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Image result for calcium rich foods, wikipediaAgain, another study finds that taking supplements is not always best for health. Many studies find that eating foods with vitamin "X" is beneficial, but taking high dose supplements may be linked to health problems (here, here, and here). Now a new study finds that long-term high dose supplementation with vitamins B6 and B12 is associated with a 30 to 40% higher lung cancer risk in men (compared to men who didn't take these supplements). Smokers had the greatest increase in risk. But interestingly, long-term use use of  vitamins B6, folate, and B12 was not associated with lung cancer risk among women.

Good food sources of vitamin B6 are: poultry, fish, organ meats, potatoes and other starchy vegetables, chickpeas, and fruit (but not citrus). Good food sources of B12 are:  Beef liver, clams, fish, meat, poultry, eggs, milk, and other dairy products.  Bottom line: if you take vitamin supplements (such as daily multi-vitamin supplements), take a "low-dose" one - one that aims for 100% of minimum daily requirements, but not mega-doses of vitamins.  From Medical Xpress:

Clear link between heavy vitamin B intake and lung cancer

New research suggests long-term, high-dose supplementation with vitamins B6 and B12—long touted by the vitamin industry for increasing energy and improving metabolism—is associated with a two- to four-fold increased lung cancer risk in men relative to non-users.

Risk was further elevated in male smokers taking more than 20 mg of B6 or 55 micrograms of B12 a day for 10 years. Male smokers taking B6 at this dose were three times more likely to develop lung cancer. Male smokers taking B12 at such doses were approximately four times more likely to develop the disease compared to non-users..... This is the first prospective, observational study to look at the effects of long-term high-dose B6/B12 supplement use and lung cancer risk. These supplements have been broadly thought to reduce cancer risk.

For this study, Theodore Brasky, PhD, of the OSUCCC - James, and colleagues analyzed data from more than 77,000 patients participants in the VITamins And Lifestyle (VITAL) cohort study, a long-term prospective observational study designed to evaluate vitamin and other mineral supplements in relation to cancer risk. All participants were aged between 50 and 76 were recruited in the state of Washington between the years 2000 and 2002. Upon enrolling in the study, participants reported information to researchers about B-vitamin usage over the past 10 years. This included dosage information.

Brasky notes these findings relate to doses that are well above those from taking a multivitamin every day for 10 years. "These are doses that can only be obtained from taking high-dose B vitamin supplements, and these supplements are many times the U.S. Recommended Dietary Allowance," he said. Two additional studies are underway at The OSUCCC - James to further evaluate high dose, long-term B6 and B12 supplementation and lung cancer risk. [Original study.]

 Another piece of the puzzle on how the brain ages. Vitamin B12 is important for brain health, and higher levels are associated with slower rates of brain changes associated with aging. And the opposite is true with homocysteine levels - increased levels are associated with faster rates of brain changes that are associated with aging (such as higher rates of total brain tissue volume loss). Keep in mind that these effects were modest, but this also raises the question of whether long-term B12 supplementation would benefit everyone or only those with a deficiency? From Medscape:

Vitamin B12 May Slow Brain Aging

Individuals with increased levels of circulating homocysteine have faster rates of brain changes associated with aging than other people, whereas higher levels of vitamin B12 are associated with slower rates of brain aging, new research suggests.

Babak Hooshmand, MD, PhD, Center for Alzheimer Research–Aging Research Center, Karolinska Institutet, Stockholm, Sweden, and colleagues found that total brain volume losses were lower in individuals with higher baseline vitamin B12 levels, whereas the opposite was true of those with increased homocysteine levels.

"Vitamin B12 and tHcy [total homocysteine] might be independent predictors of markers of brain aging in elderly individuals without dementia," the investigators write. They add, "[I]f the association is causal, supplementation with B vitamins may be effective for prevention of brain damage due to increased levels of total homocysteine. Adequately timed and powered randomized clinical trials are needed to determine efficient treatment guidelines." The research was published online April 27 in JAMA Psychiatry.

The researchers examined data on 501 participants aged 60 years and older from the Swedish National Study on Aging and Care, in Kungsholmen. All participants were free of dementia at baseline. Of these, 299 underwent repeated structural brain MRI between 2001 and 2009....Venous blood samples were collected at baseline, from which circulating levels of vitamin B12, red blood cell folate, and sulfur amino acids were determined. These were correlated with changes in brain tissue volumes and total white matter hyperintensity (WMH) over 6 years.

He also pointed to the single-center, randomized VITACOG study, in which 271 individuals older than 70 years who had mild cognitive impairment received supplementation with high-dose folic acid and vitamins B6 and B12. "They lost less brain compared to people who had normal homocysteine and normal vitamin levels, meaning that those with high levels of homocysteine or with clinical or biochemical vitamin deficiency can benefit from supplementation," said Dr Hooshmand.