The Random RDA of Goji Berries [Lurks]

I had a cough for a few weeks. So the missus, being a woman, naturally believes that this is solved by discovering some random homeopathic substance that boosts the immune system. Today this was dried Goji Berries, being heralded in some parts as a super food. Cool, I'm broadly open to super foods, some of them are very good for you. Goji Berries are in actual fact, Wolfberries.

So the thing about Goji berries is that there's a whole pile of baseless claims about how they boost libido and Christ knows what else. The reality is they're quite good because they have more vitamin C than oranges, more beta-carotene than carrots and more iron than steak. Course that all depends on how you look at it, clearly you eat more orange, carrots and steak than a few dried berries. But still, that's fine.

The thing is, my eye is drawn to the nutritional label helpfully provided on this Tescos 100gr pack of Dried Goji Berries. There it says that 25g of the stuff, about quarter of a packet and they're not that flavorsome but kind of tasty, so you'd happily scoff 25g in a sitting I think, contains 1230% of the RDA of Vitamin C. Holy smoke Batman! Yet strangely underneath it that's 17.2mg. That means that Tesco is of the belief that your Recommended Daily Allowance of Vitamin C is paulty 1.4mg. That's obviously bullshit.

So I begin to look it up. I found RDA figures for Vitamin C quoted at 45mg, 60mg and 90mg by various people so I start to understand how dodgy this stuff is. However in 1997 RDA got brought into a wider Dietary Reference Intake set of guidelines. This puts Estmated Average Requirements of Vitamin C at 75mg, and Recommended Dietary Allowance at 90mg.

Wikipedia says that the Vitamin C range of Wolfberries is quite wide, equating to about 7mg to 37mg for 25gr so Tesco's quoted 17mg is pretty much bang in the middle. So let's get on some dodgy ground and assume Tescos actually had this stuff analysed and the 17.2mg is correct. That's actually 25% of the RDA for vitamin C. In fact you would need to scoff the entire 100mg bag to get 68.9mg of Vitamin C according to the label, just shy of the 100% Vitamin C RDA. Not the 4919% that Tescos amusingly list.

Or you could drink 3/4 of a cup of orange juice and get about 75mg. Hmm.