快猫短视频

JANUARY is the time of year when many of us take a rain check on our indulgences. We politely wave away puddings, gyms heave with new recruits and plenty of us lay off the booze. This year, it is estimated that at least 1 million people will do something even more challenging: eat a vegan diet for the month.

Choose to follow suit and you can forget about that juicy bacon sandwich, say goodbye to scrambled eggs and there will be no more milk in your coffee. It is a challenge not to be sniffed at. But it is a worthy one: the evidence suggests that, done carefully, veganism is good for our health and great for the planet.

Perhaps that explains the growing trend towards part-time veganism, of which Veganuary is just one example. The vegan before 6 pm (VB6) diet is gaining popularity in the US, principally as a means of losing weight. And the meat-free Mondays campaign is also getting traction, with more restaurants offering vegan options as well as vegetarian ones. 鈥淭he thought of never eating meat again is, for most people, overwhelming,鈥� says Toni Vernelli at , a UK charity. A part-time vegan diet is more manageable and surely offers a portion of the same benefits.

Or does it? It is conceivable that some of those who dip briefly into vegan eating might not get the right balance of nutrients. With a lack of experience in making vegan meals, it is easy to opt for pre-prepared dishes, which may cancel out the positives. Can you really be a casual vegan and still reap the benefits?

The experiment

To find out, we teamed up with researchers from the Livestock, Environment and People (LEAP) programme at the University of Oxford to run a pilot experiment. A band of 19 快猫短视频 staff kept strict food diaries for a fortnight, eating their usual diet for the first week and sticking to veganism for the second. We used an app called MyFitnessPal to keep track of the food in detail. Most of the group were full-blown meat eaters, but there were three pescatarians and three vegetarians, which gave us a hint of the different benefits of swapping diet for different groups.

The LEAP researchers then analysed our diaries to see the effects on the environment and our nutrition. More research will be needed to confirm what we found, but, as far as we know, this is the first study of its kind, involving real food diaries from people dipping their toes into veganism.

Saving the environment

By Alison George

鈥淚 eat meat most days. I live for a well-cooked steak at the weekend and can鈥檛 imagine a life without yogurt, milk and cheese.鈥� These were the words of one volunteer just before our vegan experiment. Facing up to the reality of a meat and dairy-free existence can be daunting. But if you are concerned about the climate crisis, giving up animal products is one of the key things individuals can do to help.

It isn鈥檛 hard to see why veganism is better for the planet than other diets in principle. If you eat a plant, that is more efficient than taking a plant, feeding it to an animal 鈥� which makes tissue from it and belches out greenhouse gases in the process 鈥� and then eating the animal. 鈥淎 large amount of crops are used to feed animals. It鈥檚 inefficient,鈥� says , who is part of the LEAP programme. This goes for dairy products too. Indeed, cheese typically has a higher carbon footprint than the equivalent weight of pork.

Calculating the carbon footprint of food is no simple matter, however. Most assessments of the impacts of our eating habits start with hypothetical diets. Once researchers have compiled a list of foods, they estimate all the carbon emissions associated with the production of each one, including the use of fertiliser, pesticides, land and fuel. This information can then be used to calculate the total environmental impact of a food.

Carbon dioxide isn鈥檛 the only greenhouse gas emitted during these processes. There is also methane, which is 25 times as potent as CO₂ 鈥� albeit shorter-lived in the atmosphere 鈥� and nitrous oxide, which is about 300 times as potent. Studies tend to wrap these gases together in units of carbon dioxide equivalent (CO₂e), the quantity of CO₂ that would be needed to give the same greenhouse effect.

One of the most was conducted in 2018 by Joseph Poore at the University of Oxford and Thomas Nemecek at the Agroscope research centre in Zurich, Switzerland. They looked at a data set covering 119 countries and including products that represent 90 per cent of all human calorie intake. This revealed that the environmental impact of all foods was greater than previously thought, but especially that of animal products.

Meat and dairy contribute about 60 per cent of agriculture鈥檚 greenhouse gas emissions, and provide only 18 per cent of our calories. 鈥淲e calculated that cutting out animal products would reduce the greenhouse gas emissions of food systems by 49 per cent. That鈥檚 incredible cost-cutting,鈥� says Poore. A 2016 reached a similar conclusion: established vegans had a dietary carbon footprint that was 34 per cent lower than that of meat eaters. Would our experiment on part-time vegans back this up?

In general, yes. On average, there was a 53 per cent fall in greenhouse gas emissions when participants ate a plant-based diet compared with their usual one (see 鈥�Plants for the planet鈥�).

Things get more interesting when we look at the differences in carbon savings between say meat eaters going vegan and vegetarians doing so. That study of 153 Italians found no difference between the carbon footprint of a vegetarian and vegan diet. 鈥淎 likely explanation might be that, while unprocessed, plant-based foodstuffs usually replace animal-based products in hypothetical vegetarian and vegan diets, real plant-based diets are instead characterised by highly processed meat and dairy substitutes,鈥� says Francesca Scazzina at the University of Parma in Italy, who carried out the study.

Yet our three vegetarians reduced their dietary carbon footprint by 42 per cent on average, showing that serious carbon savings are possible. This aspect of our results can鈥檛 be the basis for sweeping conclusions because it only covers three people, but it is interesting nonetheless. 鈥淲e don鈥檛 realise how much difference we can actually make,鈥� says Clark.

To put this in perspective, I worked out how much carbon each of our meat eaters would have saved if they had eaten a vegan diet for a month: 80 kilograms CO₂e. That is the equivalent of forgoing a car journey of roughly 400 kilometres or an 800 km flight, such as between Switzerland and London. Each of our vegetarians would have also saved significant quantities of carbon if they carried on eating vegan for a month, about 40 kg CO₂e or the equivalent of a 200 km drive.

I have been a pescatarian for years and had assumed that the carbon footprint of my diet would be on the smaller side already. I was gobsmacked to find that giving up fish and dairy slashed it in half.

All in, food makes up about a quarter of our carbon footprint, so reducing consumption of animal products is one of the main ways I can reduce mine. Even so 鈥� and despite the fact that I love the taste of veggie burgers, tofu and lentils 鈥� I don鈥檛 think I could commit to being a full-time vegan, mainly due to the inconvenience to others I share my meals with. But I鈥檓 certainly going to be thinking vegan when it comes to making my lunch at work.

This isn鈥檛 to say that plant-based foods aren鈥檛 damaging to the environment. Our study looked only at the carbon footprint of our diets, but food production degrades the environment in other ways, not least using up water and land. Poore鈥檚 study found that it can take more water to grow nuts or peas than to produce the equivalent weight of beef. Almonds require particularly large amounts of pesticides and fertilisers. Swathes of forest have been cleared in Asia and South America to grow oil palms.

Still, even the lowest-impact animal products, such as poultry and eggs, tend to be more damaging overall than substitute vegetable proteins such as pulses and nuts. This is also true of the carbon footprint of plant-based milks, made from soya, oats, rice and more. 鈥淓ven if we could reduce all animal protein products to their lowest impact, 鈥� says Poore.

One possible benefit of going vegan part-time could be that it influences people鈥檚 habits even after they return to omnivorous eating. There is some evidence that abstaining from animal products for a while brings about long-term changes. Unpublished research from consultancy Kantar on the supermarket till receipts of more than 600 people in the UK who gave up meat for January in 2018 found that a year later they purchased less meat and eggs (although their milk and cheese consumption slightly increased).

What of our staff guinea pigs? Did their dalliance with veganism inspire them or send them running to the nearest steakhouse? An informal survey two months after our trial found that many had largely returned to their former eating habits, but there were lasting impacts to the benefit of the planet, as the quotes sprinkled around these pages show.

In future, it might be even easier to reduce the carbon footprint of our diet, with the advent of new foods that bypass the farmyard and field. Milk alternatives might be brewed from yeast in a similar way to beer, real meat could be created through tissue-culture techniques and tasty proteins might be created from thin air using bacteria that suck up CO₂ as they grow. These methods could, in theory, produce meat and dairy products with a fraction of the carbon footprint of those made from plants. Can鈥檛 imagine going vegan? One day you might not have to.

Nutrition boost?

By Helen Thomson

As I was chewing on my third vegan ready meal of the week 鈥� BBQ 鈥渞ibs鈥� made from wheat protein (a mistake) 鈥� it occurred to me that I probably wasn鈥檛 doing this right. I had assumed that going vegan, even for a short period, would mean eating a healthier diet. That, after all, is what . The plant-based diet can help you lose weight, lower your cholesterol, reduce your risk for certain cancers, even add a few years to your life. But it seemed it was all too possible to take unhealthy shortcuts. I swallowed my ribs and wondered how the others were getting on.

To get to the bottom of all this, LEAP researcher went through our food diaries with a fine-tooth comb. She calculated our total daily nutrients and worked out what percentage of our calories came from what kinds of foods. It was immediately apparent that our diets changed significantly. In the vegan week, we consumed fewer calories and less saturated fat, carbohydrate and cholesterol, while significantly increasing our fibre intake (see 鈥�Vegging out鈥�).

This seems like generally good news. In the 20th century, researchers discovered a link between high cholesterol and the furring of arteries that causes heart attacks. Although we now know that some kinds of cholesterol are bad, and others help build lean muscle and actually clean artery walls, doctors still lean towards keeping your overall cholesterol levels low.

What鈥檚 more, reducing your saturated fat intake has been firmly linked to a decreased risk of heart disease and lung, colon and breast cancers. The important detail here is what you replace those fats with. If you are swapping them for carbohydrates like white bread and low-fat dairy products, you are less likely to see those benefits, probably because of the increased sugar intake. But if you are replacing them with plant-based products such as leafy vegetables, beans and oats, the health benefits soar.

Another benefit of the vegan week was a boost to fibre consumption from around 21 grams a day to about 30g, which is the recommended daily target in the UK. Our group swapped meat for fibre-rich foods such as beans, lentils, whole grains and vegetables. A high-fibre diet can decrease risk for type 2 diabetes, cardiovascular disease and colon cancer by speeding up the passage of potential carcinogens through the gut and feeding 鈥済ood bacteria鈥�. Emerging evidence has even suggested that a high-fibre diet can help prevent infections and .

But does a week of vegan eating really make any difference? Probably not, if it is just a week, says , part of the LEAP team. We know that it takes more than a week to change your body mass index and blood pressure, for instance. 鈥淭hat said, most of the changes were really positive, and similar to the dietary changes that we鈥檙e seeing in long-term vegans,鈥� she says. That suggests that regular forays into veganism could put you on the right track for long-term health benefits.

So far, so healthy. But meat, fish and dairy provide essential nutrients. Without these staples, covering all your nutritional bases takes effort. It is recommended that 10 to 15 per cent of our diet is protein, for instance. Without it, we can suffer muscle wastage, find it more difficult to fight infections and be at greater risk of high blood pressure.

Most meat eaters in the Western world get plenty of protein, but it is more complicated for vegans. The proteins in meat are known as 鈥減erfect proteins鈥� because they can be broken down into all the essential amino acids that the body can鈥檛 produce itself. Certain vegetable proteins such as those in soya and gluten fit the same bill. But those from whole grains and legumes are harder to digest, and sometimes certain amino acids are missing altogether from rice, nuts and some cereal crops. However, Stewart points out that our participants were still getting the recommended amount of protein. In general, she says, as long as you eat plant-based protein from a variety of sources this shouldn鈥檛 be anything to worry about.

Calcium intake also decreased, which over time can lead to brittle bones, tooth decay, cataracts and fatigue. Another potential concern is with omega-3 fatty acids, which keep our cells and cardiovascular system tip-top. Although it wasn鈥檛 possible to identify this from our food diaries, without meat, vegans can lack these fatty acids. Vegans can find them in chia and flax seeds, and some nuts and leafy veg, but often take supplements to top up. Vitamin B12 is vital to our health too 鈥� potentially 鈥� and because it is made by the bacteria in animals, omnivores don鈥檛 have to give it much thought. Vegans need to look to fortified breakfast cereals and nutritional yeast to get their supply.

鈥淢any no longer see veganism as an all-or-nothing proposition鈥�

Choline is also an essential nutrient critical to brain health, especially in developing fetuses, but it is found mainly in beef, eggs and fish. , which is particularly concerning in light of current accelerated trends towards plant-based diets, says Emma Derbyshire at consultancy Nutritional Insight.

There are ways of getting all these nutrients on a vegan diet and you would know them with experience. But that is just what our part-time vegans didn鈥檛 have. A straw poll showed that our motley crew were aware they would need to find replacements for some of their nutrients, but didn鈥檛 give it much more thought. 鈥淚 was aware that getting adequate protein is an issue for vegans, but as it wasn鈥檛 a permanent lifestyle change, I didn鈥檛 go all in and make the necessary dietary changes,鈥� said one participant.

Part-time vegans might not give as much thought to their diet as full-time vegans, but that may not be a problem if they are likely to be topping up any missing nutrients on non-vegan days, says Papier. A bigger issue might be that as veganism grows in popularity, so too do vegan ready meals 鈥� like my cheeky BBQ ribs 鈥� and vegan versions of unhealthy snacks. Like their non-vegan counterparts, these can be high in sugar and salt.

Speaking earlier this year, Roger Whiteside, chief executive of UK bakery chain Greggs, whose vegan sausage rolls have become a hit, admitted to trialling veganism for its health benefits, but said he was finding it difficult to make things from scratch. 鈥淚t would be OK if I had time to cook,鈥� he said, 鈥渂ut I don鈥檛, so I have to have things that are quick and easy.鈥� Many of our part-time vegans also said they turned to quick, unhealthy ready meals instead of making the effort to find new recipes to cook at home.

Not everyone is on board with part-time veganism. The recognises that cutting down on our consumption of animal products can have a lot of positive benefits. However, Dominika Piasecka, a spokesperson for the charity, says that veganism is a deeply seated ethical conviction that killing and using animals is wrong. 鈥淚t isn鈥檛 something people can do part-time,鈥� she says.

Largely driven by the health and environmental benefits, many people no longer see the issue as an all-or-nothing proposition. If you are one of those thinking about being vegan-ish, you can rest assured that it probably has positive health benefits 鈥� particularly if you pay attention to what you might be missing.

For Papier, flexi-vegan eating has got to be a good thing. 鈥淚f you鈥檙e doing it for a day each week or one month each year, over time you will have consumed fewer meat-based products, which might have beneficial health effects.鈥� Our small trial also suggests that being a part-time vegan might lead to unexpected long-term changes. Many of our participants said they ended up being more thoughtful about what they ate, cut down their meat intake or, in one person鈥檚 case, 鈥渁t least stopped putting cheese on everything鈥�.

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