Review of the plant-based nutrition news September 2023

As we recover from the VegMed conference, our education and learning continues with a number of new and important studies. There is little doubt that a plant-based diet can prevent and treat chronic conditions and support healthy ageing and optimal athletic performance.

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PLANT-BASED DIETS AND PARKINSON’S DISEASE: This is an important and hopeful study as in general many neurological conditions are not considered preventable, and treatments remain limited. Parkinson’s disease (PD) is the second most common neurodegenerative disease worldwide, characterised by tremors, slowness in movement, stiffness, and difficulties with balance and walking. It can also cause a wide range of symptoms that are not visible — loss of smell, constipation, sleep disorders, and depression. Its prevalence is on the rise with 1 in 37 people likely to be diagnosed during their lifetime. There are some known causes, with up to 5% caused by genetic risk factors. Air pollution, industrial chemicals and synthetic pesticides have all been implicated in the disease development.

This new analysis examines the impact of a plant-based dietary pattern on the risk of PD in participants of the UK biobank study. The researchers use the plant-based dietary index to define an overall plant-based diet, a healthy plant-based diet and unhealthy plant-based diet. The study included 126,283 participants followed for almost 12 years. During that time, 577 cases of PD were recorded. The results showed that an overall and healthy plant-based diet were associated with a lower risk of PD — 18% and 22% lower respectively. However, an unhealthy plant-based diet was associated with a 38% higher risk. When considering individual foods, higher intakes of vegetables (especially tomatoes, salad, cruciferous, carrots), nuts, and tea were associated with a lower risk of PD.

This is not the first study to demonstrate the association between higher diet quality and lower risk of PD. In general, diets higher in plant-based foods and lower in meat and saturated fat, such as the Mediterranean diet have been shown to be protective. Other studies have shown a consistent association between coffee consumption and decreased risk and cow’s milk consumption and increased risk of PD. Potential mechanisms by which plant-based foods are protective include the association between dysbiosis and PD and the beneficial impact of fibre and polyphenols on the gut microbiome. In addition, plant-based diet reduced inflammation and oxidative stress, both implicated in the pathogenesis of PD.

The authors conclude ‘These results are important to help refine and inform public health messages that consider plant-based diets and provide evidence that simple dietary change has the potential to reduce PD risk’.

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FATTY ACID CONSUMPTION AND FAT DEPOSITION: This is a useful study as it addresses the impact of different types of dietary fat consumption and association with fat deposition in the liver, muscle and other organs. Visceral fat deposition is associated with insulin resistance, type 2 diabetes, cardiovascular disease and premature death.

The study included 13,849 participants from the UK Biobank study. In addition to self-reported dietary intake, blood biomarkers of fatty acid consumption were used to improve accuracy. Fat stores were quantified using MRI scanning. The study used substitution analysis to consider the question ‘instead of what?’ and whether substituting certain types of fats for other types or carbohydrate and protein reduced fat deposition in body organs.

Overall, the results showed that saturated fat consumption was associated with higher levels of liver and other organ fat deposition. In contrast, plant-derived fats were either not associated or showed an inverse association with organ fat deposition. Substituting animal sources of fat for plant sources of unsaturated fats or protein had a beneficial impact, whereas substituting animal fat for carbohydrates or free sugar did not and may have had a worse effect. Of note, most of the beneficial associations between plant fat and protein and fat stores were evident in women and less so in men.

The authors conclude ‘the type of dietary fat may be an important determinant of ectopic fat in humans consuming their habitual diet, in line with previous short-term trials. Plant fat and sources of polyunsaturated fatty acids should be preferred over animal fat and sources of saturated fatty acids’.

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PLANT-BASED DIETS AND AGEING: Plant-based diets for older adults remain an area of controversy with some continuing to believe that animal-sourced protein is required to prevent sarcopenia and frailty, despite evidence demonstrating the opposite to be true.

This study from Taiwan correlated biological markers of ageing with a plant-based dietary pattern using the plant-based dietary index. The study included 12,784 participants enrolled between 1996 and 2011, aged 50 years or older, who had completed measurements of ageing 4 times over an 8-year period. Based on these results, participants were grouped into 3 ageing trajectories — high-degree accelerating ageing, medium-degree accelerating ageing and low ageing. 10,191 participants had complete dietary data available.

The results showed that adopting a healthy plant-based dietary pattern was associated with the slow aging trajectory and that unhealthful plant-based diet led to an accelerated aging trajectory. Reducing both unhealthy plant-based foods and animal foods was shown to be associated with a slower rate of ageing. The results also showed that the main drivers of the protective effects were consumption of fresh fruits, fresh vegetables, and legumes. During the follow-up 803 participants died, with the risk of death higher in the high-degree and medium-degree accelerating ageing groups.

These data are consistent with those previously published. For example, an analysis from the UK Biobank study demonstrated that greater adherence to a healthy plant-based dietary pattern was associated with a reduced risk of death from all causes and a reduced risk of common chronic conditions. Consumption of plant protein in favour of animal protein has been associated with reduce risk of death and frailty.

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PROTEIN AND RISK OF TYPE 2 DIABETES: There is little doubt that consuming protein from plant sources supports better health and reduces the risk of a number of common chronic conditions. In part because of the healthier package compared to animal protein. Plant protein is found in foods that are rich in fibre, unsaturated fats and an array micronutrients. This is a unique paper as it assesses the impact of the type of protein consumed on type 2 diabetes remission in an interventional dietary study. Newly diagnosed type 2 diabetes participants without glucose-lowering treatment were randomised to consume a Mediterranean or a low-fat diet. Type 2 diabetes remission was assessed with a median follow-up of 60 months.

During the first year of the intervention, 177 participants were assessed. The results showed that participants who increased their consumption of plant protein, regardless of which diet intervention group they were assigned to, had a significantly higher probability of achieving remission of type 2 diabetes. This was in the absence of calorie restriction, weight loss or glucose lowering treatment. The increase in plant protein was associated with lower intake of animal protein, cholesterol, saturated fatty acids, and fat, and with higher intake of whole grains, fibre, carbohydrates, legumes, and tree nuts. Remission occurred more frequently in year 1 and 2, and was less likely in year 3 and beyond. The authors conclude ‘the results of the present study support the need to improve the quality of the diet, including dietary proteins, increasing the consumption of those of vegetal origin as dietary therapy to reverse type 2 diabetes’.

Interestingly, a paper just published reports on the association between protein consumption in Chinese pregnant women and gestational diabetes. It finds that higher consumption of plant protein reduced the risk of gestational diabetes by 57%. In contrast, higher consumption of animal protein increased the risk by 278%.

I don’t think there are any surprises here. We know that a healthy plant-based diet significantly reduces the risk of development type 2 diabetes and is a very effective way of managing the consumption and in some cases achieving remission of already established disease. This knowledge is already embedded into clinical guidelines for management of people living with type 2 diabetes.

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FOOD REALLY IS MEDICINE: The global food system is unfit for purpose with healthy diets inaccessible to a large proportion of society. Yet we know that dietary risk factors are the leading cause of chronic illness and premature death. Hence using food as medicine makes a lot of sense as we patiently wait for Governments and policy makers to prioritise healthy diets as a basic human right.

This intervention study from the US used fruit and vegetable prescriptions for people from low-income neighbourhoods with cardiometabolic risk factors such as overweight/obesity, glucose dysregulation and high blood pressure. This is the largest produce prescription study to date to assess health outcomes, pooling data across 22 program locations in the United States

3881 participants were enrolled in the study (2064 adults aged 18+ years and 1817 children aged 2–17 years) and provided with financial incentives (paper vouchers or electronic cards) to purchase fruit and vegetables from grocery stores and farmers markets. After just 6 months follow up the results showed that participants had significantly increased their consumption of fruits and vegetables, were much less likely to be food insecure and had improvements in blood weight, glucose control and blood pressure. Pretty impressive!

Using diet and lifestyle approaches to improve health makes so much sense given the array of health benefits up for grabs and the virtual absence of side-effects when compared to more standard pharmaceutical interventions. Such a shame that these strategies are not prioritised in healthcare systems around the world.

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SOYA PROTEIN AND ATHLETIC PERFORMANCE: I tend to focus on disease prevention, but plant-based diets are increasingly being used for achieving optimal physical performance, both strength and endurance. Yet their remains unfounded scepticism about the equivalence of plant protein when compared to animal sources. I hope this study can help to put this myth to rest.

The analysis brought together the results of 19 randomised controlled trials which included active, healthy participants aged 14 to 39 years. The impact of soya protein supplementation on various aspects of athletic performance was assessed. In addition, soya supplementation was compared to whey.

The take home messages from the study include that soya protein is as effective as animal protein (such as whey) when considering gains in muscle and strength if consuming 1.6g/kg or more. All studies suggested potential beneficial effects of soya protein supplementation (10–53.3 g) on exercise performance by improving high-intensity and high-speed running performance, enhancing maximal cardiac output, delaying fatigue and improving isometric muscle strength, improving endurance in recreational cyclists, increasing running velocity and decreasing accumulated lactate levels. Soya also had a favourable impact on exercise-induced oxidative stress when compared to whey protein, which may be a reason why athletes feel they recover faster on a plant-based diet. With regards impact of soya of various hormone levels, there were inconsistent results, which meant conclusions could not be made.

There are now so many studies demonstrating that an appropriately planned plant-based diet can support optimal athletic performance and is likely to have significant advantages over a meat-based diet. This recent review summarises nutritional considerations for the vegan athlete and the Switch4Good team have produced this excellent guide for plant-based athletes.

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