A review of the week’s plant-based nutrition news 3rd October 2021

This week I risk fuelling the olive oil debate (!), plus studies on cognitive function, healthy diets for children and more on the climate crisis.

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EXTRA VIRGIN OLIVE OIL AND ENDOTHELIAL FUNCTION: There is so much that the plant-based community agrees upon, but it seems many have fallen out over the issue of added oils, especially olive oil, which is the most widely researched oil. In my view, a plant-based diet can be healthy with or without added oil and it comes down to personal preference and health goals. I have written more in an article here.

This study clears up the debate on whether olive oil affects endothelial function, at least after a single dose. As expected, its all about the quality of the oil. The study tested the effect of a single dose of either high-polyphenolic extra virgin olive oil (EVOO) or a refined olive oil in 20 participants who were randomly assigned to a particular oil and then crossed over to the other oil (after a one week washout period) in a blinded fashion. The participants included were deemed at high risk of developing type 2 diabetes, which is of course associated with endothelial dysfunction and a higher risk of cardiovascular disease. Participants received their olive oils in a smoothie consisting of 1 cup frozen blueberries, 1 cup low fat yogurt and 50 mL olive oil blended together. Endothelial function was determined by flow-mediated dilation (FMD) of the brachial artery, with repeated measurements after the single olive oil dose.

The results showed that the high polyphenolic EVOO resulted in an absolute improvement of endothelial function by 4.8%. This number was derived from the fact that EVOO improved FMD by 1.2%, whereas refined olive oil reduced FMD by 3.6%. The study of course can not determine the impact of longer term consumption but these data are consistent with a prior meta-analysis showing overall that olive can improve endothelial function.

The adverse effects made me chuckle ‘There were 3 reported cases of upset stomach and/or heartburn after smoothie ingestion: two after ingestion of the high-polyphenolic EVOO smoothie, and one after ingestion of the refined olive oil smoothie’.

There are three types of olive oil. EVOO, virgin olive oil and refined. EVOO is extracted using natural methods and contains relatively higher levels of some polyphenolic compounds, naturally occurring minerals, and vitamins found in olives. High polyphenolic EVOO may have other benefits such as improvement in cognitive function when compared to a Mediterranean diet without this high quality oil, but again we have no data on the impact of EVOO on a 100% plant-based diet.

Overall, I stand with my opening statement that a plant-based diet can be healthy with or without oil, but now adding that quality of the oil is paramount. I choose to spend my money on buying more fresh produce rather than oils, but that’s a personal choice. There are plenty of whole plant sources of polyphenol compounds, many with much higher levels than EVOO.

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COGNITIVE FUNCTION AND DIET: Cognitive decline and dementia are challenges globally with a rising prevalence. In 2018, ∼50 million people were suffering from dementia and it is expected that this number will triple by 2050. The Lancet Commission on dementia estimates that 30–40% of cases could be prevented or delayed by addressing lifestyle and socioeconomic factors. A healthy diet is one of the key lifestyle factors for the prevention of dementia with the strongest data supporting a Mediterranean-style diet as recommended in the WHO guidelines.

The current study examines the impact of healthy diet patterns on the risk of cognitive decline in participants of the Doetinchem Cohort Study in the Netherlands. 7769 men and women aged 20–59 years were recruited between 1987–1991 with 3 dietary assessments conducted during the follow-up. Diet was categorised based on three healthy diet indices; the modified Mediterranean Diet Score (mMDS), the Healthy Diet Indicator (HDI — based on WHO recommendations for prevention of chronic illness), and the modified Dutch Healthy Diet 2015 index (mDHD15-index — based on the 2015 Dutch dietary guidelines). Cognitive tests were performed on 4769 participants >45 years from 1995 onwards. The final analysis included 3644 participants with complete data sets.

The results showed that adherence to all three healthy diet indices was associated with better cognitive function and a slower decline over time. The differences were in the order of 7–10% between those who were most versus those who were least adherent. A larger benefit was noted for those participants that carried two apoE4 alleles, thus at a genetically higher risk of dementia.These associations remained significant after adjusting for underlying health conditions and other lifestyle behaviours.

The underlying mechanisms for cognitive decline include inflammation, oxidative stress, dyslipidaemia and glucose dysregulation. The health of the gut microbiome is also contributory. The authors propose that a healthy diet, rich in fruits and vegetables, anti-inflammatory and antioxidant compounds and low in saturated fat may be the reason for the benefits to cognitive function.

The authors conclude ‘Adherence to a healthy diet could help to maintain a healthy cognitive function with ageing…….. for genetically predisposed persons, consuming a healthy diet might be one way to partly counteract one’s higher risk of accelerated cognitive decline’.

Addressing underlying chronic health conditions that increase the risk of dementia such as obesity, hypertension, high cholesterol, heart disease, stroke and diabetes is key for preventing dementia. I covered a systematic review last week that demonstrated the benefits of a plant-based diet for prevention of all these chronic conditions.

It’s great to see that the 2021 Danish dietary guidelines have emphasised the role of plant-rich diets for both human and planetary health. It’s just a shame that dairy alternatives such as soya milks and yogurts are not included. In addition, the sustainability of recommending regular fish consumption with a predicted global population of 10 billion by 2030 is questionable.

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Danish Dietary Guidelines 2021

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HEALTHY DIETS AND MARKERS OF CARDIOVASCULAR DISEASE IN CHILDREN: We know how important it is to foster healthy habits in childhood. Chronic illness, including overweight and obesity, is increasing in children and we know that heart disease starts in childhood or even in the womb if mother has high cholesterol levels during pregnancy. 16% of children in England are living with a chronic medical condition.

This randomised study included 192 participants (32 children and 32 parents/guardians) in each of the 3 groups. Children were aged 9–18 years, living with obesity and with high cholesterol. The study investigated the impact of three healthy diet patterns similar to those recommended by the Dietary Guidelines for Americans (Mediterranean, plant-based, American Heart Association-like) on various markers of cardiovascular risk. The study builds upon the prior pilot study conducted in 30 children and adult pairs, which showed benefits of a plant-based and American Heart Association (AHA) diet on cardiovascular risk factors. The plant-based diet consisted of only whole foods, including fruits, vegetables, beans, other legumes, and whole grains, limited salt, avocado and nuts, and no-added-fat. This group were also supplemented with vitamins B12 and D. The AHA diet encourages eating plant-based whole foods, and low-sodium intake but permits some non-whole foods, low-fat dairy, selected plant oils, lean meat, and fish in moderation. The Mediterranean diet is similar to AHA, with more emphasis given to fish and extra virgin olive oil and/or nuts. The Mediterranean group were provided with EVOO aiming to consume 4 tablespoons per day.

The participants had weight, BMI, blood pressure, and waist circumference measurements at week 4 and 52 of the study and also blood tests for total, LDL and HDL-cholesterol,high-sensitive C-reactive protein (hsCRP), MPO (myeloperoxidase), glucose, insulin, plasma TMAO (trimethylamine oxide), choline, and carnitine. The study incorporated education and support group sessions for the participants. Of note, Jane Esselstyn (daughter of Caldwell) taught the plant-based diet classes.

At four weeks, all diet groups showed significant improvements in body weight, blood pressure and MPO levels. In the AHA and plant-based groups, significant decreases were also seen in total and LDL-cholesterol. Significant improvements were seen in all children’s groups at 52 weeks in total and LDL-cholesterol, fasting glucose, MPO, and waist circumference, and in the AHA and plant-based groups, reductions in systolic and diastolic blood pressure. However, at 52 weeks there was no improvement in weight compared to baseline and in fact the plant-based group had increased weight. There were no significant changes in HDL-cholesterol, hsCRP, and insulin and interestingly in adults in the plant-based group the TMAO levels increased (although not to levels that are associate with harm), this was despite the expected reduction in choline and cartinine consumption.

The study suffered from issues of adherence to the assigned diet and there was a high level of dropout with only 32 children available for the 52 week assessment. Participants reported that the plant-based diet was less acceptable. Overall, the study confirms that healthy diet patterns adopted by families can result in improvements in biomarkers of chronic disease. It also emphasises that the best diet is one that a individual is able to stick to within the general principles of a diet that emphasises healthy whole plant foods. On a population level, more needs to be done to change the food environment and support families to make these healthy choices.

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FRUITS AND VEGETABLES IMPROVE MENTAL WELL-BEING IN CHILDREN: This study confirms that healthy foods choice are not only important for physical health but can improve mental health in children. The study analysed data from 7570 secondary school and 1253 primary school children in the Norfolk Children and Young People Health and Well-being Survey, open to all Norfolk schools during October 2017 and measured the association between nutritional factors and mental health well-being,

In terms of the diet quality of the participants its worth noting that only 25.2% of secondary school children and 28.5% of primary school children in this survey reported consuming the recommended 5-a-day fruits and vegetables, with 9.8% and 9.1%, respectively, consuming no fruits or vegetable. 21.1% of secondary and 1.7% of primary children reported consuming only a non-energy drink or nothing for breakfast. 11.4% of secondary school children did not consume lunch.

The results showed, after adjusting for other potential confounding factors, that higher combined fruit and vegetable consumption was significantly associated with better mental well-being. Just consuming 2 portions a day was associated with an improvement compared to those not consuming any fruits and vegetables, with those consuming 5 or more portions deriving a greater benefit. Consuming a conventional breakfast rather than a snack or breakfast bar was also associated with better mental health. Consuming no breakfast an energy or non-energy drink were all associated with lower mental well-being scores. Not consuming lunch was also associated with lower mental well-being and interestingly so was consuming school lunches compared to a packed lunch. These findings were very similar for primary and secondary school participants.

The authors conclusions are pretty bold and stark ‘The difference in mental well-being between children who consumed the most fruits and vegetables compared with the lowest was of a similar scale to those children experiencing daily, or almost daily, arguing or violence at home. Of course, the study design can not prove cause and effect as it is a snap shot of one point in time and it could be that poor mental health is associated with less healthy food choices (reverse causation).

However, these data are inline with those from adult studies, with a recent meta-analysis of 62 studies demonstrating better mental health well-being in those consuming the most fruits and vegetables.

Sadly, earlier this year, the Veg Facts report from the Food Foundation found a third (29%) of children aged 5–10 years old eat less than one portion of veg a day. UK Government surveys show that only 18% of children eat 5 portions of fruit and veg a day.

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CLIMATE, BIODIVERSITY AND HEALTH CRISIS: I applaud the medical community for speaking out about the global inter-related crises we are facing. More than 200 health journals have called on governments to take emergency action to tackle the “catastrophic harm to health” from climate change. Governments and leaders really do have the ability to change what seems an inevitable trajectory. However, the editorial fails to highlight the necessary and important transition needed to our food system. Without addressing the food system we will not meet global climate targets.

Our PBHP UK member Maria Carolina Rojida put together a response

Dear Editor,

We congratulate your collective initiative demanding urgent action against climate change [1]. However, despite citing many useful strategies, you only made a passing mention about production and distribution of food without touching in any depth on the paramount importance of our eating habits to human and planetary health. For instance:

• We agree with you that the destruction of nature[1] must be stopped for the sake of all the living creatures in this Planet. But let’s clarify that one of the greatest drivers of habitat destruction is our meat consumption: cattle production alone causes 40% of deforestation globally [2]. Our food system constantly converts natural habitats into farmland and reduces biodiversity.[3] Consequently, the biomass of humans and of livestock far surpass that of wild mammals. The same applies to birds where the biomass of domesticated poultry is about three times higher than that of wild birds [4].

• We agree with you that heating is contributing to declines in the yields of major crops.[1] But according to the Food and Agriculture Organisation of the United Nations (FAO), 33% of croplands are used for livestock feed production [5]. If we add that animals take large amounts of feed to produce 1 kg of meat (cattle take 25 kg, mutton 15Kg, pork 6.4Kg, and poultry 3.3Kg of feed to produce 1 kg of meat),[6] it does not make much sense to use our limited resources in this manner.

• We agree with you that our health is affected by the rapid changes in climate we are experiencing. However, while 9.43% of all deaths have been associated with non-optimal temperatures [7], dietary risk factors caused 22% of all deaths in 2017. These deaths were mostly due to noncommunicable diseases [8,9] which in turn cause 71% of all deaths [9] and can be prevented by tackling the root of the problem, our diet.

• We agree with you that the greatest threat to public health is the failure of world leaders to keep the average temperature rise below 1.5°C and to restore nature [1]. But clinicians have also failed at helping patients change the unhealthy diets that drive the destruction of nature and are a major source of greenhouse gas (GHG) emissions (animal-based foods corresponds to 57% of the global GHG emissions from food production compared to 29% from plant-based foods) [10].

If you truly recognise that more can and must be done and that only fundamental changes will reverse our situation [1], then let’s talk about our eating habits: the fundamental actions everyone can take to do what’s vital for the planet while enhancing their own vitality. In fact, individuals have been changing their diets already due to health and environmental concerns [11,12]. However, to fight climate change, sustainable diets must become generalised and clinicians are uniquely placed to encourage patients to make this transition.

As you say, clinicians must do all they can, and they should proactively contribute to prevention of further damage and act on the root causes of the crisis [1]. Since human nutrition is at the crux of the problem, they should educate and empower their patients to change their diets towards less processed and more plant-based foods.

Some clinicians may argue they lack training to provide dietary advice, but if they often recommend their patients to stop smoking without being specialised in pneumonology, why can’t they recommend dietary changes that are known to improve healthcare outcomes and help fight climate change as the EAT-Lancet Commission explained so well [13]? At this point, it comes down to honouring the Hippocratic oath and its “First do no harm” concept by stopping to neglect the power nutrition has over health and sustainability. And if they consider they lack training, they can resort to the many resources available to clinicians, such as:

• The American College of Lifestyle Medicine provides extensive online and in-person resources for different types of clinicians up to Board certification in Lifestyle Medicine [15].

• Plant-based Clinicians UK in association with the University of Winchester offer the first University-based course on plant-based nutrition in the UK along with a many other resources throughout their website [16].

• The Physicians Committee for Responsible Medicine offers many resources for clinicians including CMEs.

• Harvard University provides several online nutrition courses for clinicians [17].

• A new white paper by Food+Planet that “provides a road map of how we might meaningfully close the gap so that we can create a movement among nutrition professionals to catalyse change within the food system” [18].

As we all know, climate change is already disturbing societies worldwide and drastic changes should be implemented at all levels to protect our children’s legacy. The large-scale dietary changes towards predominantly plant-based patterns that clinicians should lead can make a great impact to stabilise Earth’s climate, protect nature, and improve human health and productivity.[13,19]. So, instead of hoping we develop technologies to remove GHG from the atmosphere, let’s reduce the methane and all the other GHG produced by animal farming by switching from animal to plant protein sources now [19].

COVID-19 demonstrated that global action and unprecedented funding can be implemented very quickly. It also showed that after eons of evolution we still follow a fight versus flight behaviour. But if we are the most intelligent beings in this planet, let’s behave as such instead of as the worst invasive species in history. After all the amazing progress we have achieved, now we face the ultimate challenge to evolve beyond our primal inclinations by learning to eat to live and thereby reach the best version of ourselves, physically, mentally, and ethically.

To summarise, in a situation where we need to do everything possible, we should invest our limited time on the exponential effect of drastically changing the actions every human does many times daily: eating and drinking. We can be sure we’ll all die someday, but what if we can give our children healthier lives and fight climate change at the same time? It sounds like the right thing to do.

1. Atwoli L, Baqui AH, Benfield T, et al. Call for emergency action to limit global temperature increases, restore biodiversity, and protect health. The Lancet. 2021;398(10304):939–941.
2. Pendrill F, Persson M, Godar J, Kastner T. Deforestation displaced: Trade in forest-risk commodities and the prospects for a global forest transition. Environmental Research Letters. 2019;14.
3. Benton T. G. BC, Harwatt H., Pudasaini R., Wellesley L. Food system impacts on biodiversity loss. 2021.
4. Yinon M. Bar-On RP, Ron Milo,. The biomass distribution on earth. PNAS. https://www.pnas.org/content/115/25/6506#sec-6. Accessed 23/09/2021.
5. Food and Agriculture Organization of the United Nations. Livestock and Landscapes. http://www.fao.org/3/ar591e/ar591e.pdf. Published 2012. Accessed 18/09/2021.
6. Alexander P, Brown C, Arneth A, Finnigan J, Rounsevell MDA. Human appropriation of land for food: The role of diet. Global Environmental Change. 2016;41:88–98.
7. Zhao Q, Guo Y, Ye T, et al. Global, regional, and national burden of mortality associated with non-optimal ambient temperatures from 2000 to 2019: a three-stage modelling study. The Lancet Planetary Health. 2021;5(7):e415-e425.
8. GBD 2017 Diet Collaborators. Health effects of dietary risks in 195 countries, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet (London, England). 2019;393(10184):1958–1972.
9. World Health Organization. Noncommunicable diseases. https://www.who.int/news-room/fact-sheets/detail/noncommunicable-diseases. Published 2021. Accessed 18/09/2021.
10. Xu X, Sharma P, Shu S, et al. Global greenhouse gas emissions from animal-based foods are twice those of plant-based foods. Nature Food. 2021;2(9):724–732.
11. McCarthy J. DS. Nearly One in Four in U.S. Have Cut Back on Eating Meat. https://news.gallup.com/poll/282779/nearly-one-four-cut-back-eating-meat…. Published 2020. Accessed 18/09/2021.
12. European Consumer Organisation (BEUC). One bite at a time: consumers and the transition to sustainable food. https://www.beuc.eu/publications/one-bite-time-consumers-and-transition-…. Published 2020. Accessed 18/09/2021.
13. Willett W, Rockstrom J, Loken B, et al. Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet (London, England). 2019;393(10170):447–492.
14. ACLM. Lifestyle Medicine Education. https://www.lifestylemedicine.org/ACLM/Education/ACLM/Education/Overview…. Published 2021. Accessed 24/09/2021.
15. ACLM. American College of Lifestyle Medicine Resources for Certification. https://www.lifestylemedicine.org/ACLM/Certification/Approved_CME. Published 2021. Accessed 24/09/2021.
16. Plant-based Clinicians UK. Plant-based Nutrition Course. https://plantbasedhealthprofessionals.com/pbn-course. Published 2021. Accessed 24/09/2021.
17. Harvard University. Online Nutrition Courses. https://online-learning.harvard.edu/subject/nutrition. Published 2021. Accessed 24/09/2021.
18. Vogliano C. G, K., Chou, S., Palmer, S. . Empowering Nutrition Professionals to Advance Sustainable Food Systems [White Paper]. 2021.
19. Harwatt H. Including animal to plant protein shifts in climate change mitigation policy: a proposed three-step strategy. Climate Policy. 2019;19(5):533–541.

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