The Vegetarian Diet: Is it Nutritionally Sufficient?
The vegetarian diet can be adopted for a variety of reasons: for some it is due to religious beliefs, for others it is for moral reasons (animal rights), environmental factors (increased sustainability) or for nutrient or health reasons (higher level of fibre and less saturated fat in plant-based foods). Recent surveys (2010 Newspoll commissioned by Sanitarium Health and Wellbeing) show that people are eating more plant-based foods with the belief that it is beneficial for their overall health. Plant-based diets include fruits, vegetables, legumes, nuts, seeds and grains. People can be classified under 5 various levels of the vegetarian diet according to how much food derived from animals is eaten (Nutrition Australia):
Semi-vegetarian: includes poultry and/or fish, dairy foods and eggs, but no red meat.
Pescetarian: includes fish and seafood but no red meet or poultry (while eggs and/or dairy foods may or may not be eaten).
Lacto vegetarian: includes dairy foods but no meat, poultry, fish or eggs.
Lacto-ovo-vegetarian: includes dairy foods and eggs, but no meat, poultry or fish. This is the most common type of vegetarian diet.
Vegan: excludes all animal products including meat, poultry, seafood, eggs and dairy foods. Most vegans also avoid honey and other animal products.
As with any diet, a vegetarian lifestyle and nutrition plan needs to be well planned in order to ensure all nutrient needs are being met. Research has shown that a well-planned vegetarian diet can reduce the risk of cancer, cardiovascular disease, metabolic syndrome, insulin resistance, type 2 diabetes, hypertension and obesity (The Medical Journal, 2012). A varied, well planned vegetarian diet can provide all nutrients essential for good health, however the nutrients of most concern for those following the vegetarian diet are Iron, Zinc, Vitamin B12, Vitamin D and Long-Chain Omega-3 Polyunsaturated Fatty Acids. Vitamin D and long-chain omega-3 polyunsaturated fatty acids are also a concern for non-vegetarian people who are exposed to minimal sunlight and lack fish in their diet.
The Medical Journal of Australia (2012) concludes the following for each important nutrient:
Protein: A vegetarian diet can meet the recommended protein requirements as long as a variety of foods are consumed and the sufficient energy requirements are met. The consumption of plant-based proteins may actually contribute to the health benefits mentioned above (reduced risk of chronic diseases such as heart disease and diabetes).
Protein Food Sources: Legumes, tofu, soymilk, tempeh, gluten, wholegrains (amaranth and quinoa), nuts, seeds, eggs, milk and yoghurt.
Iron: Vegetarians who eat a varied diet are not at any greater risk than non-vegetarians of iron deficiency. Diets rich in Vitamin C (e.g. fruit) is shown to enhance non-haem iron absorption (plant foods contain only non-haem iron). Those with low iron stores tend to absorb more iron and excrete less.
Iron Food Sources: Legumes, soybeans, wholegrains (amaranth and quinoa), iron-fortified cereals, tofu, tempeh, dried fruit, nuts, seeds, and green leafy vegetables.
Zinc: Vegetarians are at no greater risk of zinc deficiency than non-vegetarians. Vegetarians tend to adapt to lower zinc intakes due to increased absorption and retention for zinc. The inhibitory effects of phytate on absorption of zinc can be minimised by food-processing methods such as soaking, heating, sprouting, fermenting and leavening. Using yeast-based breads and sourdough breads, sprouts and pre-soaked legumes can enhance absorption of zinc.
Zinc Food Sources: Wholegrains, legumes, tofu, nuts, seeds, tempeh, eggs, milk, and yoghurt.
Calcium: Calcium needs can be met as long as a well-planned, varied diet of plant foods is consumed along with meeting sufficient energy requirements.
Calcium Food Sources: Milk, yoghurt, cheese, calcium-fortified soy, rice or oat milk, calcium-set tofu, unhulled tahini, kale, Asian green vegetables and almonds.
Vitamin B12: Vitamin B12 is of significant concern for vegetarians as it is a nutrient almost exclusively found in only animal-based foods. Vegans who limit animal foods in their diet will require vitamin B12 fortified foods or supplements. It is recommended that vegetarians or vegans have their B12 levels regularly assessed to identify any potential health problems. Pregnant and lactating vegetarian women, in particular should ensure a sufficient level of B12.
Vitamin B12 Food Sources: Milk, yoghurt, cheese, eggs, vitamin B-12 fortified soy or rice milk, vitamin B12 fortified meat analogues (vegetarian sausages and burgers).
Omega-3 fats: Intakes of the omega 3 fatty acid- linolenic acid (ALA) is similar in vegetarians and non-vegetarians, however intakes of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are low in vegetarians and virtually absent in vegans. There is currently no strong evidence that vegetarians or vegans experience adverse effects as a result of low intake of EPA and DHA, although it may be beneficial for vegetarians to double the current intake of ALA if no direct sources of EPA and DHA are being consumed. Vegetarians with increased needs (i.e. pregnant or lactating, older people, or those with chronic disease) may also benefit from taking DHA and EPA supplements (200-300mg/day) derived from microalgae.
Omega-3 fats Food Sources: Flaxseed oil, linseeds, chia seeds, walnuts, soy foods, omega-3 eggs and DHA-fortified foods (e.g. breads, yoghurts, orange juice).
Vitamin D: Vitamin D deficiency is a concern for both vegetarians and non-vegetarians alike. The current Australian intake of vitamin D is substantially below the recommended intake. Those with limited sun exposure and older adults should consider supplementing their diet with vitamin D.
Vitamin D Food Sources: Milk, eggs, vitamin D-fortified soymilk, vitamin D mushrooms.
Despite the risk of some of the above nutrient deficiencies, Nutrition Australia reports that vegetarians tend to eat a diet that is closer to the recommended pattern of food intake when compared to non-vegetarians. Vegetarian diets include higher intakes of cereal foods, vegetables and fruits and less saturated fat and salt (Nutrition Australia).
Much research still needs to be done on the optimal diet for heath and wellbeing, however placing an emphasis on consuming plenty of plant-based foods while reducing fatty meats will lead to better health outcomes. A vegetarian diet does not simply mean cutting meat from our diet. It requires careful consideration and planning to ensure all nutritional needs are being met.
If you are new to this lifestyle or want to check you are nutritionally on track, I would highly recommend consulting a nutritionist/medical practitioner.