On top of picking 5 of the ~20 estimates I mentioned to claim that low estimates of dietary lithium intake are “strictly outnumbered” by studies that arrive at much higher estimates, they also support that claim by misrepresenting some of their own sources. For example,
They say that “Magalhães et al. (1990) found up to 6.6 mg/kg in watercress at the local market,” but the study reports that as the lithium content per unit of dry mass, not fresh mass, of watercress(which the SMTM authors do not mention). This makes a big difference because Google says that watercresses are 95% water by weight.
They do the same thing with Hullin, Kapel, and Drinkall (1969). They do not mention that this study dried lettuce before measuring its lithium concentration, and reported lithium content per unit of dry mass. Google says that lettuce is 95% water by weight too, so this matters a lot.
They also mention a lot of other dry mass estimates, such as those from Borovik-Romanova (1965) and Ammari et al. (2011). This time they do disclose that those estimates are for dry mass, but they nevertheless present those estimates as contradicting Total Diet Studies, as if they were measuring the same kind of thing, when they are not.
Notably, they say “Duke (1970) found more than 1 mg/kg in some foods in the Chocó rain forest, in particular 3 mg/kg in breadfruit and 1.5 mg/kg in cacao,” and fail to mention that most of the foods in Duke (1970) have less than 0.5 mg/kg of lithium.
Also, only one of the examples SMTM used to claim that the Total Diet Studies are “outnumbered” actually attempted to quantify dietary lithium intake,[1] whereas almost all of the studies I’ve mentioned do that. This is important because a lot of the sources they cite that we don’t have access to (there are several of those) could be measuring lithium concentration in plant dry matter, as a lot of their sources that are available do, in which case seemingly high concentrations do not imply high dietary consumption.
Moreover, a lot of their post is focused on speculating that ICP-MS (the technique used by most studies) systematically underestimates lithium concentration. However:
Van Cauwenbergh et al. (1999) use atomic absorption spectroscopy (AAS) instead of ICP-MS, and arrive at the second-lowest dietary lithium intake estimate I have ever found,
Iyengar et al. (1990) mention a lot of NA-MS measurements, all of which match the low estimates I’ve found,
All of those find very low concentrations of lithium in food.
Moreover, they themselves mention a paper that uses ICP-MS and finds high concentrations of lithium in food in Romania (Voica et al. (2020)).
These studies are a substantial fraction of all of the studies on lithium concentration in food that we have. So it seems to me that their whole focus on ICP-MS, and their claim that it “gives much lower numbers for lithium in food samples than every other analysis technique we’ve seen,” does not seem warranted.
Again, I don’t think that studies that find high concentrations of lithium in food are necessarily wrong. There is no market pressure for food to have 1 µg/kg rather than 1000 µg/kg of lithium, or the other way around, the way that there is market pressure for meals to have e.g. carbohydrate/fat ratios and energy densities within a specific optimal range. Consumers do not care about whether lithium concentration is 1 µg/kg or 1000 µg/kg. And we know that lithium concentration in e.g. water varies a lot according to lithology and climate, so we shouldn’t expect this to be uniform around the world. So I don’t see how it must be the case (as the SMTM authors claim) that all studies that find low concentrations are wrong.
The example was Schrauzer (2002), which bases its estimates on hair concentration rather than actual food measurements. Ken Gillman says that this paper “has a lot of non-peer-reviewed and secondary references of uncertain provenance and accuracy: it may be misleading in some important respects.” Also, interestingly, as I mentioned in my post, the highest estimate Schrauzer (2002) provides for dietary lithium intake is from China, not really a country with a huge obesity problem.
(Note that the Ken Gillman blog post has a typo: it says that the “typical total daily lithium intake from dietary sources has been quantified recently from the huge French “Total Diet Study” at 0.5 mg/day,” a value that is 10x too high.)
On top of picking 5 of the ~20 estimates I mentioned to claim that low estimates of dietary lithium intake are “strictly outnumbered” by studies that arrive at much higher estimates, they also support that claim by misrepresenting some of their own sources. For example,
They say that “Magalhães et al. (1990) found up to 6.6 mg/kg in watercress at the local market,” but the study reports that as the lithium content per unit of dry mass, not fresh mass, of watercress (which the SMTM authors do not mention). This makes a big difference because Google says that watercresses are 95% water by weight.
They do the same thing with Hullin, Kapel, and Drinkall (1969). They do not mention that this study dried lettuce before measuring its lithium concentration, and reported lithium content per unit of dry mass. Google says that lettuce is 95% water by weight too, so this matters a lot.
They also mention a lot of other dry mass estimates, such as those from Borovik-Romanova (1965) and Ammari et al. (2011). This time they do disclose that those estimates are for dry mass, but they nevertheless present those estimates as contradicting Total Diet Studies, as if they were measuring the same kind of thing, when they are not.
Notably, they say “Duke (1970) found more than 1 mg/kg in some foods in the Chocó rain forest, in particular 3 mg/kg in breadfruit and 1.5 mg/kg in cacao,” and fail to mention that most of the foods in Duke (1970) have less than 0.5 mg/kg of lithium.
Also, only one of the examples SMTM used to claim that the Total Diet Studies are “outnumbered” actually attempted to quantify dietary lithium intake,[1] whereas almost all of the studies I’ve mentioned do that. This is important because a lot of the sources they cite that we don’t have access to (there are several of those) could be measuring lithium concentration in plant dry matter, as a lot of their sources that are available do, in which case seemingly high concentrations do not imply high dietary consumption.
Moreover, a lot of their post is focused on speculating that ICP-MS (the technique used by most studies) systematically underestimates lithium concentration. However:
Van Cauwenbergh et al. (1999) use atomic absorption spectroscopy (AAS) instead of ICP-MS, and arrive at the second-lowest dietary lithium intake estimate I have ever found,
Iyengar et al. (1990) mention a lot of NA-MS measurements, all of which match the low estimates I’ve found,
Hamilton & Minski (1972) use spark source mass spectrometry (SSMS),
Evans et al. (1985) use flame atomic emission spectrophotometry, and
Clarke & Gibson (1988) use NA-MS.
All of those find very low concentrations of lithium in food.
Moreover, they themselves mention a paper that uses ICP-MS and finds high concentrations of lithium in food in Romania (Voica et al. (2020)).
These studies are a substantial fraction of all of the studies on lithium concentration in food that we have. So it seems to me that their whole focus on ICP-MS, and their claim that it “gives much lower numbers for lithium in food samples than every other analysis technique we’ve seen,” does not seem warranted.
Again, I don’t think that studies that find high concentrations of lithium in food are necessarily wrong. There is no market pressure for food to have 1 µg/kg rather than 1000 µg/kg of lithium, or the other way around, the way that there is market pressure for meals to have e.g. carbohydrate/fat ratios and energy densities within a specific optimal range. Consumers do not care about whether lithium concentration is 1 µg/kg or 1000 µg/kg. And we know that lithium concentration in e.g. water varies a lot according to lithology and climate, so we shouldn’t expect this to be uniform around the world. So I don’t see how it must be the case (as the SMTM authors claim) that all studies that find low concentrations are wrong.
The example was Schrauzer (2002), which bases its estimates on hair concentration rather than actual food measurements. Ken Gillman says that this paper “has a lot of non-peer-reviewed and secondary references of uncertain provenance and accuracy: it may be misleading in some important respects.” Also, interestingly, as I mentioned in my post, the highest estimate Schrauzer (2002) provides for dietary lithium intake is from China, not really a country with a huge obesity problem.
(Note that the Ken Gillman blog post has a typo: it says that the “typical total daily lithium intake from dietary sources has been quantified recently from the huge French “Total Diet Study” at 0.5 mg/day,” a value that is 10x too high.)