Diet

Posted on Diabetes, Diet

Limit added sugar to six teaspoons a day to improve health, urge experts

Experts recommend reducing added (“free”) sugar consumption to around six teaspoons a day and limiting sugar-sweetened drinks to less than one serving a week after a comprehensive evidence review published by The BMJ today.  

They found significant harmful associations between sugar consumption and 45 outcomes, including asthma, diabetes, obesity, heart disease, depression, some cancers and death. 

It’s widely known that excessive sugar intake can have negative effects on health, and this has prompted the World Health Organization (WHO) and others to suggest reducing the consumption of free or added sugars to less than 10% of total daily energy intake.

But before developing detailed policies for sugar restriction, the quality of existing evidence needs to be comprehensively evaluated. 

Researchers based in China and the US therefore carried out an umbrella review to assess the quality of evidence, potential biases, and validity of all available studies on dietary sugar consumption and health outcomes.

Umbrella reviews synthesise previous meta-analyses and provide a high-level summary of research on a particular topic.

The review included 73 meta-analyses (67 of observational studies and six of randomised controlled trials) from 8,601 articles covering 83 health outcomes in adults and children.

The researchers assessed the methodological quality of the included articles and graded the evidence for each outcome as high, moderate, low, or very low quality to draw conclusions.

Significant harmful associations were found between dietary sugar consumption and 18 endocrine or metabolic outcomes including diabetes, gout and obesity; 10 cardiovascular outcomes including high blood pressure, heart attack and stroke; seven cancer outcomes including breast, prostate and pancreatic cancer; and 10 other outcomes including asthma, tooth decay, depression and death.

Moderate quality evidence suggested that sugar sweetened beverage consumption was significantly associated with increased body weight for highest versus lowest consumption, while any versus no added sugar consumption was associated with increased liver and muscle fat accumulation.

Low quality evidence indicated that each one serving per week increment of sugar sweetened beverage consumption was associated with a 4% higher risk of gout, and each 250 mL/day increment of sugar sweetened beverage consumption was associated with a 17% and 4% higher risk of coronary heart disease and death, respectively.

Low quality evidence also suggested that every 25 g/day increment of fructose intake was associated with a 22% increased risk of pancreatic cancer. 

In general, no reliable evidence showed beneficial associations between dietary sugar consumption and any health outcomes, apart from glioma brain tumours, total cholesterol, type 2 diabetes and cardiovascular disease mortality. However, the researchers say these favourable associations are not supported by strong evidence, and these results should be interpreted with caution. 

The researchers acknowledge that existing evidence is mostly observational and of low quality, and stress that evidence for an association between dietary sugar consumption and cancer remains limited but warrants further research. 

Nevertheless, they say these findings, combined with WHO, World Cancer Research Fund and American Institute for Cancer Research guidance, suggest reducing the consumption of free sugars or added sugars to below 25 g/day (approximately six teaspoons a day) and limiting the consumption of sugar sweetened beverages to less than one serving a week (approximately 200-355 mL/week).

To change sugar consumption patterns, especially for children and adolescents, a combination of widespread public health education and policies worldwide is also urgently needed, they add.

Posted on Diet

Mediterranean and low-fat diet programmes lower the risk of death and heart attack in patients at risk of cardiovascular disease

Seven dietary programmes compared; Mediterranean programmes also likely to reduce stroke risk, say, researchers

Mediterranean and low-fat dietary programmes reduce the likelihood of death and heart attack in patients at heightened risk of cardiovascular disease, finds the first comparative review based on randomised trials of seven popular dietary programmes published by The BMJ .

Dietary programmes are diets with or without exercise and other health behaviour (e.g. smoking cessation) support.

Mediterranean dietary programmes are also likely to reduce stroke risk. Still, other dietary programmes showed little or no benefit over minimal intervention (eg. usual diet or brief dietary advice from a health professional).

Current guidelines recommend various dietary programmes for patients at increased cardiovascular risk, but they have typically relied on low-certainty evidence from non-randomised studies.

Several analyses of randomised controlled trials have suggested that some diets and dietary programmes can reduce major cardiovascular events, such as heart attacks (myocardial infarction) and strokes, but any beneficial impact on death is still uncertain.

To address this, researchers trawled databases for randomised trials looking at dietary programmes’ impact on preventing death and major cardiovascular events in patients at increased risk of cardiovascular disease.

Forty eligible trials were identified involving 35,548 participants who were followed for an average of three years across seven named dietary programmes (low fat, 18 trials; Mediterranean, 12; very low fat, 6; modified fat, 4; combined low fat and low sodium, 3; Ornish, 3; Pritikin, 1). Some trials compared two different diets (eg. mediterranean vs low fat).

The researchers assessed the methodological quality of each trial and judged 13 to be at low overall risk of bias and 27 at high risk.

Based on moderate certainty evidence, Mediterranean dietary programmes were better than minimal intervention at preventing all cause mortality (17 fewer deaths per 1000 over five years), non-fatal heart attack (17 fewer per 1000) and stroke (7 fewer per 1000) for patients at intermediate risk of cardiovascular disease.

Low fat programmes were also superior to minimal intervention with moderate certainty for prevention of all cause mortality (9 fewer deaths per 1000) and non-fatal heart attack (7 fewer per 1000).

When compared with one another, there were no convincing differences between Mediterranean and low fat programmes for mortality or non-fatal heart attack.

The absolute effects for both dietary programmes were more pronounced for patients at high risk of cardiovascular disease (36 fewer all-cause deaths per 1000 and 39 fewer cardiovascular deaths per 1000 among those that followed the Mediterranean dietary programme over 5 years).

The five other dietary programmes generally had little or no benefit compared with minimal intervention typically based on low to moderate certainty evidence.

The researchers acknowledge several limitations, such as being unable to measure adherence to dietary programmes and the possibility that some of the benefits may have been due to other elements within the programmes like drug treatment and support to stop smoking.

Nevertheless, this was a comprehensive review based on a thorough literature search, rigorous assessment of study bias, and adherence to recognised GRADE methods to assess the certainty of estimates.

As such, they conclude that Mediterranean and low fat dietary programmes “probably reduce the risk of mortality and non-fatal myocardial infarction in people at increased cardiovascular risk.”

Mediterranean dietary programmes are also likely to reduce the risk of stroke, while other named dietary programmes were generally not superior to minimal intervention, they add.

Posted on Diet

Mediterranean diet associated with decreased risk of dementia

Health: Mediterranean diet associated with decreased risk of dementia
Health: Mediterranean diet associated with decreased risk of dementia


Consumption of a traditional Mediterranean-type diet – rich in foods such as seafood, fruit, and nuts – is associated with a reduced risk of dementia, reports a study published in BMC Medicine. Individuals with a higher adherence to a Mediterranean diet had up to 23% lower risk for dementia compared with those who had lower adherence to a Mediterranean diet.

Diet may be an important modifiable risk factor for dementia that could be targeted for disease prevention and risk reduction but previous studies exploring the impact of a Mediterranean diet have typically been limited to small sample sizes and low numbers of dementia cases. Oliver Shannon and colleagues analysed data from 60,298 individuals from the UK Biobank who had completed a dietary assessment. The authors scored individuals using two measures for adherence to the Mediterranean diet. During the mean follow-up of 9.1 years there were 882 cases of dementia. The authors also considered each individual’s genetic risk for dementia by estimating their polygenic risk, a measure of all the different genes that are related to risk of dementia.

The authors found that participants with the highest adherence to the Mediterranean diet had a 23% lower risk of developing dementia in comparison with those with the lowest adherence score, equivalent to an absolute risk reduction of 0.55%. There was no significant interaction between the polygenic risk for dementia and adherence to a Mediterranean diet, which the authors suggest may indicate that the association of greater adherence to a Mediterranean diet and a reduced dementia risk remains, irrespective of the individual genetic risk for dementia. This finding was not consistent across all the sensitivity analyses and the authors propose further research is needed to assess the interaction between diet and genetics on dementia risk.

The authors caution that their analysis is limited to individuals who self-reported their ethnic background as white, British or Irish, as genetic data was only available based on European ancestry, and that further research is needed in a range of populations to determine the potential benefit. They conclude that, based on their data, a Mediterranean diet that has a high intake of healthy plant-based foods may be an important intervention to incorporate into future strategies to reduce dementia risk.

Posted on Diet

Evidence for the health benefits of consuming more live microbes

New study shows lower weight and better overall health in those who consume more live microorganisms daily
New study shows lower weight and better overall health in those who consume more live microorganisms daily

Safe live microorganisms are found in a variety of foods we eat every day, from yogurt and other fermented foods, to raw fruits and vegetables. Despite the widespread idea that these mixtures of live microbes contribute to health, convincing evidence linking live dietary microbes to health benefits has been lacking.

A new study provides some of the first real-world evidence that higher consumption of live microbes may promote health. A group of scientists led by the International Scientific Association for Probiotics and Prebiotics (ISAPP) classified over 9,000 individual foods listed in the US National Health and Nutrition Examination Survey (NHANES) into three categories based on their abundance of live microbes, and then used NHANES participants’ reported food intake to quantify the food they ate that contained medium or high levels of microbes. Then they determined how these intakes correlated with various markers of health such as blood pressure and weight.

The scientists found that increased consumption of live microbes in the diet was linked with multiple measurements of better health: more favorable blood pressure, better blood glucose and insulin, lower inflammation, as well as lower waist circumference and body mass index. This established that those who consumed higher quantities of live dietary microbes showed tangible, if modest, health benefits.

While the scientific approach did not allow researchers to conclude that the live dietary microorganisms directly caused the health benefits, the results are consistent with plausible arguments that dietary exposure to live microorganisms in general could benefit health by increasing the diversity of microbes in the gut or by supporting immune function. In the past century, a reduction in the amount of fermented foods in the diet and increased consumption of processed foods has led to a dramatic reduction in the number of microbes most people consume on a daily basis. This trend may be reversing, however, since the dietary data used in the study showed that US adults have gradually increased their live microbe consumption over the 18-year study period. This may bode well for the health of the population.

This study built on two previous published papers, here and here, which conducted the preliminary work necessary to make this assessment of live dietary microbes and health.

”Although the dose-response associations we found were relatively modest, it was notable that these estimated benefits applied to several plausible and important health outcomes and were robust to adjustment for available confounders, including body mass index,” says co-lead author Prof. Dan Tancredi, PhD, of University of California – Davis. “More research that extends these findings to other populations and research that uses study designs that permit stronger causal claims is needed, especially given the potential benefits that might be available by simply substituting into the diet more foods that have safe live microbes.”

ISAPP Executive Science Officer Mary Ellen Sanders, PhD, points out the research focused not just on probiotics, but on all microbes in foods, including environmental microbes associated with raw fruits and vegetables as well as lactic acid bacteria associated with fermented foods. Thus, the study differs from probiotic research, which focuses on microbes defined to the strain level, specific dose and proven health benefits.

Co-first author Prof. Colin Hill, PhD, of University College Cork, Ireland, says it’s possible that dietary advice of the future could include a recommendation for the daily consumption of high levels of live dietary microbes. “Those foods with high levels of microbes (fermented foods, raw vegetables and fruits) are all nutritionally valuable parts of a healthy and diverse diet,” he says. “Secondly, these same foods could be providing an additional, hitherto unrecognised, health benefit due to live microbes themselves that enter the gut and interact with the host microbiome, immune system and even the enteric nervous system”.

Posted on Diet, Weight Loss

A ‘Keto-like’ diet may be linked to a higher risk of heart disease and cardiac events.

Popular weight-loss diet also associated with higher levels of LDL cholesterol
Popular weight-loss diet also associated with higher levels of LDL cholesterol


The ketogenic or “keto” diet, which involves consuming very low amounts of carbohydrates and high amounts of fats, has been gaining popularity. However, a new study presented at the American College of Cardiology’s Annual Scientific Session Together With the World Congress of Cardiology suggests that a “keto-like” diet may be associated with higher blood levels of “bad” cholesterol and a twofold heightened risk of cardiovascular events such as chest pain (angina), blocked arteries requiring stenting, heart attacks and strokes.

“Our study found that regular consumption of a self-reported diet low in carbohydrates and high in fat was associated with increased levels of LDL cholesterol— or “bad” cholesterol—and a higher risk of heart disease,” said Iulia Iatan, MD, PhD, attending physician-scientist at the Healthy Heart Program Prevention Clinic, St. Paul’s Hospital and University of British Columbia’s Centre for Heart Lung Innovation in Vancouver, Canada, and lead author of the study. “To our knowledge, our study is one of the first to examine the association between this type of dietary pattern and cardiovascular outcomes.”

Carbohydrates are the body’s first “go-to” source for fuel to provide energy for daily life. Low-carbohydrate, high-fat (LCHF) diets, like a keto diet, restrict consumption of carbohydrates (e.g., bread, pasta, rice and other grains, baked goods, potato products such as fries and chips, and high-carbohydrate fruits and vegetables). By depriving the body of carbohydrates, it is forced to start breaking down fat for energy instead. The breakdown of fat in the liver produces ketones, chemicals that the body uses as energy in the absence of carbohydrates—hence the name ketogenic, or “ketone producing.” Proponents of a ketogenic diet generally suggest limiting carbohydrates to 10% of total daily calories, protein to 20% to 30% and obtaining 60% to 80% of daily calories from fat.

Some previous studies have shown that an LCHF diet can lead to elevated levels of LDL cholesterol in some people. While elevated LDL cholesterol is a known risk factor for heart disease (caused by atherosclerosis, a buildup of cholesterol in the coronary arteries), the effects of an LCHF diet on risk for heart disease and stroke have not been well studied, Iatan said.  

For this study, Iatan and her colleagues defined an LCHF diet as consisting of no more than 25% of total daily energy or calories from carbohydrates and more than 45% of total daily calories from fat. They dubbed this an LCHF diet and “keto-like” because it is somewhat higher in carbohydrates and lower in fat than a strict ketogenic diet. They defined a “standard diet” as individuals not meeting these criteria and having more balanced eating habits.

The research team analyzed data from the UK Biobank, a large-scale prospective database with health information from over half a million people living in the United Kingdom who were followed for at least 10 years. Upon enrollment in the biobank, 70,684 participants completed a one-time self-reported 24-hour diet questionnaire and, at the same time, had blood drawn to check their levels of cholesterol. The researchers identified 305 participants whose questionnaire responses indicated that their diet during the 24-hour reporting period met the study’s definition of an LCHF. These participants were matched by age and sex with 1,220 individuals who reported eating a standard diet. This resulted in 73% of the participants in each group being women and the group’s average age was 54 years. Those on an LCHF diet had an average body mass index (BMI) of 27.7; those on a standard diet, 26.7. A BMI of 25 to 30 falls within the overweight range.

Compared with participants on a standard diet, those on an LCHF diet had significantly higher levels of both LDL cholesterol and apolipoprotein B (apoB), the protein component that sits on LDL and other atherogenic lipoprotein particles. Previous studies have shown that elevated apoB may be a better predictor than elevated LDL cholesterol for risk of cardiovascular disease, Iatan said. After an average of 11.8 years of follow-up—and after adjustment for other risk factors for heart disease, such as diabetes, high blood pressure, obesity and smoking—people on an LCHF diet had more than two-times higher risk of having several major cardiovascular events, such as blockages in the arteries that needed to be opened with stenting procedures, heart attack, stroke and peripheral arterial disease. In all, 9.8% of participants on an LCHF diet experienced a new cardiac event, compared with 4.3% of those on a standard diet, a doubling of risk for those on an LCHF diet.

“Among the participants on an LCHF diet, we found that those with the highest levels of LDL cholesterol were at the highest risk for a cardiovascular event,” Iatan said. “Our findings suggest that people who are considering going on an LCHF diet should be aware that doing so could lead to an increase in their levels of LDL cholesterol. Before starting this dietary pattern, they should consult a health care provider. While on the diet, it is recommended they have their cholesterol levels monitored and should try to address other risk factors for heart disease or stroke, such as diabetes, high blood pressure, physical inactivity and smoking.”

The study’s findings also suggest that not everyone responds to an LCHF diet in the same way.

“On average, cholesterol levels tend to rise on this diet, but some people’s cholesterol concentrations can stay the same or go down, depending on several underlying factors,” Iatan said. “There are inter-individual differences in how people respond to this dietary pattern that we don’t fully understand yet. One of our next steps will be to try to identify specific characteristics or genetic markers that can predict how someone will respond to this type of diet.”   

A limitation of the study is that participants provided dietary information at only one point in time, which should be considered when interpreting the study findings, Iatan said. Moreover, self-reports of food consumption can be inaccurate, though Iatan said this questionnaire has been extensively validated.    

Because the study was observational, it can only show an association between the diet and an increased risk for major cardiac events, not a causal relationship. However, Iatan said the findings merit further research in prospectively designed studies, especially when approximately 1 in 5 Americans report being on a low-carb, keto-like or full keto diet.