Diet

Researchers at the University of Toronto have found that a calorie labelled is not the same as a calorie digested and absorbed when the food source is almonds.

The findings, published in the journal Mayo Clinic Proceedings, should help alleviate concerns that almonds contribute to weight gain, which persist despite the widely recognized benefits of nuts as a plant-based source of protein, vitamins and minerals.

“Nuts have generally been thought of as healthy the last two decades, but the messaging around nuts has often come with a disclaimer that they are high in fat and energy,” said John Sievenpiper, principal investigator on the study and an associate professor in the departments of nutritional sciences and medicine in the Temerty Faculty of Medicine. “We still see that caveat in the media and on the internet today, and it has been part of many clinical guidelines, although that is changing.

“Other researchers have shown that there is a bioaccessibility issue with nuts – that a calorie labelled may not be a calorie absorbed. This study quantifies that effect with almonds in a relevant population.”

The researchers found that after digestion, about 20 per cent of calories derived largely from fat in almonds remained unabsorbed, which they observed in stool samples. That translated to about two per cent less energy absorbed from the diet overall among study participants.

A person eating the same amount of almonds in a daily diet of 2,000 to 3,000 calories would absorb 40 to 60 calories less than would be predicted by Atwater factors, on which many food labels are based. That could result in weight loss up to 2.9 kilograms, or 6.3 pounds, over a year, assuming no compensation in the form of increased intake or decreased energy expenditure.

Participants in the study did not gain weight, which is consistent with the majority of high-quality trials that measure nut consumption and weight gain – some of which show an association with weight loss, said Sievenpiper, who is also a staff physician and scientist at St. Michael’s Hospital, Unity Health Toronto.

The researchers used a randomized crossover trial to study 22 women and men with high cholesterol who underwent a series of three, month-long dietary interventions separated by a week-long washout period.

All study participants consumed an NCEP Step-2 diet (low in saturated fat and cholesterol, part of the U.S. National Cholesterol Education Program). The three dietary interventions were full-dose almonds (75 grams per day or three quarters of a cup); half-dose almonds plus half-dose muffins; and full-dose muffins as a study control. The nutritional makeup of the muffins matched the almonds in amount of protein, fibre and fats.

“One unique aspect of this study is that it assessed people with high cholesterol, who are at greater risk for cardiovascular disease,” said Stephanie Nishi, who was a doctoral student at U of T at the time of the study and is now a post-doctoral researcher at the Universitat Rovira i Virgili in Spain.

“That has not been done in this population before, and it’s important because this group typically gets many messages to eat more nuts, owing to the evidence for nut consumption and heart health,” Nishi said.

Nishi and Sievenpiper both said there is a big gap between the number of nuts people are recommended to consume and how many they actually eat – both generally and in populations at risk for cardiovascular and other disease.

Further barriers stemming from concerns about weight gain are counter-productive, the researchers said.

Diabetes Canada recently adjusted their guidelines based in part on the study’s findings, and to avoid the stigma around nuts and weight gain, said Sievenpiper, who has contributed to guidelines for patients with diabetes and other metabolic disorders, and for cardiovascular disease.

This study was supported by a PSI Graham Farquharson Knowledge Translation Fellowship and a Banting and Best Diabetes Centre Sun Life Financial New Investigator Award, as well as the Almond Board of California.

Cracking the code on human obesity: U of T researchers discover fruit flies may have the answer

ullahnor — Wed, 22 Feb 2017 17:30:57 +0000

Cracking the code on human obesity: U of T researchers discover fruit flies may have the answer

ullahnor Wed, 02/22/2017 - 12:30

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University Professor Marla Sokolowski: “The fly has been an excellent model organism to understand mammalian behaviour and metabolism, and so this work can point to places to look further in humans” (photo by Martin Cooper via Flickr)

Peter Boisseau

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Peter Boisseau

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A University of Toronto study on fruit flies has uncovered a gene that could play a key role in understanding obesity in humans.

The paper published online this month in Genetics examines a “foraging gene” humans share in common with fruit flies. The gene plays multiple roles, and it is found in the same locations for both fruit flies and humans – the nervous system, muscle and fat.

“What our study does is nails the gene for being very important for the traits of moving, feeding and fat storage,” says Marla Sokolowski of the department of ecology & evolutionary biology at U of T’s Faculty of Arts & Science.

In nature, fruit flies called rovers with high amounts of the gene tend to move a lot, eat very little and stay lean, while flies with low amounts of the gene called “sitters” are the opposite. The “foraging gene” encodes a cell signalling molecule called a cGMP dependent protein kinase.

The same could apply to obesity in humans.

“When we say the ‘foraging gene’ is the same, what we’re saying is that when you look at the DNA sequences of the human and the fly there is a lot of similarity, enough that you can see it’s the fly version of the gene that the human has,” says Sokolowski, a University Professor.

“So you could imagine if you are a fly, preferences for sugar, the tendency to store a lot of fat and the tendency to move less could all be contributing to the likelihood of being more obese if you have low levels of this gene, or to be leaner if you have higher levels.”

Such similarities between species are known as orthologs, meaning they are genes that evolved from a common ancestor eons ago.

When scientists first started mapping human genomes and comparing them to other organisms, they were shocked to discover humans don’t have that many more genes than flies do.

Sokolowski says the research is another part of the puzzle, and the beginning of our understanding of how what was once considered “junk DNA” is actually very important for regulating key characteristics such as behaviour and metabolism.

“No one has analyzed it in the way we have in flies, but it’s a hint from the fly. The fly has been an excellent model organism to understand mammalian behaviour and metabolism, and so this work can point to places to look further in humans.”

The study involved a technique called recombineering to manipulate DNA at the molecular level, so as to remove and then reinsert the gene in various doses to see the effects on behaviour and metabolism.

Lead author Aaron Allen was a PhD student in cell & systems biology at U of T when the work was done, and he was assisted by Sokolowski, fellow U of T student Ina Anreiter, and Oxford University collaborator Megan Neville, who taught Allen the technique.

“This kind of work is actually so cutting-edge that it takes a really good student to learn how to do this and then bring the technique back to the lab,” says Sokolowski.

“To be able to take a gene of this large size and complexity and put it back in the fly so that it works is almost at the edge of what is possible.”

Sokolowski says it’s particularly interesting that one gene should have multiple roles in feeding and obesity in the body, a characteristic known as pleiotropy.

The next question would be how exactly it plays multiple roles.

“Lots of genes have multiple roles, but the idea here is that this gene may be involved in the coordination of roles in traits important for feeding and obesity,” she says.

“We don’t know much about pleiotropy, or how it happens, or how it’s regulated at the level of the molecules. So this sets the groundwork to be able to look at that in detail.”

Double-fortified salt – developed by U of T research – fights iron deficiency in India

ullahnor — Wed, 15 Feb 2017 20:22:08 +0000

Double-fortified salt – developed by U of T research – fights iron deficiency in India

ullahnor Wed, 02/15/2017 - 15:22

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Professor Levente Diosady (centre) and his team developed a way to fortify salt with both iron and iodine. The product is now being distributed to more than 24 million people in India’s Uttar Pradesh state (photo by Mark Balson)

Tyler Irving

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Tyler Irving

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Faculty of Applied Science & Engineering

Gates Foundation

Double-fortified salt – developed at U of T to add more iron and iodine to the diets of those who don't get enough – is now being distributed to 24 million people in the state of Uttar Pradesh in India.

The Tata Trusts, India’s largest charitable foundation, is supporting the state government to procure and distribute the product while the government of Uttar Pradesh is spending more than $40 million to purchase the salt and make it available to low income consumers at subsidized prices.

The Bill & Melinda Gates Foundation is funding a comprehensive evaluation of the effectiveness of the product in reducing iron and iodine deficiencies across the population.

“We’re very excited to see our invention being distributed on such a massive scale” says U of T professor Levente Diosady, who specializes in food engineering at the Faculty of Applied Science & Engineering. “The opportunity for engineers to make a difference in the lives of people living with malnutrition is incredible.”

More than twenty years ago, Diosady was approached by Venkatesh Mannar, then a senior advisor to UNICEF, who wanted him to do some simple chemical tests on formulations for double fortified salt.

Mannar’s mission was to address deficiencies in micronutrients, vitamins and minerals needed in small but regular amounts by the human body. Lack of these nutrients can reduce overall health with huge personal and economic impact worldwide.

Ratan Tata (centre, with flowers), chairman of Tata Trusts, is congratulated by the chief minister of Uttar Pradesh at the launch of the double-fortified salt distribution program (photo courtesy of the Micronutrient Initiative)

Perhaps the biggest success story in the micronutrient world is iodized salt. Many governments around the world have mandated the enrichment of salt – an inexpensive food item consumed regularly by all people – with iodine as a means to ensure that nutritional needs are met.

“Venkatesh was born into a salt-producing family, and he knew how well iodized salt was working in places where it had been tried,” says Diosady. “He wanted to see if we could do the same with iron.”

Iron deficiency leads to anemia, a condition that leaves people feeling tired and weak, making it harder to work or study. According to the World Health Organization, iron deficiency is currently the most common and widespread nutritional disorder in the world, affecting more than two billion people, and a major contributor to maternal mortality.

But Diosady’s tests showed why iron couldn’t be added to salt in the same way as iodine: the two elements reacted with each other, converting the iodine into a form that simply evaporated away.

Undeterred, Diosady and his team began developing a method for encapsulating the iron so that it wouldn’t react with the iodine. Eventually, they packaged ferrous fumarate, an iron-rich compound, into tiny edible particles that look and feel nearly identical to salt grains, and which dissolve when consumed. These particles enabled the iron to be mixed with iodized salt, resulting in a double-fortified product.

Soon after, Mannar joined the new Micronutrient Initiative as its president and continued to work with U of T food engineers on programs that proved the acceptability, safety and effectiveness of the double-fortified salt. The results of early trials showed a significant reduction in rates of anemia among children who received the product as part of their school meals.

Today, double-fortified salt produced in the Indian state of Tamil Nadu is being added to school lunches provided to more than five million children in the state through a program supported by the Canadian International Development Agency.

The expansion of the project to the state of Uttar Pradesh was a much larger undertaking, requiring even further scale-up of manufacturing.

U of T Engineering, through a grant agreement from Canada’s International Development Research Centre, is supporting the transfer of technology to India and scale up and roll out of the product to 4.6 million families in Uttar Pradesh. Diosady and Mannar, who is now an adjunct professor at U of T, are co-investigators on the project.

“When we started, we were producing 100 grams at a time in the lab,” says Diosady. “The first order from Uttar Pradesh for the month of January 2017 alone is for 6,000 tonnes.”

Meanwhile, Diosady and his team have continued their research.

They are developing ways to encapsulate other micronutrients, such as folic acid and vitamin B12, with the hopes of making a quadruple-fortified salt. They are also working on adding iron to tea.

“Tea, like salt, is widely consumed in predictable amounts in India and South Asia” says Diosady. “If we can get an iron-fortified tea into the hands of every tea-seller, there is the potential for a very beneficial health effect.”

Fast-food "swamps" linked to greater diabetes risk: U of T research

krisha — Thu, 09 Jun 2016 19:31:06 +0000

Fast-food "swamps" linked to greater diabetes risk: U of T research krisha Thu, 06/09/2016 - 15:31

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(Lead image by Daniel Oines via Flickr)

Nicole Bodnar

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Nicole Bodnar

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Breaking Research

Diabetes

Dalla Lana School of Public Health

They're called fast-food swamps – and if you live near one, a new study from the University of Toronto shows you're at greater risk of developing diabetes.

Researchers at U of T's Dalla Lana School of Public Health say Canadians under the age of 65 have a greater risk of developing diabetes if they live near a high number of fast-food restaurants with few healthier dining options.

The study, Relative and absolute availability of fast-food restaurants in relation to the development of diabetes: A population-based cohort study, published on June 9, 2016 in the Canadian Journal of Public Health, is the first in Canada to examine whether living within walking access to various types of restaurants within urban residential areas influences the risk of developing diabetes among adults.

At the outset of the study, researchers identified people without diabetes and followed them forward in time to see who did or did not develop diabetes. After accounting for individual- and neighbourhood-level socio-economic factors and neighbourhood walkability, researchers found that individuals had a 79 per cent higher risk of developing diabetes when their neighbourhoods had a disproportionately high volume of fast-food outlets and few restaurants of another type.

“Our results show that having restaurant options that offer healthier alternatives to fast-food – for example cafes, sit-down restaurants or coffee shops – may be important for mitigating people's risk of developing diabetes,” said Polsky, a PhD candidate in the Division of Social and Behavioural Health Sciences.

“The double whammy of having high numbers of fast food restaurants with few healthier alternatives was associated with the highest risk of diabetes.”

Losing weight can make you more attractive, experts say – but there's a catch

sgupta — Thu, 03 Dec 2015 12:02:22 +0000

Losing weight can make you more attractive, experts say – but there's a catch sgupta Thu, 12/03/2015 - 07:02

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“When it comes to incentives for weight loss, some people are more motivated to look attractive than to improve their health,” Daniel Re said (photo by Allan Foster via Flickr)

Sean Bettam

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Sean Bettam

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Breaking Research

Popular diet theory debunked

sgupta — Wed, 15 Jan 2014 16:01:47 +0000

Popular diet theory debunked sgupta Wed, 01/15/2014 - 11:01

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Healthy eating habits can help you lose weight but the success of your diet has nothing to do with your blood type, researchers found (photo by U.S. Army Corps of Engineers Europe District via Flickr)

Michael Kennedy

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Michael Kennedy

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Breaking Research

Diet

Is a calorie always a calorie? Not when it comes to almonds, U of T researchers find

Cracking the code on human obesity: U of T researchers discover fruit flies may have the answer

Double-fortified salt – developed by U of T research – fights iron deficiency in India

Fast-food "swamps" linked to greater diabetes risk: U of T research

Read more U of T research on diabetes

Losing weight can make you more attractive, experts say – but there's a catch

Popular diet theory debunked