Tuesday 15 June 2021

Meat-free marvels: does a vegetarian diet reduce your risk of disease?

Is it me, or are there times when contemporary diet trends appear to verge on pseudoscientific crankery? While I briefly mentioned potentially dangerous items such as raw water and unpasteurised milk a few years' ago, it's surprising how many fad diets in developed nations bear a suspicious resemblance to the traditional ingredients of non-Western societies. 

Super foods are a particularly overhyped element of this faddish arena; the marketing suggests they can help achieve perfect 'balance' and 'wellness' in the body. Some assertions go much further, with consumption of the likes of kombucha claimed as something of a miracle cure. While the pseudocereal quinoa is sold in the West as the 'grain of the gods', it is unlikely to give the partaker any super powers. It certainly didn't save the Inca and Anasazi - who cultivated it in pre-Columbian America - from the rapid collapse of their civilisations and apparently suffered from disease and famine as much any other society.

There is a scientific basis for recommending certain non-meat items, from the antioxidants in tea and coffee to the vitamin D in mushrooms, while various plants and vegetable oils contain Omega-3 fatty acids. But a recent report has concluded that a vegetarian diet may have a marked positive effect on overall health compared to one with regular meat consumption. The research was conducted by the University of Glasgow, with the data showing substantial reductions in disease biomarkers for non-meat eaters. However, it was unable to provide an underlying reason for the positive results, once risk factors such as age, alcohol and nicotine intake had been accounted for. Cholesterol and products linked to increased risk of cancers, cardiovascular disease, and liver and kidney problems were all lower in vegetarians.

Apart from suggesting that vegetarians eat more fibre, fruit, vegetables and nuts - some of which have known health benefits - the report's conclusion also noted that rather than the positive effect of these items, avoiding processed meat products and red meat may have also contributed to the results. As someone who hasn't eaten meat in over thirty years, I find the research extremely interesting, although I think there are many other factors that should be considered, with the report forming just part of the debate. 

For example, the data was drawn from c.420,000 people living in just the UK, rather than from a variety of nations and environments. In the past century, the diet and lifestyle of most people in the West has changed enormously, with the emphasis on quick-to-prepare meat dishes including the likes of burgers and sausages, remaining at the forefront despite the replacement of physically demanding lives with predominantly sedentary ones. In other words, the diet hasn't changed to match the alteration in lifestyle. It's little wonder that obesity has outranked malnourishment in some nations.

In addition, it is thought that several billion people, predominantly in less developed regions, consume insect protein on a regular if not daily basis. This is a profoundly different diet to those of Western meat eaters with the latter's concentration on domesticated species such as cattle and horse, sheep/goat, poultry, etc. Although game, bush meat and exotic species such as crocodile are eaten in many regions, these are a much smaller element of the human diet. 

In contrast, vegetarians in many regions can eat an enormous variety of plants and fungi. The geographic and seasonal availability of many fruit and vegetables is expanding too: until a few years ago I hadn't heard of jackfruit, but it is now available as the tinned unripe variety from many stores here in New Zealand. So in both time and in space, there's no such thing as a typical vegetarian diet! This also doesn't include the differences between lacto-vegetarians and vegans; it would definitely be rather more time-consuming to plan a diet with an adequate mix of proteins in the absence of eggs and dairy products. It would therefore be interesting to conduct research to find out the health differences between these two groups.

Although some of the blame for poor health and obesity has been placed on processed and refined foods, there is an ever-increasing array of prepared vegetarian products, often marketed as meat substitutes for meatatarians wanting to cut down on their consumption of animal flesh. My daughters (regular meat eaters) and I have a penchant for fake bacon made of wheat, pea and soy and I also eat a variety of meat-free sausages and burgers as well as Quorn products. 

Many companies are now getting on the bandwagon, with products that aim to replicate the taste and texture of the real thing. Some brands such as Beyond Meat and Impossible Foods have seen a rapid rise to international success, while the UK bakery chain Greggs has benefitted from its tasty (if high-fat) Quorn-based vegan sausage roll becoming one of their top five selling products. Therefore the range of processed foods suitable for vegetarians has grown out of all proportion to those available several decades ago. Could it be that these may have detrimental health effects compared to the less refined ingredients traditionally eaten by Western vegetarians (and still eaten in developing nations)?

Just as there are shed loads of books claiming that epigenetics will allow you to self-improve your DNA through your lifestyle, diet gurus play upon similar fears (and gullibility) to encourage people to eat all sorts of weird stuff that at best maintains equilibrium and at worst can lead to serious health issues. I personally think that a wider amount of research, undertaken in all sorts of regions and societies, needs to be done before a vegetarian diet can be claimed to be distinctly superior to a meat-based one. Of course, a reduction in ruminant farming is good for the planet in general - both for saving water and reducing methane - but as far as a diet equates to health I still think that moderation and a sensible attitude can be key factors in this regard. Nevertheless the Glasgow study certainly is...wait for it...food for thought!

Friday 14 May 2021

Weedbusting for a better world: the unpleasant truth about invasive plants

There's been a lot written about New Zealand's Predator Free 2050 programme, including my own post from 2016, but while the primary focus has been on fauna, what about the invasive species of flora? Until recently it was easy to think of plants as poor man's animals, with little in the way of the complex behaviour that characterises the life of vertebrates and many invertebrates. However, that's been changing thanks to studies that show the life of plants is actually rather complex - and includes the likes of chemical signalling. Although they might not have the emotional impact of animals, land vegetation alone has about one thousand times the mass of terrestrial fauna. So they're important - and then some!

A few months' ago I was volunteering on the sanctuary island of Motuihe, less than an hour's boat ride from downtown Auckland. Our group was charged with cutting down woolly nightshade, a soil-poisoning plant native to South America. Destroying these evil-smelling shrubs made me wonder how and why they were introduced to New Zealand in the first place, considering they don't look particularly attractive and their berries are poisonous to humans. Like so many exotic plant species, they were apparently deliberately introduced as a decorative garden plant, though frankly I can't see why. 

Like many similar stories from around the world, New Zealand has been inundated with large numbers of non-native floral species. Unlike woolly nightshade, some were introduced for practical purposes, such as radiata pine for timber and gorse for hedging, while others were accidentally brought in as seeds in soil. In many cases they are stories of greed and incompetence, for which later generations have paid a heavy price. 

Although there were pioneering lone voices who from as early as the late nineteenth century could see the deleterious effects of exotic plant species on native vegetation, it wasn't until the last half century that any serious effort was made to promote their removal. British botanist and presenter David Bellamy was one of the first scientists to popularise this message, starring in a 1989 television advert to explain why Clematis vitalba (AKA Old man's beard) needed eradicating. Bellamy then went on to present the tv series Moa's Ark, which drew attention to the country's unique biota and the dangers it faced from poorly managed development. 

Given his botanical background, it's perhaps not surprising that rather than see plants as the background to dramas of the animal kingdom Bellamy made them central to the ecosystem, claiming that we should put nature before culture. Again, although lacking the dynamic aspects of fauna, invasive weeds (by definition, aren't weeds just plants in the wrong place?) such as Old man's beard can gain up to ten metres in a single growing season. You only have to look around a suburban garden - mine included - to see that constant vigilance is required to remove the likes of self-seeded wattle and climbing asparagus before they take hold and smother native species.

It isn't just on land that we face this issue: freshwater systems can easily be choked by the likes of Elodea canadensis, a North American pondweed that has escaped from its ornamental aquarium environment (thanks to highly irresponsible people, of course) and been spread by boats and fishing equipment, clogging and stagnating streams and lakes. What is worrying is that it is far short of being the worst of the fifty or so non-native aquatic plants that threaten New Zealand's waterways. Considering that around three-quarters of all invasive species in this environment have a detrimental effect, it clearly makes the point that introduced flora is just not good.

So what can - and is - being done? Thanks to numerous volunteer groups, sanctuaries for rare native species (principally fauna, but occasionally flora too) are keeping invasive weeds at bay. Outside these protected environments, annual weeding programmes aim to reduce wilding pine, but the issue here is that commercial interest still maintains the upper hand. Whether for timber plantations or carbon sequestration, species such as Douglas fir continue to be planted, allowing the seed to spread to new areas far and wide on the wind. Luckily, there are numerous websites to help the public identify and  destroy pest plants; here are just some of the online resources available for New Zealanders:

Clearly, this isn't an issue that will ever go away. With most Government-led efforts focusing on pest animal species, eradicating invasive plants has been given far less support and so they remain comparatively unknown. Perhaps it would be good if schools undertook a compulsory programme, including practical work, in the identification and removal of non-native pest flora? Trapping and poisoning invasive animals can be a complex business, but weeding is comparative child's play. Everyone can help out: in effect, this is a form of citizen science that has a positive practical effect on the environment. Why not start with your garden today?