A review of the week’s plant-based nutrition news 30th January 2022

This week I cover the significant impact of healthy lifestyles in cancer care, diet and gestational diabetes, the potential role of probiotics in COVID-19, the global crisis of antimicrobial resistance and WHO support for plant-based diets.

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HEALTHY LIFESTYLES, CANCER AND CARDIOMETABOLIC DISEASE: Not only does underlying chronic illness increase the risk of cancer, but there is an increased risk of cardiometabolic disease after a diagnosis of cancer. This makes lifestyle interventions for cancer survivorship increasingly important.

This paper reports finding from the UK biobank study and examines the impact of a healthy lifestyle on the risk for cardiovascular disease (CVD) and type 2 diabetes (T2D) before and after the onset of cancer. Two sub-groups were included. A cancer-free cohort of 397,136 individuals in the general population and a cancer-prevalent cohort of 35,564 individuals with cancer. All participants were aged 40 to 70 years, free of CVD and T2D at recruitment and then followed for median of 14 years. The healthy lifestyle index (HLI) was made up of 5 cardiometabolic disease–related healthy behaviours (smoking status, physical activity, diet, alcohol consumption, and sleep duration). If participants met the criteria for each healthy habit they received a score of 1 and if not a score of 0, so a maximum score of 5 could be obtained. A healthy diet was high in fruits, vegetables, whole grains, refined grains, fish and low in unprocessed meat and processed meat.

In the cancer-free cohort 40,097 individuals (10.1%) developed cancer during follow-up. Each 1-point increment in HLI was associated with an 8% lower risk of developing cancer. A 1-point increment in HLI was also significantly associated with a 10% lower risk for developing CVD in patients diagnosed with cancer and a 12% lower risk in those free of cancer. Each additional healthy lifestyle factor had a 17%-26% reduction in risk of death during follow up, with smoking having the strongest negative impact. A 1-point increment in HLI was also associated with a 19% reduction in risk of T2D and a 16% reduction in T2D following a cancer diagnosis.

In the cancer cohort, cancer survivors with 5 healthy lifestyle factors had a 44% reduction in the risk of developing CVD and 38% reduction in the risk of T2D. A 1-point increment in HLI was associated with risk reductions of 10% and 13% in developing CVD and T2D, respectively.

Overall the finding confirm the importance of healthy lifestyle habits for prevention of cancer, CVD and T2D and also the benefits of these healthy habits after a diagnosis of cancer when the risk of chronic conditions is even higher.

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PREVENTION OF GESTATIONAL DIABETES: Obesity is a significant risk factor for developing gestational diabetes mellitus (GDM), and an increasing number of pregnant women are overweight or obese. Gestational diabetes shares the same underlying mechanism as type 2 diabetes, namely insulin resistance. Dietary habits are key in driving insulin resistance and impacts both obesity and the risk of GDM.

This mother-child study from Finland investigated the connection between dietary intake and onset of GDM in 351 overweight or obese women. Food diaries were used to assess the quality of the diet and also calculate the inflammatory potential of the diet using the dietary inflammatory index (DII). The DII, is based on up to 45 food parameters which have been scored based on reported pro-inflammatory or anti-inflammatory effects on specific inflammatory markers in the blood. A total of 28 food parameters were available from the food diaries in this study for calculating the overall DII scores. These included energy, carbohydrate, protein, total fat, alcohol, fibre, cholesterol, SFA, monounsaturated fatty acids, polyunsaturated fatty acids, omega-3 fatty acids, omega-6 fatty acids, trans fatty acids, niacin, thiamine, riboflavin, vitamin B12, vitamin B6, vitamin A, vitamin C, vitamin E, vitamin D, iron, magnesium, zinc, selenium, folic acid, and beta-carotene.

In this cohort, 23% of participants (n=81) were diagnosed with GDM and they had a higher BMI than those that did not develop diabetes. The consumption of saturated and trans fats was higher and fibre lower in participants who developed GDM. Similarly, intakes of micronutrients abundant in plant foods including vitamin C, folate, potassium, magnesium, were lower in those who developed GDM. Overall a healthier diet pattern and a diet with lower inflammatory potential was associated with a lower risk of GDM.

Overall, a diet pattern characterised by lower intakes of saturated fat (i.e. animal-derived foods) and higher in rye bread, vegetables, fruits, and berries was associated with a lower risk of GDM. The authors hypothesise that low grade inflammation results in insulin resistance and one of the mechanisms that may be driving this is the consumption of saturated fat, which is known to increase inflammation.

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PROBIOTICS AND COVID-19: We have learnt a lot about the role of healthier diet and lifestyles for mitigating the risk of COVID-19. In particular, a healthier gut microbiome is associated with better outcomes from the pandemic virus. We know that the gut bacteria communicate with and influence the health of most of our body organs including the lungs, the so called ‘gut-lung axis’. Thus improving the health of the gut microbiome through dietary or therapeutic intervention could be a useful strategy for reducing the severity of COVID-19. Previous meta-analyses have suggested oral probiotics may have a role in respiratory infections such as colds and influenza, although the quality of the evidence remains low.

This study reports the first randomised placebo controlled study of probiotics in 300 people of Hispanic origin with symptomatic COVID-19 in the outpatient setting. Patients were enrolled within 7 days of the onset of symptoms and COVID-19 was confirmed by a PCR test. Participants took one probiotic tablet (four strain composition) prior to breakfast for 30 days. They were assessed on day 0, 15 and 30 of the study. Participants were also contacted by phone on days 5, 10 and 20. Nasopharyngeal, blood and faecal samples were collected and analysed and chest x-rays were performed. Participants were only allowed to use paracetamol as an additional medication.

During the study there were no hospitalisations or deaths. Probiotic supplementation was well-tolerated and reduced nasopharyngeal viral load, lung infiltrates and duration of both digestive and non-digestive symptoms, compared to placebo. The primary outcome of complete remission (i.e. complete symptomatic and viral clearance) on day 30 was achieved by 78 (53.1%) in the probiotic group compared to 41 (28.1%) in placebo. No significant compositional changes were detected in faecal microbiota between the probiotic and placebo groups, but probiotic supplementation significantly increased specific IgM and IgG against SARS-CoV2 compared to placebo. The authors hypothesise that this probiotic primarily acts by interacting with the host’s immune system rather than changing colonic microbiota composition.

Although these results are unlikely to influence clinical practice right away, the results support prior evidence that shows a healthier gut microbiome is important for improving outcomes from COVID-19. Whilst awaiting the results of further studies, eating a fibre-rich and diverse plant-based diet is the best approach to supporting gut health and adding fermented and probiotic foods may be a useful approach.

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AN UPDATE ON ANTIMICROBIAL RESISTANCE (AMR): One of the major threats to human health is the growing issue of AMR. This study brings us the most most comprehensive estimates of AMR burden to date. The study analyses deaths and disability-adjusted life-years (DALYs) attributable to and associated with bacterial AMR for 23 pathogens and 88 pathogen–drug combinations in 204 countries and territories in 2019.

The results showed that in 2019 an estimated 4·95 million (3·62–6·57) deaths were associated with bacterial AMR and that 1·27 million of these deaths were directly attributable to drug resistance.These are all potentially preventable deaths. Compared with all underlying causes of death, AMR would have been the third leading cause of death, with only ischaemic heart disease and stroke accounting for more deaths. This was highest in western sub-Saharan Africa, at 27·3 deaths per 100 000 and lowest in Australasia, at 6·5 deaths per 100 000. Lower respiratory tract infections were the commonest type of infection associated with AMR. The six leading pathogens for deaths associated with resistance were Escherichia coli, followed by Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa. The authors conclude ‘Our estimates indicate that bacterial AMR is a health problem whose magnitude is at least as large as major diseases such as HIV and malaria, and potentially much larger’.

One of the five recommendations for addressing this issue is to reduce antibiotic use in farming. Globally it is estimated that 66% of all antibiotics are used in farm animals. Thus reducing or eliminating meat consumption should be a major part of the solution to AMR. One study estimated that limiting meat intake worldwide to 40 g/day — the equivalent of one standard fast-food burger per person — could reduce global consumption of antimicrobials in food animals by 66%.

Meat consumption is associated with a significant increase in the risk of a number of chronic health conditions. This 2021 analysis of almost 500,000 participants from the UK Biobank study showed that consumption of red and processed meat at a level of 70g/day significantly increased the risk of ischaemic heart disease, pneumonia, colonic polyps, diverticular disease and type 2 diabetes, in the order of a 10–30% increased risk. Higher poultry intake at levels of 30g/d increased the risk of gastro-oesophageal reflux, gastritis, duodenitis, diverticular disease, gallbladder disease and type 2 diabetes in the order of a 10–17% increased risk. Consumption of as little as 50g of unprocessed red meat and 20g of processed red meat per day increased the risk of a number of these chronic diseases.

Thus limiting or avoiding meat consumption will improve personal health and positively impact the broader societal health-related issues.

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THE WORLD HEALTH ORGANISATION (WHO) SUPPORTS PLANT-BASED DIETS: This is a useful resource to share with those who are still sceptical about the benefits of a plant-based diet. The review clearly describes the co-benefits of a plant-based diet for human and planetary health. The report acknowledges that consumers may not want to completely eliminate animals foods in the diet, however, any incremental reduction in consumption would be beneficial. It clearly states that a 100% plant-based diet is healthy and nutritionally adequate when well planned. The report concludes ‘considerable evidence supports shifting populations towards healthful plant-based diets that reduce or eliminate intake of animal products and maximize favourable “One Health” impacts on human, animal and environmental health.’ We don’t need more evidence on the benefits of a plant-based diet but now require urgent implementation of this knowledge in all aspects of our society from our food production, to policy and education, public sector catering and an overhaul of the food environment such that healthy plant-based foods are accessible and affordable for all.

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