Saturday, 23 March 2019

What I wish I'd known about vegan diets

Cora Bailey rescues a sick piglet from the Randfontein dump, South Africa. Photo credit: We Animals

After 25 years of eating meat, one of my friends suggested that I try a vegetarian diet for January.  I found myself eating healthier and feeling better.  So here it is from three different lenses: nutrition, environment, and ethics. 


A plant-based diet can provide you with all the nutrition you need. The British Association of Dieticians confirmed it:
A well-planned vegan diet supports healthy living in people of all ages, including during pregnancy and breastfeeding.
But a vegan diet is not necessarily healthier than a non-vegan diet. There is no intrinsic benefit to a raw food vegan diet, and in fact it can be calorically deficient — which is a problem for children and teenagers.

However, vegans like Dr Neal Barnard and self-branded YouTube experts incorrectly argue that vegan diets cause longer lives, significantly reduce cancer risk, and even reduce ageing. Studies like the China Studies and the study of Seventh-day Adventists are often touted as proof that their diet is nutritionally superior to all others.

The evidence simply does not support this, and many of these studies are sloppy. The NHS’s Behind the Headlines reviews one such study in this article:
As this study is a cohort study, it cannot show cause and effect, as it is possible that other factors are responsible for the associations seen. Although the researchers adjusted for many of these factors, it was found that the vegetarian groups tended to be older, more highly educated and more likely to be married, to drink less alcohol, to smoke less, to exercise more and to be thinner. The reduced risk of death may be due to other lifestyle factors of vegetarians rather than diet.
And these advocates fail to mention that vegans should be making sure they get enough calcium, iron, and B12. Good diets are good advocacy. In terms of my own nutrition, I carry a small printed-out version of this chart in a notebook, and shoot for two protein sources, seven fruit/veg, and wholegrain carbs.

Yes, vegans should take a multivitamin in order to get vitamin B12, but so should all adults in the UK. I take one of these which are very cheap. All adults in the UK are recommended to take a vitamin D tablet every day, but few do. If you take a multivitamin, like the one above, with vitamin D, then you might well be the only person in your family/friends not to be deficient in a vitamin!
Summary: Nutrition is a complicated field, and there's mixed evidence about the benefits of a more plant-based diet. Evangelists are overstating the case. There are things to watch out for, e.g. iron and B12.


With the UN’s International Panel on Climate Change (IPCC) and media proclaiming the urgency of reducing global greenhouse gas emissions, many people are reducing their meat consumption in order to support the global effort to mitigate climate change. One aspect of climate change is how rapidly we produce greenhouse gases which increase the overall warming effect.

You might be wondering how significant the effect of reducing meat consumption is. Does it really make that much of a difference compared to a gas-guzzling SUV? There are different types of greenhouse gas (GHG), and the warming effect of animal agriculture comes from methane, but the effects are measured in CO2-equivalent.

In terms of CO2-equivalent,
  • Moving from a high meat diet to a low meat diet would reduce an individual’s carbon footprint by 920kg every year
  • Moving from a high meat diet to a vegetarian diet would reduce the carbon footprint by 1,230kg year
  • Moving from a high meat diet to a vegan diet would reduce the carbon footprint by 1,560kg year
For context, an individual seat on an economy return flight from London to New York has an addition to their carbon footprint of 960kg. A small family car has an carbon footprint of 2,440kg. So two adults moving to a vegetarian diet is comparable to stopping driving a car permanently. The full study is available here.

Our actions impact the environment in multiple different ways. From an environmental perspective, it doesn’t make sense to have an ‘obsession with ingredients’. The air miles that we and our food travel, and the packaging and distribution of our food also contribute to our environmental impact. If I forgo a beef burger, and instead eat only chips from a plastic takeaway box, then leave this as litter by the seaside and the plastic is ingested by a seagull, then I’m not considering the broader context of my actions and how they impact animals and the environment.

Summary: A more plant-based diet is lower impact for the environment overall because of agriculture's inefficient use of resources and contribution to climate change. But we impact the environment in other ways too.


In 2012, a group of scientists from a range of animal sciences gathered at Cambridge university. The list of talks included topics such as the neural properties of mice, the ability of African parrots to recognise themselves, and the memories of octopuses. They signed the Cambridge Declaration on Consciousness, which stated:
The absence of a neocortex does not appear to preclude an organism from experiencing affective states. Convergent evidence indicates that non-human animals have the neuroanatomical, neuro-chemical, and neurophysiological [components] of conscious states along with the capacity to exhibit intentional behaviours.
Consequently, the weight of evidence indicates that humans are not unique in possessing the neurological [components] that generate consciousness. Nonhuman animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological [components].
Animals feel and suffer in ways similar to us. For cows, pigs, rabbits, chickens, and even octopuses, fish, and probably shrimp, the evidence suggests that the lights are on. The neurological experience of pigs confined to a farrowing stall is comparable with that of a dog trapped in a small cage. 
  • Chickens have 20 different calls to communicate with each other. Chickens like to explore their environment, for example by pecking at objects. They have an innate desire to groom themselves.  Most chickens never see sunlight. The growth rate causes heart problems, foot pad burn, leg disorders, and sudden death. Chicken slaughter is rapid, automated (and often inaccurate) to minimise cost.
  • Pigs are inquisitive, social animals, and in learning tests they outperform dogs. Pigs express emotion, as happy pigs often have curly tails whereas pigs that are stressed tuck their tails between their legs. In the UK, 80 percent of piglets have their tails cut off shortly after birth, to reduce the likelihood of tail biting, a symptom of physical or mental stress.
  • Cattle are social animals and find isolation from other cattle stressful. They make lifelong friendships, and lick each other to show affection. Dairy cows live for 5 years, out of a potential of 25, where they are made to produce 10 times more milk than they would naturally, leading to around a deformities such that around third of cows are lame (unable to walk).
  • Fish: there’s evidence they navigate using complex remembered maps, and that fish kept in confined spaces exhibit signs of stress and try to cool their body temperature to calm down. As far as we can tell, fish can suffer and feel pain in ways much like many other animals. Most commercially-caught wild fish, that are alive when landed, die either from being left to suffocate in air, or by a combination of suffocation and being gutted. 
  • Eggs and dairy: as chick culling is routine in egg production, and as the treatment of egg-laying hens is similar to that of meat chickens, a similar level of suffering is generated. Dairy involves significant suffering of calves, and mothers are ultimately slaughtered themselves. 
  • Oysters and mussels: it's debated. Some people argue that oysters are conscious because of the presence of chemicals associated with pleasure and pain, but others argue that because their movement is very limited, they’re not conscious.
Summary: Surprisingly, the standard treatment for animals is pretty bad. Standards like 'free range' really don't mean anything. I think there's a clear case that farmed animals are treated badly. 

My conclusion

My initial thought was that I couldn’t be healthy on a vegetarian diet. But after a month trial of being vegetarian, I ate better and felt better than before in my life. My food bill was easily 30% cheaper. From a nutritional perspective, a diet with less meat is generally a good idea, and even a vegan diet can be very healthy, but you want to make sure you get enough iron and vitamin B12. So overall, I think the nutritional argument for a vegan diet is mixed, and depends on other factors. 

There are also environmental benefits to eating less large ruminant animals, given the many different aspects of sustainability from animal agriculture, from water usage to soil erosion. But if you’re looking for the fastest way to cut your carbon footprint, it’s probably flying less, or donating to one of these organisations (£1 averts 1 tonne of emissions). The environmental argument to have a less meat-heavy diet, and even to have a vegan diet is pretty strong.

But for me the ethical case is compelling. Tens of billions of small and large creatures are confined in small spaces, malnourished, ill, and pumped with antibiotics in order to deliver us cheap meat. And most of society turns a blind eye.

As human technology advances, I hope that we transition away from eating animals, in the way that we might transition away from coal and gas to more advanced energy systems, and we transition to synthetic meats and plant-based foods. I'm proud to try to play some small part in bringing that day forward. I hope that one day the last factory farm is closed, and that we turn our backs on what may be one of the biggest crimes of the human story. 

No comments:

Post a Comment

What is the best way to reduce your carbon footprint?

In a 2017 paper in Environmental Research Letters , the authors compare popular advice around reducing individual contributions to climate ...