Review of the week’s plant-based nutrition news April 25th 2021
This week I cover the impact of lifestyle plus socioeconomic status on cardiovascular disease, vegetarian diets and ischaemic heart disease, impact of soya on hormone health, ultra-processed food consumption in vegans and a call to action for health professionals.
HEALTHY LIFESTYLE, SOCIOECONOMIC STATUS AND CARDIOVASCULAR DISEASE (CVD): Last week I highlighted a paper which concluded that 70% of cardiovascular events could be prevented in the US if the population adhered to healthy lifestyle recommendations. We know that healthier lifestyles are associated with higher socioeconomic status (SES), which also significantly impact health outcomes.
This study is important as it examines the association between healthy lifestyles and socioeconomic status on CVD in two prospective cohort studies from the US and the UK, two countries where wealth inequity is increasing. We know for example from the Malmot report in the UK that the difference in life expectancy between areas of high and low SES is as much as 10 years.The COVID-19 pandemic has further highlighted the disadvantages faced by those of lower SES.
This study examined the relationship between SES and healthy lifestyle assessed by 4 main factors: smoking, alcohol consumption, healthy diet and physical activity levels. For the US cohort, diet was assessed using the healthy eating index (HEI-2015) and for the UK cohort this was based on adequate consumption of fruits, vegetables, whole grains, fish, shellfish, dairy products, and vegetable oils and reduced consumption of refined grains, processed meats, unprocessed meats, and sugar sweetened beverages (much like the Eatwell guide).
The results showed that unhealthy lifestyles were more prevalent in people of lower SES. Participants from low SES had a 2 fold increase in risk of CVD and death from all causes compared to participants of higher SES. Each additional healthy lifestyle factor was associated with 11–17% lower risk of death and CVD and this was applicable across all SES groups, with protective effects of healthy lifestyles stronger in lower SES groups. However, overall only 3–12% of the excess mortality risk associated with SES could be attributable to lifestyle factors. Of note, a recent systematic review of 31 studies showed that about 20% to 30% of the socioeconomic inequity in health outcomes were explained by lifestyle factors.
This study does not mean we shouldn’t promote healthy lifestyles because of the small impact, it just means we have to address upstream social and environmental factors too and advocate for stronger governmental policies to eliminate these health inequities. It remains clear that individuals from disadvantaged SES groups and unhealthy lifestyles have the highest risk of death and CVD.
VEGETARIAN DIET, ISCHAEMIC HEART DISEASE AND DEATH: Last week I reported a systematic review on the impact of a vegan diet on cardiovascular disease outcomes. The main conclusion from the paper was that we just don’t have enough studies to make strong conclusions. In contrast there are many more studies on the health outcomes of vegetarians.
Although still not large when it comes to meta-analyses, this study brought together the results of 8 observational studies with 131,869 participants followed for a median of 10.7 years and investigated the impact of a vegetarian diet compared to a non-vegetarian diet on CVD outcomes. The studies included also had vegan participants but they have been analysed within the vegetarian group and not separately. The main finding was a significant 30% reduction in the risk of ischaemic heart disease. Although there was a signal for benefit, the associations for all-cause and CVD mortality were not statistically significant.
We know that the impact on ischaemic heart disease is due to the lower BMI, blood pressure and better lipid profile in vegetarians and vegans plus the elimination of foods such as red and processed meat that increase the risk of heart disease. The impact on mortality in the studies included is inconsistent, most likely because the quality of diet has not be taken into account. A vegetarian or vegan diet if centred around dairy, eggs, or processed foods is not going to derive the best health outcomes. In studies that have considered a healthy vs an unhealthy plant-based diet, there is a reduction in risk of death too.
All in all, we have pretty good evidence that removing meat from the diet reduces the risk of developing one of our most common chronic diseases. We should therefore consider this the default diet for all of citizens.
SOYA CONSUMPTION AND HORMONE HEALTH: In every talk I give on plant-based diets there is a question on the health impact of soya foods. Some myths are so entrenched. In the last year, mainly with thanks to Mark Messina and team, we have further robust evidence that minimally processed soya foods benefit human health and do not cause any of the problems that ‘Dr Google’ suggests, including breast cancer, thyroid problems, feminisation in men and the list goes on. The only valid reason I can find to avoid soya foods is if you are one of the very rare people with an allergy to soya protein.
This HUGE study investigates whether soya or isoflavones cause disruption of the endocrine system in humans. The paper includes data from 417 reports (229 observational studies, 157 clinical studies and 32 systematic review and meta-analyses). Although soya has a large number of bioactive compounds, the isoflavones get the most attention. These are genistein, daidzein and glycitein, with genistein considered the most potent. There are ethnic differences in the metabolism of these compounds. 25% of Caucasions compared to 50% of Asians have a gut microbiome composition that convert daidzein into equol, a process thought to be associated with some of the health benefits. Isoflavones have oestrogen-like effects, which is part of the reason for the controversy regarding health impacts. However, most of these concerns have arisen following studies in animals and using human cell lines, with no convincing or reproducible harms associated with human consumption.
Soya and isoflovones have for a long time been referred to as endocrine disruptors. The World Health Organization defines an endocrine disruptor as ‘an exogenous substance or mixture that alters the function(s) of the endocrine system and consequently causes adverse effects in an intact organism, or its progeny, or (sub) populations’. Endocrine disruptors have been linked with increased risks for obesity, diabetes mellitus and cardiovascular diseases, impaired male and female reproduction, hormone sensitive cancers, thyroid disruption and neurodevelopmental and neuroendocrine abnormalities.
The current technical review is an extremely thorough and comprehensive review of both observational and clinical studies on soya and isoflavone consumption. It finds no evidence to support a negative impact on endocrine health when isoflavone is consumed at levels not exceeding Asian intake (100 mg/d). This equates to around 4 serving of soya foods per day. That’s not to say higher consumption levels are harmful, it’s just we haven’t got many studies of higher consumption nor is higher consumption desirable when a varied diet is best. The evidence includes a lack of significant effect of isoflavones on reproductive hormone levels in men and women, a possible modest effect on menstrual cycle length (slightly increased but no impact on ovulation), and a lack of effect on thyroid function and on markers of breast cancer risk. The data also supports soya consumption for breast cancer survivors and for prevention of endometrial cancer. Although data in children is more limited, there is no evidence that soya consumption in children causes harm and is likely to prevent later breast cancer development.
The authors conclude that ‘observational and clinical studies covering a broad range of health outcomes likely to be affected by endocrine active substances is that neither soyfoods nor isoflavones warrant classification as endocrine disruptors’.
ULTRA-PROCESSED FOODS, A WORRYING TREND: Ultra-processed food consumption in high and middle income countries are at worryingly high levels. In the UK, more than 50% of foods bought in supermarkets are considered ultra-processed. Decades of research have confirmed the adverse health consequences of this trend with increased rates of cardiovascular disease, type 2 diabetes, overweight and obesity and may be even cancer.
This study, although small, suggests a worrying trend for those avoiding meat consumption. This is a cross-sectional study, from the NutriNet-Santé cohort from France, and investigates the contribution of ultra-processed foods in 4 diet patterns. 19,812 meat eaters, 646 pesco-vegetarians, 500 vegetarians, and 254 vegans. The NOVA classification was used to define ultra-processed foods. Daily food intakes were collected using repeated 24-h dietary records. The results showed that those avoiding meat consumption, vegetarians and vegans, had a higher consumption of ultra-processed foods. Ultra-processed foods provided 33.0%, 32.5%, 37.0%, and 39.5% of energy intakes for meat eaters, pesco-vegetarians, vegetarians, and vegans respectively. The only comment I would make about the classification is that all plant-based drinks were classified as ultra-processed. However, plant milks with no added sugar but some fortification with nutrients such as calcium, vitamin D and B12 do play an important role in vegan diets and there are healthy versions available. On a more positive note, those avoiding meat were also consuming more unprocessed plant foods including fruits, vegetables, whole grains, legumes, nuts and seeds.
This is a worrying trend and undoubtedly driven by the corporate, industrial food complex, which is increasingly influencing all aspects of our food environment. The rise in ultra-processed, fake meat products has risen exponentially, with many high profile investors and typical meat producing companies jumping on board and buying out smaller vegan companies. This is a profit driven trend that will not benefit human health.
We know that an unhealthy plant-based diet can be just as bad for individual health as a meat-based diet, and may be a little worse. Here is an article I have written on the topic. This is an excellent new fact sheet on ultra-processed foods from the Global Food Research Program, summarising the wealth of data on the topic.
HEALTH PROFESSIONALS, CLIMATE CHANGE AND HEALTH: This week has marked Earth Day 2021. The aim of this day at it’s inception in 1970 was to give a voice to an emerging public consciousness about the state of our planet. April 22nd each year is marked as a day of action to change human behavior and create global, national and local policy changes.
Health professionals have been called to action by their professional organisations. Without a healthy planet there are no healthy people, so in the words of Dr David Katz ‘you cannot rightly call yourself a ‘health’ professional any longer if you don’t advocate frequently, and fervently, for the health of the planet’.
This paper reports findings from a large, multinational survey of health professionals (n=4654) that examined their views of climate change as a human health issue. Participants were from around the world with the majority from Canada. Participants in this survey recognised the impact of climate change and that it is caused by human activity. They acknowledged that climate change is a growing threat to human health and felt a responsibility to educate the public and policy makers. However, a number of personal, professional, and societal barriers were identified that prevented them taking action. The main one being time constraints. Other barriers included insufficient knowledge, a belief that engaging with the public would not make a difference, that one’s peers would not support their efforts and that speaking out would be ‘risky’ for them professionally and personally with the topic being ‘too controversial’. The authors state ‘Behavioural scientists (and health professionals) have long understood that even highly motivated people often do not engage in the actions that are consistent with their motivations’.
I personally have experienced all these barriers in my mission to advocate for healthy plant-based diets, an essential part of the solution for the climate and ecological crises. I have certainly been ridiculed, ignored and attacked by my peer’s and the topic is still considered controversial amongst health professionals. I also was not adequately educated on the topic when I first started out. However, this issue is too important to stay quiet. We must act now to protect the future of this planet.
My top tips are to surround yourself with like-minded people who support you and share similar motivations. Educate yourself. There are so many resources now that you don’t need to wait for the education to be directly available to you. Do what you can rather than nothing at all, as every small action counts towards the bigger picture and if you can’t take action yourself join and support an organisation that is doing so.
Times are changing (slowly), and even my work place King’s College Hospital in London has agreed to promote the international campaign No Meat May to it’s staff with myself and colleagues providing information, education and cooking events to support. You can also join Dr Laura Freeman and me at the Planetary Health Alliance annual conference on April 29th, supported by WONCA, the Global Organisation for Family Doctors for an urgent discussion on ‘Should family doctors consider being more assertive about advising their patients to cut down on red meat’. Register here with livestream here.
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