Organic vs. Conventional: The Overlooked Low Cadmium Advantage. Almost 50% Lower Cd Levels and Half-Lifes of 10-30 Years May Be Another Reason to Buy Organic

Eating organic is not so much about what you get extra (vitamins etc.), but rather about paying more for getting less. Less pesticides and, as recent studies show, significantly less cadmium.

In view of the hype around organic produce, it would appear as if this was a bogus question, but previous studies were not able to confirm any of the huge claims you will read all over the internet. The only established benefit so far - and that's certainly not one you should underestimate - appears to be a relative lack of pesticides.

Only recently scientists have compared a broad variety of organic and conventially grown crops and found that organically grown crops do tend to have a notably lower cadmium content, as well. According to  conventionally grown crops – on average, about 48 % lower (this estimate takes into account 87 previously reported comparisons).

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In view of the fact that the heavy metal cadmium (Cd) is emerging as a major cause of vascular disorders, various common cancers, kidney disease, osteoporosis and other health disorders, even in populations that do not have occupational exposure to this toxin(2–4), this is significant news.

With the exception of smokers, who are constantly exposed to significant amounts of cadmium, green vegetables, root vegetables, tubers, grains, organ meats and shellfish are the major sources of this toxin. Any reduction of the Cd levels in these foods may thus have significant beneficial health implications, since once Cd gets into your body, it cannot be excreted again.

Scientists estimate the half-life of cadmium in the human body to be 10–30 years (Suwazono. 2009)! Thus every nanogram you don't consume counts!

While cadmium can induce oxidative stress throughout the body, and interference with some of the physiological roles of Zn (as in DNA repair), the evidence that dietary (not smoke) exposure to cadmium has significant health effects is yet scarce.

There is something you can do to reduce cadmium absorption: Iron deficiency increases the efficiency of dietary Cd absorption and will put you at increased risk of toxicity. In addition to a correction of any existing iron deficiency, Zn and Mg may lessen the absorption of dietary Cd to some degree (Gallagher. 2011; McCarty. 2012)

This is partly due to the fact, though, that our ability to measure the chronic effects of very low doses of a certain toxic substance are very limited. In a recent review, McCarthy et al. (2014) list the following hitherto published studies:

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  Table 1: Whether there are more or less antioxidants in organic produce depends on the antioxidant you're looking at (Barański. 2014)

  Japanese researchers have long speculated about an involvement of cadmium exposure in the development of breast cancer and researchers from all around the world have speculated based on elevated urinary Cd concentrations that it may be responsible for 27-68% of the breast cancer cases (McElroy. 2006; Gallagher. 2010; Nagata. 2013).
• Recent multivariate-adjusted analyses of the National Health and Nutrition Survey cohort have concluded that Cd exposure may be responsible for 28 % of the myocardial infarction cases and 17 % of the total CVD and cerebrovascular disease cases (Everett. 2008; Agarwal. 2011). And data from the prospective Strong Heart Study (focusing on Native Americans) suggest that Cd exposure may account for 16, 23 and 28 % of the coronary disease, stroke and heart failure cases, respectively (Tellez-Plaza. 2013).

In spite of the fact that the epdidemiological evidence is not exactly abundant and disregarding the null results of case-control studies attempting to correlate dietary Cd intake with disease risk McCarthy et al. conclude that "if one focuses on urinary Cd concentrations when surveying Cd epidemiology, the hazard of Cd stands out crystal-clear" (McCarthy. 2014).

Organic or conventional? Learn more in my previous article about he different pesticide levels.

Bottom line: In view of the fact that vitamin content of organically grown produce is not necessarily higher (depends on the crop) and considering the fact that Baranski et al. found that organically grown crops do not have a lower content of lead or arsenic, two other mineral contaminants linked to health risks, when compared with conventionally grown crops, the lower cadmium along with the lower pesticide content I wrote about previously, remain the major scientifically verified advantages of organically grown produce.

That's obviously less than the internet gossip would suggest, but still enough to have anyone who is seriously concerned about his health can afford them choose organic over conventional produce | Comment on Facebook!

References:

• Agarwal, Shikhar, et al. "Heavy metals and cardiovascular disease: results from the National Health and Nutrition Examination Survey (NHANES) 1999-2006." Angiology 62.5 (2011): 422-429.
• Barański, Marcin, et al. "Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops: a systematic literature review and meta-analyses." British Journal of Nutrition 112.05 (2014): 794-811.
• Everett, Charles J., and Ivar L. Frithsen. "Association of urinary cadmium and myocardial infarction." Environmental research 106.2 (2008): 284-286.
• Gallagher, Carolyn M., John J. Chen, and John S. Kovach. "Environmental cadmium and breast cancer risk." Aging (Albany NY) 2.11 (2010): 804. 
• Gallagher, Carolyn M., John J. Chen, and John S. Kovach. "The relationship between body iron stores and blood and urine cadmium concentrations in US never-smoking, non-pregnant women aged 20–49 years." Environmental research 111.5 (2011): 702-707.
• McCarty, Mark F. "Zinc and multi-mineral supplementation should mitigate the pathogenic impact of cadmium exposure." Medical hypotheses 79.5 (2012): 642-648.
• McCarty, Mark F., and James J. DiNicolantonio. "Are organically grown foods safer and more healthful than conventionally grown foods?." British Journal of Nutrition 112.10 (2014): 1589-1591.
• McElroy, Jane A., et al. "Cadmium exposure and breast cancer risk." Journal of the National Cancer Institute 98.12 (2006): 869-873. 
• Nagata, Chisato, et al. "Cadmium exposure and the risk of breast cancer in Japanese women." Breast cancer research and treatment 138.1 (2013): 235-239.
• Suwazono, Yasushi, et al. "Biological half-life of cadmium in the urine of inhabitants after cessation of cadmium exposure." Biomarkers 14.2 (2009): 77-81.
• Tellez-Plaza, Maria, et al. "Cadmium exposure and incident cardiovascular disease." Epidemiology 24.3 (2013): 421-429.

Chinese Black, Green & Olong Tea is NO Health Beverage. Lead, Chromium, Cadmium and Potentially Toxic Levels of Manganese + Endocrine Disrupting PFCs Are the Rule

"Pesticide pollution: Chinese tea may not be safe to drink," this is what you could read on the website of Greenpeace in 2012, already and obviously this has not changed over the last 2 years | read more

I've actually written about the problem with toxins in tea, specifically green tea from China, before and I wouldn't be too sure, whether bad news like the previously reported "-20% Reduction in Green Tea From Just 5 Cups a Day" (learn more) could not possibly be a result of heavy metals and/or other toxins, as well. This and the fact that the data I am going to talk about in the following paragraphs is based on analyses of 43 representative tea products (including 18 green, 12 Oolong, and 13 black teas) from 7 main tea production provinces in China makes today's SuppVersity article relevant for everyone who consumes green tea from China or of unkown origin - China is the cheapest, so guess, where it's from ;-)

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Apropos "Guess where it's from!", if I had to guess, I would say that 99% of the black, green and olong tea extracts in green tea, fat burner, pre-workout, anti-oxidant, and other commercially available supplements will be from China. The fact that cadmium (Cd), inorganic and thus toxic chromium (Cr) and lead (Pb) were present in samples from Zhejiang, Fujian, Yunnan, Anhui, Hunan, Guangdong and Taiwan is relevant for ~95% of the SuppVersity readers.

You think that's an old hat? Well, what about the perfluorinated compounds (PFCs) the researchers, who are by the way working for the China Ministry of Agriculture and thus certainly not interested in making Chinese tea look like a poisonous swill, detected in all samples. The concentration of these emerging and ubiquitous organic pollutants in the samples varied. In view of the already established negative health effects of which Eriksen et al. (2009), Corsinia et al. (2012) and Posta et al. 2012) write that they encompass...

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  Would all commercially available teas have to be labeled like this? A previous study which found also Aluminum & Arsenic in tea bags, would suggest just that | read more

  thyroid dysfunction, 
• preeclampsia,
• increased risk of high cholesterol
• increased risk of cancer, 
• liver dysfunction, 
• disruption of the immune system,
• disturbances of the endocrine (=hormone) system, 
• developmental delays, and
• fertility issues

...which could potentially occur with chronic exposure to comparatively low amounts of these toxins, this is certainly disconcerting.

PFCs are everywhere: Due to their toxic effects in humans and other organisms, PFCs were added to the list of banned chemicals in the Stockholm Convention on Persistent Organic Pollutants in 2009 (Ma and others 2012). Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have been detected in animals and water samples from rain, river, wastewaters, and sea. They are present in plants and crops, including all twenty foodstuffs that were examined in 2004 in Great Britain by Gem et al. in 2006. PFCs are present in wheat, oats, potatoes, and maize (Stahl. 2009) and their concentration is the highest in plants / crops that grow in or close to the ground - including the peeled edible parts of carrots, potatoes, and cucumbers.

If you look at the maximal heavy metal content (individual circles in Figure 1) you will see that eventually, even the high manganese content of up to 240mg/100g could become problematic.

Figure 1: Box plots of Cd, Pb, Cr, Cu, Zn, and Mn contents in 43 tea products from south China. The central solid line within each box is the median, and the bottom and top of each box represent the 25th and 75th percentiles, respectively (Zhang. 2014); the values outside this range are plotted as individual outliers (o).

The upper tolerable intake level (UTI) of manganese is only 11mg for an adult. If you adhere to the recommended 3g per 150ml water you would thus exceed the UTI by ~30% with with the amount of tea you'd put into only 2 cups! That's bad news, even if the hot water does not extract the total amount of manganese. It is after all not unlikely that toxic effects such as the Parkinson-esque shaking (tremors), which is supposedly a direct result of the neurotoxicity of manganese (Dobson. 2004),  can occur with the chronic ingestion of subtoxic doses in the 5mg/day range, as well.

And while the combination of cadmium, lead and chromium is etching away your brain and nervous system, the PFCs, which were detected in form of PFOS in only 6 samples and in form of PFOAs in 33 samples, will launch an attack on your endocrine system. Unfortunately, there is no reliable information on whether or not chronic exposure to teas with  250ng/kg dw of this endocrine disruptor will or will not have permanent negative effects on your health.

Table 1: Contents of PFOA and PFOS according to origin (left) and type (Zhang. 2014)

What we do know, though is that Oolong teas were 15x more frequently contaminated than green tea. Apropos, if you look at the data in Table 1 you will see that the tea producers in the Anhui Province are either most generously intoxicating their produce with PFC-containing products, or plant their tea plants right next to some industrial complex. Here, more than 50% of all tested samples contained both PFOA and PFOS.

Green still the "greenest": In Germany "green" mean ecological and "clean" and at least for the 43 batchs of green, oolong and black tea this association holds for Chinese teas, as well. The results of the study at hand clearly show that black teas had - on average - higher amounts of heavy metals and PFCs in them than oolong or green teas. This doesn't change the fact, though, that the major and potentially toxic manganese offender in the study was a batch of green tea (unfortunately, Zhang et al. don't disclose the province it was from). So, don't make a mistake: Green tea is not generally a safe choice - at least if it's from China.

Bottom Line: Chinese tea is certainly not your best choice! I would not go so far as to say that you must avoid it like a plague, though. Firstly, we don't really know if the heavy metal and PFC levels in the produce from other countries are much lower. Secondly, only few of the samples may be considered "officially" hazardous to your health. And thirdly, there is insufficient data on both, the amount of heavy metals (specifically manganese) and PFCs that will leach out of the leaves, into your tea and make it from there across the gut lining into your blood stream, as well as their potential long-term consequences.

The initially mentioned "Drinking Green Tea Reduces Your Testosterone Levels" study, is yet only one out of countless "surprisingly" disappointing studies with green tea and green tea supplements the negate results of which could potentially be ascribed to the presence of heavy metals or PFCs in the green tea / green tea extracts that were consumed in the study. So, maybe, but just maybe, you want to take a brief look at the back of the next bag of green, oolong and black tea you buy to check, whether it's from China?

References:

• Dobson, Allison W., Keith M. Erikson, and Michael Aschner. "Manganese neurotoxicity." Annals of the New York Academy of Sciences 1012.1 (2004): 115-128.
• Ma, Jin, et al. "State of polybrominated diphenyl ethers in China: An overview." Chemosphere 88.7 (2012): 769-778.
• Stahl, T., et al. "Carryover of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) from soil to plants." Archives of environmental contamination and toxicology 57.2 (2009): 289-298.
• Zheng, H. et al. "Analysis of Trace Metals and Perfluorinated Compounds in 43 Representative Tea Products from South China." Journal of Food Science (2014). Accepted Manuscript. doi: 10.1111/1750-3841.12470