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Published on Leave a comment on Is Olive Oil Good For The Aging Brain?

Lately more and more research has been finding health benefits with frequent consumption of extra virgin olive oil (EVOO). It is also a basic part of the popular Mediterranean diet - which emphasizes fresh fruits and vegetables, nuts, legumes (beans), whole grains, some fish, and extra virgin olive oil. Now a study conducted by investigators at Temple University in Philadelphia, Pennsylvania, suggests that the olive oil in the Mediterranean diet probably promotes healthy brain aging. The researchers said: "Our study is the first demonstration that EVOO can beneficially affect memory, amyloid plaques, and tau pathology, the hallmark lesions in the brain of Alzheimer's patients."

But... note that they are taking findings from their study done on mice and hypothesizing that this is what is also going on in humans.  Their study used specially bred mice (and only 22 in total) - one group which received extra virgin olive oil in their food (starting at 6 months of age), and the other not. The researchers found that after a few months of this diet that there were differences between the 2 groups when tested at 12 months (which is also when they were euthanized). Note that mice are short lived and after 6 months they are considered "mature adults".

The researchgers now plan to test varying daily doses of EVOO on humans soon - this way they can see what the minimal dosage is for beneficial effects (if any), and if there is a maximal dosage where there are negative health effects. In the meantime, enjoy olive oil in your diet - looks like it will benefit your health in a number of ways (here, here, and here). From Medscape:

Olive Oil Key Ingredient in Alzheimer's Prevention?

Extra-virgin olive oil (EVOO) appears to protect memory and learning ability and reduces the formation of beta amyloid (Aβ) plaques and neurofibrillary tangles in the brain — the classic hallmarks of Alzheimer's disease (AD) — new animal research shows. The study, conducted by investigators at Temple University in Philadelphia, Pennsylvania, suggests that it is the olive oil component of the Mediterranean diet that likely promotes healthy brain aging.... "And results are important enough to absolutely encourage people to consume greater amounts of EVOO. Given that it's been consumed for at least 2000 years, I do not anticipate any side effects," he added.  ...continue reading "Is Olive Oil Good For The Aging Brain?"

Published on Leave a comment on Lose Weight If You Can’t Smell Your Food?

The following is a study with weird results, really weird results. And it makes me think of all the times I've heard people joke: "just smelling food makes me gain weight", because we all knew it wasn't true. But what if it was true? .... The results of this study done in mice are that actually smelling the food one eats results in weight gain, and not being able to smell the food results in weight loss - even if both groups eat the same amount of food. And the "supersmellers" (those with a "boosted" sense of smell) gained the most weight of all.

What? How could that be? Yes, the study was done in mice, but perhaps it also applies to humans (the researchers think so). The researchers think  that the odor of what we eat may play an important role in how the body deals with calories - if you can't smell your food, you may burn it rather than store it. In other words, a link between smell and metabolism. Excerpts from Science Daily:

Smelling your food makes you fat

Our sense of smell is key to the enjoyment of food, so it may be no surprise that in experiments at the University of California, Berkeley, obese mice who lost their sense of smell also lost weight. What's weird, however, is that these slimmed-down but smell-deficient mice ate the same amount of fatty food as mice that retained their sense of smell and ballooned to twice their normal weight. In addition, mice with a boosted sense of smell—super-smellers—got even fatter on a high-fat diet than did mice with normal smell.  ...continue reading "Lose Weight If You Can’t Smell Your Food?"

Published on Leave a comment on Did You Have Some Chocolate Today?

Image result for dark chocolate Chocolate lovers can rejoice - because another study, which was actually a review of other studies - found that frequent consumption of chocolate, cocoa, and cocoa flavanols (an ingredient of cocoa) is linked with beneficial health effects. These included cardiovascular benefits, and dose-dependent improvements in cognition, attention, and memory. In other words - the more frequently one eats chocolate and cocoa (especially dark chocolate), the more beneficial health effects. So eat and enjoy! From Medical Xpress:

Cocoa and chocolate are not just treats—they are good for your cognition

A balanced diet is chocolate in both hands - a phrase commonly used to justify one's chocolate snacking behavior. A phrase now shown to actually harbor some truth, as the cocoa bean is a rich source of flavanols: a class of natural compounds that has neuroprotective effects. In their recent review published in Frontiers in Nutrition, Italian researchers examined the available literature for the effects of acute and chronic administration of cocoa flavanols on different cognitive domains. In other words: what happens to your brain up to a few hours after you eat cocoa flavanols, and what happens when you sustain such a cocoa flavanol enriched diet for a prolonged period of time?

Although randomized controlled trials investigating the acute effect of cocoa flavanols are sparse, most of them point towards a beneficial effect on cognitive performance. Participants showed, among others, enhancements in working memory performance and improved visual information processing after having had cocoa flavanols. And for women, eating cocoa after a night of total sleep deprivation actually counteracted the cognitive impairment (i.e. less accuracy in performing tasks) that such a night brings about. Promising results for people that suffer from chronic sleep deprivation or work shifts.

The effects of relatively long-term ingestion of cocoa flavanols (ranging from 5 days up to 3 months) has generally been investigated in elderly individuals. It turns out that for them cognitive performance was improved by a daily intake of cocoa flavanols. Factors such as attention, processing speed, working memory, and verbal fluency were greatly affected. These effects were, however, most pronounced in older adults with a starting memory decline or other mild cognitive impairments.

And this was exactly the most unexpected and promising result according to authors Valentina Socci and Michele Ferrara from the University of L'Aquila in Italy. "This result suggests the potential of cocoa flavanols to protect cognition in vulnerable populations over time by improving cognitive performance. If you look at the underlying mechanism, the cocoa flavanols have beneficial effects for cardiovascular health and can increase cerebral blood volume in the dentate gyrus of the hippocampus. This structure is particularly affected by aging and therefore the potential source of age-related memory decline in humans."

So should cocoa become a dietary supplement to improve our cognition? "Regular intake of cocoa and chocolate could indeed provide beneficial effects on cognitive functioning over time. There are, however, potential side effects of eating cocoa and chocolate. Those are generally linked to the caloric value of chocolate, some inherent chemical compounds of the cocoa plant such as caffeine and theobromine, and a variety of additives we add to chocolate such as sugar or milk." Nonetheless, the scientists are the first to put their results into practice: "Dark chocolate is a rich source of flavanols. So we always eat some dark chocolate. Every day." [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 Improve Knee Arthritis Pain With A High Fiber Diet?

Another study finding health benefits of a fiber rich diet, which means lots of fruits, vegetables, whole grains, legumes (beans), nuts, and seeds. This time, researchers doing an a analysis of 2 studies lasting over a number of years found that there was an association with more fiber in the diet and less risk of developing knee osteoarthritis pain and of knee osteoarthritis symptoms worsening. The highest fiber group reported eating a median (middle number) 25.5 grams of fiber per day, while the lowest fiber group had a median of about 9 grams of fiber per day. They found a dose dependent relationship - the more fiber, the less osteoarthritis knee pain, and vice versa (the less daily fiber, the more they reported knee pain worsening) - this is called a "dose-dependent inverse relationship". The average fiber intake for Americans is about 15 grams per day.

The researchers also found that the more fiber in the diet, the lower their Body Mass Index (less weight) - but they say they took that into account in the analyses, and found that the amount of fiber intake was the most important thing regarding knee osteoarthritis pain. Interestingly, they did not find an association of fiber intake and x-ray evidence of osteoarthritis.  Note that this was an observational study - it observed that certain things go hand in hand, but it doesn't prove causation.

Osteoarthritis (OA) is common among adults aged 60 years and older, and is sometimes called "wear and tear" arthritis because it affects the joints. It causes pain and limits a person's physical functioning. There is a strong association between obesity, inflammation, and knee osteoarthritis. Obesity causes both inflammation and puts extra weight on the knees, and inflammation results in more joint pain. On the other hand, a high fiber diet reduces inflammation. The researchers point out that the data shows "a consistent protective association" between fiber in the diet and symptoms of knee osteoarthritis (no matter if you're overweight or not). IN SUMMARY: Eat lots of fruits, vegetables, legumes, whole grains, and nuts! From Science Daily:

Fiber-rich diet linked to lowered risk of painful knee osteoarthritis

A fibre-rich diet is linked to a lowered risk of painful knee osteoarthritis, finds the first study of its kind, published online in the Annals of the Rheumatic Diseases. The findings, which draw on two different long term studies, are broadly in line with the other reported health benefits of a fibre-rich diet. These include reductions in blood pressure, weight, and systemic inflammation, and improved blood glucose control.

The researchers mined data from two US studies in a bid to find out if dietary fibre might have any bearing on the risks of x-ray evidence of knee osteoarthritis, symptomatic knee osteoarthritis (x-ray evidence and symptoms, such as pain and stiffness), and worsening knee pain. The first of these studies was the Osteoarthritis Initiative (OAI). This has been tracking the health of nearly 5000 US men and women with, or at risk of, osteoarthritis since 2004-6 (average age 61), to pinpoint potential risk factors for the condition.  The second was part of the Framingham Offspring cohort study, which has been tracking the health of more than 1200 adult children of the original Framingham Heart Study and their partners since 1971.

Analysis of the data showed that eating more fibre was associated with a lower risk of painful knee osteoarthritis. Compared with the lowest intake (bottom 25 per cent of participants), the highest intake (top 25 per cent) was associated with a 30 per cent lower risk in the OAI and a 61 per cent lower risk in the Framingham study. But it was not associated with x-ray evidence of knee osteoarthritis. Additionally, among the OAI participants, eating more fibre in general, and a high cereal fibre intake, were associated with a significantly lower risk of worsening knee pain.

This is an observational study, so no firm conclusions can be drawn about cause and effect. Nevertheless, the researchers say: "These data demonstrate a consistent protective association between total fibre intake and symptom-related knee [osteoarthritis] in two study populations with careful adjustment for potential confounders." [Original study.]

Published on Leave a comment on Is It Possible That Eating Nuts May Prevent Colon Cancer Recurrence?

Amazing study results - if true - about some health benefits of eating nuts. Just tree nuts, not peanuts (which are actually a legume). Researchers at the Dana-Farber Cancer Institute in Boston found that colon cancer survivors who ate at least two ounces (57 grams) of tree nuts a week were 42% less likely to have their cancer return or a 53% lower chance of dying from their cancer than those who did not eat nuts. One ounce or a handful of nuts is considered a serving, but two ounces of nuts is about 48 almonds, or 36 cashews, or 96 shelled pistachios, or 38 pecan halves, or 28 walnut halves, or 42 hazelnuts.

The benefits of eating tree nuts was so surprising and so big, that the researchers caution that the study needs to be repeated (and improved) to make sure. The problem is that the study was observational, and so can't say a definite cause and effect. Perhaps people eating the tree nuts may also be doing some other protective behavior - thus there is just an association. So can't say for sure, but....the studies are adding up that eating nuts is linked with all sorts of health benefits. From STAT:

Can cashews keep colon cancer patients alive? Study says yes — but cautions abound

Surprising new research scheduled to be unveiled at a major cancer meeting next month suggests that cashews and other tree nuts might be as effective as some of oncology’s most effective treatments at keeping colon cancer from recurring after treatment — and even keeping patients from dying. If the benefit is real, a daily handful or two of cashews (cost: less than $1) could work as well as standard chemotherapy (cost: thousands of dollars). But the reported benefit comes with a big “if.”

Although the study is from a respected clinical trial, this finding was not from the original research but, instead, an add-on. The original trial randomly assigned colon cancer patients to either of two drug treatments. Later, researchers looked at cancer survivors who simply went about their lives, doing as they pleased, and tried to evaluate whether eating nuts was associated with better outcomes.In that kind of observational study, it’s not possible to say whether a given behavior — in this case, eating nuts — caused an outcome, or was instead simply associated with the true cause.

Even the study’s lead author was cautious. “This is the first study to show an association between nut consumption and cancer outcomes,” said Dr. Temidayo Fadelu of Dana-Farber Cancer Institute. “When you see an association that is more dramatic than you expect, you have to repeat [the study] in another [group of patients]. … There could be underlying confounders that we didn’t control for.” In other words, people who eat tree nuts, such as pecans, almonds, and walnuts, might be different from people who do not, something called “healthy patient bias.” They “might be more health-conscious,” said Shah. They might be wealthier, or better connected to the health care system, or have healthier habits in general. Any of those attributes might help patients survive colon cancer.

The researchers did not find an association with eating peanuts. Only tree nuts seemed to matter, to an eye-popping degree. Of 826 patients, those who reported having two or more servings per week (as 19 percent did) had a 46 percent lower risk of their cancer returning and a 53 percent lower risk of dying than those who said they did not eat tree nuts.

The study is an outgrowth of a famous clinical trial that began in 1999, testing chemotherapies in 1,264 patients with stage 3 colon cancer (meaning it had spread to lymph nodes but not to distant sites like the liver and lungs). Some patients filled out questionnaires about diet and lifestyle, once while receiving chemotherapy and again six months after treatment ended. 

Fadelu and his colleagues studied nut consumption because that has been associated with lower mortality, mostly because of a reduced risk of cardiovascular disease. “We definitely think something is going on,” with tree nuts providing a biological benefit, Fadelu said. For one thing, they decrease insulin resistance, “a potential mechanism” by which they might keep colon cancer from recurring, he said.

Published on Leave a comment on Could Changing Your Diet Prevent Gout?

Gout is something that is not discussed that much, but it has been increasing in recent years and now afflicts about  3.9% of adults in the US. Gout is a form of inflammatory arthritis, characterized by recurrent attacks of pain, tenderness, and swelling of a joint, frequently the joint of the big toe. It is caused by elevated levels of uric acid in the blood (known as hyperuricaemia).

Gout occurs more commonly in men ages 40 and older, who eat a lot of meat and seafood, drink a lot of alcohol (especially beer) or sweetened drinks, have high blood pressure, metabolic syndrome, or are overweight.  Gout used to be known as "the disease of kings" or "rich man's disease". [On the other hand, past research has shown that consumption of coffee, cherries, vitamin C foods, and dairy products, losing weight and physical fitness seems to decrease the risk.]

Recent research showed that the DASH diet reduces blood pressure and reduces uric acid in the blood, which is why a research team (study in The BMJ) now looked at  whether it lowers the risk of gout. The Dietary Approaches to Stop Hypertension or DASH diet is high in fruit, vegetables, whole grains, legumes, nuts, and low-fat dairy, and low in red and processed meats, salt, and sugary drinks. On the other hand, the typical Western diet has higher intakes of red and processed meats, sweetened beverages, sweets, desserts, French fries, and refined grains. The researchers analysed data on a total of 44,444 male health professionals, who had no history of gout at the start of the study. During the 26 years of the observational study, they documented 1731 cases of gout.

The researchers found that eating a more DASH type diet - a diet rich in fruits, vegetables, legumes, nuts, whole grains, and low in salt, sugary drinks, and red and processed meats, is associated with a lower risk of gout. On the other hand, a more 'Western' diet is associated with a higher risk of gout. They found that the effects are dose dependent - the more DASH-type diet, the lower the risk of gout. Bottom line: Once again, eating lots of fruits, vegetables, nuts, legumes, and whole grains is linked to health benefits. From Science Daily:

Diet rich in fruit, vegetables and whole grains may lower risk of gout

A diet rich in fruit and vegetables, nuts and whole grains and low in salt, sugary drinks, and red and processed meats, is associated with a lower risk of gout, whereas a typical 'Western' diet is associated with a higher risk of gout, finds a study published by The BMJ.

Gout is a joint disease which causes extreme pain and swelling. It is most common in men aged 40 and older and is caused by excess uric acid in the blood (known as hyperuricaemia) which leads to uric acid crystals collecting around the joints. The Dietary Approaches to Stop Hypertension (DASH) diet reduces blood pressure and is recommended to prevent heart disease. It has also been found to lower uric acid levels in the blood. Therefore, the DASH diet may lower the risk of gout.

To investigate this further, a team of US and Canada based researchers examined the relationship between the DASH and Western dietary patterns and the risk of gout. They analysed data on over 44,000 men aged 40 to 75 years with no history of gout who completed detailed food questionnaires in 1986 that was updated every four years through to 2012.

Each participant was assigned a DASH score (reflecting high intake of fruits, vegetables, nuts and legumes, such as peas, beans and lentils, low-fat dairy products and whole grains, and low intake of salt, sweetened beverages, and red and processed meats) and a Western pattern score (reflecting higher intake of red and processed meats, French fries, refined grains, sweets and desserts). During 26 years of follow-up, a higher DASH score was associated with a lower risk for gout, while a higher Western pattern was associated with an increased risk for gout.

 Gout. Credit: NHS in the UK

Published on Leave a comment on Higher Arsenic Levels In Babies Who Eat Rice Cereal

The research finding of so many baby foods with elevated arsenic levels (above the legal limit) in the European Union made me wonder about arsenic standards in baby cereals in the US. It turns out that the US has "parallel" standards to the European Union. The EU has "maximum 0.1 milligrams of arsenic per kilogram of rice" (this standard has been in place since January 2016), and in  2016 the US the FDA proposed a "maximum allowed standard of 100 ppb (parts per billion)" in infant rice cereal.

Why is there so much arsenic in baby cereal? It's in the rice - rice plants absorb arsenic from the soil (it may be naturally occurring in the soil or in the soil because of arsenic pesticides that were used for years). And why should we be concerned about arsenic in food? The health effects of regularly consuming infant rice cereal — and other rice-based products —containing traces of arsenic are currently unclear. But...the researchers stated that early-life exposure to arsenic, even at low concentrations, is of particular concern because infants and young children are especially vulnerable to the adverse health effects of arsenic. Arsenic is a carcinogen (causes cancer), and can have "neurological, cardiovascular, respiratory and metabolic" effects.

A Harvard Health Publication (Harvard Medical School) publication in 2016 stated: "In high doses it is lethal, but even small amounts can damage the brain, nerves, blood vessels, or skin — and increase the risk of birth defects and cancer." The FDA found that inorganic arsenic exposure in infants and pregnant women can result in a child’s decreased performance on certain developmental tests that measure learning, based on epidemiological evidence including dietary exposures.

So what should parents do? The American Academy of Pediatricians (AAP) encourages that babies and toddlers eat a variety of foods, and that this will decrease a child's exposure to arsenic from rice. They also encourage other options as first foods (rather than just rice cereal), such as oat, barley, and multigrain cereals - all of which have lower arsenic levels than rice cereal. From Science Daily:

New research shows illegal levels of arsenic found in baby foods

In January 2016, the EU imposed a maximum limit of inorganic arsenic on manufacturers in a bid to mitigate associated health risks. Researchers at the Institute for Global Food Security at Queen's have found that little has changed since this law was passed and that 50 per cent of baby rice food products still contain an illegal level of inorganic arsenic. Professor Meharg, lead author of the study and Professor of Plant and Soil Sciences at Queen's, said: "....Babies are particularly vulnerable to the damaging effects of arsenic that can prevent the healthy development of a baby's growth, IQ and immune system to name but a few."

Rice has, typically, ten times more inorganic arsenic than other foods and chronic exposure can cause a range of health problems including developmental problems, heart disease, diabetes and nervous system damage. As babies are rapidly growing they are at a sensitive stage of development and are known to be more susceptible to the damaging effects of arsenic, which can inhibit their development and cause long-term health problems. Babies and young children under the age of five also eat around three times more food on a body weight basis than adults, which means that, relatively, they have three times greater exposures to inorganic arsenic from the same food item.

The research findings, published in the PLOS ONE journal today, compared the level of arsenic in urine samples among infants who were breast-fed or formula-fed before and after weaning. A higher concentration of arsenic was found in formula-fed infants, particularly among those who were fed non-dairy formulas which includes rice-fortified formulas favoured for infants with dietary requirements such as wheat or dairy intolerance. The weaning process further increased infants' exposure to arsenic, with babies five times more exposed to arsenic after the weaning process, highlighting the clear link between rice-based baby products and exposure to arsenic.

In this new study, researchers at Queen's also compared baby food products containing rice before and after the law was passed and discovered that higher levels of arsenic were in fact found in the products since the new regulations were implemented. Nearly 75 per cent of the rice-based products specifically marketed for infants and young children contained more than the standard level of arsenic stipulated by the EU law.[Original study.]

A 2016 study done in New Hampshire also showed that babies eating rice cereals and other rice-based snacks had higher amounts of arsenic in their urine compared to infants who did not eat rice foods. From JAMA Pediatrics: Association of Rice and Rice-Product Consumption With Arsenic Exposure Early in Life

Published on Leave a comment on Should We Be Worried That Humans Are Losing Many Species of Gut Microbes?

An article was just published in a research journal to discuss the fact that humans - in part due to lifestyles which include less dietary fiber (due to eating fewer varieties and amounts of plants) and due to medical practices (such as frequent use of antibiotics) has resulted in gut "bacterial extinctions". In other words, humans (especially those living an urban industrialized Western lifestyle) have fewer gut bacterial species than those living a more traditional lifestyle, and this loss of bacterial species is linked to various diseases. Humans can increase the number of certain bacterial species, but the loss of some bacterial species is forever. 

The researchers discuss that humans have the "lowest level of gut bacterial diversity"  of any hominid and primate. They stated that the shrinking of the variety of microbial species in the human gut (the gut microbiome) began early in human evolution (as humans started eating more meat), but that it has accelerated dramatically within industrialized societies. And that evidence is accumulating that this gut bacterial "depauperation" - the loss of a variety of bacterial species - may predispose humans to a range of diseases.  Some of it is due to evolution (as humans ate more meat), and some to lifestyle changes. A term is used throughout this paper: depauperate - which means lacking in numbers or variety of species in the gut microbiome (the microbial community or ecosystem).

Other research has also shown that eating a highly processed Western diet results in gut microbial changes that are linked to various diseases (here, here, here) - that is, the microbes being fed are those associated with diseases. Also, certain diets encourage certain microbial species to flourish (here, here).  Bottom line: studies find health benefits from higher levels of dietary fiber - from fruits, vegetables, seeds, nuts, whole grains, and legumes (beans). From Current Opinion In Microbiology:

The shrinking human gut microbiome

Highlights: Humans harbor the lowest levels of gut bacterial diversity of any hominid. Humans in industrialized nations harbor fewer gut bacterial taxa than any primate. Medical practices and lack of dietary fiber may drive gut bacterial extinctions. Depauperate microbiotas may predispose entire human populations to certain diseases.

Mammals harbor complex assemblages of gut bacteria that are deeply integrated with their hosts’ digestive, immune, and neuroendocrine systems. Recent work has revealed that there has been a substantial loss of gut bacterial diversity from humans since the divergence of humans and chimpanzees. This bacterial depauperation began in humanity’s ancient evolutionary past and has accelerated in recent years with the advent of modern lifestyles. Today, humans living in industrialized societies harbor the lowest levels of gut bacterial diversity of any primate for which metagenomic data are available, a condition that may increase risk of infections, autoimmune disorders, and metabolic syndrome. Some missing gut bacteria may remain within under-sampled human populations, whereas others may be globally extinct and unrecoverable.

A typical human harbors on the order of 1013 bacterial cells in the large intestine. This gut microbiota, which can contain over a thousand species, is deeply integrated with virtually every tissue and organ system in the body. Gut bacteria process difficult to digest components of the diet, promote angiogenesis in the intestine, train the immune system, regulate metabolism, and even influence moods and behaviors.

In contrast to hunter–gatherer to agricultural transitions, adoptions of industrial and post-industrial lifestyles have led to massive reductions in bacterial richness within human gut microbiotas. Individuals living in urban centers in the United States harbor fewer gut bacterial species on average than do individuals living more traditional lifestyles in Malawi , Venezuela, Peru, and Papua New Guinea.....Industrialized and traditional lifestyles differ in many respects, confounding the identification of the specific practices that have led to decreases in gut bacterial diversity within industrialized societies. One potential cause is the rise of food processing and the corresponding reductions in the intake of dietary fiber in favor of simple sugars. Recently, studies in model systems have indicated that long-term reductions in dietary fiber can lead to the extirpation of gut bacterial taxa from host lineages. 

Other potential causes of reduced gut bacterial diversity within industrialized human populations include certain modern medical practices. For example, longitudinal studies in humans have shown that levels of gut bacterial diversity decrease drastically after antibiotic use. Although bacterial richness may recover after treatment is completed, the timeline and extent of the restoration is highly subject-dependent. The consequences of antibiotic use on gut bacterial diversity may be most severe when treatment is administered during the early years of life, before the adult microbiota has fully formed .

Published on Leave a comment on Blood Pressure Study Contradicts Sodium Limits in Dietary Guidelines

Another large recent study found that lowering sodium intakes (less than 2500 milligrams per day) wasn't linked to lower blood pressure. Over the course of 16 years, the researchers found that the study participants who consumed less than 2500 milligrams of sodium a day had higher blood pressure than participants who consumed higher amounts of sodium. However, the current 2015-2020 Dietary Guidelines for Americans recommends limiting sodium intake to 2,300 grams a day for healthy people. The researchers felt that based on recent studies with similar findings that the sodium guidelines should be changed.

This 16 year study found that people in the study who had normal intakes of sodium, but also higher intakes of potassium, calcium and magnesium exhibited lower blood pressure over the course of the study. And those people with higher combined intakes of sodium (3717 milligrams per day on average) and potassium (3211 milligrams per day on average on average) had the lowest blood pressure.

Some good potassium foods:  avocado, winter squash, sweet potato, potato, white beans, banana, spinach, salmon, dried apricots, tomato sauce, beans, and milk. Some good magnesium foods: dark leafy greens, nuts, seeds, fish, beans, whole grains, avocados, yogurt, bananas, dried fruit, dark chocolate. Some good calcium foods: milk, cheese, yogurt, kale, sardines, broccoli, white beans, and rhubarb. From Science Daily:

Low-sodium diet might not lower blood pressure: Findings from large, 16-year study contradict sodium limits in Dietary Guidelines for Americans

A new study that followed more than 2,600 men and women for 16 years found that consuming less sodium wasn't associated with lower blood pressure. The new findings call into question the sodium limits recommended by the current Dietary Guidelines for Americans. Lynn L. Moore, DSc, associate professor of medicine at Boston University School of Medicine, will present the new research at the American Society for Nutrition Scientific Sessions and annual meeting during the Experimental Biology 2017 meeting, to be held April 22-26 in Chicago.

"We saw no evidence that a diet lower in sodium had any long-term beneficial effects on blood pressure," said Moore. "Our findings add to growing evidence that current recommendations for sodium intake may be misguided." The 2015-2020 Dietary Guidelines for Americans recommends limiting sodium intake to 2,300 grams a day for healthy people. For the study, the researchers followed 2,632 men and women ages 30 to 64 years old who were part of the Framingham Offspring Study. The participants had normal blood pressure at the study's start. However, over the next 16 years, the researchers found that the study participants who consumed less than 2500 milligrams of sodium a day had higher blood pressure than participants who consumed higher amounts of sodium.

Other large studies published in the past few years have found what researchers call a J-shaped relationship between sodium and cardiovascular risk -- that means people with low-sodium diets (as recommended by the Dietary Guidelines for Americans) and people with a very high sodium intake (above the usual intake of the average American) had higher risks of heart disease. Those with the lowest risk had sodium intakes in the middle, which is the range consumed by most Americans.

The researchers also found that people in the study who had higher intakes of potassium, calcium and magnesium exhibited lower blood pressure over the long term. In Framingham, people with higher combined intakes of sodium (3717 milligrams per day on average) and potassium (3211 milligrams per day on average on average) had the lowest blood pressure.....Moore says that there is likely a subset of people sensitive to salt who would benefit from lowering sodium intake, but more research is needed to develop easier methods to screen for salt sensitivity and to determine appropriate guidelines for intakes of sodium and potassium in this salt-sensitive group of people.