Many Australians are: in fact, Australia is the world's third-fastest growing vegan market, tailing the United Arab Emirates and China, says Teresa Mitchell-Paterson.

The reasons behind this shift are many: health - the WHO suggests benefits include a reduction in heart disease, cholesterol, blood pressure, some cancers, obesity, and type 2 diabetes; and religious, environmental and ethical motivations.

Going vegan means adopting a totally plant-based diet, eschewing not only animal flesh, but all animal-derived products. The diet is restrictive, so it's no surprise that there are some potential risks relating to inadequate intake of protein, calcium, iron, vitamin B12, vitamin D, and the omega 3 essential fatty acids EPA and DHA. Tell your GP before starting a vegan diet as vegans need regular screenings of serum nutrients to ensure they’re adequate. It’s also advisable to consult a nutritionist or naturopath to ensure you eat the right foods to maximise levels of these and other nutrients.

Protein: While too little protein is an often-expressed concern of a vegan diet, most plant foods contain some protein, and the evidence suggests that vegan diets tend to have a reasonable amount, achieving the desired intake of 0.8 grams per kilogram of body weight. Protein is needed for immune function, bone and muscle health, and for fertility and pregnancy. However, what is difficult is obtaining complete protein, which refers to amino acids, the building blocks of protein. Meat and eggs are complete proteins; beans and nuts are not. Of the 20 amino acids that can form a protein, nine are essential, which means we must eat them as the body cannot make them. Combining foods – generally pulses, beans or nuts with a grain – ensures we obtain all the amino acids necessary to make a complete protein. Tofu is good source of complete protein for most vegans, but check with a nutritionist or a naturopath to ensure continuous consumption of tofu is suitable for you. Another complete source of protein is quorn, a vat-produced fermented fungus called Fusarium venenatum that grows rapidly when fed with glucose and food-manufacturing waste products, such as cereals. This mycoprotein is combined with other ingredients including colourings, artificial flavours, gluten, yeast, starch, acids, omega 6 oils, and gums to create faux meats. Quorn can cause allergic reactions and digestive discomfort.

Iron: Iron is the most widespread nutritional deficiency in the world and is a common deficiency in vegans, along with vitamin B12. Plant sources of iron are spinach and collard greens, tofu, lentils and soy beans. However, it’s difficult to obtain iron to the level delivered by 100 grams of red meat, so while vegans tend to eat enough iron, they have demonstrated low iron-storage levels. This is why it’s necessary to have your GP do a full iron profile: to ensure storage levels are adequate, as non-haem (plant-based) iron is much harder to absorb than haem iron from animal products. To complicate matters, a plant-based diet is generally high in beans, greens, grains and nuts, which contain phytates and oxalates, chemicals that inhibit iron absorption. This can be overcome by adding a little vitamin C, such as a squeeze of lemon juice, to release the iron from a non-haem source. Fermentation also promotes the release the iron from phytate and oxalate bindings, so fermenting beans and grains and activating nuts is highly recommended for vegans. Supplementation can help, but speak to a professional.

Vitamin B12: You’ll almost certainly need supplemental B12, as it’s virtually impossible to obtain sufficient from plant foods. Research shows approximately 52 percent of vegans are B12 deficient, whereas only one out of 226 omnivores – or zero percent – are deficient. B12 is important for the nervous system, energy levels, digestion, mental competence and to prevent anaemia; it also affects serotonin, our 'happy hormone', and melatonin, our sleep hormone. The recommended intake for those deficient in B12 is 1000IU, and I encourage vegans to eat B12-enriched foods every day, such as some soy products, cereals, plant-based milks, and nutritional yeast, which is often added to vegan cheeses.

EPA and DHA: The anti-inflammatory omega 3 essential fatty acid, alpha linolenic acid, is found in vegan foods such as canola oil, walnuts, flaxseeds, pumpkin seeds, and soy beans. However, two key omega 3s, EPA and DHA, are found primarily in fish, and the only way vegans can obtain these is by eating large amounts of seaweed – around 100 grams a day. EPA and DHA are major components in the retina, brain, cell membranes and sperm, and are important for reducing inflammation, blood clots, and blood pressure. Research has verified that vegetarians and vegans have approximately 50 percent less EPA and DHA than omnivores. The human body has difficulty making EPA and DHA from alpha linolenic acid. Conversion can also be disrupted by a high omega 6 intake, to the tune of a 40 percent reduction. Age can disrupt conversion of EPA and DHA from seaweed sources. Again, see a naturopath or nutritionist to ensure your diet is optimal.

Vitamin D and calcium: There’s little doubt that vegan diets deliver less vitamin D and calcium. However, they do have a high level of vitamin K2 from greens, which promotes bone mineral density. While many studies suggest bone mineral density foods are fewer in a vegan diet, lifestyle factors such as exercise and yoga can improve the outcome of bone mineral density. The body is an amazing organism: a lower intake of calcium can cause it to increase gastrointestinal absorption of calcium. So over three to four years of a lower calcium intake, the body will up-regulate its calcium receptors – and this is why long-term vegetarians and vegans rarely suffer from bone-tissue issues. The higher intake of plant oestrogens and the diet's alkaline nature may also account for good bone mineral density. While vitamin D deficiency is not unique to vegans, it's always a good idea to have blood levels checked. D3 (cholecalciferol) supplements are mostly animal-derived, but vegan-friendly D3 supplements obtained from lichen are available, as is D2 (ergocalciferol) from fungi-derived ergosterol.

Teresa Mitchell-Paterson BHSc(CompSci) MHSc(HumNut) AdvDipNat is a member of the Australian Traditional Medicine Society.