A review of the week’s plant-based nutrition news 13th September 2020
This week I cover the consumption of grains, lifestyle factors for prevention of kidney disease and health and environmental aspects of our diet choices.
WHITE RICE CONSUMPTION AND TYPE 2 DIABETES: The PURE study has generated a large amount of data, some of which has been controversial. The study was hugely ambitious and certainly one of a kind. The Prospective Urban Rural Epidemiology (PURE) study is a large, epidemiological cohort study of around 140,000 individuals aged 35–70 years (enrolled between Jan 1, 2003, and March 31, 2013) in 17–21 countries and 5 continents, including low, middle and high income countries residing in >600 communities. The study has reported controversial findings such as higher carbohydrate diets increase risk of mortatity, whereas higher fat diets, including saturated fat and dairy consumption, improve health outcomes. Yet at the same time higher intakes of fruits, vegetables and legumes improve health outcomes. So how can these results be explained. Many, including myself have written about the flaws in the study interpretation, including reasons why saturated fat and dairy consumption are associated with better health outcomes and carbohydrate consumption is not. Essential the results demonstrate that participants from low incomes countries have suboptimal calorie intakes, predominantly from refined carbohydrates, lower personal income and less access to healthcare resulting in worse health outcomes. The opposite being true for those living in high income countries, eating more meat and diary (and hence saturated fat), yet higher incomes and better access to healthcare.
Having said all this, 60% of all calories in the human diet globally comes from 3 plant sources — rice, wheat and maize. This is despite the fact that there are more than 14,000 edible plant species. For South Asians, carbohydates compose 70–80% of the diet and up until recently carbohydrate sources such as rice were much less processed. Now, white, polished rice forms a large proportion of South Asian diets and this white rice has lost much of its fibre and nutrients. The study highlighted examined the impact of white rice consumption on the risk of type 2 diabetes in 132,373 individuals in the PURE study from 21 countries (Argentina, Bangladesh, Brazil, Canada, Chile, China,Colombia, India, Iran, Malaysia, occupied Palestine territory, Pakistan, Philippines, Poland, South Africa, Saudi Arabia, Sweden, Tanzania, Turkey, United Arab Emirates, and Zimbabwe). The mean age of participants was 50 years. Participants were divided into quartiles of cooked white rice consumption; <150g/day to >450g/day (150g being 1 cup of cooked rice). The results showed that those consuming the most white rice had a 20% increased risk of developing diabetes than those consuming the least and this association was particularly strong in people from South Asian who had a 61% increased risk. The potential reasons for this are the high glycaemic index and load of white rice, similar to eating white bread, the lower fibre intake and also a possible contribution of the arsenic content in rice (although this had not been proven).
Now this study by no means proves that white rice consumption causes type 2 diabetes and the quantities being eaten are much greater than that in the UK or higher income countries. Nonetheless, there are better choices to make and plenty of well documented health benefits of choosing whole grains rather than refined versions. It is always a good idea to eat as much variety as possible, mixing up your diet with grains such as oats, millet, buckwheat, bulgar, quinoa and so forth.
WHOLE GRAIN CONSUMPTION IS BENEFICIAL FOR FATTY LIVER: This study highlights the benefits of whole grain consumption for people with non-alcoholic fatty liver disease (NAFLD), a condition that now affects up to 1 in 5 people in the UK and US. It is ultimately a disease of diet and lifestyle with diets high in saturated fat, red meat, processed foods and fructose and low in whole plant foods and fibre particurlaly implicated. Overweight, obesity and metabolic syndrome often go hand in hand with the condition, but it has to be remembered that in South Asians particularly, visceral fat can deposit even when the person does not meet conventional criteria for overweight/obesity.
This 12 week randomised controlled clinical trial included 112 patients with NAFLD. The mean age was 43 years and mean BMI 32·2. They were randomly assigned to two groups to receive dietary advice, either to obtain at least half of their cereal servings each day from whole grain foods or from usual cereals. At the end of the study, those in the whole grain group had a significant decrease in the grading of their fatty liver, a decrease in liver enzymes and blood pressure. There was no significant change in lipid profile, glycaemic status and anthropometric measurements. The participants in the intervention group had gone from eating 0 servings of whole grains per week to 8 serving and this was also associated with a reduction in calorie intake, suggesting that whole grain consumption was more satiating. These results are pretty remarkable given the short duration and single intervention. Just imagine what a shift to a 100% whole food plant-based diet might achieve!
LIFESTYLE FACTORS FOR PREVENTION OF KIDNEY DISEASE: Chronic kidney disease (CKD) is rising in incidence with around 10% of the global population have this a diagnosis. The commonest causes are type 2 diabetes and hypertension. However, there is not much emphasis on the primary prevention of CKD. This paper seeks to determine which lifestyle factors are associated with the risk of CKD and hence could be used to inform primary prevention strategies. The study is a large systematic review and meta-analysis of 104 studies, including 2,755,719 participants. The main consistent findings across all studies were that a number of measures are associated with preventing CKD onset. These include increasing dietary intake of vegetables (21% reduced odd of CKD) and potassium (a reflection of higher fruit and vegetable consumption, 22% reduced odds), increasing physical activity levels (18% reduced odds), moderate compared to no alcohol consumption (15% reduced risk), lowering sodium intake (21% increased odds), and current/previous tobacco smoking (18% increased risk). For meat consumption there were insufficient studies for a meta-analysis, but the studies that were included showed that red and processed meat consumption increased the risk of CKD.
These data provide useful information for lifestyle interventions directed towards promoting kidney health and they are consistent with established prevention strategies for cardiovascular disease, type 2 diabetes and cancer. I am not sure I can fully explain the association with moderate alcohol consumption but we can perhaps conclude that moderate (in line with Government guidelines) rather than excessive alcohol consumption (which is harmful to the kidneys) is at least not harmful for kidney health.
HOW HEALTHY IS THE UK EATWELL GUIDE? In the UK, many complain about and criticise the Eatwell guide, our national dietary guidelines published in 2016. Some say there is too much emphasis on carbohydrate- rich foods and some criticise for including processed foods such as bagels. For me, I see it as a sensible and realistic guide, which when considered in detail is a predominately plant-based diet emphasising beans and pulses rather than meat as predominate sources of protein, whole grains rather than refined grains and one third of the plate is composed of fruits and vegetables. It also acknowledges plant-based dairy alternatives as good sources of nutrients. In reality, whatever the public and health professionals think of the dietary guidelines, most UK citizens are not following them with only 28% of adults and 18% of children eating 5 portions of fruits and vegetables a day, greater than 50% of the diet coming from ultra-processed foods and rising meat consumption, with 61kg of meat eaten annually per person.
This study examined the health and environmental impact of adherence to the Eatwell guide. It included Adults from the European Prospective Investigation into Cancer — Oxford(EPIC-Oxford), UK Biobank and Million Women Study, and adults and children aged 5 and over from the National Diet and Nutrition Survey (NDNS). 557 722 participants were included for investigation of health outcomes and 5747 participants for environmental footprints. The study found that less than 0.1% of the participants adhered to all nine recommendations of the Eatwell guide and 30% adhered to at least five recommendations. Higher adherence to the Eatwell guide was assocaited with a 7% reduced risk of mortality and 30% lower dietary greenhouse gas emissions. Adherence to the recommendation on fruit and vegetable consumption was associated with the largest reduction in total mortality risk (10%) and increased adherence to the recommendation on red and processed meat consumption was associated with the largest decrease in environmental footprints. The authors suggest that these data ‘provide evidence to support strengthened national action to improve diets in the UK for the benefit of people and the planet’.
Healthier diets are thought to sometimes cost more but when the cost of the Eatwell guide has been analysed it does not differ significantly from the current diet pattern of UK citizens — £5.99 per day compared to £6.02 per day for the current diet. So all in all, I would suggest the UK public, health professionals and Government endorse and promote the Eatwell guide as it is for certain better than the current diet of the nation.
USING THE FOOD SYSTEM TO REMOVE CARBON DIOXIDE: Restoration of natural ecosystems is necessary not only to curb the loss of biodiveristy but to remove carbon dioxide from the atmosphere. The Living Planet Report from the WWF shows that our planet’s wildlife populations have now plummeted by 68% since 1970. Restoration of ecosystems is hampered by the use of land globally for animal agriculture. The study highlighted analyses how much carbon dioxide could be sequestered if we shifted to a plant-based food system. The study modelled land use of three global dietary scenarios to the year 2050 relative to the present day (base year 2015. The net carbon dioxide balance was calculated for a business-as-usual (BAU) diet, a healthier diet with approximately 70% meat reduction globally (the EAT-Lancet Commission or ELC diet) and a vegan diet with no animal-sourced foods. The BAU diet led to an increase in carbon dioxide emissions in order to meet the growing demand for meat. Both the ELC and vegan diet led to removal of atmospheric CO2, approximately equal to the past 9 and 16 years of fossil fuel emissions respectively. The authors conclude ‘Changes in diets and agricultural land use within the next two decades could contribute substantially toward carbon neutrality by 2050’. There seems little doubt that the global shift to a plant-based diet is a necessity to limit global warming to less than 1.5 °C. Overshooting this level of warming poses substantial risks to human and natural systems. In addition, a plant-based food system would require less land and therefore allow for re-wilding and restoration of wildlife habitats.
We have been warned time and time again and the current, devastating wildfires in America remind us of the direct impact of climate change and the fragility of our planet. We must act now.
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