With new diets cropping up seemingly every week touting different nutritional benefits and health-boosting effects, how do we know what’s actually good for us? Two scientists who have studied the bioavailability of nutrients found in meat explain why red meat can be a very important part of a balanced diet.

In a world where climate change, food security and health concerns dominate headlines, the efficacy and role of different proteins and adequate nutrients in our diets is a hot – and often contentious – topic. The global population is predicted to hit 10 billion people by 2060, credible forecasts expect crop demands to grow by more than 100% from 2000 to 2050, and overall food demand is also set to grow by 70% over the same period. However it happens, it’s clear that our food systems will need significant reinforcement if they’re to continue to sustain us into the future.

Professor Warren McNabb and Dr Nick Smith are two scientists with considerable form in this field, having contributed to a recently published paper examining meat with a bioavailability perspective – and for its current role in feeding the world. In that paper the two senior staff at Massey University’s groundbreaking Sustainable Nutrition Initiative hosted by the Riddet Institute came to the conclusion that meat currently plays a vital role in ensuring there is sufficient nutrition to meet the world’s needs. This research aligns with the recently published FAO report, which looks at how animal source food contributes to a healthy diet. We looked a little deeper at what’s going on here.

As kids it was drilled into us to to eat our veggies – don’t they contain all the nutrients we need?

There’s no denying that a balanced diet including vegetables will help the body to thrive, but there are some vital nutrients that aren’t found in plants. Vitamin B12, for instance, isn’t naturally found in plant-based foods and is vital for keeping the body’s blood and nerve cells happy. B12 is abundant in animal-sourced foods like red meat, dairy, eggs and seafood. The best sources of nutrients really depends on the nutrient in question: while meat is a good source of B12, there are many other vitamins that must be sourced from plant foods.

Globally, the supply of several key nutrients is heavily reliant on animal-sourced foods. If red meat and animal products were to disappear overnight, there would be a struggle to find adequate supplementation from natural sources for many of these important nutrients that keep our bodies fit and healthy, from lysine to calcium.

The word ‘bioavailability’ seems to come up often in those conversations these days. What do scientists actually mean by that though? And do we actually need to care?

Bioavailability is a pretty classic example of a complicated-sounding word with a pretty simple definition. In basic terms, when someone talks about nutrient bioavailability, they’re referring to the amount of a nutrient which is not only found within a food source, but which can actually be metabolised and used by our bodies.

One of the challenges in building a balanced diet is that in bioavailability terms, very few foods on their own can serve as what nutritional scientists term “complete” protein sources – that is, ones which contain the right quantities of all nine of the essential amino acids that our bodies need to function optimally. According to McNabb, “animal-based proteins are of higher quality than plant-based proteins because they contain all the essential amino acids – in the right proportions.” Combinations of plant proteins can have the right balance of amino acids, but their availability is lower because what surrounds the amino acids is slower and more poorly digested i.e. fibre. Some of these plant proteins even contain anti-nutritional compounds.

On top of that, the bioavailability of nutrients in red meat, such as iron, zinc, and vitamin B12, is higher than in plant-based sources. Smith points out that “the bioavailability of nutrients is an important factor when considering the nutritional value of food, as it determines how much of a nutrient our bodies can absorb and utilise.” This can be an especially important concern for those – like infants, teen girls, women of child-bearing age, pregnant women and even athletes – who may have higher-than-normal nutrient requirements.

The University of Washington study – and Beef + Lamb New Zealand’s messaging around it – talks about ‘countering inaccuracies’ in earlier research. Which sounds a bit ominous! What inaccuracies are they talking about?

For a very long time, prevailing wisdom has held that although red meat had objective nutritional benefits, it also carried associations for a range of health conditions – cancers, diabetes and stroke among the most significant. More recent research into the risk factors, however, has emphatically pushed back against that idea, saying that while some correlations may exist, they’re weaker than previously thought. With that improved understanding in mind, McNabb and Smith stress the importance of taking a more nuanced approach, one which considers the quality and quantity of red meat consumed as part of an overall balanced and varied diet. Nutrition levels also vary between meat products, with processed meat having higher risk factors compared to fresh meat.

That’s reassuring, but what about the climate cost of continuing to keep lamb and beef on our plates?

Farming is a big industry in Aotearoa, so it naturally draws a fair bit of scrutiny with regard to its environmental impact. As we examined late last year, this is another area which Beef + Lamb New Zealand is paying particular attention to – their Life Cycle Assessment project in particular attempts to much better quantify and understand the overall sustainability of how we farm red meat in this country. 

As well as giving our farmers and producers a much clearer view of how they stack up against the rest of the world, this research also allows Beef + Lamb New Zealand to identify areas for improvement, ensuring that the industry remains aware and in front of its sustainability challenges.

But we’re only a small country. How much effect can our production and consumption habits really be having?

“There is enough food for everyone, but it’s not distributed evenly, leading to a global imbalance,” says McNabb. New Zealand-produced foods feed 40 million people every year – and on average each New Zealander currently eats about 15kg of beef and lamb each year – yet there are still people here who go hungry. 

Smith says part of the solution lies in adapting our consumption habits. This includes not only reconsidering the quantity of food we consume (“need v. want”) but also the quality and types of food. Reducing the intake of highly processed foods and incorporating more whole foods can not only contribute to a healthier diet, but also mean New Zealand growers and farmers are supported, benefiting the wider economy.

So is it up to me to fix this myself, one plate of locally produced kai at a time?

Beef + Lamb New Zealand’s efforts to promote sustainable farming practices demonstrate how the New Zealand red meat industry can contribute to positive change – but they are just part of the solution. Cooperation among governments, organisations and individuals to make informed decisions and adopt more sustainable practices is needed, say McNabb and Smith.

One of the most useful tools in this change is education. McNabb and Smith hope to contribute to a more informed and balanced global food system by educating people on the role of different foods, including red meat, in sustainable food systems and diets. Addressing global nutrition issues will take a global effort, but that doesn’t mean we can’t start regionally, locally, or even in our own kitchens.