-- there have been several blogs in the past that have effused over the benefits of chocolate, typically finding that the darker the chocolate, the better:
-- a review of chocolate consumption (though none were randomized trials) found beneficial associations between chocolate and the risk of cardiometabolic disorders (coronary heart disease and stroke, diabetes, and metabolic syndrome; and the higher the chocolate consumption, the better: the highest level of chocolate consumption vs the lowest level being associated with a 37% reduction in cardiovascular disease, RR 0.63 (0.44-0.90) and 29% decrease in strokes (i did a blog on this but it seems to have disappeared, but see cad and chocolate bmj 2011 in dropbox, or doi: 10.1136/bmj.d4488 for details
-- a more recent review article extolled the many virtues of chocolate suggesting some plausible mechanisms, including improving blood pressure (polyphenols in chocolate activate endothelial NO synthase leading to vasodilation), relaxation of large peripheral arteries (?helping those with PAD), decreased cardiovascular risk and MI, stroke, improved glucose tolerance and decreased diabetes risk, (the results on many of these items are a bit mixed), some indications that there might be oncologic benefit (not strong data), improvements in the gut microbiome, suggestive anti-inflammatory effects with likely beneficial changes in several aspects of the immune system, decreased risk of cognitive decline, and it also seems to be an aphrodisiac.... see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6950163/ for the in-depth report
-- of course, almost all of these studies are observational, and those eating more chocolate may be really different from those not perhaps by doing other more healthful activities, so unable to draw causal conclusions
-- and, it is not easy to do a large RCT on chocolate. that would leave half the people in the very unenviable position of not getting chocolate to eat, or perhaps eating some weird placebo
-- but, i already hear mutterings in the background about the lead/cadmium problem.....
-- one issue is that kids and younger adults are more susceptible to the effects of heavy metals (esp lead) in brain development, though the risk remains for the rest of us
-- Chronic lead exposure (even in the 5-10 mcg/L range) can be associated with increased all-cause mortality, declines in neurocognitive functioning, psych issues (depression, phobia, anxiety, hostility), motor or sensorimotor neuropathy (though mostly with much higher exposures), tremor, hearing loss, hypertension, anemia at very high Pb levels, decreased renal function, and others
--Chronic cadmium exposure is associated with a variety of renal problems (tubular defects, Fanconi syndrome, decreased concentration capacity, kidney stones from the associated hypercalciuria), decreased bone mineral density/osteoporosis/fractures, though most with chronic cadmium toxicity are asymptomatic and symptoms mostly are from osteoporosis
-- and this is not a problem just for dark chocolate: sweet potatoes, spinach, and carrots also have high levels of lead and cadmium; rice can have high levels of arsenic
-- so, why is this happening???
-- chocolate is made from the cacao bean, which has 2 main components: cocoa solids and cocoa butter (cacao is the raw, unrefined bean from the tree; cocoa is made from fermenting the beans, cleaning/drying them, the roasted and grinding)
-- the cocoa trees grow in the tropics, esp Brazil, Ecuador, Indonesia, Nigeria, and Cameroon, with West Africa producing ¾ of the world's supply
-- dark chocolate is mostly from cocoa solids, which are loaded with flavanols (antioxidants associated with improved endothelial function, decreased inflammation and lower cholesterol levels), which is the purported explanation for the benefits noted above
-- it is likely that the dark chocolate is worse than lesser forms in concentrating heavy metals (milk chocolate, etc)
-- the likely mechanism of lead/cadmium concentration in cocoa is different:
-- cadmium is taken up by the roots of the cacao trees and makes its way into the fruits
-- lead contamination happens at different stages of the cocoa process, and are largely human-related: cacao beans when removed from the pods are covered in a sticky mucilage, are fermented on the ground or the side of the road. the lead originates in burning of gasoline and diesel fuel, leaded paint, burning of plastics/batteries/garbage, from other industries around (eg operation of smelters), use of fertilizers, emissions from coal-fired power plants, etc. And the lead from the air or ground adheres to the sticky beans.
-- it is quite concerning that the FDA has not developed limits of these toxic heavy metal for most foods, is not routinely testing food products that might have increased levels, and is not forcing companies to develop methods to make their foods safer (actually, there really should be no lead in foods: no amount of lead should be considered safe)
so, bottom line:
-- dark chocolate really should be the "good sweets", with lots of potential benefits and a multitude of pretty clear mechanisms to explain the benefit
-- this variability in lead and cadmium in different products found in the Consumer Reports' study does reinforce that it is really possible for chocolate producers to make products with lower levels of heavy metals
-- and, there is a reasonable way to ensure the healthier "good sweets":
-- we should not be processing cacao from areas of high cadmium. the ground can certainly be tested and areas with lower cadmium can be utilized (also increasing the soil pH may help, as per the "As You Sow article"), or even mixing beans from some high with low cadmium areas; and planting new trees in low cadmium areas
-- there are real mitigation strategies for lead (which is by far the worst toxin): prevent contamination while beans are fermenting and drying (shield them from lead in the air and ground), or develop a nontoxic way to clean the beans of adherent lead particles/dust
-- also pesticides have high levels of lead and cadmium, phosphate fertilizers have lots of cadmium, and sewage sludge or contaminated water has both.
-- and, studies such as these from Consumer Reports are really helpful in helping us navigate to "better chocolates", though even then consumption should be controlled. also, milk chocolate (the lesser alternative for some of us) seems to be safer. And dark chocolates with the lower cacao percent levels tend to be better
--organic chocolate does not seem to be any better, just by being "organic"
-- it is unconscionable that "we" have known about this problem for so long, that the broader population is remarkably unaware of it, that our "public health system" not only does not educate the public about this, but is doing nothing to regulate against this major toxin (they did intervene around lead paint and leaded gasoline, so seems that they could do something about this... ) And the CDC, for example, has dramatically reduced the toxic blood level of lead for kids down to 3.5 mcg/dL, who, by the way, may well be ingesting lots of chocolate (https://www.cdc.gov/nceh/lead/news/cdc-updates-blood-lead-reference-value.html#:~:text=CDC's%20Federal%20Advisory%20Committee%2C%20called,the%202015%E2%80%932018%20NHANES%20cycles.) -- so, this all is very distressing. and with the dark chocolate overeating that i have been, i do intend to check my lead and cadmium levels....
geoff
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