Whole Grain Can Contribute to Health by Changing Intestinal Serotonin Production

Adults consuming whole grain rye have lower plasma serotonin levels than people eating low-fibre wheat bread, according to a recent study by the University of Eastern Finland and the International Agency for Research on Cancer (IARC). In the study, the consumption of cereal fibre from rye or wheat was also found to reduce serotonin levels in the colon of mice. In light of the results, the health benefits of whole grain cereals may be linked, at least in part, to the alteration of serotonin production in the intestines, where the majority of the body’s serotonin is produced. The results of were published in The American Journal of Clinical Nutrition.

The consumption of whole grain cereals has been associated with a lower risk of type 2 diabetes, cardiovascular disease and some cancers, but the underlying mechanisms are still poorly understood. There may be effects on bioactive compounds contained in whole grains, phytochemicals and fibres from which different metabolites are produced by intestinal bacteria.

The new study explored how the consumption of wholegrain rye modulates concentrations of different metabolites in the bloodstream. The study employed untargeted metabolite profiling, also known as metabolomics, which can simultaneously detect numerous metabolites, including those previously unknown.

For the first four weeks of the study, the participants ate 6 to 10 slices a day of low-fibre wheat bread, and then another four weeks the same amount of wholegrain rye bread or wheat bread supplemented with rye fibre. Otherwise, they didn’t change their diet. At the end of both periods, they gave blood samples, which were analysed by a combination of liquid chromatography and mass spectrometry. Their plasma metabolite profiles between the different diet periods were then compared .

The consumption of wholegrain rye led to, among other things, significantly lower serotonin concentrations when compared to consumption of low-fibre wheat bread. The researchers also tested in mice whether the addition of cereal fibre to the diet changes serotonin production in the intestine. The diet of the mice was supplemented for nine weeks with rye bran, wheat bran or cellulose flour. The mice receiving rye or wheat bran had significantly lower serotonin in their colon.

Serotonin is best known as a neurotransmitter in the brain. However, serotonin produced by the intestines remains separated from the brain, serving various peripheral functions including modulation of gut’s motility. Increased blood serotonin has also been associated with high blood glucose levels.

“Whole grain, on the other hand, is known to reduce the risk of diabetes, and on the basis of these new results, the effect could at least partly be due to a decrease in serotonin levels,” says Academy Research Fellow Kati Hanhineva from the University of Eastern Finland.

The researchers are also interested in the association of serotonin with colorectal cancer.

“Some recent studies have found cancer patients to have higher plasma serotonin levels than healthy controls,” Scientist Pekka Keski-Rahkonen from IARC adds.

The consumption of wholegrain rye bread was also associated with lower plasma concentrations of taurine, glycerophosphocholine and two endogenous glycerophospholipids. In addition, the researchers identified 15 rye phytochemicals whose levels in the bloodstream increased with the consumption of rye fibre.

Source: Science Daily

Newly Discovered Compounds Shed Fresh Light on Whole Grain Health Benefits

Scientists have discovered new compounds that may explain whole grain health benefits, reports a new study led by the University of Eastern Finland. A high intake of whole grains increased the levels of betaine compounds in the body which, in turn, was associated with improved glucose metabolism, among other things. The findings shed new light on the cell level effects of a whole grain-rich diet, and can help in the development of increasingly healthy food products.

“Whole grains are one of the healthiest foods there is. For instance, we know that a high intake of whole grains protects against type 2 diabetes and cardiovascular diseases. Up until now, however, we haven’t understood the cellular mechanisms through which a whole grain-rich diet impacts our body,” says Dr Kati Hanhineva, Principal Investigator of the study at the University of Eastern Finland.

Using metabolomics analysis, Dr Hanhineva’s research group investigated the effects of a whole grain-rich diet on the body’s metabolites. The effects were studied in mice fed with bran-rich fodder, and in humans following a diet rich in whole grain products over the course of 12 weeks. A whole grain-rich diet increased the levels of betaine compounds in both mice and humans.

“This is the first time many of these betaine compounds were observed in the human body in the first place,” Dr Hanhineva says.

At the end of the 12-week follow-up, the researchers also observed a correlation between improved glucose metabolism and increased presence of betaine compounds in the body.

“Pipecolic acid betaine, for example, is particularly interesting. Increased levels of pipecolic acid betaine after the consumption of whole grains was, among other things, associated with lower post-meal glucose levels.”

New compound worked similarly to a heart drug in cell level experiments

One of the betaine compounds discovered by the researchers is 5-aminovaleric acid betaine, 5-AVAB, which seems to cumulate in metabolically active tissues, such as the heart. With this observation in mind, the researchers set out to further test its effects in a cell model.

“We observed that 5-AVAB reduces cardiomyocytes’ use of fatty acids as a source of energy by inhibiting the function of a certain cell membrane protein,” Researcher Olli Kärkkäinen from the University of Eastern Finland says.

“This cell level effect is similar to that of certain drugs used for cardiovascular diseases. However, it is important to keep in mind that we haven’t proceeded beyond cell level experiments yet. We need further research in animals and humans to verify that 5-AVAB really can impact the function of our body.”

However, the discovery of the new compounds associated with whole grains significantly enhances our understanding of why whole grain products are good for our health.

“In the future, we seek to analyse in greater detail the multitude of effects these new compounds can have on the human body, and we will also look into how intestinal microbes possibly contribute to the formation of these compounds,” Dr Hanhineva continues.

The findings were reported in Scientific Reports and The American Journal of Clinical Nutrition.

Source: University of Eastern Finland

Wholegrains Important for Preventing Type 2 Diabetes

​It doesn’t matter if it’s rye, oats, or wheat. As long as it is wholegrain, it can prevent type 2 diabetes. This is the finding of a new study from researchers at Chalmers and the Danish Cancer Society Research Center.

​The comprehensive study is a strong confirmation of previous research findings on the importance of whole grains for prevention of type 2 diabetes – previously sometimes known as adult-onset diabetes. Even if the link has been known for a long time, the role of different wholegrain sources has not been investigated earlier. It has also been unclear how much wholegrain is needed to reduce the risk of developing diabetes.

“Most studies similar to ours have previously been conducted in the USA, where people mainly get their wholegrain from wheat,” says Rikard Landberg, Professor at the Division of Food and Nutrition Science, and senior researcher on the study.

“We wanted to see if there was a difference between different cereals. One might expect there would be, because they contain different types of dietary fibre and bioactive substances, which have been shown to influence risk factors for type 2 diabetes.”

The amount matters

The study was conducted in Denmark, where there is a big variation in wholegrain-intake. The study showed that it made no difference which type of wholegrain product or cereal the participants ate – ryebread, oatmeal, and muesli, for example, seem to offer the same protection against type 2 diabetes.

What is more important is how much wholegrain one eats each day – and the study also provides important clarification to the scientific knowledge when it comes to daily dosages.

The participants were divided into 4 different groups, based on how much wholegrain they reported eating. Those with the highest consumption ate at least 50 grams of wholegrain each day. This corresponds to a portion of oatmeal porridge and one slice of rye bread, for example.

The proportion who developed type 2 diabetes was lowest in the group which reported the highest wholegrain consumption, and increased for each group which had eaten less wholegrain. In the group with the highest wholegrain intake, the diabetes risk was 34 percent lower for men, and 22 percent lower for women, than in the group with the lowest wholegrain intake.

“It is unusual to be able to investigate such a large range when it comes to how much wholegrain people eat,” says Rikard Landberg.

“If you divided American participants into 4 groups, the group that ate the most wholegrain would be the same level as the group that ate the least wholegrain in Denmark. In Europe, Scandinavia eats the most, Spain and Italy the least.”

Additionally, the study was uncommonly large, with 55,000 participants, over a long time span – 15 years.

In line with dietary advice

If you compare wholegrains’ role in the risk of developing type 2 diabetes against other foods that have been investigated in other studies, it is one of the most effective ways to reduce the risk when it comes to diet. Drinking coffee, and avoiding red meat, are other factors that can similarly reduce the risk of type 2 diabetes.

“Our results are in line with dietary advice, which recommends switching out foods containing white flour for wholegrains,” says Rikard Landberg.

“You get extra health benefits – white flour has some negative effects on health, while wholegrain has several positive effects, beyond protection against type 2 diabetes.”

Good to eat carbohydrates

Wholegrains are defined as consisting of all three main components of the grain kernel: endosperm, germ, and bran. Those who avoid all cereals, in an attempt to follow a low carb diet, therefore lose out on the positive health effects of wholegrain, which come principally from the bran and the germ. Rikard Landberg thinks that cereals, and carbohydrates in general, should not be avoided in diet.

“Carbohydrates are a very varied group of foodstuffs, including sugar, starch, and fibre. We should discuss these more individually, and not throw them together in one group, because they have totally different effects on our physiology and health. When it comes to wholegrains, the research results are clear: among the many studies which have been made, in varied groups of people around the world, there hasn’t been a single study which has shown negative health effects.”

Facts: Wholegrains

Wholegrains consist of all three main components of the grain kernel: endosperm, germ and bran. It can be both loose grains, and wholegrain flour. Grains such as oatmeal and rye, wheatberries, bulgur, and wholegrain couscous are all wholegrains. In bread and pasta, the wholegrain content can vary. Common cereals include wheat, rye, oats, corn, maize, rice, millet and sorghum.

Swedish dietary advice is to eat around 70g of wholegrain a day for women, and 90g a day for men. Some examples of how much wholegrain different foods contain:

  • One 50 g slice of rye bread: 16g wholegrain.
  • One 35 g serving of oatmeal porridge: 35 g wholegrain
  • One 12 g crispbread: 12 g wholegrain

Facts: The study

The study used data from a prospective Danish cohort study on diet, cancer and health. It covered more than 55,000 participants, who were between 50-65 years old when the study started. During the initiation of the cohort study in the early 1990s, healthy participants had filled in detailed forms of their eating habits. Through these, the researchers established the participants’ total wholegrain intake per day, which of the most common cereals they got their wholegrain from, (wheat, rye, oats, in grams per day), and the total number, and different types, of wholegrain products (in grams per day) – rye bread, other wholegrain breads, oatmeal porridge and muesli.

The cohort study was linked with data from Denmark’s national diabetes register, to investigate which participants developed type 2 diabetes during a 15 year period – which in total was over 7000 people.

Source: CHALMERS UNIVERSITY OF TECHNOLOGY


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Whole Grain Foods Could Help Losing Weight

Serena Gordon wrote . . . . . .

Put down that forkful of perfectly twirled white spaghetti, and grab a plate of whole grain pasta instead.

You’ll feel fuller after switching out highly processed white grains for whole-grain alternatives, a new study from Denmark contends. Plus, you’ll likely lose a little bit of weight and have reduced inflammation. Those changes could be helpful in preventing or improving type 2 diabetes, the researchers noted.

“Our analysis confirmed that there is a sound scientific basis for the dietary recommendation to eat whole grains. Rye seems to have the best effect,” said study senior author Tine Rask Licht. She’s a professor of intestinal microbial ecology at the Technical University of Denmark.

But the study also had some surprising results. Eating a diet full of whole grains didn’t appear to improve insulin sensitivity, nor did it seem to change the gut’s microbiome (the mix of bacteria that normally live in the intestines).

The study included 50 people who were at risk of metabolic syndrome, a condition that includes a number of risk factors for heart disease, such as high blood pressure, low HDL (good) cholesterol, high triglycerides (another blood fat), abdominal obesity and reduced insulin sensitivity. People with at least three these risk factors have metabolic syndrome, according to the American Heart Association.

The participants were between 20 and 65 years old. All were overweight or obese.

The volunteers were randomly split into two groups. One group ate a diet with only whole grain foods or grain products for eight weeks. Then, they consumed their regular diet for six weeks. And, finally, they spent another eight weeks eating a diet of refined grain products. The other group completed the study in the reverse order, beginning with the refined grains.

Whole grains include wheat, rye, barley, oats, brown and red rice, millet, and corn in dried form (fresh corn is considered a vegetable), the researchers said.

The volunteers had blood tests and submitted stool samples along the way so the researchers could check the DNA of their gut microbiome.

The volunteers all showed reductions in body weight and markers of systemic inflammation on the whole grain diet. Licht said she thinks whole grains help people lose a little bit of weight by filling them up and increasing satiety.

But, she added, the researchers were a bit surprised that there were no changes in the bodies’ natural bacteria after the change in diet. Other studies, she noted, have also had similar results.

Samantha Heller, a registered dietician at NYU Langone Health in New York City, said the findings support other research that has found an anti-inflammatory effect and weight loss from whole grains.

She also noted that other studies have had contradictory results regarding changes in the microbiome as well as improvements in insulin sensitivity when people switch to whole grains. She said it may be that this study was too small to see those effects, or it could be the type of grain, the amount of grain or the length of the study that account for the findings.

Heller says whole grains definitely have a place in the diet. “Whole grains are healthy. Whole grains also have vitamins and minerals, but like any starchy or carbohydrate food, you have to watch your portion size,” she said.

Whole grains should make up about one-quarter of your plate, Heller said, but added, “If you want to lose weight, shave that down a bit.” Half your plate should be non-starchy veggies, and the remaining quarter should be a protein food, she recommended.

And beware the packaging of whole grains, she added.

Even if a package says “made with whole grains,” Heller suggested double-checking the ingredient list. “A product can say ‘made with whole grains, and it’s a sprinkle of oats on top. The first ingredient on the list should be whole wheat [or another grain], or the package should say ‘100 percent whole grain’,” Heller said.

The study was published in the journal Gut.

Source: HealthDay

What Can Studies Tell Us About Whole Grains and the Heart?

Lisa Rapaport wrote . . . . . . .

Scientists haven’t yet proved beyond a doubt that a diet rich in whole grains is healthy for the heart, a research review suggests.

Researchers focused only on the gold standard for nutrition experiments: studies that randomly selected some healthy adults to consume lots of whole grains from products like cereal, rice and oats – and other healthy individuals to eat plenty of refined grains like white bread or stick to their usual diets.

None of these experiments tested whether eating whole grains might influence the risk of dying from heart disease or having a heart attack or stroke, the research review found.

All of the experiments did assess how consuming whole grains impacts risk factors for heart disease like blood pressure and cholesterol, however, and none found a difference in these risk factors based on what types of grains people ate.

But there is still a large and undisputed body of evidence documenting the many health benefits of a diet rich in whole grains, said Nour Makarem, a nutrition researcher at Columbia University in New York who wasn’t involved in the study.

“Whole grains have been associated with lower weight gain, better cholesterol, glucose and insulin levels in previous studies, which are risk factors for heart disease,” Makarem said by email.

“Whole grains are also a source of cereal fiber, which has in turn been associated with lower risk for heart disease, obesity and cancer,” Makarem added.

The American Heart Association recommends the Dietary Approaches to Stop Hypertension (DASH) diet or a Mediterranean-style diet to help prevent cardiovascular disease. Both diets emphasize cooking with vegetable oils with unsaturated fats, eating nuts, fruits, vegetables, low-fat dairy products, whole grains, fish and poultry, and limiting red meat and added sugars and salt.

In the current research review published by the Cochrane Library, the authors conclude that experiments to date testing the heart benefits of whole grains have been too small, too brief, or both, making it impossible to determine how these foods might lead to long-term heart benefits in the general population.

Combined, the nine studies included in the review had only 1,414 participants ranging in age from 24 to 70. None of the studies tested the impact of consuming whole grains for longer than four months.

Senior study author Dr. Karen Rees of the University of Warwick in the UK didn’t respond to requests for comment.

Whole grain foods encompass a range of products and include whole grain wheat, rice, maize, and oats as well as milled whole grains such as oatmeal.

High-fiber grains are only one component of a healthy diet, noted Dr. Margo Denke of Bandera, Texas, a former researcher at the University of Texas Southwestern Medical Center in Dallas who wasn’t involved in the current research review.

“We have known for some time that fiber makes a small contribution to altering risk factors for heart disease,” Denke said by email.

“The point is that whole grains, when added to a whole diet of fruits and vegetables (as seen with the DASH diet) do make a difference in cardiovascular risk factors,” Denke said. “One needs to quit asking small modifications to bear the weight of the effects of a complete diet; diet is not a simple thing and diet is a composite, an overall approach to life.”

Source: Reuters


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