Waw, what a busy year it’s been for me! I have not posted in a long time. Here we go again with a really cool study that may have practical implications for us.
But before I dive into what could be a tiny, tiny aspect of health and nutrition, I want to remind the readers that this is nitty-gritty nutrition stuff, meaning this aims at optimisation.
The scientific evidence is rather clear on the fact that achieving maximum human health does – not – quite come from these small tricks and precautions. Rather, the bulk of achievable human health is to be obtained from a high compliance with a low-fat Whole Food, fully Plant-Based diet combined with as many of the following lifestyle factors as possible: frequent movement/exercise, sufficient/restful sleep, good stress management, little to no use of harmful intoxication, loving/supportive relationships, a meaningful occupation, behaviour with low risk of accidents, etc.
Having said that, let’s do this!
In what follows, we will use the abbreviations:
BLL for Blood Lead Level
Pb for lead
A very recent study done in Bangladesh analysed the blood of 430 randomly selected pregnant women for lead, 45 of whom were selected (not randomly) and had their BLL (blood lead levels) published.
While there is no safe lead level either in blood or in food, the USA CDC (Centre for Disease Control) considered lead levels above 5 μg/dL to be elevated. The highest BLL found in the blood of these 45 pregnant women was sitting at whopping 29.1 μg/dL! This is a pregnant woman with lead levels 6 times higher that the (rather lax) US CDC threshold.
The usual routes were explored but did not yield anything from soil, to food, etc.
Interestingly, in Bangladesh, there has been a culture by which some women (possibly few only) eat small amounts of clay, soil or ashes during pregnancy, presumably to obtain nutrients (not a wise thing to do anyway, since almost all nutrients are to be found in actual food, and all the above can be contaminated with heavy metals among other contaminants). Yet, even those were not significantly contaminated with lead.
Some metal tins that were soldered with lead were also found to contaminate the food stored in them. However, that was also rather relatively minor.
Improbable source, Improbable purpose
What was the main source of contamination by very far?
Turmeric is known for a very long list of health benefits. And that is where lead was deliberately added. How unwittingly cynical!
How come? Brace yourself.
It is added in turmeric processing factories as a colouring agent for the turmeric to look more yellow.
You read this right. Unbelievable! I know.
A product called peuri locally, which is chemically a lead salt with a yellow/orange bright colour, was reported as an adulterant. Chemically speaking, peuri contains lead chromate (PbCrO4), which is the bright yellow stuff, but also also white powders like lead carbonate (PbCO3), and/or lead sulfate (PbSO4).
Besides colouring, lead is called a heavy metal for a reason, it is actually very heavy. So besides making products visually appealing, the lead products also help make the spice artificially much heavier, so producers and traders can earn more money by moving less actual turmeric. Not the first time shame is lacking under the capitalistic sun, especially under the pressures of impoverishment.
According to the authors, this practice of adding lead pigments would have started to meet customer pressures, after a one-off flood made turmeric roots look pale and lack their usual vivid colour.
How bad was the lead situation?
According to the study, the Bangladesh Standard Testing Institution limit for lead contamination is 2.5 μg/g or ppm, meaning 2.5 micrograms of lead per gram of turmeric, also known as parts per million (ppm).
8 out of 28 turmeric samples had level above the official legal limit.
The highest sample had a lead concentration of 1151.9 μg/g, which is 460 times above the threshold. This is ridiculous!
It doesn’t even end there…
In nutrition, bioavailability is the percentage of a given ingested molecule that actually gets absorbed when ingested by apparently healthy individuals. It varies from a chemical or product to another. It can be measured in vivo (in humans) or estimated by in vitro experiment, that is in a lab by simulating human digestion with various chemicals and devices.
These are the bioavailabilities of the lead from different sources:
- Pb solder in food storage tins: < 5%.
- Pb in clay and ash: < 5%.
- Pb in turmeric: 42.9 to 70% (likely made even higher by acidic foods like tomato, tamarind, kokum (mangosteen rind used for sourness in some cuisines), lime/lemon, etc.
The lead colouring added to the turmeric was very easy to absorb, not a good news.
Children absorb lead far better than adults, and they are also more sensitive to it.
Additionally, a pregnant woman’s bone dissolve a bit for a temporary period during the third trimester of pregnancy. This is a natural process to provide calcium to her child in the womb to build bones. The problem is that lead accumulates in the bones. So lead accumulated over many years pre-pregnancy is released from the bones and makes it to the bloodstream where it peaks at that stage of pregnancy. In passing, this is also why consuming bone broth is not only unnecessary but plain dangerous.
What does lead do?
The effects, in summary include: irreversible neurological damage, renal disease, cardiovascular effects, and reproductive toxicity.
For more details, read here, p. 31
What about whole dried turmeric instead of powders?
The study published the lead contents in whole turmeric fingers, in packaged and non-packaged presentations.
No specific type of turmeric was guaranteed to have levels below the limit of 2.5 μg/g. In fact the whole dried roots had even more lead in them in this particular study. It looks like grinding one’s own at home isn’t quite a way out of this problem.
Am I having contaminated turmeric?
I did not search how common this practice is.
We’re supposed to be reasonably protected by the work of food safety authorities in countries with functional infrastructures, which is just a few privileged countries presumably, and even then…
They test regularly various food samples to ensure compliance with imports requirements for contaminants, etc. The problem is those tests are not systematic, and instead done only now and then. As a result, those tests are most likely to almost only detect poor practices that are consistent in time.
That explains why, for instance, an investigation of children in the USA with elevated levels of lead found that turmeric in their homes had levels of lead averaging at 66 ppm. Context: Bangladesh’s official limit is 2.5 ppm, so this was shooting off the roof. The range was from 0.1 to 740 ppm.
The customs and food safety authorities obviously did not catch those samples high in lead.
In 2001 alone, New Zealand and Australia alone imported nearly 300 tonnes of turmeric according to Food Standards Australia New Zealand. It’s hard testing that much turmeric and everything else. It’s safe to say trusting our spices are unadulterated is a leap of faith.
Is it common to consume turmeric with abnormally high levels of turmeric outside of Bangladesh? I do not know.
What I do know is that we (my partner and I) had been buying our spices from a bulk bin to reduce waste, and we bought it from a local South Asian shop that used to be run by a Bangladeshi family. If they were still in business, I would certainly ask where the spices are from, but they closed down recently.
The best and only way to know about lead content for sure is to get yours tested. If we did that for everything we buy and eat, that would be a pricey endeavour.
But I reckon it’s worth it for a few items we use often, from the same source/brand consistently, and where the risk is believed to be high shall the product be adulterated. Turmeric definitely fits the bill.
What to do then?
I would advise purchasing certified organic turmeric and hope the organic label would exclude, test and enforce any adulteration made to the product post harvest. I would advise doing that with any naturally colourful basic ingredient. The next in line being chilli, which I have seen suspiciously bright red at some shops. I did find studies on the use of artificial colouring in chilli powders, including some banned ones because of their known adverse health effects.
Anything with a natural colour like orange or red is supposed to become less intense in colour with time. In fact turmeric is known to be a very poor dye (for non-food uses such as textiles) because the colour is very sensitive to light and fades out easily.
Turmeric and chilli being colourful spices, it is wise to get those as certified organic.
Another precaution (and fun thing to do anyway) is to make one’s one curry or spice powders, because they rely heavily on turmeric and chilli anyway.
How much to buy?
Indian cuisine is known to rely heavily on turmeric. According to the study, India reported consumption rates of 25 g of turmeric per person per month, that is 600g per year for a couple…that eats Indian cuisine every day.
Certified organic turmeric bags I’ve seen online contain in the range of 200-500g and currently go at about US$15 (in New Zealand, Australia and worldwide through iherb.com). Local organic shops may store turmeric.
Pricey for a common spice, yet rather affordable to most people in privileged countries, for about a year supply of a health-promoting spice for two people.