Research round-up - November 2010

Photograph by Lisa Hubbard

Purple Potatoes and their Phenolic Composition

Nov 2010: According to preliminary research at Queen Margaret University in Edinburgh, Purple Majesty potatoes have 3x has much antioxidant capacity as white potatoes. The purple potatoes contain anthocyanins, a flavanoid found in red and purple fruits such as blackberries, blueberries, red cabbage and red grapes. These potatoes were developed at Colorado State University in 2006 as a cross of original varieties of potatoes. They are not genetically modified. The study showed "peak plasma antioxidant capacity at 1-2 hours post consumption".

Dana's comment: the Purple Majesty taste as beautiful as they look. They mash well, are wonderful as potato wedges and are very appealing to children. The potatoes are available all year round. Union Square Greenmarket sells them as does Eataly. Check out Bon Appetit's Ceaser Potato Salad recipe.  For a healthier version, use 2 tbl of olive oil versus 1/4 of a cup and skip the parmesan cheese. You won't notice a difference in taste.

Blueberry Supplementation Improves Memory

Nov 2010: Researchers at the University of Cincinnati identified that drinking 2 1/2 cups of wild blueberry juice daily improved memory test scores (paired associate learning and word list recollection) after 12 weeks. There were also trends suggesting reduced depressive symptoms as well lower glucose levels. The researchers concluded “the findings of this preliminary study suggest that moderate-term blueberry supplementation can confer a neurocognitive benefit".

Dana's comment: Blueberries, like the purple potatoes, contain anthocyanins, which are associated with improved signaling in the brain. Wild blueberries contain more of the anthocyanins than cultivated blueberries. Look at for wild blueberries in the frozen section of the supermarket. Add them to a breakfast smoothie or snack on them with a dollop of Greek yogurt, but don't confine yourself to just blueberries, experiment with blackberries, red grapes and red cabbage. Antioxidants work synergistically together and the greater the variety the more powerful the impact. Remember, we are still discovering new polyphenol compounds so just because a food has less of one compound does not mean that it is inferior - the compound is likely to be discovered in the future.

High Protein - Low Glycemic Diet is Better for Weight Maintenance

25 Nov 2010: A large scale study funded by the European Commission, looked at 5 different dietary approaches for weight maintenance following a mean 11kg weight loss. All maintenance options had the same calories. The low-protein–high-glycemic-index diet was associated with subsequent significant weight regain, while the low glycemic and high protein diets saw a continued decrease in weight.


Dana's comment: A calorie is not just a calorie and it's a travesty that this dogma continues to be espoused. Controlling your weight is about regulating the hormones that influence weight loss. If you eat a high glycemic diet (think rice cakes, bagels and pasta) you cause a surge in insulin which triggers fat storage and inhibits the oxidation of fat. Eat a moderate amount of clean protein and get the vast majority of your carbohydrates from vegetables. It is this combination that stimulates the hormone glucagon which encourages fat burning and satiety.

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.