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Published on Leave a comment on Common Chemicals Linked to Chronic Diseases

Another study was just published with worrisome findings about phthalates. Phthalates are a group of chemicals used widely in common consumer products such as food packaging, toys, medical devices, medications, and personal care products. They are endocrine disruptors (can interfere with normal hormonal function) and are linked to a number of health problems (here, here, and here).

The study looked at urban Australian men and found that the higher the level of phthalates, the higher the rate of cardiovascular disease, type-2 diabetes, and hypertension. The researchers also found that higher levels of chronic low-grade inflammatory biomarkers (meaning higher levels of low-grade inflammation) was associated with higher levels of phthalates. All these findings confirm what other studies, done in other countries, have found.

Phthalates, which are measured in the urine,  were detected in 99.96% of the 1504 men. Eating a western dietary pattern (fast food, highly processed, low fiber) was also associated with higher phthalate levels.  However, they did not find an association of phthalate levels with asthma and depression. From Science Daily:

Everyday chemicals linked to chronic disease in men

Chemicals found in everyday plastics materials are linked to cardiovascular disease, type-2 diabetes and high blood pressure in men, according to Australian researchers. Researchers from the University of Adelaide and the South Australian Health and Medical Research Institute (SAHMRI) investigated the independent association between chronic diseases among men and concentrations of potentially harmful chemicals known as phthalates.

Phthalates are a group of chemicals widely used in common consumer products, such as food packaging and wrappings, toys, medications, and even medical devices. Researchers found that of the 1500 Australian men tested, phthalates were detected in urine samples of 99.6% of those aged 35 and over. "We found that the prevalence of cardiovascular disease, type-2 diabetes and high blood pressure increased among those men with higher total phthalate levels," says senior author Associate Professor Zumin Shi, from the University of Adelaide's Adelaide Medical School and the Freemasons Foundation Centre for Men's Health, and a member of SAHMRI's Nutrition & Metabolism theme.

"While we still don't understand the exact reasons why phthalates are independently linked to disease, we do know the chemicals impact on the human endocrine system, which controls hormone release that regulate the body's growth, metabolism, and sexual development and function. "In addition to chronic diseases, higher phthalate levels were associated with increased levels of a range of inflammatory biomarkers in the body," he says.

Age and western diets are directly associated with higher concentrations of phthalates. Previous studies have shown that men who ate less fresh fruit and vegetables and more processed and packaged foods, and drank carbonated soft drinks, have higher levels of phthalates in their urine.... Associate Professor Shi says that although the studies were conducted in men, the findings are also likely to be relevant to women. "While further research is required, reducing environmental phthalates exposure where possible, along with the adoption of healthier lifestyles, may help to reduce the risk of chronic disease," he says. [Original study.]

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Published on 1 Comment on Is Coffee From Lightly Roasted Coffee Beans Best For Health?

Should the results of this study determine what kind of coffee one drinks? Does it really make a difference? Eh...Not for me (because all coffee seems to be beneficial), but it might for you.

Studies show that daily drinking of coffee appears to have health benefits. Studies have linked coffee consumption with lower rates of cancer (here and here), cardiovascular disease, and diabetes. Coffee contains beneficial chemicals (such as caffeine and chlorogenic acid) that are antioxidant and anti-inflammatory, and could help fight chronic inflammatory diseases. It turns out that how much coffee beans are roasted changes how much chlorogenic acid they contain, but the amount of caffeine basically stays the same among the different roasting levels.

Researchers in Korea compared the caffeine and chlorogenic acid components of Arabica coffee beans at different roasting levels: Light, Medium, City, and French roast. They then tested various protective antioxidant and anti-inflammatory properties of the different coffee extracts in various "cell models" (meaning in the lab, not on real people). They found that chlorogenic acid levels were higher in light roasted coffee extract than the other roasted groups, and also light roasted coffee extract had the highest antioxidant activity. The results found that increasing degrees of roasting reduced antioxidant and anti-inflammatory activities.

From the Journal of Medicinal Food: Cellular Antioxidant and Anti-Inflammatory Effects of Coffee Extracts with Different Roasting Levels

During roasting, major changes occur in the composition and physiological effects of coffee beans. In this study, in vitro antioxidant effects and anti-inflammatory effects of Coffea arabica green coffee extracts were investigated at different roasting levels corresponding to Light, Medium, City, and French roast. Total caffeine did not show huge difference according to roasting level, but total chlorogenic acid contents were higher in light roasted coffee extract than other roasted groups. In addition, light roasted coffee extract had the highest antioxidant activity.... The expression of mRNA for tumor necrosis factor-alpha and interleukin-6 was decreased in cells treated with the coffee extracts and the expression decreased with increasing roasting levels. These data suggest that coffee has physiological antioxidant and anti-inflammatory activities and these effects are negatively correlated with roasting levels in the cell models.

Coffee is one of the most popular beverages worldwide. Increasing consumption of coffee is related to the pleasing taste and aroma, as well as its physiological effects. Coffee is proposed to exert beneficial effects against cancer, cardiovascular disease, obesity, and diabetes. Coffee contains phenolic compounds such as caffeic acid, chlorogenic acid, ferulic acid, vanillic acid, and other phytochemicals. The quality of coffee is significantly related to the roasting process.... During roasting, there are numerous changes in coffee bean compound profiles and the aroma is increased. Major changes in coffee bean composition occur during roasting as a result of the Maillard reaction..... Roasting markedly affects chlorogenic acid, leading to hydrolysis of chlorogenic acid. New compounds are formed during the roasting process; one of these is melanoidin. Its formation might alter the overall antioxidant capacity of coffee beans after roasting.

Coffee is a rich source of antioxidants that may contribute to prevention of oxidative stress-related diseases. The antioxidant properties of coffee may reflect the presence of both phenolic and nonphenolic bioactive compounds, such as caffeine and chlorogenic acids. Previous studies have shown that coffee has protective effects against oxidation and DNA damage in human cell models and has been shown to possess an in vitro antioxidant activity that lessens lipid peroxidation and neoplastic activity. 

Caffeine is the major component in coffee extract and has antioxidant property. Chlorogenic acid is another well-known efficient antioxidant in coffee extract; it was highest in Light roast coffee extract and highest with low roasting temperature and lowest in Dark roasted extract. Carbohydrates, protein, and chlorogenic acid are all decreased in coffee during the roasting process.... Caffeine contents showed no differences among roasting levels, but chlorogenic acid content decreased as roasting degree increased..... The effect of coffee roasting on the antioxidant properties of coffee extracts was investigated in several earlier studies; antioxidant capacity decreased in Dark roast coffee. The antioxidant property of coffee extracts prepared with different roasting levels was also determined in this study. The best antioxidant activity was evident in Light roast coffee extract and the lowest in French roast coffee.

Published on Leave a comment on Eating Fresh Fruit Is Linked to Lower Risk of Diabetes and Diabetic Complications

 Good news! Once again a study has confirmed that eating fresh fruits is associated with a lower incidence of type 2 diabetes. And even better - there is a dose related relationship - the more one eats daily, the better. So don't worry about the "sugar content" of fruit - the key is to eat fruit (as well as vegetables) to lower the risk of getting diabetes. And if you have type 2 diabetes, it will lower the incidence of death and complications from diabetes.

Here are the numbers for the 7 year study done in China of almost half a million people: eating fresh fruit was associated with a 12% lower risk of developing diabetes (compared to those never or rarely consuming fresh fruit). And in those who already had diabetes at the start of the study, consuming fresh fruit more than three days a week was associated with a 17% lower relative risk of dying from any cause and a 13%–28% lower risk of developing diabetes-related complications than those who consumed fruit less than one day per week.

Yes, I remember the advice that used to be given and is still given in parts of the world - that if you have diabetes, to restrict fruit, but studies are showing that advice to be wrong. Note that eating fresh fruits and vegetables has lots of other health benefits also - including lower rates of heart disease, stroke, and better mental (cognitive) functioning. From Science Daily:

Fresh fruit consumption linked to lower risk of diabetes and diabetic complications

In a research article published in PLOS Medicine, Huaidong Du of the University of Oxford, Oxford, United Kingdom and colleagues report that greater consumption of fresh fruit was associated with a lower incidence of diabetes, as well as reduced occurrence of complications in people with diabetes, in a Chinese population.

Although the health benefits of diets including fresh fruit and vegetables are well established, the sugar content of fruit has led to uncertainty about associated risks of diabetes and of vascular complications of the disease. Du and colleagues studied nearly 500,000 people participating in the China Kadoorie Biobank over about 7 years of follow-up, documenting new cases of diabetes and recording the occurrence of vascular disease and death in people with pre-existing diabetes.

The researchers found that people who reported elevated consumption of fresh fruit had a lower associated risk of developing diabetes in comparison with other participants (adjusted hazard ratio [aHR] 0.88, 95% CI 0.83-0.93), which corresponds to an estimated 0.2% reduction in the absolute risk of diabetes over 5 years. In people with diabetes, higher consumption of fresh fruit was associated with a lower risk of mortality (aHR 0.83, 95% CI 0.74-0.93 per 100g fruit/d), corresponding to an absolute decrease in risk of 1.9% at 5 years, and with lower risks of microvascular and macrovascular complications. [Original study.]

Published on Leave a comment on Many Heart Disease, Stroke, and Type 2 Diabetes Deaths Linked to Diet

Is this really a surprise to anyone at this point? According to a recent study: Almost half of all deaths in the United States in 2012 that were caused by cardiometabolic diseases such as heart disease, stroke and type 2 diabetes, have been linked to "suboptimal diets" - that is, to eating poorly and so not getting enough of certain foods and nutrients, and too much of other foods. Deaths due to heart disease, stroke, or type 2 diabete were linked to: high sodium (salt) intake, not eating enough nuts and seeds, a high intake of processed meats, and low intake of seafood omega-3 fats.

The study looked at consumption of 10 foods or nutrients that are associated with cardiometabolic diseases: fruits, vegetables, nuts/seeds, whole grains, unprocessed red meats, processed meats, sugar-sweetened beverages (SSBs), polyunsaturated fats, seafood omega-3 fats, and sodium. The researchers incorporated data from National Health and Nutrition Examination Surveys, from studies and clinical trials, and from the National Center for Health Statistics. So how should one eat for heath? Lots of fruits and vegetables, legumes (beans), nuts, seeds, whole grains, fish, and less processed food and fast food. (A plus of this is that it also feeds your beneficial gut microbes.) Read ingredient lists and try to avoid whatever foods have ingredients that you ordinarily wouldn't cook with or don't understand what they are (for example, colors, additives, titanium dioxide, artificial or natural flavors, etc.). From Science Daily:

High number of deaths from heart disease, stroke and diabetes linked to diet

Nearly half of all deaths in the United States in 2012 that were caused by cardiometabolic diseases, including heart disease, stroke and type 2 diabetes, have been linked to substandard eating habits, according to a study published in the March 7 issue of JAMA and funded by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health. Of the 702,308 adult deaths due to cardiometabolic diseases, 318,656, or about 45 percent, were associated with inadequate consumption of certain foods and nutrients widely considered vital for healthy living, and overconsumption of other foods that are not.

The list includes foods and nutrients long-associated with influencing cardiometabolic health. The highest percentage of deaths was linked to excess consumption of sodium. Processed meats, sugar-sweetened beverages and unprocessed red meats were also consumed in excess. Americans did not consume enough of some foods that have healthful effects such as fruits, vegetables, nuts and seeds, whole grains, polyunsaturated fats and seafood omega-3 fats.

The study also shows that the proportion of deaths associated with diet varied across population groups. For instance, death rates were higher among men when compared to women; among blacks and Hispanics compared to whites; and among those with lower education levels, compared with their higher-educated counterparts. The authors concluded that "these results should help identify priorities, guide public health planning, and inform strategies to alter dietary habits and improve health." The study findings were based on death certificate data collected by the National Center for Health Statistics, part of the Centers for Disease Control and Prevention.

Published on Leave a comment on Gluten Free Diets and Arsenic, Mercury, Diabetes

Image result for wheat bread wikipedia Low gluten or gluten-free diets are a necessity for those suffering from Celiac disease or who are gluten intolerant. But low gluten diets are also followed by many people who do not have these diseases simply because they think it may be healthier for them. But is it healthier? Two recent studies raise health concerns about low gluten or gluten-free diets. Gluten is a protein found in wheat, rye and barley.

The first study found that people who eat a low gluten or gluten-free diet are at risk for increased exposure to arsenic and mercury (which are toxic metals that can lead to cardiovascular disease, cancer and neurological effects). This is because gluten-free products often contain rice flour, which is used as a substitute for wheat. Rice is known to bioaccumulate certain toxic metals, including arsenic and mercury from fertilizers, soil, or water. People who reported eating gluten-free had higher concentrations of arsenic in their urine, and mercury in their blood, than those who did not. The arsenic levels were almost twice as high for people eating a gluten-free diet, and mercury levels were 70 percent higher. Unfortunately the U.S. does not have regulations for arsenic exposure in foods (but Europe does).

The second study found that a low-gluten diet may  raise the risk of type 2 diabetes. Diets higher in gluten were associated with a lower risk of developing type 2 diabetes. In the study, those who ate less gluten also tended to eat less cereal fiber which is known to be protective against developing type 2 diabetes.

From Science Daily: Gluten-free diet may increase risk of arsenic, mercury exposure

People who eat a gluten-free diet may be at risk for increased exposure to arsenic and mercury -- toxic metals that can lead to cardiovascular disease, cancer and neurological effects, according to a report in the journal Epidemiology. Gluten-free diets have become popular in the U.S., although less than 1 percent of Americans have been diagnosed with celiac disease -- an out-of-control immune response to gluten, a protein found in wheat, rye and barley. A gluten-free diet is recommended for people with celiac disease, but others often say they prefer eating gluten-free because it reduces inflammation -- a claim that has not been scientifically proven. In 2015, one-quarter of Americans reported eating gluten-free, a 67 percent increase from 2013.

They found 73 participants who reported eating a gluten-free diet among the 7,471 who completed the survey, between 2009 and 2014. Participants ranged in age from 6 to 80 years old. People who reported eating gluten-free had higher concentrations of arsenic in their urine, and mercury in their blood, than those who did not. The arsenic levels were almost twice as high for people eating a gluten-free diet, and mercury levels were 70 percent higher.

For Science Daily: Low gluten diets linked to higher risk of type 2 diabetes

Eating more gluten may be associated with a lower risk of developing Type 2 diabetes, according to research presented at the American Heart Association's Epidemiology and Prevention / Lifestyle and Cardiometabolic Health 2017 Scientific Sessions....In this long-term observational study, researchers found that most participants had gluten intake below 12 grams/day, and within this range, those who ate the most gluten had lower Type 2 diabetes risk during thirty years of follow-up. Study participants who ate less gluten also tended to eat less cereal fiber, a known protective factor for Type 2 diabetes development.

After further accounting for the potential effect of cereal fiber, individuals in the highest 20 percent of gluten consumption had a 13 percent lower risk of developing Type 2 diabetes in comparison to those with the lowest daily gluten consumption (approximately fewer than 4 grams).

Published on Leave a comment on Eating An Egg A Day May Be Beneficial?

Remember all the dietary advice that for years told us to avoid or limit consumption of eggs - that since they were high in cholesterol, they were bad for us and would increase our risk for heart disease? And the nonsense that we should only eat the egg whites while throwing out the yolks? Hah...That advice was wrong, which another recent study confirms.

Eggs are an amazingly nutritious food. They’re loaded with high quality protein, healthy fats, vitamins, minerals, high in choline (a brain nutrient), biotin, antioxidants, lutein, and zeaxanthin. One review of studies (involving millions of people) looked at whole egg consumption  and found that high egg consumption (up to one egg per day) is not associated with increased risk of coronary heart disease or stroke, and in fact there was a reduced risk of hemorrhagic stroke. Only among diabetics was there an elevated risk of coronary heart disease with high egg consumption (up to 1 egg per day). Another study found a lower risk of type 2 diabetes in middle-aged men (see post).

A recent study from Finland found that neither cholesterol nor egg intake (eating one egg per day) was associated with an increased risk of dementia or Alzheimer's disease in Finnish men who were followed for 22 years. Instead, eating eggs was associated with better cognitive performance in certain areas such as executive function, which includes memory, problem solving, and planning (they were given neuropsychological tests). From Science Daily:

High cholesterol intake and eggs do not increase risk of memory disorders

A new study from the University of Eastern Finland shows that a relatively high intake of dietary cholesterol, or eating one egg every day, are not associated with an elevated risk of dementia or Alzheimer's disease. Furthermore, no association was found in persons carrying the APOE4 gene variant that affects cholesterol metabolism and increases the risk of memory disorders. APOE4 is common in Finland.

The dietary habits of 2,497 men aged between 42 and 60 years and with no baseline diagnosis of a memory disorder were assessed at the onset the Kuopio Ischaemic Heart Disease Risk Factor Study, KIHD, in 1984-1989 at the University of Eastern Finland. During a follow-up of 22 years, 337 men were diagnosed with a memory disorder, 266 of them with Alzheimer's disease. 32.5 per cent of the study participants were carriers of APOE4.

The study found that a high intake of dietary cholesterol was not associated with the risk of dementia or Alzheimer's disease -- not in the entire study population nor in the carriers of APOE4. Moreover, the consumption of eggs, which are a significant source of dietary cholesterol, was not associated with the risk of dementia or Alzheimer's disease. On the contrary, the consumption of eggs was associated with better results in certain tests measuring cognitive performance. 

Published on Leave a comment on Are You Getting Enough Magnesium?

Magnesium is a mineral found in the human body that is necessary for good health. New research analysed 40 studies and found that a diet rich in magnesium is associated with a reduced risk of stroke, heart failure, diabetes, and death ("all cause mortality").

Even though there are many magnesium rich foods, it is estimated that many people don't get enough magnesium in the diet, especially if they eat a lot of processed, low-fiber foods. Current Recommended Dietary Allowances (RDAs) are 320 mg daily for adult females and 420 mg daily for adult males (NIH magnesium fact-sheets - here and here). Especially good sources of magnesium are green leafy vegetables, legumes (beans), nuts, seeds, chocolate, and whole grains. In general, foods containing dietary fiber provide magnesium.From EurekAlert:

Dietary magnesium associated with reduced risk of heart disease, stroke and diabetes

A diet rich in magnesium may reduce the risk of diseases including coronary heart disease, stroke and type-2 diabetes according to a new meta-analysis published in the open access journal BMC Medicine. This analysis of the evidence on dietary magnesium and health outcomes is the largest to date, involving data from more than one million people across nine countries.

The researchers, from Zhejiang University and Zhengzhou University in China, found that people in the highest category of dietary magnesium consumption had a 10% lower risk of coronary heart disease, 12% lower risk of stroke and a 26% lower risk of type-2 diabetes compared to those in the lowest category. Their results also indicate that an extra 100 mg per day of dietary magnesium could also reduce risk of stroke by 7% and type-2 diabetes by 19%.

Magnesium is vital for human health and normal biological functions including glucose metabolism, protein production and synthesis of nucleic acids such as DNA. Diet is the main source of magnesium as the element can be found in foods such as spices, nuts, beans, cocoa, whole grains and green leafy vegetables.

Original study. from BMC Medicine: Dietary magnesium intake and the risk of cardiovascular disease, type 2 diabetes, and all-cause mortality: a dose–response meta-analysis of prospective cohort studies

Increasing dietary magnesium intake is associated with a reduced risk of stroke, heart failure, diabetes, and all-cause mortality, but not CHD [coronary heart disease] or total CVD [cardiovascular disease]. These findings support the notion that increasing dietary magnesium might provide health benefits....Magnesium is essential to all living organisms, as it controls the function of many crucial enzymes, including those that utilize or synthesize ATP ....

Published on Leave a comment on A Daily Handful of Nuts Keeps the Doctor Away?

A large review of nut studies found that people eating a daily handful of nuts (about 20 g) have a lower risk of heart disease, cancer, stroke, premature death, and death from respiratory disease, type 2 diabetes, and infectious disease. Truly impressive. Benefits seem to be for all nuts, and also peanuts - which are called nuts, but are actually legumes (other posts about nut consumption benefits). An earlier post discussed how some of these effects could be to nuts lowering systemic inflammation throughout the body. Bottom line: try to eat a handful of nuts every day or most days a week for your health. And make it a variety of nuts - walnuts, almonds, hazelnuts, cashews, pistachios, pecans, Brazil nuts, and peanuts. From Science Daily:

A handful of nuts a day cuts the risk of a wide range of diseases

A large analysis of current research shows that people who eat at least 20g of nuts a day have a lower risk of heart disease, cancer and other diseases. The analysis of all current studies on nut consumption and disease risk has revealed that 20g a day -- equivalent to a handful -- can cut people's risk of coronary heart disease by nearly 30 percent, their risk of cancer by 15 percent, and their risk of premature death by 22 percent. An average of at least 20g of nut consumption was also associated with a reduced risk of dying from respiratory disease by about a half, and diabetes by nearly 40 percent, although the researchers note that there is less data about these diseases in relation to nut consumption.

The study, led by researchers from Imperial College London and the Norwegian University of Science and Technology, is published in the journal BMC Medicine. The research team analysed 29 published studies from around the world that involved up to 819,000 participants, including more than 12,000 cases of coronary heart disease, 9,000 cases of stroke, 18,000 cases of cardiovascular disease and cancer, and more than 85,000 deaths. While there was some variation between the populations that were studied....the researchers found that nut consumption was associated with a reduction in disease risk across most of them.

The study included all kinds of tree nuts, such as hazel nuts and walnuts, and also peanuts -- which are actually legumes. The results were in general similar whether total nut intake, tree nuts or peanuts were analysed. What makes nuts so potentially beneficial, said Aune, is their nutritional value: "Nuts and peanuts are high in fibre, magnesium, and polyunsaturated fats -- nutrients that are beneficial for cutting cardiovascular disease risk and which can reduce cholesterol levels. "Some nuts, particularly walnuts and pecan nuts are also high in antioxidants, which can fight oxidative stress and possibly reduce cancer risk. Even though nuts are quite high in fat, they are also high in fibre and protein, and there is some evidence that suggests nuts might actually reduce your risk of obesity over time."

The study also found that if people consumed on average more than 20g of nuts per day, there was little evidence of further improvement in health outcomes. [ORIGINAL STUDY]

Published on Leave a comment on Poor Diets May Lead To Vitamin C Deficiency

  It turns out that scurvy and vitamin C deficiency is still around these days. Scurvy is a disease resulting from a lack of vitamin C. Most animals can synthesize vitamin C, but not humans. We must eat foods containing vitamin C to get the vitamin.

Vitamin C deficiency results in defective formation of collagen and connective tissues (in our bones, skin, tendons, muscles), and symptoms may include weakness, feeling tired, curly hair, sore arms and legs, bruising, bleeding gums, and impaired wound healing.

A recent small Australian study looked at diabetic persons with chronic foot wounds (foot ulcers that didn't heal after several months). Their vitamin C levels were tested and if found to be low, then they were given vitamin C supplements of 500 or 1000 mg daily, and the result was that within 2 to 3 weeks the wounds were healed. The one person with a zinc deficiency was given 50 mg daily of zinc supplement and that wound also promptly healed.

Treatment of scurvy is by taking vitamin C supplements (the Mayo Clinic recommends taking 400 to 1000 milligrams of vitamin C  daily for one week). Vitamin C deficiency can be easily prevented by a diet that includes fruits and vegetables. The recommended daily intake for adult women is 75 milligrams and for adult men it is 90 milligrams, which can be easily met by eating fruits and vegetables, especially if they are fresh (uncooked).

Good sources of vitamin C include: oranges, lemons, kiwi fruit, black currants, papaya, guava, pineapple, mango, strawberries, and vegetables such as bell peppers (red, yellow, green), tomatoes, potatoes, kale, brussels sprouts, and broccoli. It is possible to be vitamin C deficient even if the person is of normal weight or overweight - it all comes down to the diet and whether fruits and vegetables are eaten. Bottom line: Eat some daily!

From Medical Xpress: Poor diet sees scurvy reappear in Australia

Scurvy, a disease historically associated with old-world sailors on long voyages, is making a surprise comeback in Australia, with health officials Tuesday revealing a rare spate of cases. Caused by vitamin C deficiency, the condition used to be a common—and often fatal—curse among seafarers who went months without fresh fruit and vegetables.  ...continue reading "Poor Diets May Lead To Vitamin C Deficiency"

Published on Leave a comment on Time For Doctors To Prescribe Exercise

We all know that exercise is beneficial for health. Research suggests that exercising out in nature is best for several varied reasons -  including that it lowers markers of inflammation, and that it's good for our gut microbiome (community of gut microbes). The following excerpts are written by Dr. John La Puma encouraging other doctors to prescribe exercise for their patients and why.

An important message of his is that exercise is more important than a drug prescription for a number of conditions, including diabetes prevention, reducing the risk of recurrence of several cancers (he mentions breast cancer, but it also holds for prostate cancer). While exercising and walking out in nature may be best, any exercise anywhere is better than no exercise. (Other posts on exercise as prescription medicine are here and here; and check the category exercise for all exercise research posts).

From Medscape: Rx: Exercise Daily -- Outdoors. Doctor's Orders

With dazzling Olympic feats on display all summer, too many of my patients are still literally immobilized. Medically, sitting too long shuts off the enzyme lipoprotein lipase. In people who are sedentary, the enzyme doesn't break down fat to create energy, like it should. But medical prescription for exercise has lagged even the slowest runner. Why? Some reasons are time, training, and money. Time especially is a scarce commodity: The average clinician visit lasts just 20 minutes. Fitness is a shamefully small part of medical training. And as doctors, we don't get paid for discussing exercise, let alone monitoring a prescription and assessing the response. 

Finally, there are practical reasons. Clinicians find it difficult to persuade patients that exercise is more effective than medication for any number of conditions, including stroke recovery, diabetes prevention, and treatment of low back pain. Regular exercise reduces the risk for recurrent breast cancer by approximately 50%. Given all these reasons, it's easy to see why fitness prescriptions are seldom more than an afterthought. Yet even without formally prescribing the frequency, intensity, time, and type of exercise, clinicians can speak with patients and families about fitness in inspiring, life-changing ways.

Because clinicians have a secret weapon to use that most people don't even know about—location. Exercising in nature (in sight of and preferably near water or greenery, whether a deserted beach or an urban park) is better. Walking city streets and the office itself can be harder on your health than you think. In both environments, your attention is demanded and directed—sometimes by digital interruptions, sometimes by vehicles, toxins, or duties. In nature, your attention is drawn, not pushed, to a variety of often unexpected but not unpleasant sounds, colors, aromas, textures, and forms.

A recent Stanford study of nature therapy showed significantly reduced rumination after a 90-minute walk in nature, compared with a 90-minute walk through an urban environment. On MRI, "nature walkers" showed lower activity in an area of the brain linked to risk for mental illness, the subgenual prefrontal cortex, compared with "urban walkers." In other words, nature offers a sense of something bigger than ourselves on which to focus. MRIs show the way the brain changes when that sense occurs to us.

Exercising in nature may improve a person's immune system by enriching the diversity in the microbiota. Microbiota buffer the immune system against chronic stress-related disease. They appear to act as a hormone-producing organ, not simply a collection of beneficial bacteria. Microbiota are sensitive and responsive to physical environmental changes as well as dietary ones. So, exercise in nature may favorably boost microbiota.

And finally, exercise in nature is clinically preferred and calming. A Norwegian study showed that exercise in nature and in view of nature improves both mood and diastolic blood pressure vs exercise without nature. A Chinese study showed higher energy levels, and lower levels of interleukin-6 and tumor necrosis factor (both markers of inflammation), in a forest walking group compared with an urban exercising group. A British study showed significantly improved mood and self-esteem with "green" exercise, with the largest benefits from 5-minute engagements. Five minutes!

Of course, there are areas in our country and world in which it is dangerous to walk, never mind exercise. It may not be as easy to generate sweat and intensity with outdoor exercise as it is with indoor exercise. It may be stormy, or baking hot, or otherwise harsh outside, and the cool recesses of one's own bedroom or the gym may be just perfect for you today. And with the 2013 total cost of inactivity estimated at $24.7 billion for the United States, and with the public sector bearing almost one half of that expense, any exercise anywhere is better than none.  Yet physicians have a therapeutic tool few others in our culture wield—a prescription pad—and we have every patient's attention, at least for a few minutes. Patients try harder when doctors advise them about fitness.