Just trawled around for some dietary info ...
6.7.7 Lithium
Different groups of animal food contain low levels of lithium (Li), ranging from 0.0003 to 0.0006 mg/kg. The lowest levels are registered for milk and dairy products, whereas the highest levels are found in fish (see Table 6.13 and Table 6.14). Concentrations of this element in honey broadly range from 0.0003 to 0.005 mg/100g (see Table 6.15).
Mineral Components in Food, Piotr Szefer, Jerome O. Nriagu, CRC Press, 2006
ISBN 1420003984, 9781420003987
So from the above figures, an upper concentration of lithium found 'naturally' in honey would be 0.05 mg/kg - or roughly one hundred times greater than the upper concentration levels of lithium found within the other foods cited.
However,
The Encyclopedia of Food Sciences and Nutrition (Second Edition), 2003, provides the following:
In line with the low lithium content of cereals, flour and other cereal products contained little lithium. Honey and sugar are also extremely poor in lithium. Ready-to-serve soups with meat and eggs were richer in lithium, whereas various puddings, macaroni, and vermicelli usually contained < 1 mg lithium kg-1 dry matter (Table 4).
All vegetables and potatoes contain > 1.0 mg lithium kg-1 dry matter. Peeling potatoes decreases their lithium content, as potato peel stores more lithium than the inner part of the potato that is commonly eaten.
As a rule, fruits contain less lithium than vegetative parts of plants (vegetables). Lemons and apples contained significantly more lithium, with about 1.4 mg kg-1 dry matter, than peas and beans, which, like the different kinds of cereals grains, are extremely lithium-poor as seeds.
Owing to the small amounts used in their application, spices do not contribute much lithium to the diet. It is surprising that mustard is relatively lithium-rich, with 3.4 mg kg-1 dry matter, whereas mustard seed contains extremely little lithium.
On average, eggs, meat, sausage, and fish deliver significantly more lithium per kg of dry matter than most cereal foodstuffs. Eggs, liver, and kidneys of cattle had a mean lithium content of 5 mg kg-1. Beef and mutton contain more lithium than poultry meat. Green fodder and silage consumed by cattle and sheep are much richer in lithium than the cereals largely fed to poultry. Sausage and fish contain similar amounts of lithium to meat. There were significant differences between the lithium content of milk: milk contains a high lithium concentration of 10 mg kg-1 dry matter.
Thus it would appear possible that bees collecting nectar and pollen from flowering mustard (a common catch-crop) may be returning fairly high levels of lithium in that particular batch of honey. As there's no such substance as 'standard' honey - it would appear to be somewhat meaningless to be quoting any lithium-content figures for 'honey'.
However, I think it's highly relevant to current concerns that lithium would appear to be present in a whole range of common foodstuffs at trace levels.
LJ