Category: Diet and Nutrition

The Type 2 Diabetes Risk from Potatoes May Hinge on Their Preparation

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French fries were associated with an increased risk of developing type 2 diabetes (T2D), while other forms of potatoes – including baked, boiled, and mashed – were not, according to a new study led by Harvard T.H. Chan School of Public Health. The study also found that swapping any form of potato for whole grains may lower the risk of T2D.

The study was published July 30 in the BMJ. [Regrettably, no mention is made of SA’s beloved slap tjips – Ed.]

According to the researchers, while previous studies hinted at a link between potatoes and T2D, the evidence was inconsistent and often lacked detail on cooking methods and the potential effects of substituting other foods for potatoes. “Our study offers deeper, more comprehensive insights by looking at different types of potatoes, tracking diet over decades, and exploring the effects of swapping potatoes for other foods,” said lead author Seyed Mohammad Mousavi, postdoctoral research fellow in the Department of Nutrition. “We’re shifting the conversation from, ‘Are potatoes good or bad?’ to a more nuanced—and useful—question: How are they prepared, and what might we eat instead?”

The researchers examined the diets and diabetes outcomes of 205,107 men and women enrolled in the Nurses’ Health Study, Nurses’ Health Study II, and Health Professionals Follow-up Study. For more than 30 years, participants regularly responded to dietary questionnaires, detailing the frequency with which they consumed certain foods, including French fries; baked, boiled, or mashed potatoes; and whole grains. They also reported on new health diagnoses, including T2D, and various other health, lifestyle, and demographic factors, which the researchers controlled for. Over the course of the study period, 22,299 participants reported that they developed T2D.

The study found that three servings weekly of French fries increased the risk of developing T2D by 20%. Baked, boiled, and mashed potatoes were not significantly associated with T2D risk. The researchers calculated, however, that eating whole grains – such as whole grain pasta, bread, or farro – in place of baked, boiled, or mashed potatoes could reduce the risk of T2D by 4%. Replacing French fries with whole grains could bring T2D risk down by 19%. Even swapping refined grains for French fries was estimated to lower T2D risk.

The researchers complemented their study with a novel meta-analytic approach to estimate how swapping potatoes for whole grains could affect the risk of T2D, using data from previously published cohort studies. This involved two separate meta-analyses: one based on data from 13 cohorts examining potato intake and the other from 11 cohorts on whole grain intake, each encompassing over 500 000 participants and 43 000 T2D diagnoses across four continents. The results were closely consistent with those of the new study.

“The public health message here is simple and powerful: Small changes in our daily diet can have an important impact on risk of type 2 diabetes. Limiting potatoes – especially limiting French fries – and choosing healthy, whole grain sources of carbohydrate could help lower the risk of type 2 diabetes across the population,” said corresponding author Walter Willett, professor of epidemiology and nutrition. “For policymakers, our findings highlight the need to move beyond broad food categories and pay closer attention to how foods are prepared and what they’re replacing. Not all carbs—or even all potatoes—are created equal, and that distinction is crucial when it comes to shaping effective dietary guidelines.”

Source: Harvard T.H. Chan School of Public Health

Eggs are Sunny-side up for Cholesterol Levels

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From poached to panfried, when it comes to eggs, it’s all sunny side up, as new research from the University of South Australia confirms that this breakfast favourite won’t crack your cholesterol.

Long blamed for high cholesterol, eggs have been beaten up for their assumed role in cardiovascular disease (CVD). Now, UniSA researchers have shown definitively that it’s not dietary cholesterol in eggs but the saturated fat in our diets that’s the real heart health concern.

In a world-first study, researchers examined the independent effects of dietary cholesterol and saturated fat on LDL cholesterol (the ‘bad’ kind), finding that eating two eggs a day – as part of a high cholesterol but low saturated fat diet – can actually reduce LDL levels and lower the risk of heart disease.

CVD is the leading cause of death worldwide, responsible for nearly 18 million deaths each year. In Australia, one person dies from CVD every 12 minutes, accounting for one in four of deaths nationwide.

Lead researcher, UniSA’s Professor Jon Buckley, says it’s time to rethink the reputation of eggs.

“Eggs have long been unfairly cracked by outdated dietary advice,” Prof Buckley says.

“They’re unique – high in cholesterol, yes, but low in saturated fat. Yet it’s their cholesterol level that has often caused people to question their place in a healthy diet,” Prof Buckley says.

“In this study, we separated the effects of cholesterol and saturated fat, finding that high dietary cholesterol from eggs, when eaten as part of a low saturated fat diet, does not raise bad cholesterol levels.

“Instead, it was the saturated fat that was the real driver of cholesterol elevation.

“You could say we’ve delivered hard-boiled evidence in defence of the humble egg.”

“So, when it comes to a cooked breakfast, it’s not the eggs you need to worry about – it’s the extra serve of bacon or the side of sausage that’s more likely to impact your heart health.”

Source: University of South Australia

​​​​Artificial Sweetener May Be a Greater Diabetes Risk than Sugar

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An Australian study has found that drinking just one can of artificially sweetened soft drink a day may increase the risk of developing type 2 diabetes by 38 per cent.​​​

​​​​Surprisingly, that risk for artificially sweetened soft drink is even higher than for those who consume sugar-sweetened beverages, such as regular soft drinks, where the risk was found to be 23 per cent higher.​​​

​​​​The research, conducted by a team from Monash University together with RMIT University and the Cancer Council Victoria, followed more than 36 000 Australian adults over nearly 14 years.​​​

​​​​The study – led by Distinguished Professor Barbora de Courten from Monash University and RMIT University, Associate Professor Allison Hodge, from the Cancer Council Victoria, and Monash PhD student Robel Hussen Kabthymer, and published in ​​Diabetes & Metabolism​​ – adds to growing global concern about the health effects of both sugary and artificially sweetened drinks.​​​

​​​​“Drinking one or more of these beverages each day – whether sweetened with sugar or artificial substitutes – was linked to a significantly higher chance of developing type 2 diabetes,” said Mr Hussen Kabthymer.​​​

​​​​Professor de Courten, senior author on the study, said the findings challenge the common assumption that artificially sweetened beverages are a safer choice.​​​

​​​​“Artificial sweeteners are often recommended to people at risk of diabetes as a healthier alternative, but our results suggest they may pose their own health risks,” she said.​​​

​​​​While the link between sugary drinks and diabetes could largely be explained by obesity, the connection between artificially sweetened drinks and type 2 diabetes remained strong even after adjusting for body weight, suggesting a potentially direct effect on metabolism.​​​

​​​​Professor de Courten said the findings have important implications for public health policy.​​​

​​​​“We support measures like sugary drink taxes, but our study shows we also need to pay attention to artificially sweetened options. These are often marketed as better for you; yet may carry their own risks. Future policies should take a broader approach to reducing intake of all non-nutritive beverages.”​​​

​​​​The study analysed data from the long-running Melbourne Collaborative Cohort Study, also known as Health 2020, involving participants aged 40–69 years, and adjusted for diet, exercise, education, and health history.​​​

Source: Monash University

A Nighttime Pistachio Snack May Reshape Gut Microbiome in Prediabetes

Eating pistachios every night for 12 weeks altered gut bacteria, according to new study

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Prediabetes affects a third of people in the United States and most of them will develop Type 2 diabetes, yet effective dietary intervention strategies remain limited. Pistachios have shown promise in improving markers of diet quality, yet little is known about how they influence the gut microbiome – a key player in glucose regulation and inflammation.

A new study led by Kristina Petersen, associate professor of nutritional sciences at Penn State, determined that nighttime pistachio consumption affects gut bacteria in adults with prediabetes. Though the potential therapeutic implications of the findings remain unclear, according to Petersen, they may prove significant for people who are working to improve their metabolic health.

The findings, published in the journal Current Developments in Nutrition, suggested that replacing a traditional carbohydrate-based bedtime snack with pistachios may reshape the gut microbiome. A previous study by these researchers demonstrated that pistachios have a similar effect on blood glucose as 15 to 30 grams of carbohydrates.

“Pistachios seem to be able to meaningfully shift the gut microbial landscape in adults with prediabetes especially when consumed as a nighttime snack.”

Kristina Petersen, associate professor of nutritional sciences at Penn State

“A common dietary recommendation for individuals with prediabetes is to consume a nighttime snack consisting of 15 to 30 grams of carbohydrates to help regulate overnight and morning blood glucose levels,” said Terrence Riley, lead author of this research who earned his doctorate in nutritional sciences at Penn State and currently works as a postdoctoral research fellow at Louisiana State University. “As an example, you could eat one or two slices of whole grain bread.”

Researchers observed that consuming about two ounces of pistachios each night for 12 weeks resulted in significantly different stool microbial community profiles compared to those who consumed the recommended 15 to 30 grams of a carbohydrate snack. Specific bacterial groups, including Roseburia and members of the Lachnospiraceae family – known as “good” bacteria that produces beneficial short-chain fatty acids like butyrate – were more abundant following the pistachio condition.

According to Petersen, butyrate serves as a primary energy source for colon cells, helps maintain the gut barrier and supports anti-inflammatory processes.  

“Pistachios seem to be able to meaningfully shift the gut microbial landscape in adults with prediabetes especially when consumed as a nighttime snack,” Petersen said. “These microbiome changes may offer other long-term health benefits – potentially helping to slow the development of Type 2 diabetes or to reduce systemic inflammation – which we hope to explore in future research.”

The study involved 51 adults with prediabetes and was conducted over two 12-week periods separated by a break, so the effects of the first part of the trial would not affect the second part. By the end of the study, all participants received both treatments. Stool samples were collected and analysed using 16S rRNA gene sequencing, a technique that can help classify bacteria based on their genetic makeup.

Petersen noted that participants who ate pistachios also experienced reductions in several bacterial groups that have been linked to less favorable metabolic outcomes.

“Levels of Blautia hydrogenotrophica – a bacterium that helps produce compounds that can build up in the blood and harm kidney and heart health – were lower after pistachio consumption,” Petersen said. “Levels of Eubacterium flavonifractor, which breaks down beneficial antioxidant compounds from foods like pistachios, also decreased.”

Petersen added that the strength of this study is the design used – a randomised crossover clinical trial, in which all participants receive both treatments in a randomised order. By including all participants in the pistachio group and the standard care group, the study helped the researchers better understand how specific foods like pistachios can influence the gut microbiome.

While the study demonstrated shifts in gut bacteria, it remains unclear whether these changes directly translate to improvements in health – a question that requires further research, Petersen said.

Source: Pennsylvania State University

Consuming Certain Sweeteners May Increase Risk of Early Puberty

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Consuming certain sweeteners commonly found in foods and beverages may increase the risk of early puberty in children, particularly among those who are genetically predisposed, according to a study being presented Sunday at ENDO 2025, the Endocrine Society’s annual meeting in San Francisco, Calif. 

The researchers found that consuming aspartame, sucralose, glycyrrhizin and added sugars was significantly associated with a higher risk of early puberty, especially in children with certain genetic traits. The more of these sweeteners the teens consumed, the higher their risk of central precocious puberty.

“This study is one of the first to connect modern dietary habits – specifically sweetener intake – with both genetic factors and early puberty development in a large, real-world cohort,” said Yang-Ching Chen, MD, PhD, of Taipei Municipal Wan Fang Hospital and Taipei Medical University in Taipei, Taiwan. “It also highlights gender differences in how sweeteners affect boys and girls, adding an important layer to our understanding of individualised health risks.” 

A type of early puberty known as central precocious puberty is increasingly common. It can lead to emotional distress, shorter adult height, and increased risk of future metabolic and reproductive disorders.

Chen’s previous research found that certain sweeteners can directly influence hormones and gut bacteria linked to early puberty. For example, one artificial sweetener, acesulfame potassium or AceK, was shown to trigger the release of puberty-related hormones by activating “sweet taste” pathways in brain cells and increasing stress-related molecules. Another sweetener, glycyrrhizin (found in liquorice) was found to change the balance of gut bacteria and reduce the activity of genes involved in triggering puberty. 

“This suggests that what children eat and drink, especially products with sweeteners, may have a surprising and powerful impact on their development,” Chen said.

The new findings come from the Taiwan Pubertal Longitudinal Study (TPLS), begun in 2018. The study included data from 1407 teens. Central precocious puberty was diagnosed in 481 teens. The researchers assessed teens’ sweetener intake through validated questionnaires and testing of urine samples. Genetic predisposition was quantified using polygenic risk scores derived from 19 genes related to central precocious puberty. Early puberty was diagnosed based on medical exams, hormone levels and scans. 

Sucralose consumption was linked to a higher risk of central precocious puberty in boys and consumption of glycyrrhizin, sucralose and added sugars was associated with a higher risk of central precocious puberty in girls.

“The findings are directly relevant to families, paediatricians and public health authorities,” Chen said. “They suggest that screening for genetic risk and moderating sweetener intake could help prevent early puberty and its long-term health consequences. This could lead to new dietary guidelines or risk assessment tools for children, supporting healthier development.”

Source: The Endocrine Society

Beetroot Juice Lowers Blood Pressure in Older People by Changing Oral Microbiome

Pic by Jim Wileman – University of Exeter images

The blood pressure lowering effect of nitrate-rich beetroot juice in older people may be due to specific changes in their oral microbiome, according to the largest study of its kind.

Researchers at the University of Exeter conducted the study, published in the journal Free Radical Biology and Medicine, comparing responses between a group of older adults to that of younger adults. Previous research has shown that a high nitrate diet can reduce blood pressure, which can help reduce risk of heart disease.

Nitrate is crucial to the body and is consumed as a natural part of a vegetable-rich diet.  When the older adults drank a concentrated beetroot juice ‘shot’ twice a day for two weeks*, their blood pressure decreased – an effect not seen in the younger group.

The new study, funded by a BBSRC Industrial Partnership Award, provides evidence that this outcome was likely caused by the suppression of potentially harmful bacteria in the mouth.  An imbalance between beneficial and harmful oral bacteria can decrease the conversion of nitrate (abundant in vegetable-rich diets) to nitric oxide. Nitric oxide is key to healthy functioning of the blood vessels, and therefore the regulation of blood pressure.

Study author Professor Anni Vanhatalo, of the University of Exeter, said: “We know that a nitrate-rich diet has health benefits, and older people produce less of their own nitric oxide as they age. They also tend to have higher blood pressure, which can be linked to cardiovascular complications like heart attack and stroke. Encouraging older adults to consume more nitrate-rich vegetables could have significant long term health benefits. The good news is that if you don’t like beetroot, there are many nitrate-rich alternatives like spinach, rocket, fennel, celery and kale.”

The study recruited 39 adults aged under 30, and 36 adults in their 60s and 70s through the NIHR Exeter Clinical Research Facility. The trial was supported by the Exeter Clinical Trials Unit. Each group spent two weeks taking regular doses of nitrate-rich beetroot juice and two weeks on a placebo version of the juice with nitrate stripped out. Each condition had a two week “wash out” period in between to reset. The team then used a bacterial gene sequencing method to analyse which bacteria were present in the mouth before and after each condition.

In both groups, the make-up of the oral microbiome changed significantly after drinking the nitrate-rich beetroot juice, but these changes differed between the younger and older age groups.

The older age group experienced a notable decrease in the mouth bacteria Prevotella after drinking the nitrate rich juice, and an increase in the growth of bacteria known to benefit health such as Neisseria. The older group had higher average blood pressure at the start of the study, which fell after taking the nitrate-rich beetroot juice, but not after taking the placebo supplement.

Co-author Professor Andy Jones, of the University of Exeter, said: “This study shows that nitrate-rich foods alter the oral microbiome in a way that could result in less inflammation, as well as a lowering of blood pressure in older people. This paves the way for larger studies to explore the influence of lifestyle factors and biological sex in how people respond to dietary nitrate supplementation.”

Dr Lee Beniston FRSB, Associate Director for Industry Partnerships and Collaborative Research and Development at BBSRC, said: “This research is a great example of how bioscience can help us better understand the complex links between diet, the microbiome and healthy ageing. By uncovering how dietary nitrate affects oral bacteria and blood pressure in older adults, the study opens up new opportunities for improving vascular health through nutrition. BBSRC is proud to have supported this innovative partnership between academic researchers and industry to advance knowledge with real-world benefits.”

Source: University of Exeter

Intermittent Energy Restriction May Improve Outcomes in People with Obesity and Type 2 Diabetes

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Intermittent energy restriction, time-restricted eating and continuous energy restriction can all improve blood sugar levels and body weight in people with obesity and type 2 diabetes, according to a study being presented Sunday at ENDO 2025, the Endocrine Society’s annual meeting in San Francisco, Calif.

“This study is the first to compare the effects of three different dietary interventions intermittent energy restriction (IER), time-restricted eating (TRE) and continuous energy restriction (CER) in managing type 2 diabetes with obesity,” said Haohao Zhang, PhD, chief physician at The First Affiliated Hospital of Zhengzhou University in Zhengzhou, China.

Although researchers identified improved HbA1c levels, and adverse events were similar across the three groups, the IER group showed greater advantages in reducing fasting blood glucose, improving insulin sensitivity, lowering triglycerides, and strengthening adherence to the dietary interventions.

“The research fills a gap in directly comparing 5:2 intermittent energy restriction with a 10-hour time-restricted eating in patients with obesity and type 2 diabetes. The findings provide scientific evidence for clinicians to choose appropriate dietary strategies when treating such patients,” Zhang says.

Zhang and colleagues performed a single-centre, randomised, parallel-controlled trial at the First Affiliated Hospital of Zhengzhou University from November 19, 2021 to November 7, 2024.

Ninety patients were randomly assigned in a 1:1:1 ratio to the IER, TRE or CER group, with consistent weekly caloric intake across all groups. A team of nutritionists supervised the 16-week intervention.

Of those enrolled, 63 completed the study. There were 18 females and 45 males, with an average age of 36.8 years, a mean diabetes duration of 1.5 years, a baseline BMI of 31.7kg/m², and an HbA1c of 7.42%.

At the end of the study, there were no significant differences in HbA1c reduction and weight loss between the IER, TRE and CER groups. However, the absolute decrease in HbA1c and body weight was greatest in the IER group.

Compared to TRE and CER, IER significantly reduced fasting blood glucose and triglycerides and increased the Matsuda index, a measure of whole-body insulin sensitivity. Uric acid and liver enzyme levels exhibited no statistically significant changes from baseline in any study group.

Two patients in the IER group and the TRE group, and three patients in the CER group, experienced mild hypoglycemia.

The IER group had the highest adherence rate (85%), followed by the CER group at 84% and the TRE group at 78%. Both the IER and CER groups showed statistically significant differences compared with the TRE group.

Zhang said these findings highlight the feasibility and effectiveness of dietary interventions for people who have obesity and type 2 diabetes.

Source: The Endocrine Society

Common Sugar Substitute Shown to Impair Brain Cells, Boost Stroke Risk

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New University of Colorado Boulder research shows the popular sugar substitute erythritol comes with serious downsides, impacting brain cells in numerous ways that can boost the risk of stroke. The study was published in the Journal of Applied Physiology.

“Our study adds to the evidence suggesting that non-nutritive sweeteners that have generally been purported to be safe, may not come without negative health consequences,” said senior author Christopher DeSouza, professor of integrative physiology and director of the Integrative Vascular Biology Lab.

First approved by the Food and Drug Administration in 2001, erythritol is a sugar alcohol, often produced by fermenting corn, and found in hundreds of products made by various brands. It has almost no calories, is about 80% as sweet as table sugar, and has a negligible impact on insulin levels, making it a favourite for people trying to lose weight, keep their blood sugar in check or avoid carbohydrates.

But recent research has begun to shed light on its risks.

One recent Cleveland Clinic study involving 4000 people in the US and Europe found that men and women with higher circulating levels of erythritol were significantly more likely to have a heart attack or stroke within the next three years.

DeSouza and first author Auburn Berry, a graduate student in his lab, set out to understand what might be driving that increased risk.

To test impacts of erythritol on cells, researchers in the lab treated human cerebral microvascular endothelial cells (hCMECs)  for three hours with about the same amount of erythritol contained in a typical sugar-free beverage.

They observed that the treated cCMEVs were altered in numerous ways: 

They expressed significantly less nitric oxide, a molecule that relaxes and widens blood vessels, and more endothelin-1, a protein that constricts blood vessels. Meanwhile, when challenged with thrombin, cellular production of the natural clot-busting compound t-PA was “markedly blunted.” The erythritol-treated cells also produced more reactive oxygen species (ROS), aka “free radicals,” metabolic byproducts which can age and damage cells and inflame tissue.

Thrombophilia. Credit: Scientific Animations CC4.0.

Previous research has shown that as little as 30g of erythritol (about as much as you’d find in 600mL of sugar-free ice cream) can also cause platelets to clump together, potentially forming clots.

“Big picture, if your vessels are more constricted and your ability to break down blood clots is lowered, your risk of stroke goes up,” said Berry. “Our research demonstrates not only that, but how erythritol has the potential to increase stroke risk.”

DeSouza notes that their study used only a serving-size worth of the sugar substitute.
For those who consume multiple servings per day, the impact, presumably, could be worse.

The authors caution that their study was a laboratory study, conducted on cells, and larger studies in people are now needed.

That said, De Souza encourages consumers to read labels, looking for erythritol or “sugar alcohol” on the label.

“Given the epidemiological study that inspired our work, and now our cellular findings, we believe it would be prudent for people to monitor their consumption of non-nutrient-sweeteners such as this one,” he said.

Source: University of Colorado Boulder

Food Insecurity is Associated with Symptoms of Anxiety and Depression

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Changes in food insecurity go hand in hand with symptoms of anxiety and depression, according to research published in the open access journal PLOS Mental Health. Melissa Bateson of Newcastle University, UK, and colleagues at École Normale Supérieure, Northumbria University and York University, collected monthly data from adults in the UK and France and found that changes in food insecurity one month went hand-in-hand with changes in symptoms of anxiety and depression the next. The authors propose that interventions to reduce food insecurity might have immediate positive impacts on mental health.

Social determinants play a role in the development of poor mental health, and food insecurity has been associated with increased anxiety and depression, though it has been unclear whether this effect is causal and the timescale over which it occurs. The authors collected monthly data between September 2022 and August 2023 from almost 500  adults in the UK and France. They assessed food insecurity for the previous week and measured anxiety and depression with two commonly used questionnaires — GAD-7 and PHQ-8.

The team found a surprisingly high prevalence of food insecurity, with 39.5% of participants experiencing it in at least one month of the study. For those individuals, fluctuations between food insecurity and security were associated with changes in anxiety and depression, with deteriorations in mental health occurring when they experienced food insecurity and improvements when food security improved. The authors were able to predict mental health variations based on food security changes during the previous month. Such rapid changes in mental health suggest that the effects could be related to food security rather than longer-term nutritional changes which would take longer to manifest in mood alterations.

The authors state their results support the hypothesis that food insecurity could rapidly cause symptoms of anxiety and depression, such that interventions to prevent food insecurity might be likely to  quickly and effectively reduce prevalence of anxiety and depression symptoms in populations currently experiencing periodic food insecurity.  

The authors note: “What really impressed us was how rapidly symptoms of anxiety and depression responded to changes in participants’ food insecurity status and the large size of the effects”.

They add: “Our results suggest that eliminating periodic food insecurity in those currently experiencing it could reduce the number of people with clinically concerning symptoms of anxiety and depression by 20 percentage points.”

Provided by PLOS

Plant-based Diets Must Also Be Healthy to Reduce IBD Risk

Irritable bowel syndrome. Credit: Scientific Animations CC4.0

A large prospective study published in Molecular Nutrition and Food Research reveals that a healthy plant-based diet is linked with a reduced risk of inflammatory bowel disease (IBD).

For the study, 143 434 individuals in the UK reported on their dietary intake. During an average follow-up of 14.5 years, 1117 participants developed inflammatory bowel disease – 795 cases of ulcerative colitis and 322 cases of Crohn’s disease.

A healthy plant-based diet was associated with an 8% lower risk of ulcerative colitis, and a 14% lower risk of Crohn’s disease. An unhealthy plant-based diet was associated with a 15% higher risk of Crohn’s disease, with results suggesting that this was in part due to higher intake of vegetable oils and animal fats. Fruits and vegetables were identified as protective factors against inflammatory bowel disease.

Blood analyses suggested that the benefits seen in this study might be explained by the anti-inflammatory properties of plant-based foods.

“Our research indicates that a healthy plant-based diet may protect against inflammatory bowel disease, with its anti-inflammatory properties playing a key role,” said corresponding author Zhe Shen, MD, of the Zhejiang University School of Medicine, in China.

Source: Wiley