Dec 23, 2014

Diet may influence gut bacteria more than genes

More and more studies are revealing the important role that our gut bacteria play in our health. Their trillions of cells vastly outnumber ours. Fortunately, many of them are "friendly," in that they help us digest food and crowd out pathogens that cause disease.

But the mix of gut microbes varies considerably from person to person and also over time. And, until now, it has not been clear whether this variation is due mostly to genes (nature), or things we can change (nurture), such as diet and lifestyle.

Peter Turnbaugh, an assistant professor of microbiology and immunology at the University of California San Francisco (UCSF), and colleagues describe how - by studying hundreds of mice - they discovered diet may have a stronger influence on gut bacteria than genes.

Prof. Turnbaugh says in a healthy adult, the same strains and species of gut microbes can live in the gut for years, while their relative abundance - the sizes of their populations - can change quite a lot over time.

"These new results emphasize that, unlike a mammalian genome - which is relatively constant - the microbial genomes that comprise the gut microbiome are relatively plastic," he adds.

Findings suggest it may not be necessary to tailor gut bacteria treatments

Prof. Turnbaugh explains that one day it may be possible to treat diseases by shaping the balance of bacteria in the gut. And these new findings suggest it may not be necessary to tailor treatments differently for each person, because "the microbial response to a given diet may be similar for many people's microbial communities."

In another recent study in humans, Prof. Turnbaugh and colleagues found the mix of gut microbes changed quickly when diets varied between vegan and animal-based - after just a few days.

In this new study, they used hundreds of mice with a wide range of well-defined genetic backgrounds.

They fed the mice two different diets, altering between a high-fat, high-sugar diet (14.8% protein, 44.6% fat and 40.6% carbohydrate) and a low-fat, plant-based diet (22.2% protein, 16.0% fat and 61.7% carbohydrate).

Switching diet changed gut mix in days, showed influence lasts for months
The researchers discovered that switching the mice to a high-sugar, high-fat diet changed the mix of microbes in their gut to a new, stable mix within 3 days. The effect was repeatable and was mostly independent of the genetic variations among the mice, they note.

Regardless of the mice's genetic makeup, the high-fat, high-sugar diet increased the abundance of Firmicutes bacteria and reduced the abundance of Bacteroidetes bacteria.

The team found that varying diet had a much stronger influence on gut microbe mix than genetic variation. And the influence can last for several months.

Prof. Turnbaugh says they are not sure whether changes in the gut's microbe mix are a direct result of changes in the diet - which changes the mix of nutrients in the gut that the bacteria are exposed to - or an indirect result of the effects of diet on the overall body of the host.

Past diets also play a role in determining gut microbe mix. The team also found that when they returned the mice to their original diets, changes in the gut microbe mix were largely reversible - but not quite. It seems that imprints of past diets - as well as current diet - play a role in determining gut microbe mix.

Dec 16, 2014

Ginger can treat stomach issues, boost immunity and more

Few herbs have received as much praise throughout history as ginger, the rhizome of the Zingiber officinale plant. Testimonials of ginger's significant medicinal properties have been recorded as far back as ancient Greece, though it was also mentioned in the ancient literature of Europe, Asia and the Middle East. The ancient healing systems of China and India particularly venerated ginger, and often prescribed it to treat fatigue, poor blood circulation and nausea.

Ginger remains the world's most widely cultivated herb, and a large number of studies confirm its numerous health benefits. Like most herbs, almost all of these benefits stem from ginger's many bioactive compounds; it contains few vitamins or minerals in significant amounts.

Research into ginger

Treatment for gastrointestinal complaints - Ginger has been used for centuries as a home remedy for constipation, bloating, gastritis, gastric ulcerations, indigestion, morning sickness and countless other gastrointestinal issues. A study also found that ginger could help the muscles of the stomach contract, thereby boosting digestion. According to a review ginger is effective at treating gastrointestinal conditions due to its high concentrations of antioxidants, whose free radical-scavenging abilities bestow the herb with gastroprotective effects.

Rich in anti-inflammatory gingerols - Ginger is rich in bioactive, anti-inflammatory compounds called gingerols and shogaols. These substances are believed to be the reason why so many people with rheumatoid arthritis or osteoarthritis experience reductions in pain and improvements in movement after consuming ginger on a regular basis. For example, a study found that crude ginger extracts and gingerol derivatives could prevent joint inflammation. A later study discovered that ginger could alleviate neuropathic pain in rats.

Boosts immune function - Ginger is a proven diaphoretic, meaning it can increase perspiration. Though most of us are aware that sweating can detoxify our bodies, German researchers have recently discovered that sweat contains a natural antibiotic named dermcidin that can ward off bacterial, fungal, viral and microbial infections. For this reason, eating more ginger can directly boost our body's immune system and protect us from common infections such as Staphylococcus aureus (a common cause of skin conditions) and Candida albicans.

Natural aphrodisiac and antidepressant  - According to a study ginger extracts have a positive effect on the reproductive functions of male rats due to its "potent  antioxidant properties and androgenic activities." These results confirm the allegations of ancient Chinese and Indian medicine, which claimed for centuries that ginger is a potent aphrodisiac. Moreover, the aforementioned gingerols in ginger are known to possess sedative properties, which might help explain why ginger is also an effective antidepressant that can improve low moods.

Consuming ginger

While ginger root can be eaten raw, it is far more pleasant to consume in tea or powdered form. Ginger tea is an especially popular way to consume ginger and is probably the most accessible way to treat a persistent stomach complaint. Some people like to add honey or lemon to the tea to boost its stomach-settling qualities.

Dec 12, 2014

Can High-Fructose Corn Syrup Make You Hungrier?

Fructose - a kind of sugar found in a wide variety of foods and beverages - may encourage overeating, new research suggests.

Fructose may be best known to consumers in the form of high-fructose corn syrup, which has long been added to manufactured foods from sodas to cookies.

Distinct from sugar known as glucose (produced by the natural breakdown of complex carbohydrates), fructose is also a "simple" sugar and a natural component of fruit.

However, "in a series of studies we have found that when compared to glucose, the simple sugar, fructose, is a weaker suppressor of brain areas that help control appetite and the motivation to eat," said study co-author Dr. Kathleen Page, an assistant professor of clinical medicine at the Keck School of Medicine of the University of Southern California in Los Angeles.

In other words, people are more likely to remain feeling hungry after a meal with lots of fructose versus one with lots of glucose.

Prior research has indicated that, when compared with glucose consumption, ingesting fructose sparks a smaller release of hormones such as insulin that give rise to a sense of being full, according to background information with the study. Recent investigations have also suggested that only glucose, not fructose, curtails hunger by slowing down activity in a specific region of the brain (the hypothalamus), the researchers said.

The small, new study builds on both findings.

More than two-thirds of American adults are overweight or obese, which puts them at risk of heart disease, type 2 diabetes and certain cancers. Many experts believe that changes in U.S. food production, including widespread use of high-fructose corn syrup, are to blame.

For the current effort, the researchers enlisted 24 men and women ages 16 to 25 to participate in a hunger exercise.

All participants were instructed to consume a drink sweetened with either glucose or fructose. Then they were asked to view images of various foods (including, for example, chocolate cake) and indicate the degree to which they felt hunger. The exercise took place while each was hooked up to a functional magnetic resonance imaging (fMRI) scanner in order to track real-time brain activity in a "reward" center of the brain known as the nucleus accumbens.

Hunger was greater among those who had consumed the fructose drink, the authors found. At the same time, the fructose mix provoked greater activity in the targeted brain region, which translated into a greater desire to eat.

However, Page stressed that the current findings are "preliminary." More work is needed before broad conclusions can be drawn about how sweeteners in manufactured food products actually influence hunger and the overall risk for obesity, she said.

For example, "it's important to note that both fructose and glucose are found in almost equal quantities in both high-fructose corn syrup and table sugar," Page said. "We don't yet know whether the brain responds differently to high-fructose corn syrup compared to glucose or sucrose [table sugar]."

And a trade association representing the corn refining industry in the United States countered that the study doesn't reflect real-life consumption.

"The subjects in this study were given large amounts of pure fructose and pure glucose separately, which almost never occurs outside a laboratory setting," the Corn Refiners Association said in a statement. "While those who received pure fructose may have reacted as if they were less sated, these study conditions did not correspond to anything like a natural setting in which people normally would be consuming roughly equal amounts of glucose in combination at the same time."

But Lona Sandon, a registered dietitian and assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas, said the study findings are consistent with other research.

"We have known for quite some time that the insulin response to glucose in the bloodstream is a normal response to signal the brain and body that calories have been consumed," Sandon said. "Fructose does not trigger the same response of insulin."

The interplay between glucose and insulin is probably an important part of weight regulation, she added.

The bottom line, said Sandon, is that added sugars bring no nutritive value to foods. Her advice? "Choose whole, nutrient-rich foods and whole grains most of the time."

Dec 5, 2014

Beetroot juice improves athletic performance and cardiovascular health

Many studies have shown that beetroot juice can improve athletic performance. Now, a study conducted by scientists at Kansas State University has shown that the beverage could also provide an important quality of life boost to people suffering from heart failure.

"Remember, for every one football player in the United States, there are many thousands of heart failure patients that would benefit from this therapy," researcher David Poole said. "It's a big deal because even if you can only increase oxygen delivery by 10 percent, that can be the difference between a patient being wheelchair-bound versus getting up and walking around and interacting with his or her family."

Improves patients' ability to exercise

Prior research by the same team showed that due to its high nitrate content, beetroot juice increases blood flow to skeletal muscles that are engaged in exercise. This, in turn, increases the oxygen flow to those muscles.

In the new study, the researchers found that, after drinking beetroot juice, participants experienced a 38 percent increase in blood flow to their skeletal muscles while exercising. Significantly, blood flow increased most to the fast-twitch muscles that are used for explosive running. These muscles are typically less oxygenated than other skeletal muscles.

The increased oxygen flow would be enough to significantly improve quality of life in heart failure patients, the researchers said.

"Heart failure is a disease where oxygen delivery to particular tissues, especially working skeletal muscles, is impaired, decreasing the capacity to move the arms or legs and be physically active," Poole said.

By enabling heart failure patients to get more exercise, beetroot juice could be the first step in producing deeper, more permanent health improvements.

"The best therapy for these patients is getting up and moving around," Poole said. "However, that is often difficult. Increasing the oxygen delivery to these muscles through beetroot can provide a therapeutic avenue to improve the quality of life for these patients."

The researchers have already begun a clinical trial to directly test the effects of beetroot juice in heart failure patients. The research is being conducted in collaboration with the University of Exeter and is funded by the National Institutes of Health.

Increases athletic speed, stamina and power

Why does beetroot juice have such a dramatic effect on blood flow? The answer lies in the drink's high concentration of a chemical known as nitrate. Indeed, just 70 milliliters of beetroot juice contains as much nitrate as 100 grams of spinach.

In the body, nitrate is transformed into nitrite, which has been shown to help protect blood vessels from injury. The nitrite is eventually transformed into nitric oxide, which dilates blood vessels and thereby increases blood flow. Because more oxygen is delivered to muscle cells, these cells are therefore able to produce more power and perform for longer without tiring.

Beetroot juice has been shown to increase both speed and endurance in athletes. For example, one study found that athletes who drank beetroot juice used 19 percent less oxygen and performed for 17 percent longer. Another,  found that cyclists who drank beetroot juice completed a track faster than cyclists given a placebo. A pair of similar studies, conducted by researchers from Maastricht University Medical Centre in the Netherlands found that consumption of beetroot juice improved not just the cyclists' speed but also their power output.