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Mercury in Rice. What it means for you and for children.

Key points for Mercury in Rice:

Mercury from air pollution accumulates in rice

Mercury in rice may be high enough to harm brain development

Relying on rice as a staple food may be bad idea.

We know mercury is bad for you. It harms brain development and increases risk of heart disease. There is also evidence that it may increase risk of diabetes (Jeppesen et al. 2015).  It is especially bad for pregnant women, young infants and women who may become pregnant because of the harm it may do to their future children. Women and children (as well as men) are advised to limit the amount of mercury they eat by limiting intake of some kinds of fish.  Older, larger predators (swordfish, tuna) that eat high on the food chain are likely to have the most mercury. Younger, smaller fish have less time to build up mercury in their tissues.  They are thus less likely to pass it on to human consumers.   Fish, especially oily fish, has a lot of health benefits though.  Fish, or oil from fish, has been associated with reduced cardiovascular disease, less depression, and higher IQ. Regulators have tried to balance risk from mercury against some of the health benefits of fish.  That’s a tough one.  The best strategy seems to be to limit high-risk fish, and enjoy lower risk fish.

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Mercury in Rice: how it gets there

Mercury in rice starts with burning of coal, trash, and forest fires.  Mercury is released to air.  Mercury can travel the globe and is widely distributed.  The most dangerous form of mercury is methyl-mercury. This is mercury that has entered the environment and been transformed from elemental mercury to mercury with a methyl group on it.  The methyl group lets mercury lodge in fatty tissue, including the brain and other nervous tissue.  Methylation is done by bacteria in low-oxygen conditions.  The bacteria transform the mercury, small mud-dwellers pick it up.  The mud-dwellers get eaten by fish.  Which get eaten by larger fish. Which get eaten by us . . . where the mercury stays.  The bacteria that transform mercury are found on lake, river and ocean bottoms.  But these same bacteria are also found in rice paddies.  This mercury starts with air pollution, which settles in agricultural areas.  Sometimes far-away agricultural areas, but ends up in rice.   Scientists at the University of South Carolina and in China have been studying mercury in rice and its effects on children who do not eat fish (Rothenberg et al. 2016).  These are important studies because they show how mercury impacts children without the beneficial effects of fish confusing the picture. A strategy to reduce mercury exposure may be to reduce the amount of rice you eat.

Babies, Children and Mercury in Rice

So far the effects observed have been small, but measureable, declines in cognition. Or IQ to simplify things. It is important to note that the people studied live in China, and eat more rice than most Americans.  I asked the lead researcher, Susan Rothenberg, if American rice had less mercury than rice in China.  “unfortunately, American rice has similar levels of Mercury.”  So . . . it looks like buying local, or American rice, will not help.  Something that may be important is that rice is a staple food for babies. It is often the first solid food we feed our children.  One of the reasons we are advised to eat a varied diet is so that we will get a wide range of nutrients.  It can also be important to eat a varied diet so that you do not get too much of a particular contaminant like mercury.  I would not know what to suggest to parents, other than to talk to your baby’s pediatrician or dietary specialist for questions about child nutrition.  Varying a young child’s diet can be challenging.  Sorry there.  More research is coming out and we may reinvestigate mercury exposures in children.  Till then, less rice, perhaps.  Oh.  And clean air is important.

Genchi G, Sinicropi MS, Carocci A, Lauria G, Catalano A. 2017.  Mercury exposure and heart diseases.  Int. J Environ Res Public Health. 14(1): pii: E74. doi: 10.3390/ijerph14010074

Jeppesen C, Valera B, Nielsen NO, Bjerregaard P, Jorgensen ME. 2015.  Association between whole blood mercury and glucose tolerance among adult Inuit in Greenland.  Environ Res. 142(PtA): 192-7.

Rothenberg SE, Yu X, Liu J, Biasini FJ, Hong C, Jiang X, Nong Y, Cheng Y, Korrick SA. 2016.  Maternal methylmercury exposure through rice ingestion and offspring neurodevelopment: a prospective cohort study.  Internaional Journal of Hygiene and Environmental Health.  (In Press).

New evidence that BPA alters male behavior: another reason to avoid plastic water bottles

We’ve known for quite some time that BPA (bisphenol A) is an endocrine disruptor.  We’ve known since at least 2002 that BPA may change behavior in female rodents making them less attentive mothers.  Exposed mothers spend less time with their offspring, and may be less likely to retrieve them back to the nest if they stray.  Or are displaced by a researcher. That is one of the ways by which researchers test rodent parenting skills.  In many rodent species, only the female is involved in parental care.  But others are more like us, where both partners are involved in caring for offspring.  A new study (2015) shows that male behavior may also be altered by BPA.  Investigators used a species of mouse where both parents are involved in infant care. The newer study with males is important because because only female behavior had been studied before.

How can a chemical like BPA change behavior?

Chemicals that happen to resemble the normal molecules that control development can change the way the brain develops.  BPA resembles estrogen.  It resembles estrogen enough that it can interact with estrogen receptors or block them.  There are different kinds of estrogen receptors.  BPA can either block them or activate them depending on what kind of receptor it hits.  This is particularly important during fetal development because any abnormalities that develop are likely to persist. An adult with the occasional too much estrogen here or there will probably be fine.  I explained this to my ex once, but he continued to recoil from BPA in sales receipts like a teenage girl offered a spider.  An adult human male is at much less risk than an infant, but, to be fair, no one has tested them yet.  Teenagers, it should be noted, may be more vulnerable to estrogen-like chemicals (such as BPA) than adults (see Blaustein et al. 2015) because their brains are undergoing so many changes.

Estrogen is important in brain development and influences later typical male and female behavior.   BPA-exposed males were  less likely to mark their territories when another male was around.  Researchers suggest this is important because they may be less likely to engage in other male-mouse behaviors like protecting their mates from other males that could reduce their reproductive success.  While BPA does seem to influence how males dosed with BPA during development behave as adults, the effects are stronger in females. BPA appeared to influence how males were “viewed” by females.  Females seemed to be less invested in the care of infants produced by BPA-dosed males.  Why is unknown.  Did BPA make the fathers dorkier?  Was their less masculine behavior enough to make the mother mice value their own offspring less?  Did males exposed to BPA produce offspring less able to evoke nurturing behavior in their mothers?   There have been a few headlines “BPA turns Parents into Deadbeats” etc.  That is a bit of a jump, but interesting to think about in terms of what studies might be designed to evaluate humans: “BPA-exposed men express less interest in football” or “BPA-exposed men are more likely to share the remote during couple-based TV activities.”

What makes a woman a good mother anyway?  What makes her value her mate?  Surely a lot of social factors are involved, but there are complex hormonal and neurological factors that are likely important as well.  The two are probably intertwined.  Too much to discuss here.  What is important is that there is so much we do not understand about ourselves and and so much we don’t understand about what determines who we become.  Why add BPA to the mix?

Conclusion for BPA

Early exposure to BPA may alter behavior in adulthood.  We don’t know enough about BPA or about development to know if the levels at which people are exposed are completely without impact.  Until we know more, be conservative, especially if you are pregnant or might become pregnant.  Use a glass bottle or a non-plastic cup.  Plastic is bad for the environment anyway.

Blaustein JD, Ismail N, & Holder MK (2015). Review: Puberty as a time of remodeling the adult response to ovarian hormones. The Journal of steroid biochemistry and molecular biology PMID: 26004504

Palanza PL, Howdeshell KL, Parmigiani S, & vom Saal FS (2002). Exposure to a low dose of bisphenol A during fetal life or in adulthood alters maternal behavior in mice. Environmental health perspectives, 110 Suppl 3, 415-22 PMID: 12060838

Williams SA, Jasarevic E, Vandas GM, Warzak DA, Geary DC, Ellersieck MR, Roberts RM, & Rosenfeld CS (2013). Effects of developmental bisphenol A exposure on reproductive-related behaviors in California mice (Peromyscus californicus): a monogamous animal model. PloS one, 8 (2) PMID: 23405200

Rosenfeld CS (2015). Bisphenol A and phthalate endocrine disruption of parental and social behaviors. Frontiers in neuroscience, 9 PMID: 25784850

The WODMASTERS Rhino Design ruminates on Vitamin K

Vitamin K may keep your brain from falling apart

Keeping your brain from falling apart is serious business.  Tape and twine have their places, but we are writing to report on some other . . . . “stuff.”   Today’s stuff is Vitamin K.

Vitamin K, Health and Research

Research is indicating that Vitamin K may be important in protecting brain function. Researchers recently measured vitamin K levels in blood (as serum phylloquinone) and compared them with how well people did on several tests of cognitive function. People with higher levels of Vitamin K did better on tests of verbal memory and recall.   320 men and women between the ages of 70 and 85 participated in the study. This is good news because we do have some control over our vitamin K intake. The study has its limitations of course.  A blood test measures only what is currently in a person’s system.    The blood test used in this study was not able to measure people’s Vitamin K intake over a long period of time.

What is Vitamin K?

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Vitamin K is a fat soluble vitamin.  There are two common forms K1 and K2.  K1 comes from plants.   K1 was the form of vitamin K evaluated on the study of cognitive function.

Animals (like us) use K1 to make K2.  K2 is also synthesized by bacteria in the gut.   People may have many different kinds of gut bacteria.  Your gut bacteria will be influenced by your diet and medical history.

Vitamin K is best known as the vitamin the helps blood clot.  Good dietary sources of Vitamin K include:

  • Leafy greens
  • Brussels sprouts, cabbage, cauliflower, broccoli
  • Grains (minor sources)
  • Liver, eggs, meat, fish

Vitamin K may be important for maintaining bone health as well as brain health.  Vitamin K is being evaluated as a possible treatment for osteoporosis.  Until we hear more on that it is probably best to eat real food and plenty of vegetables rather rely on supplements.  Vitamins in vegetables come “packaged” with many other biologically important molecules.  You may need the entire package (by which we mean vegetable not multivitamin).  A dose of one particular molecule may not be particularly helpful.

Presse N, Belleville S, Gaudreau P, Greenwood CE, Kergoat MJ, Morais JA, Payette H, Shatenstein B, & Ferland G (2013). Vitamin K status and cognitive function in healthy older adults. Neurobiology of aging, 34 (12), 2777-83 PMID: 23850343

Knapen MH, Drummen NE, Smit E, Vermeer C, & Theuwissen E (2013). Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 24 (9), 2499-507 PMID: 23525894

Cell Interior by David Bolinsky

Breakthrough of the Year: Sleep cleanses the brain.

From the Editors at Science:
Science 20 December 2013:
Vol. 342 no. 6165 pp. 1440-1441
DOI: 10.1126/science.342.6165.1440-a
  • NEWS

To Sleep, Perchance to Clean

In work that Science‘s editors named a runner-up for Breakthrough of the Year, researchers studying mice have found experimental evidence that sleep helps to restore and repair the brain.

 Why do we sleep?

Questions of biology don’t get much more fundamental than that. This year, neuroscientists took what looks like a major stride toward an answer.

Most researchers agree that sleep serves many purposes, such as bolstering the immune system and consolidating memories, but they have long sought a “core” function common to species that sleep. By tracking colored dye through the brains of sleeping mice, scientists got what they think is a direct view of sleep’s basic purpose: cleaning the brain. When mice slumber, they found, a network of transport channels through the brain expands by 60%, increasing the flow of cerebral spinal fluid. The surge of fluid clears away metabolic waste products such as β amyloid proteins, which can plaster neurons with plaques and are associated with Alzheimer’s disease.

Until this discovery, researchers thought the brain’s only way to dispose of cellular trash was to break it down and recycle it inside cells. If future research finds that many other species undergo this cerebral housekeeping, it would suggest that cleaning is indeed a core function of sleep. The new findings also suggest that sleep deprivation may play a role in the development of neurological diseases. But with a causal role far from certain, it’s too early for anyone to stay awake worrying.

References and Web Sites

E. Underwood, “Sleep: The Brain’s Housekeeper?” Science 342, 6156 (18 October 2013).

L. Xie et al., “Sleep Drives Metabolite Clearance From the Adult Brain,”Science 342, 6156 (18 October 2013).