Research round-up - October 2010

Low levels of vitamin B12 linked to Alzheimer’s
Oct 19 2010: A study published in the journal Neurology by researchers at the Karolinska Institute in Stockholm, Sweden has indicated that people with low levels of vitamin B12 may have a greater risk of developing Alzheimer’s disease. Over a seven year period, Hooshmand et al. followed 271 healthy individuals aged between 65 and 79. All participants did not have dementia at the start of the study. They examined the relationship between homocysteine (tHcy) levels and holotranscobalamin (holoTC), the active fraction of vitamin B12. High levels of tHcy have been associated with an increased incidence of cardiovascular disease and linked to negative effects on the brain, such as stroke. It is thought that elevated levels of vitamin B12 can help reduce tHcy levels. By the end of the study, 17 people had developed Alzheimer’s disease. The study found that for each micromolar increase in the concentration of tHcy, the risk of Alzheimer's disease increased by 16%. However a 1 pmol/L increase in holoTC reduced the risk of developing Alzheimer's by 2 %. The study results suggest that both tHcy and low holoTC may be involved in the development of the disease.

Dana's comment: from age 30 onwards, our body starts to produce less HCL which inhibits the secretion of intrinsic factor required for B12 absorption. Taking sublingual B12 bi-passes the digestive tract and enables its absorption. Nonetheless, if suboptimal levels of HCL exists the preferable route is to supplement with HCL and potentially zinc. Check via challenge tests.

Luteolin may reduce brain inflammation and related memory loss
A study in The Journal of Nutrition has suggested that luteolin (a flavonoid found in celery, carrots, peppermint and chamomile) reduces brain inflammation and related memory loss in aged mice, with luteolin directly inhibiting the release of inflammatory molecules in their brain. Johnson et al. from the University of Illinois conducted two studies. In the first study, Johnson et al. found that the microglial cells treated with luteolin, before toxin lipopolysaccharide (LPS) was added, had 70% less inflammation than those that weren't treated with the luteolin. The researchers concluded that luteolin was neuroprotective.

In the second study young adult mice (3-6 months) competed against aged adult mice (22-24 months). Half the mice in each group were fed a diet supplemented with 20 mg/d of luteolin for 4 weeks. The study found little difference within the two groups of young adult mice. However, the aged mice on the luteolin-supplemented diet showed improved working memory and reduced inflammation of the hippocampus putting them on a par with the young adult mice. In conclusion the researchers state that their findings suggest dietary luteolin enhanced spatial working memory by mitigating microglial-associated inflammation in the hippocampus.

Dana's comment - we don't need a study to tell us to eat carrots and celery but it's always validating when science supports common sense. Dip celery and carrots sticks in hummus for an afternoon snack or drink a green juice with kale, celery, cucumber and a carrot for an afternoon pick-up.

Soy isoflavones and hormone dependent breast cancer recurrence
Oct 18 2010: A study by scientists from the Harbin Medical University and published in the journal CMAJ has examined the associations between dietary intake of soy isoflavones and recurrence of hormone dependent breast cancer. The chemical structure of soy isoflavones is similar to that of estrogen which means they exhibit estrogen-like effects in the body. To determine the impact of soy isoflavones on hormone-dependant breast cancer, Kang et al. followed 524 women, of which 248 were premenopausal and 276 postmenopausal, for five to six years. All subjects had had breast cancer surgery and were receiving adjuvant endocrine therapy, of either Tamoxifen or Anastrozole. At baseline the women completed a food frequency questionnaire, which included reporting on consumption of soymilk, soy flour, dry soybeans, fresh soybeans, soybean sprouts and tofu amongst others. The study found that post-menopausal breast cancer survivors who consumed the most soy isoflavones (of over 42 mg/day), had a 12.9% decreased risk of hormone-dependent breast cancer recurrence compared with those who consumed the least (about 15 mg/day). They found that women consuming over 42mg/day and taking anastrozole had a 18.7% lower risk of hormone-dependent breast cancer recurrence. The study notes that they did not find the same association with premenopausal breast cancer survivors who had high soy consumption.

Dana's comment: Soy in it's natural state - miso, tempeh, tofu, edamame exhibit a weak estrogenic effect on the body which can provide protection from more potent forms of estrogen including endogenous estrodial and xenoestrogens such as BPA from plastics. However, processed soy such as soy protein isolate found in protein bars, food fortified with protein and some soy milk is highly refined and a very concentrated form of soy with potent estrogenic effects. Soy protein isolate is the 'white bread' of the soy family and should be avoided by everyone not just women at risk of hormone-dependent cancer recurrence.