The consumption of whole grain cereals has been associated with a lower risk of type-2 diabetes, cardiovascular disease and some cancers. How it does this – whether via effects from bioactive compounds contained in whole grains, or the effect that phytochemicals and fibres have on intestinal bacteria – is still the subject of some speculation.

In a new study researchers from the University of Eastern Finland and the International Agency for Research on Cancer (IARC) tested the metabolic effects of consuming an enriched wheat bread against wholegrain rye bread in 15 human volunteers.

For the first four weeks of the study, the participants ate 6 to 10 slices a day of either whole grain rye bread or a white wheat bread enriched with fermented rye bran. In a second 4-week testing period, all participants ate the same amount of rye-free white wheat bread. Otherwise, they didn’t change their diet.

At the end of both testing periods, they gave blood samples, which were analysed by a combination of liquid chromatography and mass spectrometry. In particular the researchers were looking to compare the samples for concentrations of certain metabolites (the end product of metabolism) which might indicate a risk

Serotonin-glucose connection

The consumption of wholegrain rye led to, among other things, significantly lower serotonin concentrations when compared to consumption of the wheat bread. This finding was confirmed in a separate feeding test involving mice.

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 say the findings, published in the American Journal of Clinical Nutrition, may also shed some light on the development of 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 ingredient of concern is calcium propionate (also known as E282) which is added to ready-made foods to which prevent mold growth. Propionate (propionic acid) is a naturally occurring short-chain fatty acid found in butter and some types of cheese, but calcium propionate, used in food production, is a synthetic ingredient.

An international team of researchers led by Harvard TH Chan School of Public Health combined data from a randomized placebo-controlled trial in humans with results from mouse studies. Results showed that in humans consuming calcium propionate can trigger a cascade of metabolic events that leads to insulin resistance and hyperinsulinemia. Insulin resistance is when the body doesn’t respond well to the hormone insulin, which helps cells take in sugar, or glucose. Such resistance can lead to the high blood sugar levels seen in people with diabetes.

That’s the conclusion of Italian scientists after performing a meta-analysis of studies looking at combined consumption of these two herbal remedies.

Berberine occurs naturally in medicinal plants such as goldenseal and Oregon grape, while silymarin is found in the seeds of the milk thistle plant.

The scientists reviewed the findings of five randomised, double‐blind, placebo‐controlled clinical trials (RCTs) – considered the gold-standard of evidence. Results showed that co-consumption of berberine and silymarin was associated with significant improvements in across several cholesterol measurements.

The findings, which showed that the combination was associated with reductions in total cholesterol of 25 mg/dl, of triglycerides of 28 mg/dl, and of LDL cholesterol of 29 mg/dl, while HDL cholesterol levels were increased by 6 mg/dl, were published in the journal Phytotherapy Research​​.

In addition to these benefits, the data also showed the herbal combo produced significant reductions in blood glucose levels were observed, with average decreases of 7.5 mg/dl.

A synergistic effect

The data suggest the two herbal remedies work best together.

“[Berberine] lipid‐lowering efficacy in humans is well‐known and definitely confirmed by a previous meta‐analysis of 27 clinical studies with overall 2,569 participants​,”​ write the scientists from the universities of Bologna, L’Aquila, and Palermo in Italy.

“In comparison with that meta‐analysis, our findings show that the addition of silymarin to [berberine] is able to improve its positive effect on lipid and glucose metabolism in humans, allowing for the administration of lower doses of [berberine] and accordingly reducing the associated risk of gastrointestinal discomfort which is demonstrably dose related. ​

“As a matter of fact, considerations on tolerability of low doses of [berberine] may also have important clinical implications, because it is well known that hypercholesterolemia is an asymptomatic clinical condition in which adherence and persistence on prescribed lipid‐lowering medications are relatively low, and discontinuation rates are even higher in presence of adverse events or drug reactions.

The studies analysed included data from 497 individuals and the length of the studies was between three to 12 months. Doses of berberine were 500 or 1,000 mg/day; doses of silymarin doses were either 105 or 210 mg/day.

• For more on the benefits of pulses see our articles: Get more pulses into your diet and Green beans: why pulses are the eco-friendly option for feeding – and saving – the world

Natural Health News — Two new studies have revealed the importance of vitamin D in both preventing, and lessening some of the inflammation caused by, diabetes.

In the first scientists from California and Seoul in South Korea collaborated to study a group 903 healthy older adults with no indications of either pre-diabetes or diabetes during clinic visits from 1997 to 1999, and then followed the participants through 2009. Vitamin D levels in blood were measured during these visits, along with fasting plasma glucose and oral glucose tolerance.

Over the course of time, there were 47 new cases of diabetes and 337 new cases of pre-diabetes, in which blood sugar levels are higher than normal but not yet high enough to be categorized as type-2 diabetes.

In this study, published in PLOS One, the researchers identified the minimum healthy level of 25-hydroxyvitamin D in blood plasma to be 30 nanograms (ng) per millilitre (ml). That’s 10 ng/ml above the generally recommended level – though increasingly nutritionists argue that higher levels, as much as 50 ng/ml would be a better benchmark.

“We found that participants with blood levels of 25-hydroxyvitamin D that were above 30 ng/ml had one-third of the risk of diabetes and those with levels above 50 ng/ml had one-fifth of the risk of developing diabetes,” said first author Sue K. Park, MD, in the Department of Preventive Medicine at Seoul National University College of Medicine in South Korea.

More is better

According to study co-author Cedric F. Garland, DrPH, adjunct professor in the UC San Diego School of Medicine Department of Family Medicine and Public Health, to reach 25-hydroxyvitamin D levels of 30 ng/ml, would require dietary supplements of 3,000 to 5,000 international units (IU) per day, less with the addition of moderate daily sun exposure with minimal clothing (approximately 10-15 minutes per day outdoors at noon).

The current recommended average daily amount of vitamin D is 400 IU for children up to 1 year; 600 IU for ages 1 to 70 years (less for pregnant or breastfeeding women) and 800 IU for those over 70.  Higher daily amounts of vitamin D are generally considered safe, but as with everything there are limits. Very high blood serum levels exceeding 125 ng/ml have been linked to adverse side effects, such as nausea, constipation, weight loss, heart rhythm problems and kidney damage. This is why many doctors recommend having your blood levels of vitamin D tested before considering high dose supplements.

Reducing inflammation

In a second study – an analysis of 20 high quality trials – Australian researchers from Monash University, Melbourne found that supplemental vitamin D could help reduce inflammation in people with diabetes.

The study looked at vitamin D status and levels of inflammatory biomarkers – substances produced by the body when inflammation is present. A well-known example of this is C-reactive protein (CRP) produced by the liver in response to inflammation, infection and tissue injury. In this study, published in Nutrition Reviews, vitamin D supplementation CRP, as well as other important biomarkers such as tumour necrosis factor alpha and erythrocyte sedimentation rate. It also helped increase levels of leptin a hormone that helps to regulate energy balance by inhibiting hunger.

Chronic low-grade inflammation is widely known to be present in, and precedes, the development of type-2 diabetes and raises the risk of a whole range of diabetes complications such as damage to blood vessels.

“This is the first ever systematic review and meta-analysis on this topic in patients with type-2 diabetes,” commented senior researcher Associate Professor Barbora de Courten. “If vitamin D supplementation can improve inflammation, as shown here, there may be important benefits for patients with type-2 diabetes, given that elevated inflammatory markers promote insulin resistance, dyslipidaemia [an abnormal amount of triglycerides, cholesterol and/or fat phospholipids in the blood] and atherosclerosis.”

Building the case for supplementation

The majority of the trials analysed used vitamin D3 in doses of 200-6000 IU daily. A handful looked at very large doses e.g. 50 000-60 000 IU weekly or bi-weekly or a single bolus dose of 300 000 IU.

The researchers say it is too soon to make the blanket recommendation that everyone with diabetes should be given vitamin D supplements and recommend assessing need the need for and level of supplementation on a case by case basis.

However taken together along with other studies that show that low vitamin D status is linked to metabolic syndrome and poorer mental health in women with type-2 diabetes there is an increasingly strong case for vitamin D supplementation where diabetes is a risk.

According to the UK’s NICE (National institute of Clinical Excellence) people who are diagnosed with a chronic physical health problem such as diabetes are 3 times more likely to be diagnosed with depression than people without it.

People with diabetes who are also suffering from depression are at greater risk of suffering from an episode of ‘diabetic burnout’ – a state of disillusionment and frustration around their disease and a consequent disregard for their blood sugar levels, which can seriously threaten their health.

Past research suggests that vitamin D supplementation has been shown to help improve both type-2 diabetes and some forms of depression, independent of one another. However, until now, there has been no data looking at women, who are statistically more likely to experience depression, and whether vitamin D could help.

In a recent study funded by the National Institute of Health (NIH), and published in the Journal of Diabetes Research, scientists tried to determine whether vitamin D supplementation could improve mental health status among women with type-2 diabetes.

Raising blood levels of the sunshine vitamin

A total of 50 women with type-2 diabetes and symptoms of depression were included in the study. All received weekly high-dose supplementation of 50,000 IU vitamin D2 per week for a total of 6 months (a dose that he been studied previously in obese individuals). Vitamin D2 is the form found in plant-based foods, as opposed to D3 which is found in meat and fish and which is synthesised by the body in the presence of sunlight.

The researchers used several standard tools to evaluate the participants’ mental and physical health status. Among their findings were:

• Compliance with the study was high; a total of 92% attended all of the required visits for the study.
• Blood levels of vitamin D (25(OH)D) increased significantly; from an average of 19 ng/ml (47.5 nmol/l) at the beginning, to 34.29 ng/ml (85.73 nmol/l) after 3 months and 37.6 ng/ml (94 nmol/l)
• The participants experienced a significant improvement in depression and anxiety symptoms, as well as mental health status.

Even after adjusting for several variables, including participants’ weight, their race and the season, the relationship between vitamin D supplementation and depression remained significant. Though not statistically significant, those who were not taking mood stabilising medications also experienced an improved response from vitamin D supplementation.

More data needed

The researcher’s chose to supplement the participants with large weekly doses of vitamin D2 instead of daily doses of D3, which has been proven to be more efficient in raising and maintaining healthy vitamin D levels. While the supplement regimen did increase blood levels of vitamin D, even after 6 months participants levels were still not within optimal range (40-60 ng/ml). Nevertheless the researchers believe that this initial research is promising.

It would be interesting to see the same study repeated with vitamin D3 and in particular see if those not on mood stabilising drugs had a bigger response, and indeed the researchers say they are already planning this as their next study. Watch this space.

A diet rich in fruit and vegetables has previously been associated with a lower risk of certain cancers and cardiovascular conditions.

The French researchers suspected there might also be a benefit for type-2 diabetes risk, on the basis of previous studies showing that certain antioxidants, such as vitamins C and E, lycopenes or flavonoids, could reduce the risk of the disease. However, these studies looked only at isolated nutrients, not at the total antioxidant capacity of the diet.

Writing in the journal published in Diabetologia, they suggest that dietary compounds with antioxidant activity may have cumulative/synergistic antioxidant effects, and therefore wanted to verify whether overall diet, according to its antioxidant capacity, is associated with diabetes risk.

Tracking antioxidant consumption

Using data from a long term study of French women the researchers were able to track information on diet and diabetes for 64,233 women over a period of 13 years.

All the study participants were free from diabetes and cardiovascular disease at the time of inclusion in the study.

Each woman completed a dietary questionnaire at the beginning of the study, including detailed information on more than 200 different food items. This allowed the researchers to compare the women’s diet to existing databases on the antioxidant capacity of different foods and calculate a score for ‘total dietary antioxidant capacity’ for each participant. The group then analysed the associations between this ‘score’ and the risk of diabetes over the course of the study.

The results showed that diabetes risk diminished with increased antioxidant consumption. Women with the highest antioxidant scores had a reduction in diabetes risk of 27% compared with those with the lowest scores.

Beneficial foods included walnuts, prunes, blueberries, strawberries or hazelnuts, dark chocolate (including hot chocolate drinks), tea, chicory and wine, to name just a few.

‘This link persists after taking into account all the other principal diabetes risk factors: smoking, education level, hypertension, high cholesterol levels, family history of diabetes and, above all, BMI, the most important factor’, said first author Francesca Romana Mancini.

Not all antioxidants are equal

The foods and drinks that contributed the most to a high dietary antioxidant score were fruits and vegetables, tea and red wine (consumed in moderate quantities). The authors excluded coffee from the analysis, because the high antioxidant levels in coffee beans might mask the effects of antioxidants from other sources.

They also state that the high molecular weight of the antioxidants in coffee means that they are not as well absorbed in the body as antioxidants from other sources. In the final analysis, in this study, women who consumed the least coffee and the most fruit and vegetables actually had a lower risk of type-2 diabetes.

Ms Mancini concludes: ‘We know that these molecules counterbalance the effect of free radicals, which are damaging to cells, but there are likely to be more specific actions in addition to this, for example an effect on the sensitivity of cells to insulin. This will need to be confirmed in future studies’.

In a human study, published in the journal Gut, Danish researchers led by the National Food Institute, Technical University of Denmark, examined the effect of exchanging refined grain products in the diet – such as white bread and pasta – with wholegrain varieties. The study involved 50 people and lasted 8 weeks.

Among the known benefits of eating wholegrains, instead of refined grain products, is a lower risk of cardiovascular diseases. All the individuals in this study were at risk of developing either cardiovascular disease or type-2 diabetes.

Reducing inflammation

Blood tests showed that the participants had less inflammation in their bodies when eating wholegrains. In particular, it appeared that rye had a beneficial effect on the blood’s content of inflammatory markers.

Inflammation is a natural response of the body to an infection, but some people have elevated levels of inflammation (so-called low-grade inflammation) even though there is no infection. This is particularly the case in overweight people. In overweight people, an increased level of this subclinical inflammation may lead to increased risk of developing type-2 diabetes.

Results also showed that participants eat less when wholegrain products are on the menu – likely because wholegrain consumption increases satiety. While eating the wholegrain diet, participants also generally lost weight.

The researchers used DNA sequencing of stool samples to see whether the different diet types affected the participants’ gut bacteria composition. Overall, the analysis did not show major effects from the dietary grain products on the composition of the gut bacteria.

“However, even though the analysis did not reveal significant changes in the average gut microbiota after wholegrain consumption, it may well be that the individual composition of our gut microbes has an impact on the individual reaction of our body to dietary wholegrains, given that our bacteria help us digest the fibres in the wholegrains.” Professor Tine Rask Licht from the National Food Institute says.

Overall, says Professor Licht: “Our analysis confirmed that there is a sound scientific basis for the dietary recommendation to eat wholegrains. This may particularly apply to people, who are at increased risk of developing cardiovascular disease or type 2 diabetes,” Professor Tine Rask Licht from the National Food Institute says.

The researchers note that useful future studies might look more deeply into the different effects of different types of wholegrains.