we are exposed to electro-magnetic fields (EMF) when being near electrical equipment, fluorescent lights, driving in a car or train, talking in a mobile phone or surfing the net.
There's a lot of info suggesting that being exposed to various forms of EMF can affect (reduce) the levels of various minerals and vitamins.
EMF doesn't only affect humans, but the food itself - through freezing (or keeping food in a fridge), electrical heating (as opposed to using gas/wood), use of food processors and so on.
From http://www.ylana.com/radiate.htm :
"Florescent lights in milk counters have been shown to destroy 30% of the vitamin A in the milk in just 24 hours. Vitamin A strengthens the immune system. If uncleared, what are these lights doing to those working under them for extended periods of time? "
"Exposure of rats to 570 µW/cm 2, 2 GHz, for 15 days (3 hr./day) led to a decrease in vitamin B6 levels in blood, brain, liver, kidney, and heart; the levels of the vitamin in skeletal muscle increased".
About cobalt, which is the core atom in the B12 vitamin:
"Cobalt itself is naturally magnetic with unusually high permeability to magnetic fields. [...] Amazingly we are just learning what nature has unseeingly already known. By stopping EMFês from penetrating our cells, we prevent DNA damage which leads to healthy cell division." http://www.rfsafe.com/Why_RF_Radiation_Safe.htm
About "Low frequency pulsed magnetic fields" and therapeutic effect of chemicals:
"When LFMF (Low frequency pulsed magnetic fields ) was combined with adriamycin (doxorubicin), cisplatin, mitimycin C, and other chemotherapeutic drugs, LFMF improved the transport of drugs into cells and reduced the therapeutic dose of these drugs." 14-16 http://brightspot.org/cresearch/magfields.html
If you eat plant based food that has been exposed to chemical fertilizers (instead of cow dung), been watered with water that has been chlorinated (and transported in copper tubes), been blanched/frozen, and then cooked in a microwave owen or on an electrical stove - and maybe even has gone through a food processor AND been exposed to a lot of light, the nutrient levels, including vitamin B12 levels, most likely have been reduced.... seven times. Wait, the food isn't fresh any longer either, that makes it eight. Oh, and the heat itself (not only the EMF from your heating) reduce vitamin levels too. Nine. And that's before it enters your body, which in itself most likely contains B12 reducing elements, like mercury (unless you never ate fish/use amalgam/have had vaccines)...
Don't blame it on the plants...