ScienceDaily (June 28, 2012) - Millions of people worldwide are exposed to arsenic from contaminated water, and we are all exposed to arsenic via the food we eat. New research published in BioMed Central's open access journal Nutrition Journal has demonstrated that people who ate more dietary vitamin B12 and animal protein had lower levels of arsenic (measured by deposition in toenails). Total dietary fat, animal fat, vegetable fat and saturated fat were also all associated with lower levels of arsenic, while omega 3 fatty acids, such as those found in fish oil, were associated with increased arsenic.
Long term exposure to high levels of arsenic is known to cause skin lesions, cancer and cardiovascular disease, and also affects fetal development. Even low concentrations of arsenic are potentially dangerous. Arsenic is found in some water supplies, but more people are exposed via their diet. Staples such as rice contain arsenic, especially the toxic inorganic forms, while fish, although high in total arsenic, contains organic forms which are thought to be less toxic.
Inside the body arsenic is methylated to aid excretion in urine but arsenic also has an affinity for keratin and can be deposited in hair and nails as they grow. Consequently levels of arsenic preserved in nails or hair can be used as a biomarker for arsenic exposure over periods of months to years.
Researchers from Dartmouth College and the Geisel School of Medicine at Dartmouth looked at the levels of arsenic in toenails of residents of New Hampshire who all use private groundwater wells as their household water source.
Results of the study showed that arsenic in nails was positively associated with both alcohol and omega 3 fatty acids, however, lower levels of arsenic were found for people who ate greater amounts of vegetable and animal fat. Prof Kathy Cottingham, who directed the study, explained, "While there may be a direct interaction between fats and arsenic preventing absorption or binding to keratin in nails, the results may simply reflect dietary preference, with people who eat a diet rich in fats not eating foods high in arsenic, such as rice."
Joann Gruber, who led the study, noted that, "Humans can be very efficient at removing arsenic from the body. Improved methylation reduces the amount of inorganic arsenic circulating in the body. Surprisingly, we didn't see a reduction in toenail arsenic with other dietary factors known to be necessary for arsenic methylation such as folic acid. This may be because the population we sampled had adequate amounts of these factors in their diet."
The authors are currently working on similar studies in children, through the Children's Environmental; Health and Disease Prevention Center at Dartmouth.
Source: ScienceDaily (June 28, 2012) http://www.sciencedaily.com/releases/2012/06/120629005456.htm

Comments
The above paper shows that food serves as a major source for arsenic exposure. And Rice which is a major staple food to a greater number of people could contain substantial amount of arsenic.
Note that the dangers of arsenic depend on its type, if it is inorganic or organic. However, rice has been shown to have both and it depends on the origin, i.e. from Asia, Europe or America. The origin of the rice, in particular, makes a big difference on which of the arsenic forms may likely be dominant. From a health perspective, the inorganic arsenic is more easily absorbed by the body than the organic form. This means that the inorganic form could be dangerous.
Since exposure to arsenic in food is inevitable, certain measures could be taken to lessen any associated health impact if not prevent it. And this above article may be explaining some of the reasons why arsenic exposure have not caused extremely serious health problems in Ghana, even though its presence is significantly high in the country on a global scale. However it is not conclusive if it is contributing to the short life expectancies in Ghana and Africa as a whole.
Arsenic is known to cause several medical conditions including skin lesion. And the article points out that that people who ate more dietary vitamin B12 and animal protein had lower levels of arsenic so is the total dietary fat; animal fat, vegetable fat and saturated fat.
Rice forms a large part of the Ghanaian diet and mostly eaten with soup, stew or sugar and milk. Our soups or stews mostly have animal fat, vegetable fat and/or saturated fat while milk contains vitamin B12 and proteins. Eating rice over time without soup/stew or milk results in a skin disease known locally as “beriberi” which is basically a skin lesion possibly from the arsenic exposure.
Our local diet which involves soup/stew or milk should have sufficient soup/stew or milk to reduce any harm posed by arsenic or heavy metals. However, depending on the arsenic load of the food; the total dietary fat, vitamin B12 and animal proteins may not be sufficient hence external interventions including periodic detoxification may be required. Cysteine food supplements and/or Cysteine-rich foods can be used. Though, animal fats and some saturated fats have been found to reduce the effects of arsenic in the body, animal and saturated fats should be consumed in moderation to prevent associated health effects. This information supports that some of our food combinations has some scientific basis.
It is worth to mention that while we are scared of arsenic in water; we are still exposed substantially through foods. Knowing what you are eating or drinking will help you tailor necessary solutions or remedies to improve on your longevity.

Alexander Anim-Mensah, PhD
Dayton Ohio
alexraymonda@yahoo.com