The risks of dietary risk studies

Two recent correspondence articles published in The Lancet have highlighted some of the challenges in global dietary intake and risk estimation studies. These studies are held in high regard and widely used, so their quality is of great importance.


The first article highlights the differing estimates of two global dietary intake studies: the Global Dietary Database and the Global Burden of Disease (GBD) study 2017. Both report country-level intakes of food groups among adult populations, but are calculated quite differently: the former largely from aggregated dietary survey data, and the latter largely from national level food availability data.


The outcomes of the two approaches showed wide variation in many countries: more than 10-fold differences in several countries across multiple food groups. Among these were consumption of sugar-sweetened beverages, an important target for reduction. Inaccurate estimation of consumption can lead to inaccurate or disproportionate estimates on public health.


The second article also considers the GBD study, but compares the dietary disease burden estimated in the 2017 study with the recently published 2019 GBD study.
The burden on human health of diets low in fruit, nuts and seeds, vegetables, and specific fatty acids had more than halved. Meanwhile, diets high in red meat moved from the 15th largest contributor to diet related disease burden, to 5th, with 36 times higher deaths attributed to these diets than were found in the 2017 study.


The cause of these changes was altered methods in calculating disease burden. The latest study assumed relationships between high red meat diets and heart disease, breast cancer, stroke, diabetes, and colon cancer, whereas the earlier study only included the last two conditions. It also set zero intake as the optimum for minimising health risk, while the previous study used a moderate intake value. These health associations are contended in the scientific literature, as described fully by the authors . A response has since been published, explaining that the upcoming 2020 study will wind back its estimates on meat following further changes to methodology.


The importance of these global studies of dietary intake and associated health outcomes cannot be questioned: there is an urgent need for this data to inform public health decision making. However, these studies are often among the most widely cited and reused in public health policy, thus their conclusions have far-reaching consequences.
The authors of these articles emphasise the importance of having multiple models to identify areas of uncertainty. The results also highlight the weaknesses of relying solely on food availability data, rather than consumption. The articles feature calls for stronger dietary data in low- and middle-income countries; standardisation of food group classifications and disease burden estimation; and caution when interpreting the reliability of such estimates.

Comparing the environmental cost of foods: Nutritional LCAs

The environmental impact of a food, be that carbon footprint, water use, land use or some other factor, can be estimated by life cycle analysis (LCA). With the environmental impact of food an increasingly important consideration for many consumers, industry and policymakers, the FAO have recently published a report on the challenges and opportunities of nutritional LCAs – those that attempt to capture the nutritional value of food alongside its environmental impact.

LCAs are strongest when used to identify hotspots or areas for improvement within the supply chain for a single item. They can be used to answer industry questions like: where should we act first to lower the footprint of our product? They can also be used in comparisons between two otherwise identical products for consumers: which one should I buy? However, challenges arise when LCAs are used to compare the impacts of very different products.

Take Energy Rating labels on electrical appliances as an example. Analogous to LCAs, these are an indication of the relative energy usage of a particular model compared with other appliances of the same type. These are useful for comparing two refrigerators, but do not really help when comparing refrigerators with freezers. They are even less useful when comparing a refrigerator with a washing machine: the appliances have completely different functions, and a purchaser would be unlikely to use them to choose which of the two to take home.

Even within the category of refrigerators, ratings become less relevant when comparing different size models, as they provide a different level of service. Without considering the service or benefit provided by the product we do not have a fair basis on which to compare the footprint or cost of providing that service.

The same problem exists when comparing foods. When we look at the footprint of food products and start making comparisons, we need to be clear on the service or benefit being provided by the products to ensure we are making a valid comparison. However, the service provided by a food item depends on the purpose for which it is consumed.

Food is consumed for a variety of reasons: as a source of nutrition, for sensory experience or pleasure, or for social and cultural purposes. Accounting for these different purposes is not straightforward. For example, from a nutritional perspective, alcoholic beverages provide very little benefit, but many consumers may still place high value on their sensory or social purposes.

The FAO report focuses on nutrition, rather than the other services provided by food, and looks at how nutritional information can be combined with environmental impact data.

One approach is to try and bring together the “benefit” and “cost” into a single analysis: the development of a nutritional LCA (nLCA), a life cycle analysis that includes nutrition.

There are two different methods by which this can be done:

  • As part of the definition of the functional unit (e.g., land use per 100 kcal)
  • As part of the human impact assessment, what is often thought of as the cost side of the analysis (e.g., likely impact on human health)

Neither of these approaches is easy.

Shifting functional units

Often, an LCA uses mass as the functional unit. For example, if considering the water use needed to grow rice, an LCA might report results as “litres of water used per kg of rice”. In this case, the functional unit is “1 kg of rice”.

Putting nutrition into the functional unit moves away from just using mass. In the simplest form, this may be evaluating a set of foods based on the amount of a particular nutrient they contain. Protein is often used for this purpose. Our rice example would then change to “litres of water used per kg protein in rice”.

However, protein is not a single nutrient needed by the body, but rather a collection of amino acids, which are the essential nutrients. Not all proteins are created equal, having both different concentrations of these amino acids and varying in their digestibility. Rice protein is therefore different to soy protein, for example. Thus, comparing water use per kg protein does not capture this information. Sophisticated methods that include protein quality exist, but are challenging and rarely used.

Most food items provide more than one nutrient, and we need a broad range of nutrients to remain healthy. The DELTA Model® estimates the ability of the global food system to supply a basket of 29 nutrients, and would include more given suitable data. Evaluating a food item based on only one target nutrient misses this complexity.

An alternative to selection of a single nutrient as the functional unit is to use a basket of nutrients to create some form of nutrient reference score. The intention of this score would be to provide a more “balanced” view of the nutrition provided by foods. However, what nutrients should make up this score? Do they all have equal weighting? Or are some more important than others? And how does this relate to the needs of an individual? The scientific literature contains many different suggestions, each with their strengths and weaknesses. Each is at risk of introducing some form of bias into the assessment.

Another important consideration is portion size. Once we move away from a functional unit based on mass, we lose some of the context around the amount of food that needs to be consumed to deliver a particular nutrient or group of nutrients, and how that relates to the size of a normal serving. Functional units “per serving” have also been explored, but face the same problems as mass based units.

Bringing human health into the assessment

The alternative approach is to leave the functional unit as the mass of the food item and build the nutritional assessment into the impact side of the LCA. This requires having data on the expected impact of consuming a food for human nutrition or health. The main approach that has been considered to date uses epidemiological data on diets, health, and mortality. This is usually of the kind captured in the Global Burden of Disease (GBD) study, which calculates statistical links between consumption of food groups and expected lifespan or quality of life.

Unfortunately, this data is limited to comparatively coarse effects. The GBD study reports statistical measures for 15 health aspects related to diet and 3 related to nutrient deficiency. The statistical associations are the result of a complex analysis that attempts to isolate the impact of individual food factors on overall outcomes. Changes in assumptions used in the analysis between the 2017 and 2019 data sets resulted in significant changes in the apparent impact of several food groups. These have been highlighted in a recent letter to The Lancet, and would have a major effect on any nLCA employing this data.

In general, the benefits of consumption of food or nutrients follow a curve. Initially there is a positive impact on health, with increasing consumption providing nutrients essential to bodily functions and growth. This benefit is reduced once daily requirements are met, and, if consumption continues to increase, may eventually have negative health outcomes.

This is illustrated with the energy content of diets: eating insufficient calories leads to wasting, but eating too many leads to obesity and a range of related health conditions, and just how much is too few or too many depends upon the need of the individual. Sodium is another example: a diet deficient in sodium can have serious health consequences. However, many diets contain a considerable excess of sodium, carrying health risks for many individuals.

Putting food and nutrients in context

Food items are consumed as part of meals and diets, and it is at this level that we need to apply considerations of nutritional sufficiency. The relative nutritional benefit of consuming a food item varies based on the dietary context of the individual. For example, the protein or amino acid content of a food item may be of limited value in a diet that is otherwise oversupplied with this nutrient, but of immense value in a diet that is deficient.

Within the DELTA Model we have implemented a simple nutrient contribution measure for food items. This is based on the sum of the relative contribution the food item makes to each of the nutrients captured in the model. As such, it gives a higher weighting to nutrients that have low global availability and a lower weighting to nutrients that are abundant.

For example, the default 2018 DELTA Model scenario has a 34% deficiency for calcium against global requirements (achieving 66% of target), whereas phosphorous has a 150% excess (250% of target). Thus, a food that provides 33% of the daily target for calcium gets a score of 0.5, whereas 33% of the daily target of potassium scores only 0.13 – approximately ¼ the importance. A similar approach has recently been published for the individual dietary context.

The right use of nLCA

The challenges described above stem from trying to compare refrigerators with washing machines, and lead us to the fact that nutrition does not easily collapse into a single score.

The scope of comparisons, or the grouping of foods into groups becomes important. If food items are grouped with others that provide or purport to provide similar nutritional benefits, we can make more realistic comparisons that better reflect the real choices facing us.

As an example, we might compare the nutritional LCA of milk with that of a plant beverage and use a nutritional functional unit that reflects the role of these items within the overall diet. Milk products make a significant contribution to the global supply of calcium, phosphorous, and potassium, six indispensable amino acids, dietary fat, overall protein, and vitamins A, B2, B5, and B12. A nutritional functional unit could be designed that reflects this nutritional value to enable us to compare milks and milk-alternatives when consumed as a source of nutrients. However, this same approach would not necessarily be appropriate if the purpose of the product was simply to whiten a cup of coffee. The intended service or benefit of foods must be understood when deciding how to compare costs.

Whilst the concept of a universal nutritional LCA that provides all the information necessary to support a wide range of decisions is attractive in its apparent simplicity, the reality is that nutrition and environmental impacts are too complex, and too important, to be reduced to a single number.

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The dietary trio of healthy, nutritious and climate-friendly

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A recent study and accompanying editorial have compared dietary nutrient density and diet-related greenhouse gas emissions to understand whether individuals consuming more nutritious diets with lower carbon footprints have a longer lifespan than others.

The short editorial highlights some of the issues in interpreting data for the relationships between mortality and food. Nutrient density, as measured here, can be assessed through multiple metrics. Similarly, climate impact can be measured in many ways, here via greenhouse gas emissions in CO2-equivalents.

Although the impact of nutrition on death rate is an important consideration in assessing the impact of diets on health, it is limited and does not account for broader lifestyle impacts on mortality. 

Similarly, although climate impact is an important consideration in assessing the impact of diet on the environment, land, water, and fertiliser use (among other factors) must also be considered in assessments of the environmental efficiency of diets.

Within these limitations the study found several interesting associations, with notable differences between women and men. 

In the female cohort, mortality was 13% lower for those consuming diets with a high nutrient density and a low climate impact compared to those on low nutrient density and high climate impact diets. However, the same reduction in mortality was found for those consuming diets with a high nutrient density and high climate impact, indicating that nutrient density was the most important factor in the reduced mortality rate.

For men, mortality was 11% higher for diets having a low nutrient density and low climate impact compared to diets having a low nutrient density and high climate impact. It was suggested that this was due to sugar content: sugar has a small climate impact, but a clear negative impact on health when overconsumed.

The editorial makes some useful suggestions for how improvements can be made to such studies, such as considering food intake rather than reducing the assessment to individual nutrients. These results emphasise that climate-friendly diets are not always healthy, and vice versa, but that healthy, climate-positive diets can be achieved.

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Linking agricultural conditions to childhood undernutrition

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A study of infant malnutrition in the West African country of Burkina Faso has established a link between its prevalence and local agricultural conditions.

Climatic conditions play a major role in determining the performance of agricultural land and food production, with local and seasonal variation. The availability of food is an output of this performance, with clear implications for nutrition. In this study, the authors combined household nutrition surveys, malnutrition data and a remotely sensed drought indicator to investigate associations between agricultural conditions and malnutrition.

The Water Requirement Satisfaction Index (WRSI) combines precipitation, temperature, humidity, wind, and solar radiation data to ascertain whether the water needs of an area of cropland are being met. WRSI is a useful risk management tool employed in many parts of the world to study drought and crop yield.

Localised WRSI data was combined with household survey data from Burkina Faso, focusing on 1,721 children aged between 6 months and 2 years old. Around a third of the children were malnourished, as were a quarter of their mothers. Just 15% of the infants had achieved the WHO’s minimum dietary diversity standard over the 24 hours before the survey.

As found by previous studies, undernourished mothers were more likely to have undernourished children in their care. Low dietary diversity, recent diarrhoea, and lower education level of mothers were also associated with malnutrition.

The novel finding of this research was the association between higher WRSI values and reduced chances of malnutrition. These higher values, indicative of regions where the water needs of agricultural production were being met, were also associated with increased infant dietary diversity.

While better agricultural conditions could reasonably be expected to tally with greater food availability and thus reduced rates of malnutrition, studies that consider the interactions between agricultural production due to local climate and nutritional outcomes are rare. These results emphasise the interconnections in our food system – in this case, between rainfall and nutrient adequacy – that have a profound effect on the outcomes for people.

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The strength of dairy in the diets of the elderly

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A study published recently in the British Medical Journal indicated positive links between dairy intake and significant reductions in bone fractures and falls among the elderly.

The randomised controlled trial took place over a two-year period in 60 aged care facilities in Victoria, Australia. Half of the 7,000 participants continued with their regular diet, with the other half increasing their dairy intake from an average of 2 to 3.5 serves per day. Food products used to increase dairy intake included milk, cheese, yoghurt and skim milk powder.

When comparing the increased dairy intake group to the control, this study found a 33% reduction in all fractures including a 46% reduction in hip fractures, and a 11% reduction in falls in the group having more dairy in their diet. The elderly residents (average age 86 years) in this group also demonstrated significant improvement in lean mass (appendicular) and bone mineral density over the course of the 2-year study compared to the control group. More lean mass (legs and arms) and higher bone mineral density may have contributed to the reduction in falls and fractures.

At the onset of the trial, the participants had below recommended daily intake levels of both calcium and protein – common for institutionalised elderly individuals. This must be considered when applying the results further as initial intake levels may determine the positive effect of increased dairy in the diet. Nonetheless, such results will be beneficial to consider in the implementation of public health measures for fracture and fall prevention in this demographic.

With an aging population globally, it is now more critical than ever to consider nutritional interventions as a public health measure in the aged care setting and wider community. The health of this demographic has been shown to be significantly influenced by dairy intake. This must be considered as we look to the future and explore our food production systems, which must provide future generations with the required nutrients to support healthy ageing and avoid preventable injury.

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More about what you eat, and less about how much

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A recent article in The American Journal of Clinical Nutrition has highlighted the inconsistency of rising obesity rates despite focused efforts to eat less and exercise more. The paper critiques the current energy balance model (EBM) and offers a review of an alternative model that considers the underlying biological processes at play. It suggests weight gain is as much about what we eat as it is about how much.

According to the EBM, obesity is understood as an imbalance of energy. If an individual consumes more energy than expended, the surplus energy is stored as body fat. This has led to the common approach of eating less and moving more to achieve weight loss. EBM assumes all calories are metabolically alike, thus excluding the causal mechanisms of food quality, structure, or composition on processes that may impact weight gain. This simplistic approach to a complex biological system faces the risk of inaccuracies and may cause misguided obesity management practices.

The present paper reviews an alternative model: the Carbohydrate Insulin Model (CIM), against various hypotheses and advocates for the accuracy of this model over the EBM. CIM considers the source of calories, versus the calorie content exclusively. It suggests calorie-independent mechanisms are at play where the compounds in food can impact hormonal and metabolic responses. Among these factors, glycaemic load (GL) plays a significant role: hormonal responses to high glycaemic foods (easily digested, high sugar) drive an increased energy positive imbalance resulting in weight gain. A focus on the quality of the calorie sources should be considered, where consuming lower GL foods is favourable over attaining a calorie deficit.

CIM is not without criticisms of its own, as the authors identify claims by previous research challenging the validity of CIM. This has caused misinterpretations of the model, such as “Energy expenditure is not increased by low- compared with high-carbohydrate diets in some feeding studies”. The review provides explanations to these misleading statements, often due to weak evidence or trial errors.

Whether CIM offers a more accurate representation of weight management or not, this paper highlights the importance of considering the types of foods we consume and their impact on our hormones and metabolism for a more sustainable pathway toward healthier living. Taking a wider lens, it also exemplifies the need for researchers to consider multiple models to improve our understanding of complex systems, an idea that can be applied to modelling the global food system.

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Eating your greens for a healthy heart

Two recent publications in the Journal of the American Heart Association have together shown the benefits on heart health through diets rich in plants, both for young adults and older woman. The studies followed participants for 15 and 30 years, providing robust insights to the intersection between nutrition and cardiovascular health.

The first study enrolled just under 5,000 participants between 18-30 years of age. Participants’ food consumption was tracked, with examiners ranking foods based on their cardiovascular health risk to allow participants’ diets to be scored. In a 32-year follow-up, the individuals with diet qualities in the top 20% of participants had a 52% lower risk of developing cardiovascular disease. It was also found that participants who improved their diets later in the study saw significant reductions in the likelihood of contracting heart disease.

The second study included 123,330 postmenopausal women of the Women’s Health Initiative in the US whose ages ranged between 50 and 79, none of whom had cardiovascular disease at enrolment. The study analyzed the women’s adherence to a Portfolio Diet over a 15-year period and any later contraction of heart disease. Not recommended as an exclusive diet, the Portfolio Diet rather offers recommendations of healthy foods. Findings suggested that those women with the closest alignment to the Portfolio Diet were 11% less likely to develop any type of cardiovascular disease, 14% less likely to develop coronary heart disease and 17% less likely to develop heart failure.

Both studies were observational in design, therefore they cannot determine a cause and effect relationship. Residual confounding factors cannot be ruled out and results may not be generalisable across other population groups, such as for men (specifically for the postmenopausal woman study) or across ages, cultures or ethnicities as both studies were carried out in the US.

These studies provide positive insights into the health benefits of diets rich in plant-based foods. This is not to say a plant only diet is recommended, as neither study considered restrictive diets, but rather food consumption that saw high levels of plant-based material saw the most benefit to human health . Such considerations on nutrition and health are significant to the conversation and dialogue around sustainable food systems. If sustainable human nutrition and health are not achieved in a population, other aspects of sustainability become less important.

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Dairy in a low-cholesterol diet

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A recent study on dairy’s role in cardiometabolic health has added further nuance to the topic by indicating the different outcomes total dairy and individual dairy products have on biomarkers of disease.

Cardiometabolic diseases including cardiovascular disease, diabetes and chronic renal failure are now the number one cause of death in our aging population. The main cause of these diseases is an unhealthy lifestyle. A broad range of biomarkers (indicators of a disease that can be found in the blood) have been identified and can be used to determine onset. Some studies have linked dairy intake with increased risk of individuals developing cardiometabolic disease. The present study tested these associations to further understand how dairy products can influence cardiometabolic health by measuring biomarkers.

The cross-sectional study included over 35,000 women aged 50 to 79, spanning 40 clinical centres across the US. Concentrations of 20 different biomarkers were compared.

The key findings were:

  • Lower triglyceride (type of fat associated with cardiometabolic disease) was associated with greater intake of total dairy. This was driven by full-fat dairy products
  • Greater total milk and yoghurt intake were associated with lower concentrations of total cholesterol, while greater butter intake was associated with higher cholesterol concentrations
  • Greater total dairy, total and full-fat cheese and yoghurt were consistently associated with lower concentrations of glucose, insulin and C-reactive protein (all of which are biomarkers of cardiometabolic disease).

These findings do not support conclusions of dairy playing a role in cardiometabolic disease, and more specifically the health benefit for low-fat dairy product varieties over full-fat, as promulgated by some health authorities. The challenge in finding consistent outcomes for the role of dairy in the onset of cardiometabolic disease calls for further research in the area. What has been made obvious is the critical role that nutrition plays in the health of our populations and that individual products, rather than food groups, should be considered.

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Trends in undernourishment show promise

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A study of undernourishment in 76 countries found positive results, but not all global regions are progressing at the same rate.

Although overnutrition continues to grow globally, undernutrition rates are decreasing. Undernutrition currently affects more than 800 million people, either as protein-energy malnutrition or micronutrient deficiencies. 

The researchers used data from 1991-2013 from the FAO and the World Bank to analyse both undernutrition and related factors. The countries studied were mostly developing countries located in sub-Saharan Africa, Asia or Latin America. 

Undernourishment and child mortality showed decreasing trends overall. Urban populations, GDP, food production and agricultural land had all increased over the study period. However, when grouped into regions, the Eastern Mediterranean countries (Iran, Iraq, Jordan, Tunisia and Yemen) showed a late upwards trend in undernourishment, possibly due to political unrest in this region in the latter years of the study period. 

A problem noted by the authors is in equal distribution of food, both between countries and within national populations. This is a conclusion also reached by the DELTA Model, which shows that apart from a few micronutrients, the global food system in 2018 would have supplied sufficient nutrition for the world’s population, had it been equally distributed. The problems of unequal distribution are bound up in many other social, economic, political and environmental factors. 

While it is reassuring to see the decreases in undernourishment and infant mortality shown by this study, it also highlights areas that remain to be improved.

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Saturated facts

For nearly 50 years it has been believed that saturated fat is linked to heart disease. However, the scientific evidence does not universally support this assertion and recommendations are being made to change dietary guidelines and public knowledge around saturated fat. 

In response to increasing rates of heart disease in Western populations in the mid-20th century, the results of epidemiological studies comparing diets in different countries suggested that saturated fat intake could be a risk factor. Minimising the intake of saturated fat-containing foods such as red meat, dairy and chocolate was advised as a result. Currently, the NZ and UK dietary guidelines recommend reducing saturated fat intake, while the US and Australian Dietary Guidelines recommend the restriction of saturated fatty acids (SFAs) to less than 10% of total calorie intake in order to reduce the risk of cardiovascular disease (CVD). 

Saturated fatty acids (SFA), colloquially termed saturated fat, are molecules found in many common foods, especially animal fats and certain plant oils. Saturated refers to the molecular structure of the fatty acids, which have only single bonds between the carbon atoms, which cannot bond with any more hydrogen: thus, saturated with hydrogen. 

The claim that saturated fats were linked to negative health outcomes was accepted by public health institutes such as the World Health Organisation and the American Heart Association, and quickly caught on as a widespread belief. This has become so ingrained that, despite evidence to the contrary, it is proving difficult to change nutritional guidelines and the opinions of medical professionals, nutritionists, and consumers.  

A recent study, published in the Journal of the American College of Cardiology (JACC), performed a meta-analysis of randomized trials and observational studies on saturated fat. It was found that there were no beneficial effects of reducing SFA intake on cardiovascular disease and total mortality. While it was found that SFAs do increase cholesterol in most individuals, they increase concentrations of large particles of low-density lipoprotein (LDL) cholesterol, which is less correlated with CVD risk than the small, dense particles.  

An important finding of this study was that health effects could not be predicted from the SFA nutrient group alone; consideration of the overall macronutrient distribution and food matrix was necessary. Different SFAs have different physiological effects, which are further influenced by the foods they are found in and the carbohydrate content of the diet. Several foods relatively rich in SFAs but also rich in other nutrients, such as whole-fat dairy, dark chocolate, and unprocessed meat, were not associated with increased CVD or diabetes risk. 

There are calls to examine the overall risks of foods containing SFA, rather than SFA themselves. Likewise, the replacement of SFA-containing foods with those containing other fatty acids, often recommended in nutritional guidelines, was found unlikely to reduce CVD events or mortality. The authors of this last publication warned that current recommendations to replace SFA with alternative fatty acids may hinder efforts to get people to adopt more beneficial lifestyle changes, thinking that this single dietary change may be sufficient to reduce their CVD risk. 

One of the studies included in the JACC meta-analysis was the PURE (Prospective Urban Rural Epidemiological) study of 135,000 people from 18 countries on five continents. It found all types of fat (saturated, mono-unsaturated and polyunsaturated) were not associated with CVD, and saturated fat had an inverse association with stroke. Additionally, fat intake was associated with lower risk of total mortality. In contrast, a diet high in carbohydrates was associated with higher overall mortality risk.  

The claims around the negative consequences of fat intake may themselves have caused health problems. Reduction of saturated fat in the diet can lead to excessive consumption of carbohydrates as a replacement. Prevalence of obesity and type 2 diabetes has exploded in recent years, as seen in the chart below. Dr James Muecke, 2020 Australian of the Year, wrote in the Canberra Times“A flawed dietary guideline, which we have obediently and blindly followed for 40 years, is literally killing us. We’ve been encouraged to eat less fat and consume more carbs and yet we’ve never been fatter, our teeth never more rotten, and type 2 diabetes and its complications never more prevalent.” Dr Mueke makes clear the far greater need to prioritise reductions in excess carbohydrate consumption, rather than reductions in fat, to reduce the rate of non-communicable diseases in developed nations like Australia.

Rapidly increasing prevalence of obesity globally over the last 40 years. Source: World Health Organisation

In addition, advice to reduce consumption of nutrient-rich foods such as dairy and meat risks limiting the intake of nutrients such as calcium, iron, zinc, riboflavin and Vitamin B12. The Global Burden of Disease study shows that in the main, global health problems are caused more by what people do not eat – either through poor choice or through lack of choice – rather than an excess of certain foods. With the exception of excess sodium, the highest association of mortality and disability-adjusted life years globally was with insufficient intake of nutrient-rich foods. The study also showed the problems of consuming excess sugars. Consuming calorie-rich but nutrient-poor foods (e.g., sugary drinks) can displace nutrient-rich foods in the diet. The Global Burden of Disease study demonstrates that diets low in nutrient-rich foods are correlated with higher mortality. Importantly, saturated fat intake did not appear with any link to higher burden of disease. 

Number of deaths per 100 000 population attributable to individual dietary risks at the global level in 2017. Reproduced from the Global Burden of Disease study.

It is important for policy makers and health institutes to take all evidence into account when- designing nutritional guidelines. Arbitrary recommended intake levels for saturated fat will be less useful for the prevention of CVD or reduced mortality than targeting excess consumption, particularly of carbohydrates, and micronutrient deficiencies. Foods containing saturated fat, such as meat and dairy, can contribute to a nutritious balanced diet. They certainly should not be removed from the diet due to their saturated fat content, which has inconsistent links to modest impacts on CVD. Replacing these foods with carbohydrates will likely cause greater damage. 


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