This article has been republished in the MJA
It is not only what a diet excludes, but what it includes, that shapes health outcomes. This article is a practical guide for doctors to help them advise patients on nutrient-rich foods, which should form the basis of all types of plant-based diets. Of the recognised types of plant-based diets (Box 1), the most widely studied is the lacto-ovo-vegetarian diet.
Plant-based diets focus on fruits, vegetables, legumes, nuts, seeds and grains. Some vegetarian diets also include eggs and dairy, and a few traditional (eg, Mediterranean and Asian) plant-based diets include limited amounts of meat and/or seafood.
Plant-based diets may provide health benefits compared with meat-centred diets, including reduced risks of developing chronic diseases such as obesity, heart disease, colorectal cancer and type 2 diabetes.1
Plant-based diets more closely match recommended dietary guidelines to eat plenty of fruits, vegetables, legumes and wholegrains, and to limit intakes of saturated fats and sugars.3
A 2010 national Newspoll survey of 1200 adults indicated that 70% of Australians consume some plant-based meals in the belief that eating less meat and more plant foods improves overall health (Newspoll Research, Leaders in Nutrition, May 2010, com-missioned by Sanitarium Health and Wellbeing).
A vegetarian diet does not mean just cutting out meat. Careful planning, along with knowledge of practical ideas for using a variety of plant foods, is needed to ensure nutritional requirements are met, particularly for new vegetarians or those with special needs.
Nutrients that may need more attention in a vegetarian diet include iron, zinc, calcium, vitamin B12, vitamin D and omega-3 fats. It may be beneficial to refer people to an Accredited Practising Dietitian experienced in vegetarian nutrition.
Any dietary change can increase preparation time to begin with, but cooking plant-based meals need not be more time consuming after some training and regular practice.
A minimally processed plant-based diet, with limited (if any) amounts of animal foods derived from animals lower down the food chain, provides environmental advantages over a Western-style meat-rich diet.4-6
Studies of Australian vegetarians have found that although their protein intakes are significantly lower than those of omnivores,7,8 their intakes still easily meet recommended dietary intakes (RDIs) because most omnivores eat much more protein than is required. Most plant foods contain some protein, with the best sources being legumes, soy foods (including soy milk, tofu and tempeh), nuts and seeds. Grains and vegetables also provide protein. A glossary of protein-rich plant-based foods is provided in Box 3.
As most plant foods contain limited amounts of one or more essential amino acids it was once thought certain combinations had to be eaten at the same meal to ensure sufficient essential amino acids. Research has found that strict protein combining at each meal is unnecessary, provided energy intake is adequate and a variety of plant foods are eaten over the course of a day, including legumes, wholegrains, nuts and seeds, soy products and vegetables.9 Soy protein is a complete protein as it has a Protein Digestibility-Corrected Amino Acid Score (PDCAAS) equivalent to that of eggwhite or dairy protein (casein).10
Vegetarian diets can contain as much or more total (non-haem) iron as mixed diets; this iron comes primarily from wholegrain breads and cereals.11,12 Iron deficiency anaemia is not more common among vegetarians, although their iron stores (serum ferritin levels) are often lower.7,12,13 Some studies have found that lower iron stores are associated with reduced risk of chronic diseases (such as cardiovascular disease and type 2 diabetes), which may partly explain the lower risk of these diseases in vegetarians.14,15
Dairy products are not the only sources of calcium in the diet. Fortified soy, rice and oat milks, unhulled tahini, Asian greens, almonds and calcium-set tofu are good sources of bioavailable calcium in non-dairy diets.16,17 Calcium needs can be met using plant foods as long as adequate amounts of these foods are consumed each day.
Vegetarian diets can be planned to supply the required levels of nutrients during pregnancy. Research shows there are no significant health differences in babies born to vegetarian mothers.18 The higher fibre content and lower energy density of many vegetarian diets may offer significant advantages, including a reduced risk of excess weight gain.19 Further, some studies suggest that a lower intake of meat and dairy products reduces the pesticide content of breast milk.20,21
Vegetarian diets are appropriate for children of all ages.2 The growth of vegetarian and vegan children is similar to that of non-vegetarian children if meals are planned well, according to the American Academy of Pediatrics22 and American Dietetic Association.2
As for all healthy diets, meal planning for plant-based diets should focus on incorporating a wide variety of minimally processed foods from each of the main food groups to ensure a plentiful supply of nutrients and phytonutrients.
The Healthy Eating Plate device (Box 4) has been created as a visual guide for planning plant-based meals at home.
Wholegrains: these are preferred over refined grain foods (eg, brown rice instead of white rice), and can occupy about a quarter of a main meal plate. When choosing grain foods, choose those with a low glycaemic index (GI). Low GI carbohydrates help to regulate blood glucose and insulin levels, lower the levels of low-density lipoproteins and triglycerides and raise the high-density lipoprotein level, and can assist with weight management.23-25
Plant proteins: from sources such as legumes, nuts, seeds, soy products or vegetarian convenience products should occupy about a quarter of a main meal plate. Semi-vegetarians may sometimes substitute fish, poultry or red meat.
Dairy or calcium-fortified soy, rice or oat products: these may be liquids or solids, and consumed as a side dish or integrated into the contents of a main meal plate. Lower fat varieties are preferable. The lower protein content of rice and oat beverages may not be suitable for infants and young children.
While it is desirable to plan to include all of these components in each meal, different cooking styles and cuisines may determine the composition of a meal and whether the recommended balance of nutrients is eaten at each meal or spread over the meals for the day.
When choosing alternatives to dairy foods (eg, soy or rice milk), look for products enriched with calcium and vitamin B12.
Tofu, tempeh, Quorn (meat-free, soy-free products based on high-quality mycoprotein), textured vegetable protein, canned and frozen or chilled convenience products (eg, Sanitarium Vegie Delights, Fry’s Vegetarian foods and Syndian Natural Food Products) are available in most supermarkets.
Many varieties of legumes and wholegrains are available in Asian, Indian and health food shops.
Vegetarian cheese, dairy-free margarine/chocolate or frozen convenience meals may sound healthy, but many can hide excess kilojoules, fat, sugar or salt.
3. Stock your pantry with a flexible range of ingredients, with an emphasis on whole foods to make it easy to prepare a meal (eg, wholegrain spaghetti, canned brown lentils and a tomato-based pasta sauce for spaghetti bolognaise).
7. Choose cooking oils that have high levels of omega-9 (eg, extra virgin olive oil, macadamia oil) or omega-3 (eg, canola oil) fatty acids. Do not heat flaxseed oil or chia oil (because they have a very high omega-3 fatty acid content making them highly prone to oxidation), and store in the fridge.
It is not necessary for people to take supplements routinely just because they follow a plant-based diet. However, depending on dietary restrictions, health, and stage of life, certain supplements may be beneficial. For example, those eating a vegan or low-dairy diet should ensure a sufficient intake of foods fortified with vitamin B12 or take a supplement that provides at least the RDI of vitamin B12. Patients beginning a plant-based diet should see their doctor or an Accredited Practising Dietitian for further advice on their individual supplement needs. In some cases, high doses of supplements may be harmful.
There are many health benefits from eating a plant-based diet, but, as with any eating plan, it is important that it is well planned to ensure that nutritional needs are met. In this article, we provide a basic guide to preparing healthy plant-based meals that incorporate key nutrients. It is intended as a starting point, as individual needs will vary. An Accredited Practising Dietitian can help develop an eating plan specific to individual needs.
This practical paper is intended for use in patient education and may be reproduced for this purpose. Additional resources are shown in Box 7. For further details on the scientific evidence behind these recommendations please see the other articles in this supplement.
1 Types of plant-based diets1
2 Sources of key nutrients in a vegetarian or vegan diet*
3 Glossary of protein-rich plant food
There are many protein-rich plant foods available, including whole foods such as legumes, traditional products like tofu, and faux meats, which can make transition to a plant-based diet easier and more convenient.
5 Some delicious plant-based meal and snack ideas
Free images of the Healthy Eating Plate device and sample plant-based food plates developed by the first author can be downloaded in full colour and high-resolution for educational purposes (www.sueradd.com/resources/healthyeatingplate.html).
For one-on-one dietary advice, find an Accredited Practising Dietitian with expertise in vegetarian nutrition (www.daa.asn.au).
Nutrition information, recipes, cooking classes and forums can be found at the Australian Vegetarian Society (www.veg-soc.org).
Sanitarium Health & Wellbeing Australia website (www.sanitarium.com.au) provides an abundance of free vegetarian recipes and other practical information.