Skip to content

Category: nutrition

Published on

Very interesting. Gives people a way to eat red meat, but not increase their colorectal cancer risk (by also eating resistant starch, e.g., potato salad or beans). From Science Daily:

Eating resistant starch may help reduce red meat-related colorectal cancer risk

Consumption of a type of starch that acts like fiber may help reduce colorectal cancer risk associated with a high red meat diet, according to a study. "Red meat and resistant starch have opposite effects on the colorectal cancer-promoting miRNAs, the miR-17-92 cluster," said one researcher. "This finding supports consumption of resistant starch as a means of reducing the risk associated with a high red meat diet.

Unlike most starches, resistant starch escapes digestion in the stomach and small intestine, and passes through to the colon (large bowel) where it has similar properties to fiber, Humphreys explained. Resistant starch is readily fermented by gut microbes to produce beneficial molecules called short-chain fatty acids, such as butyrate, she added.

"Good examples of natural sources of resistant starch include bananas that are still slightly green, cooked and cooled potatoes [such as potato salad], whole grains, beans, chickpeas, and lentils. Scientists have also been working to modify grains such as maize so they contain higher levels of resistant starch," said Humphreys.

After eating 300 g of lean red meat per day for four weeks, study participants had a 30 percent increase in the levels of certain genetic molecules called miR-17-92 in their rectal tissue, and an associated increase in cell proliferation. Consuming 40 g of butyrated resistant starch per day along with red meat for four weeks brought miR-17-92 levels down to baseline levels.

The study involved 23 healthy volunteers, 17 male and six female, ages 50 to 75. Participants either ate the red meat diet or the red meat plus butyrated resistant starch diet for four weeks, and after a four-week washout period switched to the other diet for another four weeks.

Published on

Fish consumption was beneficial for the brain, but brain differences among the groups not correlating with blood omega-3 levels was a surprise. From  Science Daily:

Eating baked, broiled fish weekly boosts brain health, study says

Eating baked or broiled fish once a week is good for the brain, regardless of how much omega-3 fatty acid it contains, according to researchers. The findings add to growing evidence that lifestyle factors contribute to brain health later in life. Scientists estimate that more than 80 million people will have dementia by 2040, which could become a substantial burden to families and drive up health care costs.

"Our study shows that people who ate a diet that included baked or broiled, but not fried, fish have larger brain volumes in regions associated with memory and cognition," Dr. Becker said. "We did not find a relationship between omega-3 levels and these brain changes, which surprised us a little. It led us to conclude that we were tapping into a more general set of lifestyle factors that were affecting brain health of which diet is just one part."

Lead investigator Cyrus Raji, M.D., Ph.D., who now is in radiology residency training at UCLA, and the research team analyzed data from 260 people who provided information on their dietary intake, had high-resolution brain MRI scans, and were cognitively normal at two time points during their participation in the Cardiovascular Health Study (CHS), a 10-year multicenter effort that began in 1989 to identify risk factors for heart disease in people over 65.

"The subset of CHS participants answered questionnaires about their eating habits, such as how much fish did they eat and how was it prepared," Dr. Raji said. "Baked or broiled fish contains higher levels of omega-3s than fried fish because the fatty acids are destroyed in the high heat of frying, so we took that into consideration when we examined their brain scans."

People who ate baked or broiled fish at least once a week had greater grey matter brain volumes in areas of the brain responsible for memory (4.3 percent) and cognition (14 percent) and were more likely to have a college education than those who didn't eat fish regularly, the researchers found. But no association was found between the brain differences and blood levels of omega-3s.

"This suggests that lifestyle factors, in this case eating fish, rather than biological factors contribute to structural changes in the brain," Dr. Becker noted. "A confluence of lifestyle factors likely are responsible for better brain health, and this reserve might prevent or delay cognitive problems that can develop later in life."

Published on

Great reason to enjoy spicy food. From Science Daily:

Chili peppers for a healthy gut: Spicy chemical may inhibit gut tumors

Researchers report that dietary capsaicin – the active ingredient in chili peppers – produces chronic activation of a receptor on cells lining the intestines of mice, triggering a reaction that ultimately reduces the risk of colorectal tumors.

...the current study suggests one potential remedy might be spicy capsaicin, which acts as an irritant in mammals, generating a burning sensation in contact with tissue. Capsaicin is already broadly used as an analgesic in topical ointments, where its properties as an irritant overwhelm nerves, rendering them unable to report pain for extended periods of time. It's also the active ingredient in pepper spray.

The researchers fed capsaicin to mice genetically prone to developing multiple tumors in the gastrointestinal tract. The treatment resulted in a reduced tumor burden and extended the lifespans of the mice by more than 30 percent. The treatment was even more effective when combined with celecoxib, a COX-2 non-steroidal anti-inflammatory drug already approved for treating some forms of arthritis and pain.

Published on

This research review suggests that 5 servings a day of fruits and vegetables has the best health benefits. They surprisingly did not find that fruit/vegetable consumption was protective against cancer. But the authors point out that other studies of cancer and fruit/vegetable consumption have also been inconsistent, and this might be partly explained if certain fruits and vegetables only have effects on certain cancers. From Medical Daily:

An Apple A Day Keeps The Doctor Away? Actually It's 5 Apples, And They Keep Death Away

A review of the eating habits of more than 800,000 people seems to discredit the old maxim about "an apple a day." In fact, five servings of fruit and vegetables offers the best health benefits, particularly against heart disease, and reduces your chances of dying for any reason.

After calculating the odds, researchers write in the Journal of Epidemiology and Community Health that "the risk of all-cause mortality was decreased by 5 percent for each additional serving a day of fruit and vegetables." But, contrary to other reports, they found the benefits drop off after five servings, at which point, they wrote, "we observed a threshold." Previous studies have said seven fruit and vegetable servings is the optimum number.

Other studies have also made the case for fruits and vegetables as a ward against cancer. This one, led by Professor Frank B. Hu in the Harvard School of Public Health, saw no evidence for that. They did, however, find a "significant inverse association" between a fruit and veggie diet and death by heart disease. "The results support current recommendations to increase consumption to promote health and overall longevity," Hu and his colleagues wrote.

Of course, the authors admit, the studies they looked at may have been corrupted by participants lying or guessing on their diet questionnaires. But one thing this study has going for it is the massive sample size. They looked at 16 papers involving 833,234 people and 56,423 deaths. Most of those deaths — as is the case in the general population — were caused by cardiovascular disease and cancer. The people who lived longest adhered to what's called the Mediterranean diet, which favors carrots and tomatoes to steak and bacon.

Published on

Two related articles, the first from a month ago, but both discuss eating fresh foods of summer and the effect on the microbiota. From Gut Microbiota Worldwatch:

Seasonal diet changes affect the composition of our gut microbiota

The mix of bacteria that live in our gut changes throughout the year, to match the food we eat in every specific season. For example, bacteria that process fresh fruit and vegetables are more abundant in the summer, and those that process fats are mode abundant in winter times. A group of scientists at the University of Chicago has found evidence of this seasonal shift in the gut flora, by studying the remote Hutterite population, in North America. The traditional diet and common meals of this community have allowed researchers to study the effect of one common diet in a large population over a long period of time.

Hutterites live in communal farms (colonies) and eat meals in common dining rooms, using traditional recipes that have been relatively stable over time and between colonies. They have little contact with the world outside their colonies, which translates into a very homogeneous genetic pool. Sixty Hutterites from six colonies answered questionnaires about what they ate over the course of a year. During the same period, scientists sampled their stool periodically, to find the genetic sequences of bacteria contained in their gut.

The Hutterites’ diet is relatively stable, except that in summer they eat more fresh fruit and vegetables, and in winter they eat less, and turn to frozen or canned food. Remarkably, their gut flora responded to these changes with massive modification in the abundance of certain bacteria. For example, during summer Bacteroidetes were more abundant: this group of bacteria contain complex carbohydrate digesters, which may be at work in processing fresh fruit and vegetables.

On the other hand Actinobacteria increased in winter: these microbes are associated with processing fat, and with a decreased content of fibre in food. Researchers also found seasonal shifts in other types of bacteria, whose associations with food are still unknown. Notably, the trends were almost identical in all six colonies, possibly a result of a very homogenous lifestyle carried on in a very similar environment.

Although Hutterites live in a relatively isolated way, they use technology and medicine, which makes their lifestyle closer to the general population than that of other more traditional communities. That is why the authors believe that these results may be extended to the general population.

This healthy living article promotes eating fresh fruits and vegetables (tomatoes, blueberries, asparagus, and leeks) as good for the gut microbiome. From Huffington Post:

4 Summer Foods That Can Help Trim Your Waist

Published on

Future microbiome research and therapy will have to take into account that diet affects the gut microbes of men and women differently. From Science Daily:

Diet affects males' and females' gut microbes differently

The microbes living in the guts of males and females react differently to diet, even when the diets are identical, according to a new study. These results suggest that therapies designed to improve human health and treat diseases through nutrition might need to be tailored for each sex.

The researchers studied the gut microbes in two species of fish and in mice, and also conducted an in-depth analysis of data that other researchers collected on humans. They found that in fish and humans diet affected the microbiota of males and females differently. In some cases, different species of microbes would dominate, while in others, the diversity of bacteria would be higher in one sex than the other.

These results suggest that any therapies designed to improve human health through diet should take into account whether the patient is male or female.

Genetics and diet can affect the variety and number of these microbes in the human gut, which can in turn have a profound influence on human health. Obesity, diabetes, and inflammatory bowel disease have all been linked to low diversity of bacteria in the human gut.

Why men and women would react differently to changes in diet is unclear, but there are a couple of possibilities. The hormones associated with each sex could potentially influence gut microbes, favoring one strain over another. Also, the sexes often differ in how their immune systems function, which could affect which microbes live and die in the microbiome.

One notable exception in Bolnick's results was in the mice. Although there was a tiny difference between male and female mice, for the most part the microbiota of each sex reacted to diet in the same manner. Because most dietary studies are conducted on mice, this result could have a huge effect on such research, and it raises questions about how well studies of gut microbes in lab mice can be generalized to other species, particularly humans.

Published on

This research illustrates how little we currently know about gut bacteria.But it did show the importance of diet. From Science Daily:

Monitoring rise and fall of the microbiome

Trillions of bacteria live in each person's digestive tract. Scientists believe that some of these bacteria help digest food and stave off harmful infections, but their role in human health is not well understood.

To help shed light on the role of these bacteria, a team of researchers led by MIT associate professor Eric Alm recently tracked fluctuations in the bacterial populations of two research subjects over a full year. The findings, described in the July 25 issue of the journal Genome Biology, suggest that while these populations are fairly stable, they undergo daily fluctuations in response to changes in diet and other factors...."To a large extent, the main factor we found that explained a lot of that variance was the diet."

There are a few thousand strains of bacteria that can inhabit the human gut, but only a few hundred of those are found in any given individual, Alm says. For one year, the two subjects in the study collected daily stool samples so bacterial populations could be measured. They also used an iPhone app to track lifestyle factors such as diet, sleep, mood, and exercise, generating a huge amount of data.

Analysis of this data revealed that dietary changes could produce daily variations in the populations of different strains of bacteria. For example, an increase in fiber correlated with a boost in the populations of Bifidobacteria, Roseburia, and Eubacterium rectale. Four strains -- including Faecalibacterium prausnitzii, which has been implicated in protecting against inflammatory bowel disease -- were correlated with eating citrus.

During the study, each of the two subjects experienced an event that dramatically altered the gut microbiome. Subject B experienced food poisoning caused by Salmonella, and Subject A traveled to a developing nation, where he experienced diarrheal illness for two weeks.

During Subject B's infection, Salmonella leapt from 10 percent of the gut microbiome to nearly 30 percent. At the same time, populations of bacteria from the phylum Firmicutes, believed to be beneficial to human health, nearly disappeared. After the subject recovered, Firmicutes rebounded to about 40 percent of the total microbiome, but most of the strains were different from those originally present.

Subject A also exhibited severe disruptions to his microbiome during his trip, but once he returned to the United States, it returned to normal. Unlike Subject B's recovery from food poisoning, Subject A's populations returned to their original composition.

Published on

Great reason to add more rosemary and oregano to your diet. From Science Daily:

Rosemary, oregano contain diabetes-fighting compounds

The popular culinary herbs oregano and rosemary are packed with healthful compounds, and now lab tests show they could work in much the same way as prescription anti-diabetic medication, scientists report. In their new study, researchers found that how the herbs are grown makes a difference, and they also identified which compounds contribute the most to this promising trait.

Elvira Gonzalez de Mejia and colleagues point out that in 2012, type-2 diabetes affected more than 8 percent of Americans and cost the country $175 billion. ... Recent research has shown that herbs could provide a natural way to help lower glucose in blood. So Gonzalez de Mejia's team decided to take a closer look.They tested four different herbs, either greenhouse-grown or dried commercial versions, for their ability to interfere with a diabetes-related enzyme, which is also a target of a prescription drug for the disease.

They found that greenhouse herbs contained more polyphenols and flavonoids compared to the equivalent commercial herbs. But this didn't affect the concentration required to inhibit the enzyme. Commercial extracts of Greek oregano, Mexican oregano and rosemary were better inhibitors of the enzyme, required to reduce risk of type-2 diabetes, than greenhouse-grown herbs.

Published on

Even though it looks to be a modest effect, it is still good news. But they should have added kefir to the list of probiotic containing foods. From Science Daily:

Eating probiotics regularly may improve your blood pressure

Eating probiotics regularly may modestly improve your blood pressure, according to new research in the American Heart Association journal  Hypertension. Probiotics are live microorganisms (naturally occurring bacteria in the gut) thought to have beneficial effects; common sources are yogurt or dietary supplements.

"The small collection of studies we looked at suggest regular consumption of probiotics can be part of a healthy lifestyle to help reduce high blood pressure, as well as maintain healthy blood pressure levels," said Jing Sun, Ph.D., lead author and senior lecturer at the Griffith Health Institute and School of Medicine, Griffith University, Gold Coast, Queensland, Australia. "This includes probiotics in yogurt, fermented and sour milk and cheese, and probiotic supplements."

Analyzing results of nine high-quality studies examining blood pressure and probiotic consumption in 543 adults with normal and elevated blood pressure, researchers found:

  • Probiotic consumption lowered systolic blood pressure (the top number) by an average 3.56 millimeters of mercury (mm Hg) and diastolic blood pressure (the lower number) by an average 2.38 mm Hg, compared to adults who didn't consume probiotics.
  • The positive effects from probiotics on diastolic blood pressure were greatest in people whose blood pressure was equal to or greater than 130/85, which is considered elevated.
  • Probiotics with multiple bacteria lowered blood pressure more than those with a single bacteria.

We believe probiotics might help lower blood pressure by having other positive effects on health, including improving total cholesterol and low-density lipoprotein, or LDL, cholesterol; reducing blood glucose and insulin resistance; and by helping to regulate the hormone system that regulates blood pressure and fluid balance," Sun said.

Published on

After posting yesterday "Probiotic Misconceptions", I was pleasantly surprised that today's NY Times had an article (by Jane Brody) raising similar concerns. What was good is that she wrote about supplements not being regulated. She also left out that probiotic beneficial organisms are found in more than the gut. A case in point being the sinuses - because healthy sinuses also have Lactobacillus sakei (according to the Abreu et al study of 2012), and which has been the basis for my family's successful kimchi treatment for sinusitis (see Sinusitis treatment link for the method). From the NY Times:

Probiotic Logic vs. Gut Feelings

The label on my bottle of Nature’s Bounty Advanced Probiotic 10 says it contains 10 probiotic strains and 20 billion live cultures in each two-capsule dose. The supplement provides “advanced support for digestive and intestinal health” and “healthy immune function.” I have no way to know if any of this is true. Like all over-the-counter dietary supplements, probiotics undergo no premarket screening for safety, effectiveness or even truth in packaging. 

To be sure, lay and scientific literature are filled with probiotic promise, and I am hardly the only consumer who has opted to hedge her bets. The global market for probiotic supplements and foods is expected to reach $32.6 billion this year,with a projected annual growth of 20 percent or more.

 Beneficial micro-organisms have since been shown to inhabit three main locations in the digestive tract: the stomach, the lower part of the small intestine and the large intestine. To better understand the current enthusiasm for enhancing the body’s supply of these micro-organisms, some definitions are needed.

■ Prebiotics are nondigestible carbohydrates that stimulate the growth and activity of beneficial micro-organisms (that is, probiotics) in the gut. They are found naturally in oats, wheat, some fruits and vegetables (bananas, onions, garlic, leeks, asparagus, soybeans, honey and artichokes), and in breast milk, and they are added to some infant formulas.

■ Probiotics are defined by the World Health Organization as “live micro-organisms which when administered in adequate amounts confer a health benefit on the host.” The ailments that probiotics are said to benefit range from infection-caused diarrhea, inflammatory bowel diseases and irritable bowel syndrome to asthma, allergy and Type 1 diabetes.

■ Synbiotics are a combination of prebiotics and probiotics. They are found in so-called functional foods like yogurt and kefir, fermented foods like pickles and some cheeses, and in some supplements.

That probiotic organisms are important to health is not questioned. As researchers at the Institute for Immunology at the University of California,Irvine have written intestinal micro-organisms play “an important role in the development of the gut immune system, digestion of food, production of short-chain fatty acids and essential vitamins, and resistance to colonization from pathogenic microorganisms.”

Dr. Walker has explained that probiotics enhance defensive action by the cells that line the gut. When a person takes antibiotics, especially the broad-spectrum antibiotics most often prescribed, many of these beneficial microbes are destroyed along with the disease-causing bacteria. Patients on antibiotics are often told to consume yogurt with active cultures to replenish the beneficial organisms.

In an extensive review of the evidence published in 2010 in the journal Pediatrics, an expert committee concluded that probiotics might limit the course of virus-caused diarrhea in otherwise healthy infants and children. But the committee said there was not sufficient evidence to justify routine use of probiotics to prevent rotavirus-caused diarrhea in child care centers. Nor did the committee endorse taking probiotics during pregnancy and nursing or giving them to infants to prevent allergic disorders in those at risk.

Only a small percentage of probiotic foods and supplements have the backing of peer-reviewed published research. They include Dannon’s Activia yogurt and DanActive drink and the supplements Culturelle and Align. Although kefir contains even more probiotic strains than yogurt, clinical studies have not shown it to be effective in preventing or treating infectious diarrhea.

The challenge in taking probiotics is to get the microbes past the stomach, where most are killed by gastric acid, said Robert Dunn, a biologist at North Carolina State University. Once in the intestines, they must compete effectively with the microbes already present.

Dr. Dunn, author of "The Wild Life of Our Bodies," says there is good reason to remain skeptical of probiotics. “There are hundreds of kinds of prebiotics and probiotics in stores,” he said. “As a consumer, it’s almost impossible to figure out what is best. What are the specific species in your intestines, and how will what you take compete with them?” Still, he added, taking them doesn’t seem harmful. 

There is growing evidence for the role of the appendix in restoring a healthful balance of microbes in the body. Though long considered an expendable, vestigial organ, the appendix is now being looked at as “a storehouse of good bacteria,” Dr. Dunn said. In a study of recovery rates from Clostridium difficile, which causes a severe form of infectious diarrhea, often following antibiotic therapy, patients whose appendixes had been removed were more likely to have a recurrent infection than those who still had appendixes.