Is it possible to be completely vegan

The latest nutrient in question is creatine — a white, powdery substance often found in fitness shakes. This has led scientists to wonder whether a creatine deficit could be holding some people back.

For one study, researchers tested how the intelligence of vegetarians and omnivores changed after five days on supplements. In contrast, the omnivores were relatively unaffected. This hints that, unlike the vegetarians, they already had the appropriate amount of creatine in their brains.

Creatine, carnosine, taurine, omega-3, heme iron and vitamins B12 and D3 only occur naturally in foods made from animal products Credit: Getty Images. Nevertheless, Cofnas finds the potential creatine deficits in vegans disturbing.

But there are 40 or something essential nutrients. Instead, they need to be taken individually. Benton agrees. Cofnas takes a harsher view. As for Gandhi, he eventually abandoned his illicit relationship with meat, and went back to vegetarianism. He also ditched salt, then went back to it, and attempted veganism — though after a bout of dysentery practically reduced him to a living skeleton, he decided that milk products were necessary, in order for a person to be healthy.

An earlier version of this article stated omega-3 generally only occurs in animal products. The article has been corrected to make clear there are three types of omega-3 fatty acids and that one of these, ALA, is found mainly in plants. The article also stated that Nathan Cofnas was a biologist at the University of Oxford. He is in fact studying philosophy of biology at the University of Oxford and has co-authored studies looking at the impact of the vegan diet on health and the brain.

The article has been corrected to reflect that. Join one million Future fans by liking us on Facebook , or follow us on Twitter or Instagram. If you liked this story, sign up for the weekly bbc.

The Vegan Factor Food. How a vegan diet could affect your intelligence. My advice is to replace products in your diet with alternatives step by step, be it milk, mayonnaise or yoghurt.

Kill the haters with kindness — and delicious food. And cook for them — you get to show them how yummy things are. Be empathic towards people expressing negative attitudes. Just try to educate them as best you can. Humour helps. My farts smell like broccoli.

You can just sprinkle a handful of toasted pine nuts over some pasta or add a can of beans into your chilli. Heather Russell, a registered dietician at the Vegan Society , says there is no cause for concern. In reality, they can provide all the essential protein building blocks that we call amino acids. Good sources include beans, lentils, chickpeas, soya products, peanut butter, cashew nuts and pumpkin seeds. If you are going vegan, it is important to make sure you get enough vitamin B12 — commonly found in meat, eggs and fish — as without it, you will feel exhausted and weak.

Alternatively, you can take a B12 supplement, which you can buy in most pharmacies and health-food stores. Russell also advises you think about your calcium intake. While the beetle does not need to be killed in order to harvest the shellac, some beetles are inevitably killed or injured in the shellac collection process.

Most people associate the word "shellac" with furniture, but it can be used as wax to coat fruits and vegetables, and is disguised in candy as "confectioner's glaze. Beeswax, which comes from bees, is also used to preserve fruits and vegetables and delay rot. Casein, a milk product, is used in wax to coat fruits and vegetables.

The wax can also be vegetable-based. The FDA requires a label or sign to identify fruits and vegetables that have been coated with wax but does not require the label to state whether the wax is of animal or vegetable origin. Any vehicle, commercial or personal, that travels at a great rate of speed is also a potential killing machine for a variety of animal life forms, large and small. Birds get sucked into airplane engines. Numerous deer are killed by cars, trucks, and trains every year, not to mention companion animals, raccoons, armadillos, possums, and even snakes.

And, as anyone who drives can tell you, insects hitting car windshields is a fact of life—and for the insects, a fact of death. Certain rubber materials, paints, glues, plastic products, and other chemicals routinely contain animal products but because they are not foods, manufacturers are not required to disclose their ingredients—though many in fact do. This is generally not done in pursuit of animal welfare, however. Product labeling is a consumer protection that warns people of potentially reactive ingredients or allergens.

If you want to make sure a product you're using is animal-free, it's incumbent on you to do the research. Contact the company if you have to or find an alternative product you know to be animal-free. Aside from the known animal ingredients in various products, consumer products are killing animals in the form of farming, mining, drilling, and pollution. The manufacture and harvesting of products made of wood, metal, plastic, rubber, or plants is often a detriment to wildlife habitats.

They found that if all animals were removed from the planet, the amount of food available to humans to eat would increase by 23 per cent. This is because the grains that are currently used to feed animals could be consumed by humans. This would lead to an increased supply of certain important nutrients, including carbohydrates, copper, magnesium and cysteine.

There would actually be more than the population needs. However the supply of some important nutrients that we now get from animal products would decrease, including calcium, vitamins A and D, B12, arachidonic, eicosapentaenoic and docosahexaenoic fatty acids.