August 2021. About this episode: The largely plant-based Mediterranean diet is a well-studied dietary pattern. Research tells us that following…
Common myths about plant-based eating
Common myths about plant-based eating
Choosing a diet rich in plant-based foods is good for your health, and that of our planet (1). But many myths cloud plant-based eating. We unpack some of the most common myths, to sort fact from fiction!
Myth 1: Plant-based diets lack protein
A concern for many people seeking to reduce their meat intake and switch to a plant-based diet is the impact this may have on their protein intake – both the quality and quantity of protein (2,3).
But eating less meat doesn’t mean you’re going to suffer from a lack of protein. Protein is found in a wide variety of foods. For most Australians, it’s near impossible not to get enough protein if you’re eating a healthy, balanced diet.
Meeting protein needs
Most people in developed countries tend to exceed their protein needs (4,5). And studies show it’s certainly possible to achieve equivalent protein quality and quantity by partly or completely removing animal products, in favour of a plant-based diet.
Plant-based protein foods include wholefood staples like nuts, seeds and legumes, as well as plant-based meat alternatives and less commonly-consumed foods like algae and insects. Even foods like oats, rice, vegetables and fruit provide some protein, even if the amount is relatively small.
Table 1: Protein recommendations for Australians
|Protein RDI (per day)|
|19-70 years||64g (or 0.84g/kg body weight)|
|>70 years||81g (or 1.07g/kg body weight)|
|19-70 years||46g (or 0.75g/kg body weight)|
|>70 years||57g (or 0.94g/kg body weight)|
Source: Nutrient Reference Values (NRVs) for Australia and New Zealand (6). See the NRVs for more protein information for different life stages and levels of physical activity.
Did you know that nuts are among the richest sources of plant protein? Of the common sources of plant protein that Australians eat – grains, legumes, nuts and soy – nuts generally have the highest plant protein content per 100g (7).
What about protein quality?
Animal products provide an important source of nutrients and have been described as ‘complete’ protein sources with ‘high biological value’. This is because they contain all nine essential amino acids – the amino acids our body is unable to make itself.
Many plant foods do not contain all the essential amino acids, so are often termed ‘incomplete’ protein sources (8).
But the terms ‘complete’ and ‘incomplete’ have been challenged in more recent years with respect to plant proteins. This is because they refer to the essential amino acids in a single food. But most plant-based foods are eaten in combination and from a variety of sources, such that healthy plant-based diets can meet requirements for all essential amino acids (8).
Combining different sources of plant protein across the day increases the protein quality. For example, eating both nuts and legumes over the day provides us with all nine essential amino acids.
Myth 2: All plant-based foods are healthy
Not all plant-based foods are created equal. Just because a food is plant-based doesn’t automatically make it a healthy choice! What’s more, a person’s overall dietary pattern is what really counts.
A healthy plant-based diet is one that is both balanced and diverse. Ideally, it should prioritise nutrient-dense, whole foods, like fruit, vegetables, nuts, seeds, wholegrains and legumes – while limiting less-healthy, highly-processed foods.
A 2021 study, published in the journal Nutrients, found that when less-healthy, plant-based options are chosen there’s a risk of unknowingly increasing certain undesirable nutrients (like sodium and fat), while reducing the overall nutrient density of the diet (8).
According to the researchers, many novel plant-based products (including plant-based meat alternatives) are similar to animal products in energy (or kilojoules), but lower in protein, calcium, potassium, magnesium, zinc and Vitamin B12, while being higher in sodium and fat.
What’s the plant-based diet index?
Scientists use measures, such as the plant-based diet index, to rate the nutrient density and impact on health of plant foods (9).
High-quality plant foods such as fruits, vegetables, nuts, wholegrains and legumes score high on the healthful plant-based diet index (hPDI), and lower-quality plant foods, including juices/sweetened beverages, refined grains, potatoes/fries and sweets, rate high on the unhealthful plant-based diet index (uPDI), due to them being high in added sugars and refined grains.
In large prospective cohort studies, the hPDI has been more strongly associated with decreased coronary heart disease (CHD) risk and the uPDI linked with increased CHD risk (9).
Eating a plant-centred, high-quality diet starting in young adulthood (18-30 years old) is linked with a lower risk of heart disease by middle age, according to research that tracked study participants over 32 years (10).
Myth 3: A plant-based diet means saying goodbye to meat
A plant-based diet means opting for mostly plants, but there’s still room for animal-sourced foods, like lean meats and poultry, fish, eggs and dairy foods.
Research has placed two plant-based diets in the spotlight, due to their health benefits:
- The Mediterranean diet is a well-studied example of a ‘do-able’ plant-based eating pattern low in red meat, with plenty of whole plant-sourced foods (like nuts, seeds, legumes, whole grains, fruit, vegetables and herbs) and high in heart-healthy unsaturated fats (1). It’s been linked with many health benefits, while having a lower environmental impact, compared to typical omnivorous Western-style diets (11).
- The Flexitarian diet is a ‘flexible, vegetarian’ eating pattern – which increases healthy plant-based foods, while reducing (but not completely cutting out) meat. Studies suggest a Flexitarian diet may be a practical ‘middle-ground’ approach for some people, with similar health benefits to a vegetarian diet (12). It includes abundant plant-based protein foods.
Both dietary patterns place whole foods, like fruit, vegetables, nuts, seeds, wholegrains and legumes, front and centre!
Around 11 million deaths worldwide could be prevented simply by moving towards a more plant-based diet. It is not a question of all of nothing, but rather small changes for a large and positive impact (1).
Did you know? Sustainability messages, such as eating more plant-based foods, have not been integrated into the majority of official dietary guidelines around the world (13).
- Willett, W. et al., Food in the Anthropocene: The EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet, 2019. 393: 447–92.
- Sanchez-Sabate, R. et al., Understanding attitudes towards reducing meat consumption for environmental reasons. A qualitative synthesis review. Sustainability, 2019. 11: 6295.
- Fehér, A. et al., A comprehensive review of the benefits of and the barriers to the switch to a plant-based diet. Sustainability, 2020. 12: 4136.
- Australian Bureau of Statistics. Australian Health Survey: Usual Nutrient Intakes 2011-12. Available at: https://www.abs.gov.au/statistics/health/health-conditions-and-risks/australian-health-survey-usual-nutrient-intakes/latest-release
- U.S. Department of Agriculture. What We Eat in America, NHANES 2017–2018, Individuals 2 Years and Over (Excluding Breast-Fed Children), Day 1; U.S. Department of Agriculture: Oakland, MD, USA, 2020.
- National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand. Available at: https://www.nrv.gov.au/nutrients/protein
- Food Standards Australia New Zealand. Australian Food Composition Database (Release 1). Available at: https://www.foodstandards.gov.au/science/monitoringnutrients/afcd/Pages/default.aspx
- Tso, R., Forde, C.G., Unintended consequences: Nutritional impact and potential pitfalls of switching from animal- to plant-based foods. Nutrients, 2021. 13: 2527.
- Satija, A., et al., Healthful and unhealthful plant-based diets and the risk of coronary heart disease in U.S. adults. J Am Coll Cardiol, 2017. 70: 411–22.
- Choi, Y., et al., Plant-centered diet and risk of incident cardiovascular disease during young to middle adulthood. J Am Heart Assoc, 2021. Epub ahead of print. Available at: https://www.ahajournals.org/doi/10.1161/JAHA.120.020718?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub++0pubmed&
- Fresán, U., et al., Global sustainability (health, environment and monetary costs) of three dietary patterns: Results from a Spanish cohort (the SUN project). BMJ Open, 2019. 9.
- Hemler, EC., Hu, FB., Plant-based diets for cardiovascular disease prevention: All plant foods are not created equal. Curr Atheroscler Rep, 2019. 21: 18.
- Kovacs B. et al., The carbon footprint of dietary guidelines around the world: A seven country modelling study. Nutrition Journal, 2021. 20(15).
Published August 9, 2021