Diet

Posted on Diabetes, Diet, Obesity

More evidence that sugary drinks cause weight gain

More evidence that sugary drinks cause weight gain
More evidence that sugary drinks cause weight gain

A review of dozens of studies from the last decade, led by researchers at the University of Toronto and Harvard University, recently found that sugar-sweetened beverages promote weight gain in children and adults.

The review, published in the American Journal of Clinical Nutrition, is the largest and most thorough analysis to date of research on sweetened drinks, and overweight and obesity — both of which heighten risks for diabetes, heart disease, some cancers and other diseases.

Vasanti Malik led the study, with colleagues in Toronto and Boston. Malik is an assistant professor of nutritional sciences at U of T’s Temerty Faculty of Medicine and the Joannah & Brian Lawson Centre for Child Nutrition. She spoke with writer Jim Oldfield about the findings, and take-aways for public policy and personal health.

Why do this study now?

Our last meta-analysis on this topic was 2013. You want to update a meta-analysis every five to 10 years anyway, but especially in this area because there has been so much new research the last decade. Evidence has continued to accumulate showing associations among sugar-sweetened beverages, or SSBs as we call them, and weight and chronic disease. And it’s very important to have an updated synthesis of that evidence, especially for public policy. The Canada Food Guide is clear on the need to limit SSBs and recommends water as the drink of choice, and added sugar intake including SSBs has declined in Canada, in part due to public policies. But levels here are still too high. As well, the USDA Dietary Guidelines for Americans are arguably not as strong, and with U.S. policymakers coming together soon to discuss the 2025 guidelines, our study will be an important piece of evidence to inform their work. 

What did your study show?

We expected to find a positive association between SSBs and weight gain, among adults and children, and in cohort studies and randomized clinical trials. And that was exactly what we found. We analyzed 85 studies, which totalled over half a million participants. In cohort studies, which follow people over long periods of time, each serving-per-day increase in SSBs was associated with a 0.42-kg (almost one-pound) higher body weight in adults. In children, we saw a 0.07-unit higher body-mass index (just under one-twelfth of a BMI unit). Perhaps most striking, findings from our dose-response analysis showed that weight gain increases with increasing levels of SSB intake, in both children and adults. A dose–response relationship provides strongevidence for a cause-and-effect relationship.  

How much weight gain might one drink a day lead to over time?

Well, we estimated that associated change in body weight over a one-year period. For adults, one additional 12-ounce serving a day was linked to a 0.20-kg higher body weight (about half a pound) in one year. Over 10 years, that could be about five pounds. In children, we observed a 0.03-unit higher BMI for each additional daily serving of SSBs over a one-year period. Although these results may seem modest, weight gain is a gradual process, with adults averaging about one pound (0.45 kg) of weight gain per year. So, limiting SSB consumption could be an effective way to prevent age-related weight gain. Limiting SSB intake among children is also an important strategy to help them develop healthy lifestyle habits and weight trajectories.

How common is excess consumption of these drinks?

It’s very common. Sugar-sweetened beverages include sodas, fruit drinks, sports and energy drinks, and they are the largest source of added sugar in the North American diet. Moreover, the rise in consumption of these drinks has mirrored the epidemic of overweight and obesity. In 2016, almost two billion adults were estimated as having overweight and 650 million had obesity. Even more worrying, the rate of increase in obesity in children and adolescents is now greater than in adults. The prevalence of childhood obesity has increased more than four-fold globally since the 1970s, which is truly alarming.

What are some of the health effects of SSBs?

A typical 12-ounce serving of an SSB contains over 140 calories and more than eight teaspoons of sugar. That nearly reaches the recommended daily limit for added sugar, which is no more than 10 per cent of total calories, or about 200 calories for a 2000-calorie per day diet. These drinks are sugar in liquid form. They’re usually made with table sugar, high-fructose corn syrup or other sweeteners that provide calories, and are digested rapidly, more so than sugar consumed as a solid. This bolus of glucose increases blood sugar levels, which triggers a glycemic response that over time can lead to insulin resistance and diabetes. The fructose component also floods the liver, which can cause lipogenesis (creation of fat), which puts a person on the path to fatty liver and metabolic disease. Fructose also increases uric acid, which contributes to insulin resistance and risk for cardiovascular and other diseases. Insulin spikes from the glycemic response can result in an appetite cascade and over-eating, as can excess insulin in the blood over longer periods. Some evidence shows that SSBs activate the dopaminergic reward system in the brain and encourage addictive behaviour, and that they alter the gut microbiome, but we need more research on those effects.

Are you optimistic, given these effects and the research evidence?  

Intake levels of SSBs have come down in the developed world. We’re still seeing increases in the developing world, but taxes in some of those countries are working. Thailand introduced a tax that has reduced consumption, as has Mexico and South Africa. At least 85 countries now have a tax on SSBs, which in part reflects the World Health Organization’s stand on this issue. In Canada, Newfoundland introduced a tax recently, and several U.S. regions and cities have had a tax for years, in response to public health efforts, more awareness and advocacy. The general effect of these taxes is reduced intake, and the revenues can be put toward further public health measures and health care. Other changes will help in Canada and elsewhere as well, such as limiting marketing to children, and better front-of-pack and nutrition labels. All these efforts will push intake down, but it’s important to remember that as that happens, people need access to clean, safe drinking water as an alternative. That’s an ongoing challenge globally, and in many parts of Canada, that we really need to address.

Vasanti Malik holds a Canada Research Chair in Nutrition and Chronic Disease Prevention at the University of Toronto, and an adjunct position in Nutrition at the Harvard T.H. Chan School of Public Health. Michelle Nguyen, a doctoral student at U of T, conducted the study analysis and wrote the paper.

Posted on Diet, Weight Loss

Keto vs vegan: Study of popular diets finds over fourfold difference in carbon footprints

Keto and paleo diets were found to be the least sustainable -- and have the lowest diet quality scores -- of the six popular diets examined
Keto and paleo diets were found to be the least sustainable — and have the lowest diet quality scores — of the six popular diets examined

This may be tough to swallow for those on keto or paleo diets.

A new study from Tulane University which compared popular diets on both nutritional quality and environmental impact, found that the keto and paleo diets, as eaten by American adults, scored among the lowest on overall nutrition quality and were among the highest on carbon emissions.

The keto diet, which prioritizes high fat and low carbs, was estimated to generate almost 3 kg of carbon dioxide for every 1,000 calories consumed. The paleo diet, which eschews grains and beans in favour of meats, nuts and vegetables, received the next lowest diet quality score and also had a high carbon footprint, at 2.6 kg of carbon dioxide per 1,000 calories.

The study, published in The American Journal of Clinical Nutrition, compiled diet quality scores using data from more than 16,000 adult diets collected by the CDC’s National Health and Nutrition Examination Survey. Individual diets were assigned point values based on the federal Healthy Eating Index and average scores were calculated for those eating each type of diet.

The study’s senior author Diego Rose, professor and nutrition program director at Tulane University School of Public Health and Tropical Medicine, said that while researchers have examined the nutritional impact of keto and paleo diets, this is the first study to measure the carbon footprints of each diet, as consumed by U.S. adults, and compare them to other common diets.

“We suspected the negative climate impacts because they’re meat-centric, but no one had really compared all these diets – as they are chosen by individuals, instead of prescribed by experts – to each other using a common framework,” Rose said.

On the other end of the spectrum, a vegan diet was found to be the least impactful on climate, generating 0.7 kg of carbon dioxide per 1,000 calories consumed, less than a quarter of the impact of the keto diet. The vegan diet was followed by vegetarian and pescatarian diets in increasing impact.

The pescatarian diet scored highest on nutritional quality of the diets analyzed, with vegetarian and vegan diets following behind.

The omnivore diet – the most common diet, represented by 86% of survey participants – sat squarely in the middle of the pack of both quality and sustainability. Based on the findings, if a third of those on omnivore diets began eating a vegetarian diet, on average for any given day, it would be equivalent to eliminating 340 million passenger vehicle miles.

Notably, however, when those on omnivorous diets opted for the plant-forward Mediterranean or fatty meat-limiting DASH diet versions, both carbon footprints and nutritional quality scores improved.

“Climate change is arguably one of the most pressing problems of our time, and a lot of people are interested in moving to a plant- based diet,” Rose said. “Based on our results, that would reduce your footprint and be generally healthy. Our research also shows there’s a way to improve your health and footprint without giving up meat entirely.”

A 2021 United Nations-backed study found that 34% of greenhouse gas emissions come from the food system. The major share of those emissions come from food production, with beef being responsible for 8-10 times more emissions than chicken production and over 20 times more emissions than nut and legume production.

While the environmental impacts of specific foods have been studied extensively, Rose said this study was important because “it considers how individuals select popular diets that are composed of a wide variety of foods.”

Going forward, Rose still has questions about how to encourage eating habits that are better for people and the planet.

“I think the next question is how would different policies affect outcomes and how could those move us toward healthier, more environmentally friendly diets?” Rose said.

Posted on Diabetes, Diet

Plant-based low-carbohydrate diet linked with lower risk of premature death for people with type 2 diabetes

Plant-based low-carbohydrate diet linked with lower risk of premature death for people with type 2 diabetes
Plant-based low-carbohydrate diet linked with lower risk of premature death for people with type 2 diabetes
  • Adhering to a plant-based low-carbohydrate diet was associated with a reduction in overall cardiovascular and cancer mortality among people with type 2 diabetes
  • Researchers observed the most substantial health benefits among people who not only adhered to this diet but also had other healthy habits, such as exercising, not smoking, and consuming alcohol in moderate amounts

Following a low-carbohydrate diet comprised primarily of plant-based foods was significantly associated with a lower risk of premature death among people with type 2 diabetes, according to a new study by researchers at Harvard T.H. Chan School of Public Health. It is the first prospective cohort study to examine the relationship between low-carbohydrate diet patterns and mortality among people with diagnosed type 2 diabetes.

“While avoiding refined and highly-processed carbohydrates has been widely recommended to lower the risk of developing type 2 diabetes, our study provides the first empirical evidence on how low-carb diets can help manage the progression of existing diabetes,” said lead author Yang Hu, research associate in the Department of Nutrition.

The researchers analyzed 34 years of health data from 7,224 women participating in the Nurses’ Health Study and 2,877 men participating in the Health Professionals Follow-up Study, all of whom developed type 2 diabetes after those studies began. The participants completed questionnaires on lifestyle and medical history every other year, allowing the researchers to assess the compositions of their diets and score them according to intake of animal proteins and fats, vegetable proteins and fats, high-quality carbohydrates, and low-quality carbohydrates.

The findings showed a 24% reduction in all-cause mortality among those adhering to a low-carbohydrate dietary pattern. The health benefits were stronger for low-carbohydrate diets emphasising plant-based foods and high-quality carbohydrates, such as fruits, vegetables, and whole grains. Those diets were also associated with lower cardiovascular disease and cancer mortality. Low-carbohydrate diets emphasising animal products and low-quality carbohydrates, such as potatoes, added sugars, and refined grains, were not significantly associated with lower mortality.

The researchers observed the strongest health benefits among people adhering to other healthy habits, such as not smoking, regularly exercising, and drinking alcohol in moderation, alongside a plant-based low-carbohydrate diet.

“This study, once again, underscores the importance of diet quality when choosing among various diets for diabetes control and management,” said Qi Sun, senior author and associate professor in the Departments of Nutrition and Epidemiology.

Posted on Diet, Weight Loss

How better planning and behaviour regulation may lead to eating less fat

New research suggests coaching overweight or obese pregnant women to improve their ability to plan and progress toward goals may be key to helping them lower the amount of fat in their diet.

Maternal diet quality affects prenatal development and long-term child health outcomes. Still, the stress that typically increases during pregnancy – often heightened by concern for fetal health and anxiety over impending parenthood – may derail efforts to focus on healthful eating, previous research has shown.  

In this new study, researchers at The Ohio State University set out to identify the pathway between stress and total fat consumption, with a broader goal to evaluate an intervention designed to improve the diets of pregnant women who are overweight or obese.

Through a series of questionnaires and statistical analysis, the team found that two thinking-related skills – planning, and execution of those plans – were weakened in women whose stress was high, and those skill gaps were associated with higher total fat intake.

These two skills are known as executive functions, a set of multiple thinking processes that enable people to plan, monitor behavior and execute their goals.

“People with a higher level of stress tend to have a higher intake of fat, too. If stress is high, we’re so stressed out that we’re not thinking about anything – and we don’t care what we eat,” said lead author Mei-Wei Chang, associate professor of nursing at Ohio State.

“That’s why we focused on executive functions as a mediator between stress and diet. And with this baseline data, we have reasons to believe that designing an intervention around executive functions could improve dietary outcomes,” she said. “I would anticipate the results could be similar for nonpregnant women, because it’s all about how people behave.”

The study was published recently in the Journal of Pediatrics, Perinatology and Child Health.

The 70 women enrolled in the study had a pre-pregnancy body mass index of between 25 (scores between 25 and 29.9 are categorized as overweight) and 45 (scores of 30 and higher are categorized as obese).

The participants completed questionnaires assessing both overall perceived stress and pregnancy-related stress, as well as executive functions – specifically focusing on metacognition, or the ability to plan, and behavior regulation, the ability to execute those plans. They also completed two 24-hour dietary recalls of their calorie intake and consumption of total fat, added sugar, and fruits and vegetables.

“We were really interested in the mediation role of executive functions. The mediator is what makes everything happen,” Chang said. “We wanted to know: If we focus an intervention on executive functions, would that carry through to behavior change in dietary intake?

“Weight loss interventions often involve a prescribed diet or meal plan, and you are told to follow it. But that doesn’t lead to behavior change in the long term.”

Statistical modeling showed that higher perceived stress was associated with a worsened ability to plan and monitor behavior, and that pathway was linked to higher total fat intake. Similarly, higher levels of pregnancy-related stress were associated with a lower ability to plan, which in turn was associated with worsened ability to monitor behaviors related to carrying out the plan – and these factors were linked to higher fat consumption.

These pathways suggested that an intervention designed to lower stress would function as a starting point to improve the diet, and enhancing skills through coaching – emphasizing the ability to plan, including being flexible with planning, and behavior monitoring, particularly when making food choices – would be key to changing eating patterns.

“You need to improve executive functions, and you also need to lower stress,” Chang said. She and colleagues are now analyzing data on the effectiveness of an intervention for the study participants that emphasized stress management and boosting executive function to promote healthy eating.

Executive functions are regulated by a specific region of the brain, and strengths or weaknesses in these skill areas are thought to be affected by a variety of physiological factors. Previous research has found that executive function deficits are more likely to occur in women who are overweight or obese than in women whose weight is categorized as normal.

“Executive function is not well-studied, and it is not related to intelligence. But people with low executive function are unable to make detailed plans and stick to them, and that’s how they get into trouble,” Chang said. “Metacognition and behavior regulation must go hand in hand – that way you have a much better chance to control your behaviors, and then you will eat better.”

Posted on Diet

New antioxidants are found in beef, chicken, and pork!

Antioxidants discovered in meat!

Osaka Metropolitan University researchers developed a new protocol for selective and highly sensitive detection, discovering five types of 2-oxo-imidazole-containing dipeptides(2-oxo-IDPs) using mass spectrometry. The 2-oxo-IDPs, present in living organisms, exhibit very high antioxidant activity, and were found to be abundant in meat including, beef, pork, and chicken. CREDIT Hideshi Ihara, Osaka Metropolitan University

 Imidazole dipeptides (IDPs), which are abundant in meat and fish, are substances produced in the bodies of various animals, including humans, and have been reported to be effective in relieving fatigue and preventing dementia. However, the physiological mechanism by which IDPs exhibit these activities had not been determined previously.

A research team, led by Professor Hideshi Ihara from the Osaka Metropolitan University Graduate School of Science, was the first to discover 2-oxo-imidazole-containing dipeptides (2-oxo-IDPs)—which have one more oxygen atom than normal IDPs—and found that they are the most common variety of IDPs derivatives in the body. The researchers also found that they have remarkably high antioxidant activity.

In their study, the researchers established a method for selective and highly sensitive detection of five types of 2-oxo-IDPs using mass spectrometry, which enables quantitative detection of trace 2-oxo-IDPs in living organisms. Using this method, they revealed for the first time that beef, pork, chicken, and other meats contain antioxidants, not only IDPs but a variety of 2-oxo-IDPs. Their findings were published in Antioxidants.

“We hope that this research method, which enables advanced analysis of 2-oxo-IDPs, will be applied to basic biology and medicine, agriculture, and pharmacy, where it will help improve peoples’ health and prevent diseases,” concluded Professor Ihara.