    Secondly, RDA is kind of a misnomer. You don’t actually need to eat that every day, because the body stores and uses a lot of nutrients as needed. It’s really supposed to be used as more of an average over time. This is why it’s important to eat a good variety of different foods within the main food groups. Meatless mondays don’t cause you to instantly collapse from iron deficiency.

    Third, there’s a commercial aspect to it. Food manufacturers love using RDI because it lets them imply their product is healthy, and they love it when public health messaging is “eat more X” when X is a major component of whatever they produce (e.g. iron fortified cereals).