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It's reassuring to see that there are positive things one can do to maintain brain health as one ages. With normal aging, the brain typically shrinks a little with each passing decade  - starting from about the age of 40. But one recent Australian study, which reviewed the results of many other studies, found that exercise slows down this shrinkage in humans, specifically in the left hippocampus. That is, that aerobic exercise had a significant positive effect on the volume of the left hippocampus. This matches the result of animal studies.

The researchers pointed out that some studies found increases also in other parts of the human brain from exercise (e.g. in the white matter), but that they did not look at and review those studies. [See posts on research.] The good news is that positive effects were from exercise programs generally lasting less than 12 months. But it is unknown which type of exercise is best, or whether it is general "activity level and movement" that is most important. Bottom line: Get out there and move, move, move for brain health. And for cardiorespiratory fitness. It's all linked and it's all good. From Medical Xpress:

Exercise maintains brain size, new research finds

Aerobic exercise can improve memory function and maintain brain health as we age, a new Australian-led study has found. In a first of its kind international collaboration, researchers from Australia's National Institute of Complementary Medicine at Western Sydney University and the Division of Psychology and Mental Health at the University of Manchester in the UK examined the effects of aerobic exercise on a region of the brain called the hippocampus, which is critical for memory and other brain functions.

Brain health decreases with age, with the average brain shrinking by approximately five per cent per decade after the age of 40. Studies in mice and rats have consistently shown that physical exercise increases the size of the hippocampus but until now evidence in humans has been inconsistent.

The researchers systematically reviewed 14 clinical trials which examined the brain scans of 737 people before and after aerobic exercise programs or in control conditions. The participants included a mix of healthy adults, people with mild cognitive impairment such as Alzheimer's and people with a clinical diagnosis of mental illness including depression and schizophrenia. Ages ranged from 24 to 76 years with an average age of 66. The researchers examined effects of aerobic exercise, including stationary cycling, walking, and treadmill running. The length of the interventions ranged from three to 24 months with a range of 2-5 sessions per week.

Overall, the results – published in the journal NeuroImage– showed that, while exercise had no effect on total hippocampal volume, it did significantly increase the size of the left region of the hippocampus in humans.

"When you exercise you produce a chemical called brain-derived neurotrophic factor (BDNF), which may help to prevent age-related decline by reducing the deterioration of the brain," Mr Firth said. "Our data showed that, rather than actually increasing the size of the hippocampus per se, the main 'brain benefits' are due to aerobic exercise slowing down the deterioration in brain size. In other words, exercise can be seen as a maintenance program for the brain.".... Interestingly, physical exercise is one of the very few 'proven' methods for maintaining brain size and functioning into older age.

A recent study looked at 2 specific antioxidant levels in a variety of mushroom species. Mushrooms are an excellent source of nutrients, such as riboflavin and other B vitamins, selenium, copper, potassium, dietary fiber, as well as high levels of antioxidants ergothioneine (ERGO) and glutathione (GSH). The study found the highest levels of these antioxidants in yellow oyster and porcini mushrooms.

Ergothioneine (ERGO), which is found throughout the human body, is a critical antioxidant that acts with other antioxidants to protect against oxidative stress in the mitochondria (in our cells). What foods are good sources of ERGO? Mushrooms have the highest levels, but other foods with high ERGO content include red beans, black beans, kidney beans, oat bran, liver, and king crab.

Glutathione (GSH) is produced by the body and found in every cell - thus the major antioxidant within cells. It also helps the liver remove chemicals (detoxification) of a wide range of toxins, drugs, pollutants, and carcinogens, and maintenance of immune functioning. Low GSH levels are associated with increased risks for cancer, cardiovascular diseases, arthritis and diabetes. So you want to maintain optimal tissue levels of GSH (through dietary intake) because it is so critical for maintaining health. What foods are good sources of GSH? Mushrooms, and many fresh (raw) fruits and vegetables, including asparagus, avocados, potatoes, spinach, squash, tomatoes. Also fresh, uncooked meats and dairy products (raw milk) and eggs. From Science Daily:

Mushrooms are full of antioxidants that may have antiaging potential

Mushrooms may contain unusually high amounts of two antioxidants that some scientists suggest could help fight aging and bolster health, according to a team of Penn State researchers. In a study, researchers found that mushrooms have high amounts of the ergothioneine and glutathione, both important antioxidants, said Robert Beelman, professor emeritus of food science and director of the Penn State Center for Plant and Mushroom Products for Health. He added that the researchers also found that the amounts the two compounds varied greatly between mushroom species.

Beelman said that when the body uses food to produce energy, it also causes oxidative stress because some free radicals are produced. Free radicals are oxygen atoms with unpaired electrons that cause damage to cells, proteins and even DNA as these highly reactive atoms travel through the body seeking to pair up with other electrons. Replenishing antioxidants in the body, then, may help protect against this oxidative stress.

According to the researchers, who report their findings in a recent issue of Food Chemistry, the amounts of ergothioneine and glutathione in mushrooms vary by species with the porcini species, a wild variety, containing the highest amount of the two compounds among the 13 species tested. The more common mushroom types, like the white button, had less of the antioxidants, but had higher amounts than most other foods, Beelman said....Mushrooms that are high in glutathione are also high in ergothioneine, for example. Cooking mushrooms does not seem to significantly affect the compounds, Beelman said.

"It's preliminary, but you can see that countries that have more ergothioneine in their diets, countries like France and Italy, also have lower incidents of neurodegenerative diseases, while people in countries like the United States, which has low amounts of ergothioneine in the diet, have a higher probability of diseases like Parkinson's Disease and Alzheimer's," said Beelman. "Now, whether that's just a correlation or causative, we don't know." [Original study.]

The following study was done in England, but the results should be taken seriously and may (probably) apply to the US also - painted and enameled glassware ("externally decorated glassware") may contain high levels of lead and cadmium. The researchers found that more than 70% of the products (52 out of 72) tested positive for lead, and the metal was found in all colors, including the decorated gold leaf of some items. A similar number (51 out of 72) tested positive for cadmium, with the highest concentrations usually encountered in red enamel.

They found this in products manufactured both in Europe and China - which is why I think the results apply to painted or decorated glassware in the USA also. It probably also applies to some (many?) painted ceramics. So beware!  If you use painted or enameled glassware, you are at increased risk for ingesting lead and cadmium, both of which are linked to health problems - especially for developing fetuses and children. The best safe level of each is zero. The researchers mention that there are newer alternatives that are safe (lead and cadmium free). From Science Daily:

Drinking glasses can contain potentially harmful levels of lead and cadmium

Enameled drinking glasses and popular merchandise can contain potentially toxic levels of lead and cadmium, a study has shown. Researchers at the University of Plymouth carried out 197 tests on 72 new and second-hand drinking glass products, including tumblers, beer and wine glasses, and jars.

They found lead present in 139 cases and cadmium in 134, both on the surface of the glasses and, in some cases, on the rims, with concentrations of lead sometimes more than 1000 times higher than the limit level. Tests showed that flakes of paint often came away from the glass under when simulating sustained use, indicating the substances could be ingested over a prolonged period.

The study, published in Science of the Total Environment, analysed a range of glassware using portable x-ray fluorescence (XRF) spectrometryMore than 70% of the products (52 out of 72) tested positive for lead, and the metal was found in all recorded colours, including the decorated gold leaf of some items. A similar number (51 out of 72) tested positive for cadmium, with the highest concentrations usually encountered in red enamel.

The lead concentrations ranged from about 40 to 400,000 parts per million (ppm), while quantities of cadmium ranged from about 300 to 70,000 ppm. According to the US Office of Environmental Health Hazard Assessment, the limit levels for the externally decorated lip area of drinking glass are 200 ppm and 800 ppm respectively.

In the research, Dr Turner highlights that the Federation of European Screen Printers Associations says organic inks are becoming more popular than metallic pigments because of environmental concerns, and that such inks were evident on a number of newly-purchased products which proved negative for lead and cadmium.

He also says that additional analyses confirmed that hazardous elements are also used to decorate a wider range of consumer glassware that has the potential to be in contact with food, including the exteriors of bottles for the storage of beer, wine or spirits, the external text and logos on egg cups, jugs and measuring cups, and the undersides of coasters and chopping boards. "Given that safer alternatives are available to the industry, the overall results of this study are both surprising and concerning," Dr Turner added. "Why are harmful or restricted elements still being employed so commonly to decorate contemporary glassware manufactured in China, the European Union and elsewhere? " [Original study.]

Another study has shown health benefits from eating a diet rich in whole grains, as compared to one with lots of refined grains (think bagels, muffins, white bread). Fifty overweight Danish adults were randomly assigned to either a group where all grains eaten were whole grains or a group where all grain products were of refined grains. They did this for 8 weeks, then ate their usual diet for a few weeks (the "washout period"), and then were assigned to the other dietary group for 8 weeks.

They found that eating the diet rich in whole grains resulted in: consuming fewer calories (the whole grains made them feel fuller), losing weight, and a decrease in chronic low-grade inflammation (by measuring blood inflammation markers). The whole grain rye seemed to be especially beneficial. But interestingly, the researchers found that the whole grain diet did not significantly change the gut microbe composition. But they did find that 4 strains of Faecalibacterium prausntzii and one of Prevotella copri increased in abundance after whole grain and decreased after refined grain consumption. F.prausnitzii is a desirable and beneficial keystone species in the gut (here and here).

Other studies show that eating a diet rich in whole grains (rather than refined grains) is associated with a decreased risk of several diseases, including type 2 diabetes and cardiovascular diseases. Bottom line: choose whole grains whenever possible. From Science Daily:

Several reasons why whole grains are healthy

When overweight adults exchange refined grain products -- such as white bread and pasta -- with whole grain varieties, they eat less, they lose weight and the amount of inflammation in their bodies decreases. These are some of the findings of a large Danish study headed by the National Food Institute, Technical University of Denmark. 

The study included 50 adults at risk of developing cardiovascular disease or type 2 diabetes. Blood tests showed that the participants had less inflammation in their bodies when eating whole grains. In particular, it appeared that rye had a beneficial effect on the blood's content of inflammatory markers. Inflammation is the natural response of the body to an infection, but some people have slightly elevated levels of inflammation (so-called low-grade inflammation) even though there is no infection. This is particularly the case in overweight people. In overweight people, an increased level of 'unnecessary' (subclinical) inflammation may lead to increased risk of developing type 2 diabetes.

The study also shows that participants eat less when whole grain products are on the menu -- presumably because whole grain consumption causes satiety. While eating the whole grain diet, participants have generally lost weight. The researchers used DNA sequencing to analyze stool samples from the participants in order to examine whether the different diet types affected the participants' gut bacteria composition. Overall, the analysis did not shown major effects of the dietary grain products on the composition of the gut bacteria. [Original study.]

So you finally lost weight by diligently dieting, but now the issue is how to keep the weight from creeping back up again. Keeping strict watch over what you eat (basically continuing to diet)? Or exercising? Or...? Another issue muddying the waters is that a big weight loss also lowers the metabolism rate - something that occurred to former participants of the reality TV show The Biggest Loser. They lost enormous amounts of weight during the 30 week competition (over 100 pounds on average), but 6 years later much of the weight was regained, and they were burning hundreds fewer calories each day at rest. So they had become metabolically much slower over time.

A study looking at 14 former participants of The Biggest Loser 6 years after the show found that a large persistent increase in physical activity was essential for long-term maintenance of weight loss. Those who regained the least weight were the most active, and vice versa. On the other hand, food intake (keeping calorie intake low) wasn't the most important. How much of an increase in physical activity was needed to maintain the weight loss? Researchers found that an increase of about 80 minutes of daily moderate activity (such as brisk walking) or 35 minutes of daily vigorous activity was needed. From Medscape:

The Biggest Loser: Physical Exertion Is Key to Keeping Weight Off

Persistent increased physical activity is likely essential for long-term maintenance of weight loss, new research from participants in the US TV reality show The Biggest Loser suggests.... Using objective measures for both energy intake and physical activity in 14 former Biggest Loser contestants 6 years after they participated in the competition, Dr Kerns and colleagues found that those who had regained the least weight were the most active, and vice versa. Food intake, on the other hand, had very little effect on long-term weight-loss maintenance.

Asked to comment, Eric Ravussin, PhD, Boyd Professor at Louisiana State University, Baton Rouge, and coeditor of Obesity, told Medscape Medical News that the data align with those of follow-ups to major trials — including the Diabetes Prevention Program and the Action for Health Diabetes (Look AHEAD) study as well as with the National Weight Control Registry — of thousands of people who have lost at least 30 pounds and kept them off for at least a year. "The successful losers…all report high levels of physical activity" for weight maintenance, in contrast to weight loss, for which caloric deficit plays a far greater role, Dr Ravussin noted.

The reason for the difference between what works for weight loss vs maintenance, he said, probably has a lot to do with metabolic adaptation. This was the subject of another Biggest Loser paper published in Obesity in 2016, in which a person's metabolism slows down in response to a large drop in weight, making weight-loss maintenance difficult without an extra "push" from exercise, he explained.

The subjects in the new study were 14 participants with class III obesity who participated in a single season of The Biggest Loser, during which they underwent an intensive 30-week diet and exercise program and lost an average of 60 kg. Most regained weight after the program ended, although the degree of regain was highly variable. The median weight loss after 6 years was 13%. Seven subjects above the median weighed 24.9% less than baseline (maintainers) while the seven below the line (regainers) weighed 1.1% above their baseline. The maintainers had significantly greater increases in physical activity from baseline compared with the regainers..... that 35 minutes a day of intensive exercise, or 80 minutes of moderate activity, would roughly approximate the calorie expenditures among the maintainers.

Interesting study finding - that both high and low levels of magnesium is associated with a higher risk of dementia. Magnesium is an essential mineral needed for more than 300 biochemical reactions in the body. According to a large study done in the Netherlands of people who were followed for about 8 years - there was a U-shaped incidence of dementia based on their levels of magnesium. The lowest incidence was in those with "in the middle" normal levels of magnesium in the blood. All the study participants were mentally healthy when the study started.

The researchers stated that magnesium levels are considered "relatively stable over time", but a limitation of the study is that they only looked at magnesium levels once - at the beginning of the study, so they could have changed over time. Of course further studies are needed. [Other posts on magnesium and health - here, here, and here.]

Magnesium is widely available in foods. Foods that are good sources of magnesium include: spinach and other dark green leafy vegetables, almonds, cashews, peanuts, bananas, soybeans, kidney and black beans (legumes), whole grains, lentils, seeds, yogurt, brown rice, potatoes, and avocados. It is recommended that magnesium is obtained from the diet, and not from supplements (due to health risks from high doses). From Science Daily:

Both high, low levels of magnesium in blood linked to risk of dementia

People with both high and low levels of magnesium in their blood may have a greater risk of developing dementia, according to a study published in the September 20, 2017, online issue of Neurology®, the medical journal of the American Academy of Neurology.

The study involved 9,569 people with an average age of 65 who did not have dementia whose blood was tested for magnesium levels. The participants were followed for an average of eight years. During that time, 823 people were diagnosed with dementia. Of those, 662 people had Alzheimer's disease. The participants were divided into five groups based on their magnesium levels. Both those with the highest and the lowest levels of magnesium had an increased risk of dementia, compared to those in the middle group.

Both the low and high groups were about 30 percent more likely to develop dementia than those in the middle group. Of the 1,771 people in the low magnesium group, 160 people developed dementia, which is a rate of 10.2 per 1,000 person-years. For the high magnesium group, 179 of the 1,748 people developed dementia, for a rate of 11.4 per 1,000 person-years. For the middle group, 102 of the 1,387 people developed dementia, for a rate of 7.8. Kieboom noted that almost all of the participants had magnesium levels in the normal range, with only 108 people with levels below normal and two people with levels above normal[Original study.]

Once again a study finds that pesticide exposure is linked to an adverse health effect - that pesticide exposure in the home during pregnancy and early childhood is linked to an elevated risk of brain tumor in the child. Other studies have also found that pesticides used in the home are associated with a higher risk of childhood cancers.

This is because pesticides do cross the placental barrier, as the study researchers point out: "There is evidence that pesticides cross the fetal-placental barrier since residues of some insecticides have been found in umbilical cord blood, neonatal hair, and meconium following maternal exposure during pregnancy." Also, the International Agency for Research on Cancer (IARC) has classified "more than twenty pesticide chemical compounds as potential human carcinogens".

The following are examples (but there are more) of other studies finding pesticide and childhood cancer links: A meta-analysis published in 2015 in Pediatrics by researchers at Harvard University found that children exposed to indoor insecticides (also herbicides) have a higher risk of certain childhood cancers, specifically leukemia, lymphomas, and brain tumors. A 2013 study published in Cancer Causes and Control found that professional pest control applications in the home within a year of conception and during pregnancy was associated with a higher risk of childhood brain tumors. A review of studies published in 2010 found that pesticide exposure during pregnancy and childhood increased the risk of childhood leukemia.

The good news is that there are alternatives to exposing fetuses and children to toxic pesticides at home - by using alternative ways of dealing with pests, such as least toxic Integrated Pest Management (IPM) or organic methods. That means doing other things (such as sealing or caulking holes, putting out traps and baits, vacuuming), a focus on least toxic methods and on prevention (here and here), rather than routinely applying toxic pesticides. If needed, least toxic pesticides include boric acid and vinegar. Other sources of pesticide exposure for pregnant women and children are foods and exposure in settings outside the home - perhaps even a friend's yard. By the way, pesticide exposure for everyone is linked to a higher risk of health problems, not just pregnant women and children.

From Science Daily: Pesticide use during pregnancy linked to increased risk of childhood brain tumors

Previous epidemiological studies have suggested that exposure to pesticides during pregnancy may have a possible role in the development of childhood brain tumors. In a new International Journal of Cancer analysis, researchers found a link between maternal residential pesticide use -- particularly insecticides -- and the risk of childhood brain tumorsThe analysis included 437 malignant childhood brain tumor cases and 3102 controls from two French studies. Pesticide use was associated with a 1.4-times increased risk of childhood brain tumors.

The investigators noted that many pesticide compounds are classified as probable carcinogens, and there is evidence that some insecticides can pass through the feto-placental barrier. "Although such retrospective studies cannot identify specific chemicals used or quantify the exposure, our findings add another reason to advise mothers to limit their exposure to pesticides around the time of pregnancy," said Nicolas Vidart d'Egurbide Bagazgoïtia, lead author of the study. [Original study.]

OK, this study was done in mice, but it's the kind of study results that everyone hopes (and thinks) is also true for humans. So drink a nice cuppa black tea and think about how you're increasing bacteria in the gut associated with weight loss.

Black tea (as well as green tea) has polyphenols that stimulate the growth of gut bacterium and the formation of short-chain fatty acids. By the way, the mice were given decaffeinated tea extracts, so theoretically both decaf and caffeinated tea should have benefits. The big question though is - will drinking black tea daily actually result in weight loss? From Medical Xpress:

Black tea may help with weight loss, too

UCLA researchers have demonstrated for the first time that black tea may promote weight loss and other health benefits by changing bacteria in the gut. In a study of mice, the scientists showed that black tea alters energy metabolism in the liver by changing gut metabolites. The research is published in the European Journal of Nutrition. The study found that both black and green tea changed the ratio of intestinal bacteria in the animals: The percentage of bacteria associated with obesity decreased, while bacteria associated with lean body mass increased.

Previous studies indicated that chemicals in green tea called polyphenols are absorbed and alter the energy metabolism in the liver. The new findings show that black tea polyphenols, which are too large to be absorbed in the small intestine, stimulate the growth of gut bacterium and the formation of short-chain fatty acids, a type of bacterial metabolites that has been shown to alter the energy metabolism in the liver.

The researchers also collected samples from the mice's large intestines (to measure bacteria content) and liver tissues (to measure fat deposits). In the mice that consumed either type of tea extract, there was less of the type of bacteria associated with obesity and more of the bacteria associated with lean body mass. However, only the mice that consumed black tea extract had an increase in a type of bacteria called Pseudobutyrivibrio, which could help explain the difference between how black tea and green tea change energy metabolism.

The new study also concluded that both green tea and black tea have different effects on liver metabolism. According to Henning, the molecules in green tea are smaller and can more readily be absorbed into the body and reach the liver directly, while black tea molecules are larger and stay in the intestine rather than being absorbed. When black tea molecules stay in the intestinal tract, they enhance the growth of beneficial bacteria and the formation of microbial metabolites involved in the regulation of energy metabolism. [Original study.]

A newly published study suggests that exercising an hour or more per week could lower the incidence of depression. The study followed 33,000 adults in Norway  for 11 years, and found that an hour or more of weekly exercise was associated with 12% fewer cases of developing depression. But note that it didn't prevent anxiety. Interestingly, the researchers found that "regular leisure-time exercise of any intensity" had these positive effects - it doesn't have to be aerobic or incredibly strenuous exercise. Exercise is associated with a number of biological changes that could have an impact on mental health. From Science Daily:

One hour of exercise a week can prevent depression

A landmark study led by the Black Dog Institute has revealed that regular exercise of any intensity can prevent future depression -- and just one hour can help. Published in the American Journal of Psychiatry, the results show even small amounts of exercise can protect against depression, with mental health benefits seen regardless of age or gender.

In the largest and most extensive study of its kind, the analysis involved 33,908 Norwegian adults who had their levels of exercise and symptoms of depression and anxiety monitored over 11 years. The international research team found that 12 percent of cases of depression could have been prevented if participants undertook just one hour of physical activity each week.

A healthy cohort of participants was asked at baseline to report the frequency of exercise they participated in and at what intensity: without becoming breathless or sweating, becoming breathless and sweating, or exhausting themselves. At follow-up stage, they completed a self-report questionnaire (the Hospital Anxiety and Depression Scale) to indicate any emerging anxiety or depression.

Results showed that people who reported doing no exercise at all at baseline had a 44% increased chance of developing depression compared to those who were exercising one to two hours a week. However, these benefits did not carry through to protecting against anxiety, with no association identified between level and intensity of exercise and the chances of developing the disorder. [Original article.]

Is frequent sauna bathing beneficial? That's what one study suggests. When the study started all 1621 men (aged 42 to 60) had normal blood pressure and none had been diagnosed with hypertension, and the follow-up was about 22 years later. The study took place in Finland, where sauna bathing is an important part of the culture - for all men, from all walks of life. The study found that frequent sauna bathing lowered the risk of developing hypertension - 46% when comparing men who sauna bathed once a week vs those who sauna bathed 4 to 7 times a week.

How could sauna bathing have these effects? There are several possibilities, but one is that sauna bathing produces "acute vasodilation" of the blood vessels, which leads to a significant drop in blood pressure. The temperature in the sauna is usually from 80 °C to 100 °C (176 to 212 degrees Fahrenheit), and the average sauna session (in this study) lasted an average of 14.4 minutes. From Science Daily:

Frequent sauna bathing keeps blood pressure in check

Frequent sauna bathing reduces the risk of elevated blood pressure, according to an extensive follow-up population-based study carried out at the University of Eastern Finland. The risk of developing elevated blood pressure was nearly 50% lower among men who had a sauna 4-7 times a week compared to men who had a sauna only once a weekThe same researchers have previously shown that frequent sauna bathing reduces the risk of sudden cardiac death, and cardiovascular and all-cause mortality. Elevated blood pressure is documented to be one of the most important risk factors of cardiovascular diseases.

The Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) involved 1,621 middle-aged men living in the eastern part of Finland. Study participants without elevated blood pressure of over 140/90 mmHg or with diagnosed hypertension at the study baseline were included in this long-term follow-up study. Based on their sauna bathing habits, men were divided into three sauna frequency groups: those taking a sauna once a week, 2-3 times a week, or 4-7 times a week. During an average follow-up of 22 years, 15.5% of the men developed clinically defined hypertension. The risk of hypertension was 24% decreased among men with a sauna frequency of 2-3 times a week, and 46% lowered among men who had a sauna 4-7 times a week.

Sauna bathing may decrease systemic blood pressure through different biological mechanisms. During sauna bathing, the body temperature may rise up to 2 °C degrees, causing vessels vasodilation. Regular sauna bathing improves endothelial function, i.e. the function of the inside layer of blood vessels, which has beneficial effects on systemic blood pressure. Sweating, in turn, removes fluid from the body, which is a contributing factor to decreased blood pressure levels. Additionally, sauna bathing may also lower systemic blood pressure due to overall relaxation of the body and mind.

[NOTE: Above photo is of interior of a modern Finnish sauna. Credit: Wikipedia]