When organisations as illustrious as the Intergovernmental Panel on Climate Change recommend Westerners eat less meat, it’s not only Kiwi farmers who worry. Food scientists argue plant-based diets can ignore the protein-packed power of red meat and milk, especially for the young and the elderly. And while agriculture has big environmental problems to solve, New Zealand’s grass-fed sheep and cattle still underpin a high-quality food industry. Glenda Lewis reports.
Fifty years ago, he says, Pākehā New Zealanders followed a variation of a traditional British diet. “It was flawed in many respects – not very flavoursome, often lacking in fibre and variety, with vegetables seriously overcooked – and then, as now, we had too much sugar. But at least people didn’t struggle as much with their weight… eggs and porridge for breakfast, sandwiches and fruit for lunch, and meat and three veg for dinner. Prepared well, it was actually a very good diet. But let’s not go back to those days. We all relish today’s new ways of cooking and tastier foods from other cultures.
“The problem has been that the loudest voices on diet and weight often have vested interests. Those voices are then amplified by sound-bite media, constantly confusing everyone by alternately vilifying and extolling single diet components,” says Moughan, fellow laureate of the Massey University, Palmerston North-based Riddet Institute, a national centre of research excellence comprising more than 120 scientists around New Zealand, mainly in universities and crown research institutes. They specialise in food science and technology, human nutrition, digestion and how to get the best from our food.
It’s time to take stock. In 2011, Moughan was appointed chair of the United Nations Food and Agriculture Organisation Expert Consultation project to review recommendations on protein quality in human diets, and in 2014 he was appointed to an international think-tank on world food security. He sits on numerous international bodies concerned with food, nutrition and food production sustainability.
Protein is the obvious place to start in evaluating diets. We are largely made of proteins of one kind or another; they also play many critical roles in the body. Moughan begins his “nutrition 101” interview by emphasising that not all proteins are equal. They are made up of different amino acids – often described as the building blocks of proteins – in different proportions. Nine of the 21 amino acids that are found in foods are called “essential” because our bodies cannot make or store them, and so we need to eat them every day.
All proteins from animal sources (meat, fish, poultry, eggs, milk), and soya bean, contain all nine essential amino acids in the right proportions for us. Conversely, most plant proteins, except for soya bean, have one or more of the nine essential amino acids either missing altogether or present only in small amounts. Most vegetarians and vegans are aware of this and eat complementary combinations, such as peanut butter and wholegrain bread.
Proteins don’t just build flesh, hair, nails and sinew. For example, one of the essential amino acids, tryptophan, is needed to make the hormone serotonin. A lack of it can result in mood disorders, anxiety and depression. Tryptophan is low in plant sources, although a good mixed vegetarian diet should contain enough of it, especially one including tryptophan-rich milk.
Animal-sourced foods, particularly milk and milk products, are the most complete and nutrient-rich sources of protein, for the lowest calories. Meat, poultry and fish are more energy-dense, but still provide more key amino acids per calorie than equivalent vegetable protein sources. For example, to get the same 27g of protein in 100g of lean beef (235kcal) – in which the protein has all the required amino acids and is readily absorbed – you need to eat at least 392g of chickpeas (494kcal), 117g of peanut butter (693kcal), or 614g of cooked quinoa (736kcal). And the beef contains many more micronutrients, such as iron and vitamin B12. (For a protein content comparison of common foods, check out riddet.ac.nz/protein/)
Generally, you have to eat a lot more plant sources of protein to get the same amount of protein as from animal sources. Moreover, it is harder for the human digestive system to break down plant cell walls and get at the proteins and other nutrients. Scientists call this “bioavailability”. “It’s important to understand this variability,” says researcher Sylvia Chungchunlam, who works with Moughan on protein evaluation. “This is an efficiency factor that people often ignore when comparing agricultural produce and practice.”
Milk is the most digestible source of the nine essential amino acids, which makes it ideal for the young and the elderly. Nature designed it as a complete food for young animals that are growing fast. Animal milks (human, cow, sheep, goat, camel) are very similar in composition.
Professor Mark Thomas, University College London, says most New Zealanders of European ancestry carry a genetic mutation that enables them to continue to digest the milk sugar lactose into adulthood. “This mutation arose randomly and became common in Europeans, as well as some southern Asian and African populations, over the last 7500 years. It conferred a huge advantage, which meant that natural selection favoured the mutation. Carrying these lactase-digesting mutations had major impacts on the development of agriculture in different parts of the world during the last 4000 years, at least.
Milk gave us a safe, reliable and portable supply of clean food and fluid on long and arduous journeys, seeing us through desert crossings and crop failures. It’s said that horse milk gave the Mongol conquerors the means to travel thousands of miles across the steppes.”
A fundamental principle of the agricultural economy is that ruminants (cud-chewing cattle, sheep, antelopes, deer, giraffes and their relatives) can digest food we can’t, and convert it into meat and milk that we can eat. Grazing animals dispose of, and create value from, all the wasted parts of crops such as wheat and corn. They have gut microbiomes that can attack the tough bonds in plant cellulose.
Meat production from ruminants in general should not be confused with the feed-lot production of beef, where animals are given corn and soya that grow on good, arable land and could be eaten by humans. Pastoral meat production should not compete with other food crops. To stop ruminant production on some areas of the Earth could affect the livelihoods and way of life of millions of people, as well as removing a sink for inedible plant waste material.
Distinguished Professor Harjinder Singh, director of the Riddet Institute, says in New Zealand three-fifths of agricultural land is best used for grazing, so drastically reducing sheep and cattle numbers is not the way forward.
Singh believes the arguments currently playing out around the shift towards plant-based diets are “simplistic and have become polarised, as so often happens. It is very unhelpful at a time when we all need to pull together and keep cool heads. When you delve into the science, you soon find that every crop comes with its own environmental problems – like heavy use of pesticides and attendant damage to animals, insects, soils and waterways. There are legions of factoids and figures on all these things, but people are best to try to understand the basic underlying principles.
“The dietary guidelines issued by the IPCC are general and do not take account of local circumstances. Earth is a mosaic of different soils, climates and opportunities. We must have both animal and plant agriculture to achieve the most efficient food economy as well as balanced diets. I fully support the argument that because we are the lowest carbon-footprint producer of meat and dairy in the world, any reduction in our output will just create a vacuum for other, less-sustainable producers to fill, which they surely will. This may be worse for animal welfare, too. Of course, stocking levels are debatable, and we must continue to work very hard to reduce emissions or offset them down to zero; also to prevent water pollution, and constantly strive to improve the welfare of farm animals.”
Dr Suzanne Hodgkinson, a scientist at Riddet who researches protein quality, adds: “We must be very careful that with this trend towards plant-based diets, parents are not misled into withdrawing milk from children’s diets. Stories are already starting to come through about catastrophic results of parents putting young children onto vegan diets. And low-fat milk is not suitable for infants under two, as it doesn’t contain essential fatty acids and lacks fat-soluble vitamins. Young children need the energy from whole milk.
“It’s not just about physical growth, but cognitive development, too. The calcium in milk is highly bioavailable, which means children and adults are able to absorb and utilise it efficiently, unlike the calcium naturally present in ‘milks’ of vegetable origin.
“It’s also a big mistake to try to reduce or cut milk from the diets of children who are overweight. Milk is actually a low-calorie way of giving them all the nutrients they need, which is why the government decided to deliver half a pint free to every school child from 1937 [to 1967] as a public health measure.”
The Fonterra Milk for Schools programme was needed because recent Ministry of Health research showed two-thirds of children were not getting enough calcium. The co-operative now supplies 70% of primary schools with free milk.
“Milk is also an easy and very good way for older people and invalids to boost their protein intake for muscle retention and healing,” says Hodgkinson.
Vegetarians who consume milk, yoghurt and cheese find it much easier than vegans to balance their diets. They just have to pay attention to where they are sourcing their iron and vitamin B12; some take dietary supplements. Auckland dietitian Caryn Zinn has concerns about the lack of vitamin B12 and easily absorbable iron in vegan diets, especially among menstruating teenage girls.
The four most common micronutrient deficiencies in the New Zealand population are iron, iodine, selenium and vitamin D. A small amount of red meat satisfies most of your requirements for iron, in a form that is readily absorbed by the body.
Proteins, wherever you get them from, make you feel fuller quicker, for longer. Most people notice this when they have eggs rather than cereal for breakfast. A 2013 US study of teenage girls showed if they ate a high-protein breakfast, they were far less likely to eat high-calorie, less-nutritious foods (rubbish, if you like) the rest of the day, and this helped with weight control.
Adults need between 0.8g and 1.2g of high-quality protein per kilogram of body weight, every day. New research by Moughan’s US collaborator, Professor Bob Wolfe, an expert on nutrition for older people, suggests this should be even higher – from 1.0g to 1.5g. After age 40, you should have a bigger proportion of protein in your diet to maintain or develop muscle mass. For example, a woman over 40, weighing 65 kilos, requires at least 78g of high quality protein a day (65kg x 1.2g per kilogram of body weight).
We also need to do enough exercise to build up and retain muscle. Research finds that older people on higher protein diets stay stronger and more independent for longer. The over-40s can stimulate muscle synthesis by having milk and vitamin D (rich in eggs and free in sunlight respectively) at breakfast and then a glass of milk before bed.
“A big fault in the way many people in New Zealand eat, and certainly a fault with the traditional ‘meat and three veg’ regimen, is to have most of the day’s protein in the evening meal,” says Riddet Institute deputy director Professor Warren McNabb.
“To get the best value out of your food, and not waste an increasingly precious piece of meat, you should spread your protein intake evenly throughout the day. You can’t store protein. So if you eat a 200g steak for dinner and then sit in your easy chair watching the rugby for the rest of the evening – not always a relaxing pastime, actually – half of it may end up converting to fat, unless you’ve been out on the farm fencing, or at the gym lifting weights just before the meal. A lot of the meat servings at restaurants are too big and get wasted, either thrown in the bin or converted to unwelcome baggage on the hips.”
We throw away about 157,000 tonnes of food a year, and most of that food is wasted by consumers, not food producers.
“This is sadly true, but it’s not hopeless,” says Moughan. “What people need to do is forget about how much they weigh and instead concentrate on changing their body composition – turning fat into muscle. That means consuming a higher proportion of protein in the diet and getting more exercise. You will feel fuller and more satisfied rather than deprived. The more muscle and lean body mass you have, the more you can eat without putting on weight. Muscle cells use energy – provided you actually use them – and are constantly being renewed, which uses even more energy, unlike fat cells, which are akin to inert storage units.”
He is quick to add: “I am certainly not recommending that you follow an Atkins-type diet of unlimited bacon and eggs to the exclusion of fruits, vegetables and grains. Just eat a higher proportion of good-quality protein, get lots of fibre, and do the right type of exercise regularly. Even half an hour of dedicated brisk walking three times a week is good. If you do that, you will probably automatically consume fewer fats, oils and refined [highly processed] carbohydrates. And don’t worry if you weigh more in the short term. Muscle, on a per calorie basis, weighs more than fat.
“Balance is important. We need fruits and vegetables to supply some of our vitamins [like vitamin C, E and K], fibre, carbohydrates and other components.”
Counter-intuitively, vegetarian and vegan diets can be more calorific because you have to eat a much greater quantity to get the same amount of protein, and there is a tendency to consume more fats, oils and refined carbohydrates. This is especially true when aiming for higher protein intakes. Which is not to say that many vegetarians are not perfectly healthy, slim and fit, or that many meat eaters are not unhealthy and overweight.
However, it is not animal protein that has driven the obesity epidemic, according to Teresa Davis, professor of paediatrics-nutrition at Baylor College of Medicine in Houston. While giving a public lecture in Palmerston North during a 2018 visit, she reported that in the US, average daily calorie intake by adults increased from 2060 calories in 1970 to 2630 in 2008 – a whopping 570 extra calories. Davis showed the extra calories have come mainly from oils, fats, flours and cereals, and interestingly not very much at all from extra sugar, which was already quite high in 1970.
She said in Western countries, people derive two-thirds of their protein from animal sources; in developing countries it is the other way around – they get two-thirds from plant sources. It is projected that by 2050 the demand for animal proteins from the developing world will likely double, as their middle classes grow.
Lisa Te Morenga, senior lecturer in Māori health and nutrition at Victoria University, says with the increasing use of social media in the last 10 years, there has been a rise in conflicting messages about what we should or shouldn’t be eating. “First it was high-fat diets, then paleo and now vegan and plant-based diets are dominating headlines. I worry about the impact of all this conflicting messaging on New Zealanders’ diets, and how this might affect population health long-term. Unfortunately, we have little idea of what New Zealanders are eating right now as we haven’t had a national adult nutrition survey since 2008/2009, and the last children’s survey was in 2002. Given that the Global Burden of Disease project cites poor nutrition as the number one risk factor for early death, this really is an urgent priority. We need to monitor the effectiveness of food and nutrition policy and research in New Zealand.”
McNabb has caveats about changing diets. “Our digestive systems have not evolved much in the last few thousand years. A switch to getting all your proteins from plants is challenging; it is quite a different nutritional scenario.”
Riddet Institute postdoctoral researcher Lakshmi Dave, a vegetarian by upbringing and now by choice, says her biggest concern with modern diets is ultra-processed foods and drinks, especially sugary ones, and processed red meats. Dave is a strong advocate of dairy foods and having lots of in-season fruits and vegetables on the plate, including those that are available but for whatever reason are not commonly cooked and eaten. Neglected or “minor” crops – New Zealand native puha, for instance – are important for sustainable and climate-resilient food systems as they help diversify food production. They are also nutritionally significant since they tend to be rich in key micronutrients. “Unfortunately, these crops tend to be marginalised due to inadequate research, unsupportive agricultural policies, and modern dietary patterns that rely on a very limited number of ‘major crops’,” says Dave.
“Newbie vegetarians and vegans must be careful with things like pulses and legumes, such as red beans, which must be properly soaked, germinated and/or pressure-cooked to reduce the levels of anti-nutrients that can compromise their nutritional value and digestibility. Frozen vegetables and cans of cooked chickpeas, red beans, etc, in water don’t count as ‘ultra-processed’ in my book, but you should aim to have a dietary pattern in which meals prepared from minimally processed ingredients are the mainstay. And don’t starve your gut microbiota – get enough fibre!”
Says Moughan: “It’s all very well for the well-off to push for sole plant diets, but for much of the population, cost is really important. It’s not as simple as some would advocate. Animal proteins are more expensive to produce and, as with plant foods, there are external costs of production, like pollution, which are not taken into account. However, in terms of their comparative power to provide amino acids, vitamins and minerals, animal proteins are very good value for money. This may be counter-intuitive to many people.”
No matter the source of protein, we have been told time and again that we should eat a wide range of fruits, vegetables, nuts, seeds, legumes and grains, for additional micronutrients, and especially plant fibre to keep our gut in good health. Says McNabb: “Diversity is absolutely key to a healthy diet. A bit of this, bit of that. Try new things. When I introduced my mother to bok choy, you’d have thought I was trying to kill her. The Mediterranean diet is good because it is diverse, not because of any one ingredient, like olive oil.”
Chicken is the number-one animal protein in New Zealand; we produce 125 million chickens annually for local consumption and export. It is cheaper than red meat and very adaptable to different recipes. The total protein content in chicken and fish is virtually the same as in red meat, but they all come with different complements of micronutrients – iron and B12 in red meat, for instance, omega 3 in fish.
So, bottom-line, how much red meat can we reasonably eat to stay within our protein allowance, and get all the benefits of the iron and other vitamins it contains, without any elevated risk of bowel or other cancers, and cardiovascular disease?
There is “active disagreement” about the cancer risk associated with fresh red meat. Riddet investigator Mike Boland says research points both ways. The risk associated with high meat consumption is confounded by other lifestyle factors. People who eat a lot of meat may also be overweight and/or smoke, drink more, get less exercise, and eat fewer fruits and vegetables and fibre generally.
Otago University professor in human nutrition and medicine Jim Mann and co-researcher Lisa Te Morenga report: “We argue that red meat can have a valuable place in the diet as a rich source of high-quality protein and important micronutrients, but that its place should not be a big one. We stand by guidelines recommending a 100-150g serving of red meat no more than a few times a week, up to a maximum of 500g per week, and believe that most New Zealanders would benefit from increasing their intake of fibre-rich vegetable protein sources like beans, legumes and wholegrains.”
Boland adds: “Grass-fed meat and milk are the main dietary source of CLA [conjugated linoleic acid], which is an important anti-cancer factor in the diet. It is much lower in grain-fed beef. New Zealand beef is generally grass-fed, and this is one of its many advantages. You simply cannot compare industrial, grain-fed beef production with our low carbon-emission, grass-fed system, on land that is mostly only suitable for grazing [or trees].”
The unequivocal support for red meat and dairy from these scientists seems surprising in the face of so much pressure to cut right back on these food groups or remove them from our diets. In August, the UN’s Intergovernmental Panel on Climate Change (IPCC) advised that switching to a plant-based diet would help fight climate change; its message – to the West – was we need to buy less meat, milk, cheese and butter, but also eat more locally sourced seasonal food and throw less of it away.
According to a 2018 University of Oxford study, cutting meat and dairy products from your diet could reduce your carbon footprint from food by two-thirds.
Kiwis’ only experience of food rationing was in World War II, when they were limited to 8oz (225g) of butter a week, and a kilo of meat, about two-thirds of what they were used to. It was positively over-indulgent compared to the current, vegan-leaning “climate diet”. Coal miners on the West Coast were unhappy and lobbied for an extra 4oz (113g) of butter. Milk was not rationed at all. No one complained about sending the meat we sacrificed to feed hard-pressed Britain, which was on much smaller rations, and we supplied the troops in the Pacific with vegetables. There was a “dig for victory” campaign to encourage everyone to supplement commercial crops by growing vegetables in their back gardens.
Are we now, in this new climate-crisis scenario, to dine on juicy lamb chops while the rest of the world chews hemp seed and the ocean laps at our feet? What is the Riddet Institute’s response to the clarion calls to shift to largely plant-based diets?
Harjinder Singh, who shared the 2012 Prime Minister’s Science Prize with Moughan, specialises in the science and technology of milk and milk products. He glances at the view from his Massey University office before answering in his quiet, measured manner.
“I grew up in India, where a large proportion of the population is vegetarian but has a long tradition of consuming milk and milk products. Meat consumption is relatively low, mainly because of religious reasons and cost. In many parts of Asia and Africa, millions of children are physically stunted as a result of malnutrition and the unavailability of affordable, high-quality animal protein.
“We know that milk and milk products are easily the best way of delivering a complete nutrient package to children who are starving and need high-quality protein for their growth and development. If we care about the poor, the world must continue to produce milk and milk products in formats that are affordable and available for everyone. New Zealanders have the luxury of choosing the diet they want to follow, and we must respect their decisions. Many children do not.”
He agrees that the Western world will have to cut back on its high meat consumption. “I strongly urge people not to eat more meat than they actually need – and not to waste food. These are the first and most immediate things we can do to cut carbon emissions. Another argument for continuing to consume moderate amounts of dairy and meat in New Zealand is the fact they are locally available. There is no point ‘replacing’ milk with expensive, imported nut juices of lower nutritional value, which may have very high environmental costs for another country.
“No one knows quite what the future holds with regard to the uptake of synthetic meat and dairy products, but given the increase in world population and our lead position as a producer of grass-fed meat and milk, there is justifiable confidence that New Zealand’s markets will be secure for the foreseeable future. We need to evaluate the nutritional value of these new products and the environmental impacts of their feedstocks and manufacture.”
Perhaps worrying he’s at risk of seeming a conservative defender of the traditional farming faith, Singh adds: “At the Riddet Institute, we are working with and not against international trends. We’re exploring all kinds of proteins and ways we can boost the nutritional value of animal and plant proteins. Our scientists are highly focussed on the world’s food security problems and the urgent need to increase efficiency and output, while reducing carbon emissions at the same time. It’s a huge challenge for our scientists and partner organisations [Massey, Auckland and Otago universities, AgResearch and Plant & Food Research]. New Zealand wants to continue to lead the world in food science.
“I did my PhD studies in Ireland, where people are still haunted by the catastrophic famine of the 1840s. I am more aware than most of the good fortune of New Zealanders to have access to such rich sources of food. It was in search of a secure food supply, and land to grow it on, that Māori and Europeans sailed thousands of miles across the Pacific. We can continue to enjoy our premium produce, share it with the rest of the world and also contribute our knowledge of best agricultural practice and food technology.”
The bottom line
- Spread your protein intake evenly through the day.
- Do not eat more meat than you need.
- Eat proportionately more protein if you’re over 40 (at least 1.2g per kilo of body weight).
- Have a diverse diet – “a bit of this, bit of that”.
- Be aware of the benefits of milk, for children, teenagers and older adults especially.
- Do NOT yo-yo diet. Change your body composition by eating more protein (and fruit and vegetables) and getting exercise to turn that protein into muscle.
- If you are vegetarian or vegan, be aware of the lower “bioavailability” of plant proteins and other essential nutrients, and think about your sources of iron, zinc, vitamin A, vitamin B12 and other vitamins in the B-complex group. Eat the necessary combinations of your protein sources to make sure you are getting the nine essential amino acids.
- Eat local and take advantage of the good food we produce.
- Moderation, moderation, moderation.
Case Study: Loaves and Fishes – and Lentils
Buchanan (above) is remarkably positive about his cooking challenges. “Gluten is easy to avoid, and dairy replacements are easy to get.” He has folders for printouts of recipes he gathers from the paper and online. He has vastly expanded his repertoire of vegetable dishes. Favourites are fennel, celeriac, cauliflower, broccoli, parsnips, leeks, yams, kumara and capsicum.
“There’s a pretty good range in the local supermarket and greengrocer in Miramar, and I usually get my meat from the Strathmore butcher,” he says. For Lani’s benefit, he now replaces cream with coconut cream, which he has really got to like as an ingredient.
Originally from Gore, Buchanan says his Auntie Maimie, a businesswoman, was considered avant-garde because she had what in the 1950s were exotic vegetables – such as broccoli and celery – chosen and delivered by Mr Willie Gee, the greengrocer. In Buchanan’s own house there were a lot of roasts, which inevitably led to even more cold meat lunches with simple lettuce and tomato salads.
A once- or twice-a-year highlight was eating at the Grosvenor steakhouse in Ōamaru when his parents were returning him to St Kevin’s Boarding School after the holidays. “Of course the steak was very well done, and the restaurant was unlicensed,” says Buchanan. “Things have changed so much, including in Gore.
“When I cook, I don’t think in terms of protein or fats, but taste. The [information on plant versus animal sources of protein] resonates with me as I know how much vegie curry Jack eats at a sitting. I now understand why.”