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In the US and other developed countries it is generally accepted that blood pressure increases with age -  that a blood pressure rise starts in childhood and that it's a normal part of aging. However, a new study found that this is not true - a South American rainforest tribe (the Yanomami) who do not eat a western diet (at all!) and have an active lifestyle, have the exact same blood pressure throughout life. This was true for all the individuals studied - from age 1 to 60. A nearby village of the Yekwana tribe have some western influences on lifestyle and diet, had the same low blood pressure in childhood, but showed increases with age.

The researchers feel that a Western diet and lifestyle play a role in the blood pressure increasing over the life span. They are now looking at the gut microbes of the two tribes to see what role they have in these blood pressure differences. Bottom line: get off your butt  and get active, and eat a high fiber, whole food diet (to feed the beneficial microbes) -  and avoid highly processed foods if you can. Easier said than done. From Science Daily:

Study of two tribes sheds light on role of Western-influenced diet in blood pressure

...continue reading "Blood Pressure Doesn’t Always Increase With Age"

There have been many posts on this blog about diet, fiber, microbes, and the association of diet with various diseases, such as cancer. A recent journal article by M. Song and A. Chan reviewed studies that looked at the link between diet, gut microbes (the gut microbiota or gut microbiome), and colorectal cancer (what we typically call colon cancer).

In summary, research from the last 20 years has found that diet and colorectal cancer (CRC) go hand in hand, and that diet determines the microbes (microbiota) living in the gut - that is, what you feed the microbes determines what microbes will live and thrive in the gut. Also, certain microbes in the gut are linked to inflammation and cancer formation, and others to its prevention. In other words, there is potential to prevent colorectal cancer with certain diets, and to increase the odds of colorectal cancer with other diets.

What are main dietary factors linked to colorectal cancer? Western diet (lots of processed foods, red and processed meat, low in fiber, refined grains), low levels of dietary fiber, low intake of omega-3 fatty acids from seafood (or fish oil), and obesity. The researchers point out that a Western diet is associated with gut dysbiosis (microbial imbalance), loss of gut barrier integrity, and increased levels of inflammation. What should one do? Basically think to yourself: "I need to feed the beneficial microbes in my gut, so I need to eat lots of fruits, vegetables, whole grains, and seafood (omega-3 fatty acids)" - this is what the researchers call a "prudent pattern diet". And try to maintain a normal weight. Some excerpts from Current Colorectal Cancer Reports:

Diet, Gut Microbiota, and Colorectal Cancer Prevention: a Review of Potential Mechanisms and Promising Targets for Future Research

AbstractDiet plays an important role in the development of colorectal cancer. Emerging data have implicated the gut microbiota in colorectal cancer. Diet is a major determinant for the gut microbial structure and function. Therefore, it has been hypothesized that alterations in gut microbes and their metabolites may contribute to the influence of diet on the development of colorectal cancer.We review several major dietary factors that have been linked to gut microbiota and colorectal cancer, including major dietary patterns, fiber, red meat and sulfur, and obesity

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the fourth leading cause of cancer death in the world. Over the past few decades, numerous epidemiologic studies have identified a range of dietary factors that may potentially promote or prevent CRC. Likewise, increasing evidence has implicated the gut microbiota in CRC development. Biological plausibility is supported by habitation of numerous gut microbes in the large intestine and the functional importance of the gut microbiota in maintenance of the gut barrier integrity and immune homeostasis, the disruptions of which are among the most important mechanisms in colorectal carcinogenesis. Given the critical role of diet in the configurations of gut microbial communities and production of bacterial metabolites, it has been proposed that diet may influence CRC risk through modulation of the gut microbial composition and metabolism that in turn shape the immune response during tumor development.

Although gut bacterial abundance may respond rapidly to extreme changes in diet, predominant microbial community membership is primarily determined by long-term diet, and substantial inter-individual variation persists despite short-term dietary change. .... Thus, this review focuses on the dietary factors that have strong mechanistic support, including dietary pattern, fiber, red meat and sulfur, and omega-3 fatty acid. Given the close link between diet and obesity and the predominant role of obesity in CRC as well as the substantial data linking the gut microbiome to obesity, we also include obesity at the end of the review.

DIETARY PATTERNS: Convincing data indicate that a “Western dietary pattern,” characterized by high intake of red or processed meat, sweets, and refined grains, is associated with higher risk of colorectal neoplasia; in contrast, diets that are rich in fruits, vegetables, and whole grains (“prudent pattern diet”) are associated with lower risk of CRC. Western diets are associated with gut dysbiosis (microbial imbalance), loss of gut barrier integrity, increased levels of inflammatory proteins, and dysregulated immune signatures.

A potential role of the gut microbiota in mediating the dietary associations with CRC risk is suggested by the dramatic difference of the gut microbial structures between populations consuming different diets. Rural Africans, whose diet is high in fiber and low in fat, have a strikingly different gut microbial composition than urban Europeans or African Americans consuming a Western diet, which parallels the lower CRC rates in Africa than Western countries. For example, the African gut microbiota is characterized by a predominance of Prevotella genus that are involved in starch, hemicellulose, and xylan degradation, whereas the American microbiota is predominated by Bacteroides genus with a higher abundance of potentially pathogenic proteobacteria, such as Escherichia and Acinetobacter. .... Moreover, a crossover study indicates that switching African Americans to a high-fiber, low-fat diet for 2 weeks increases production of SCFAs, suppresses secondary bile acid synthesis, and reduces colonic mucosal inflammation and proliferation biomarkers of cancer risk.

Fiber: Numerous prospective studies have linked higher fiber intake to lower risk of CRC. The most recent expert report from the World Cancer Research Fund and the American Institute for Cancer Research in 2011 concludes that evidence that consumption of foods containing dietary fiber protects against CRC is convincing. Besides systemic benefits for insulin sensitivity and metabolic regulation, which have been implicated in colorectal carcinogenesis, fiber possesses gut-specific activities, such as diluting fecal content, decreasing transit time, and increasing stool weight, thereby minimizing exposure to intestinal carcinogens.

Moreover, soluble fiber can be fermented by bacteria in the lumen of the colon into SCFAs [short-chain fatty acids], including butyrate, acetate,and propionate. Higher fiber intake has been shown to enrich butyrate-producing bacteria in the gut, such as Clostridium, Anaerostipes, Eubacterium, and Roseburia species, and increase production of SCFAs. SCFAs have been suggested as the key metabolites linking the gut microbes to various health conditions, especially CRC

Red Meat and Sulfur: There is convincing evidence that red and processed meats are associated with increased risk of CRC. Recently, the Int. Agency for Research on Cancer has classified processed meat as a carcinogen to humans. Mechanisms underlying the pro-cancer effects of red or processed meats include heme iron, N-nitroso compounds, or heterocyclic amines, and hydrogen sulfide production. Hydrogen sulfide has been implicated in inflammatory disorders associated with risk of CRC, such as ulcerative colitis, and directly with CRC.

Omega-3 Fatty Acid: Marine omega-3 polyunsaturated fatty acid, including eicosapentaenoic acid, docosahexaenoic acid, and docosapentaenoic acid, possesses potent anti-inflammatory activity and may protect against CRC. Fish oil, a rich source of omega-3 fatty acid, is the most popular natural product used by US adults. Substantial data support the beneficial effect of omega-3 fatty acid on CRC prevention and treatment.

Dietary fat composition is a major driver of the gut microbial community structure. Compared to other types of fat, omega-3 fatty acid have been associated with higher intestinal microbiota diversity and omega-3 fatty acid-rich diet ameliorates the gut dysbiosis induced by omega-6 polyunsaturated fatty acid or antibiotics.

Obesity: Since the 1970–1980s, the prevalence of obesity has markedly increased worldwide. The obesity epidemic is believed to be largely driven by global westernization characterized by overconsumption of easily accessible and energy-dense food and a sedentary lifestyle. Obesity is an established risk factor for CRC and several other cancers. Possible mechanisms include increased insulin levels and bioavailability of insulin-like growth factor 1, altered secretion of adipokines and inflammatory cytokines, and changes in sex hormone levels.

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

Interesting idea - that perhaps our community of gut microbes being out of whack (dysbiosis) leads to hypertension. This study was done in both humans and mice - with an analysis of bacteria in both hypertensive individuals and pre-hypertensives, and also healthy individuals (the controls). Then the microbes from 2 hypertensive individuals were transplanted into mice (fecal microbiota transplants). And lo and behold - the mice became hypertensive with an alteration of their gut microbes. This is amazing!

The study showed that transplanting microbes from hypertensives to non-hypertensives caused an elevation in blood pressure in the formerly healthy group. This shows the direct influence of gut microbes on blood pressure. The bacteria found in both the pre-hypertensives and hypertensives (especially an overgrowth of Prevotella and Klebsiella bacteria) are those linked to inflammation. And what kind of diet is linked to that bacteria? A high fat diet. Yes, the Western diet with lots of fat and highly processed foods.

The researchers talked about other research also showing Prevotella being associated not only with hypertension, but also other diseases (e.g., periodontal diseases and rheumatoid arthritis). On the other hand, Faecalibacterium, Oscillibacter, Roseburia, Bifidobacterium, Coprococcus, and Butyrivibrio, which were "enriched" in healthy controls, were lower in pre-hypertensive and hypertensive persons. In the past I have posted about a "special" bacteria that is even called  a "keystone" gut bacteria - Faecalibacterium prausnitziithat is linked to health and is low or absent in the gut in a number of diseases ((here and here). It is not available in a supplement at this time (because it dies within a few minutes upon exposure to oxygen), but diet influences it. A high animal meat, high animal fat, high sugar, highly processed foods, and low fiber diet (the typical Western diet) lowers F. prausnitzii numbers, while a high-fiber, low meat diet increases F. prausnitzii numbers.

What you can do: Feed the beneficial gut microbes by increasing the amount of fruits, vegetables, whole grains, seeds, nuts that you eat. And cut back on the greasy, high fat processed and fast foods.

The following excerpt is misleading - for example, it ignores the first part of the actual study which looked at the gut bacteria of pre-hypertensives, hypertensive, and healthy people. Then gut bacteria from hypertensive people were transplanted into healthy mice, and gut bacteria from healthy people were transplanted into hypertensive mice. Also, it wasn't rats, but mice used in the study. It goes to show why it's important to look at original studies - not just believe articles out there blindly. [See original study.] From Science Daily: Unhealthy gut microbes a cause of hypertension, researchers find

Researchers have found that the microorganisms residing in the intestines (microbiota) play a role in the development of high blood pressure in rats mice....Scientists studied two sets of rats mice, one group with high blood pressure ("hypertensive") and one with normal blood pressure ("normal").... All animals were then given antibiotics for 10 days to reduce their natural microbiota. After the course of antibiotics, the researchers transplanted hypertensive microbiota to normal blood pressure rats mice and normal microbiota to the hypertensive group. 

The researchers found that the group treated with hypertensive microbiota developed elevated blood pressure. A more surprising result is that the rats mice treated with normal microbiota did not have a significant drop in blood pressure, although readings did decrease slightly. This finding is "further evidence for the continued study of the microbiota in the development of hypertension in humans and supports a potential role for probiotics as treatment for hypertension," wrote the researchers. "Studies showing that supplementing the diet with probiotics (beneficial microorganisms found in the gut) can have modest effects on blood pressure, especially in hypertensive models."

NOTE that the actual study said in its CONCLUSIONS:  "Taken together, we have described clearly the disordered profiles of gut microbiota and microbial products in human patients with pre-hypertension and hypertension, established the relationship between gut dysbiosis and hypertension, and provided important evidence for the novel role of gut microbiota dysbiosis as a key factor for blood pressure changes. Our findings point towards a new strategy aimed at preventing the development of hypertension and reducing cardiovascular risks through restoring the homeostasis of gut microbiota, by improving diet and lifestyle or early intervening with drugs or probiotics."

Another article commenting that increasing the amount of dietary fiber eaten by people eating a typical Western diet (which is low in fiber) will improve their gut microbiome (community of microbes). Research is finding that the added dietary fiber is food (nutrition) for microbes in the gut, and eating additional fiber daily will help restore or increase bacterial diversity, which then should lead to health benefits. Note: Easy ways to increase dietary fiber are increasing intake of whole grains, legumes, nuts, seeds, fruits, and vegetables. Think of food writer Michael Pollan's advice: "Eat food. Not too much. Mostly plants."

Researchers feel that fiber intake needs to be increased to more than current dietary guidelines, and that beneficial effects to the microbiome starts to occur rapidly (within 2 weeks) of changing to a higher fiber diet. This post from January 21, 2016 discussed the Sonnenburg research on gut microbe depletion (from a low fiber diet), and this April 28, 2015 post discussed the O'Keefe research (changing the diet has big effect on colon cancer risk) - both studies are mentioned below. See the page Feeding Your Gut Microbes for more information. From Science Daily:

Can more fiber restore microbiome diversity?

Scientists are pushing to restore human health in Western countries by changing our diet to restore the microbial species lost over the evolution of Western diet. Researchers advocate for strategically increasing dietary fiber intake as one path forward in regaining microbial biodiversity.

Insufficient nutrients for our gut microbes have been linked to a loss of certain beneficial bacterial species in industrialized societies and are likely impacting our immunological and metabolic health, although more data is needed. For example, most Westerners consume half of the amount of dietary fiber recommended by dietary guidelines, which nutritionists refer to as the "fiber gap," which is a problem because dietary fiber is the primary source of nutrition (e.g., carbohydrates) accessible to gut bacteria in humans.

"The idea to boost fiber levels is not new," says Jens Walter of the University of Alberta, Canada. "However, depletion of the microbiome adds a new perspective to this low-fiber Western diet that we are currently eating." Earlier this year, Stanford University's Justin Sonnenburg found that mice fed a typical Western diet (high in fat and carbohydrates and low in fiber) transferred a lower diversity of beneficial microbial species to future generations. The re-introduction of the microbes' preferred fiber at that stage did not result in a return of some (good) species, indicating that extinctions had occurred in only a few generations.

Walter and co-author Edward Deehan, his PhD student, are concerned that a dramatic shift away from a diet similar to the one under which the human-microbiome symbiosis evolved is a key factor in the rise of non-communicable disorders like obesity. "There is a lot of epidemiological evidence that fiber is beneficial, and food products containing dietary fiber have FDA-approved health claims for both colon cancer and coronary heart disease. There is also quite a bit of clinical evidence (although it is less consistent)," Walter says. "The most pressing issue at the moment that neither consumption of fiber in society nor the doses used in clinical research are high enough."

People living in non-industrialized societies have an average intake of fiber that is much higher than the low norms of Western societies. The authors note the recent work from the Stephen J.D. O'Keefe lab in Nature Communications in which modern African-Americans were given a traditional South-African diet that contained 55 grams of daily dietary fiber and had improved markers for colon cancer within two weeks.

A recent study using mice, and following them for 4 generations, has implications for Americans who typically eat a low-fiber diet (average of 15 grams daily). Note that current dietary guidelines recommend that women should eat around 25 grams and men 38 grams daily of fiber. The researchers found that low-fiber diets not only deplete the complex microbial ecosystems residing in the gut, but can cause an irreversible loss of diversity within those ecosystems in as few as three or four generations.

This is because fiber feeds the millions of microbes in the gut - and so a fiber-rich diet can nourish a wide variety of gut microbes, but a low-fiber diet can only sustain a narrower community. As the generations went by, the rodents’ guts became progressively less diverse, as more and more species were extinguished. If the fourth-generation mice switched to high-fiber meals, some of the missing microbes rebounded, but most did not. It took a fecal transplant (mice style) to get back the missing microbes. From Science Daily:

Low-fiber diet may cause irreversible depletion of gut bacteria over generations

A study by Stanford University School of Medicine investigators raises concerns that the lower-fiber diets typical in industrialized societies may produce internal deficiencies that get passed along to future generations. The study, conducted in mice, indicates that low-fiber diets not only deplete the complex microbial ecosystems residing in every mammalian gut, but can cause an irreversible loss of diversity within those ecosystems in as few as three or four generations.

Once an entire population has experienced the extinction of key bacterial species, simply "eating right" may no longer be enough to restore these lost species to the guts of individuals in that population, the study suggests. Those of us who live in advanced industrial societies may already be heading down that path.

Over and over studies find that a person's diet is linked to health and diseases, and now a study finds that an unhealthy diet is linked to shrinkage of the brain, specifically the volume of the left hippocampus. The biggest effects on the hippocampus are found with both greater consumption of an unhealthy diet and lower consumption of a healthy diet.  The hippocampus is a brain structure associated with both learning and memory, as well as mood regulation, and is specifically implicated in depression. In dementia and Alzheimer's disease, the hippocampus is one of the first regions of the brain to suffer damage.

So....you want to protect your hippocampus from shrinkage. The researchers themselves  suggest that the effects may be reversible, and suggest "dietary interventions to promote hippocampal health". Once again, a healthy diet means lots of plant-based foods (for example, a Mediterranean based diet with lots of fruits, vegetables, legumes, nuts, berries, seeds), and decreasing a Western-style diet with highly processed foods, low fiber, lots of meat, fat,  and refined sugars. From Medscape:

Unhealthy Diet May Shrink the Brain

Consumption of an unhealthy Western diet characterized by meat, hamburgers, chips, and soft drinks, may reduce the volume of the left hippocampus, whereas a healthy diet of fresh vegetables and fish may increase hippocampal volume. In a study of more than 250 individuals, investigators found that during a period of 4 years, there was a difference of more than 200 cubic millimeters in hippocampal volume between individuals who ate a healthy diet and those who consumed an unhealthy diet.  ...continue reading "Shrink Your Brain With An Unhealthy Diet"

Prostate cancer diagnosis is scary enough, but knowing that dietary changes can increase favorable odds is good. Once again a Mediterranean style diet  or "healthy diet"(whole grains, fruits, vegetables, seeds, nuts, legumes, olive oil, and fish) is beneficial, while a Western diet (highly processed foods, red meat, processed meat, and dairy) is linked to higher rates of death. This study was from the Harvard School of Public Health and followed male physicians for an average of 14 years after prostate cancer diagnosis. From Science Daily:

Western diet may increase risk of death after prostate cancer diagnosis

After a prostate cancer diagnosis, eating a diet higher in red and processed meat, high-fat dairy foods, and refined grains--known as a Western diet--may lead to a significantly higher risk of both prostate cancer-related mortality and overall mortality compared with eating a diet rich in vegetables, fruits, fish, whole grains, legumes, and healthy oils, according to a new study from Harvard T.H. Chan School of Public Health.

The study, which appears online June 1, 2015 in the journal Cancer Prevention Research, offers insight on how diet may help improve survivorship for the nearly three million men living with prostate cancer in the U.S."There is currently very little evidence to counsel men living with prostate cancer on how they can modify their lifestyle to improve survival. Our results suggest that a heart-healthy diet may benefit these men by specifically reducing their chances of dying of prostate cancer," said Jorge Chavarro, assistant professor of nutrition and epidemiology at the Harvard Chan School and senior author of the study.

Researchers examined health and diet data from 926 men participating in the Physicians' Health Study I and II who were diagnosed with prostate cancer. They followed the men for an average of 14 years after their diagnosis, grouping them into quartiles according to whether they followed a Western dietary pattern or a "prudent" (higher consumption of vegetables, fruits, fish, legumes, and whole grains) dietary pattern.

They found that men who ate mostly a Western diet (those in the highest quartile of the Western dietary pattern) had two-and-a-half times higher risk of prostate cancer-related death--and a 67% increased risk of death from any cause--than those in the lowest quartile. Men who ate mostly a "prudent" diet had a 36% lower risk of death from all causes.

Once again, research finds that eating highly processed foods is not the best, this time for cognitive performance of 17 year olds. From Medical Xpress:

Western diet leads to poorer performance

Higher intake of a western diet by 14-year-olds has been linked with diminished cognitive performance at age 17.

Researchers found that participants with a western dietary pattern—characterised by high intakes of takeaway food, red and processed meat, soft drink, fried and refined food—scored lower in cognitive tasks, particularly those involving reaction time/psychomotor function, visual attention, learning and memory.

Chips and crisps came in for a particular drubbing: their high consumption was significantly associated with longer reaction times on detection tasks. In contrast to their peers, study participants with a high intake of fruits and leafy vegetables had better cognitive performance, which lead researcher Dr Anett Nyaradi says could be due to increased micronutrient content. This includes folate from leafy green vegetables, which previous research has linked to enhanced cognitive development.

Led by UWA and the Telethon Kids Institute, the study involved 602 members of the Western Australian Pregnancy Cohort (Raine) Study....Dr Nyaradi says several factors may be at play in this diet-related decline in cognitive skills, including the level of omega-6 fatty acids in fried foods and red meat.

Metabolic pathways function best with a balanced 1:1 ratio of omega-3 and omega-6 fatty acids, but the western diet can shift this to a 1:20 or 1:25 ratio.High intake of saturated fat and simple carbohydrates has been linked to impairment in the functioning of the hippocampus, a brain structure centrally involved in learning and memory that increases its volume during adolescence, Dr Nyaradi says.

"Adolescence represents a critical time period for brain development. It is possible that poor diet is a significant risk factor during this period…indeed, our findings support this proposition."