Can changing your eating habits save the planet?

Recent reports from several heavy hitters conclude we need to slash the meat and dairy if we’re going to have any chance of tackling global climate change and reducing our impacts on the planet.

In August, a United Nations’ Intergovernmental Panel on Climate Change report said a plant-based diet and sustainably produced animal protein can help tackle climate change.

...changing your diet could leave you with more change in your pocket. Unlike forking out for an electric car or installing solar panels, the payback is instant.

And in January, the EAT-Lancet Commission, comprised of 37 experts from 16 countries, stated changing what we eat was the biggest step we could take to improving our health and the planet’s. The commission recommended we should be doubling the amount of fruits, vegetables, legumes and nuts we eat, and cutting back by more than 50% less healthy foods such as red meat and added sugars. Dairy products were also in the firing line.

Closer to home, a yet-to-be published New Zealand review “Achieving Healthy and Sustainable Diets” also concludes the best diets for sustainability are mainly plant-based with low amounts of meat, particularly beef and lamb. Seven of the 12 studies reviewed by the authors also recommended less dairy in our diets.

The good news in all of this is that changing your diet could leave you with more change in your pocket. Unlike forking out for an electric car or installing solar panels, the payback is instant.

How much can you save?

We calculated the cost of a week’s shopping for one person using the EAT-Lancet guidelines. We then compared it with a standard food basket based on the University of Otago’s annual food cost survey for an adult male.

Not only will following the EAT-Lancet guidelines reduce your environmental footprint, you’ll also save cash. Our EAT shopping list cost $53 a week, $8 less than the standard food basket. That’s a saving of $416 a year. You’ll spend more on fruit, vegetables and nuts, but that cost is offset by buying less meat, eggs and dairy products.

Download this table as a PDF (28.9 KB).

Co-convenor of OraTaiao (New Zealand Health and Climate Council) and senior lecturer in environmental sustainability and public health at Otago University Dr Alex Macmillan describes the EAT recommendations as a win-win for people and planet.

“In New Zealand we have high rates of diseases that are associated with high levels of meat and dairy intake, especially bowel cancer, but also obesity and heart disease. Eating more plants has health benefits such as reduced heart disease, stroke, type 2 diabetes and bowel cancer,” Dr Macmillan said.

...meat and dairy should no longer be considered essential for health and wellness

Recent research published in the Journal of the American Heart Association found people who ate the most plant-based foods had a 16% lower risk of having a cardiovascular disease, 32% lower risk of dying from cardiovascular disease, and 25% lower risk of dying from any cause compared to those who ate the least plant-based foods.

Obesity statistics also highlight the problems with current diets. Dr Macmillan said a third of Kiwi kids are overweight or obese, with rates higher among Maori and Pasifika children. This is related to undernutrition, especially poor fruit and vegetable intake, as well as eating highly processed foods

Dr Macmillan said meat and dairy should no longer be considered essential for health and wellness. “However some groups, like pregnant women, teenagers and young children, may need special consideration if they’re ditching them. People following an entirely plant-based diet may need to supplement with vitamin B12,” she said.

Dr Lisa Te Morenga, Victoria University Maori health and nutrition senior lecturer, said most of us would benefit from eating less animal protein, though believes going completely plant-based will be unrealistic for the majority. For Maori, the connection between health and wellbeing, and environmental health is readily perceived, so a shift to plant-based diets could be an easier sell for Maori than other groups, she said.

How green is New Zealand food?

Dairy products

Cow’s milk has long been regarded as a staple in dietary guidelines because it’s a good source of protein, vitamin B12, vitamin D and calcium. The Ministry of Health’s guidelines, last updated in 2015, recommend we consume at least two servings of milk products daily.

However, the EAT-Lancet Commission recommends we reduce dairy to about 250g per day – the equivalent of about one glass of milk.

Dairy’s green credentials get a bad rap. The Ministry for the Environment’s Greenhouse Gas Inventory reports that between 1990 and 2017 emissions from the agriculture sector increased by 13.5%. That’s mainly due to the dairy herd nearly doubling and an increase of about 650% in the use of nitrogen-containing fertiliser.

DairyNZ chief executive Dr Tim Mackle describes New Zealand as the most emissions efficient milk producer in the world, emitting 36% of the global average. According to a case study of 53 Waikato dairy farms, published in the Journal of Cleaner Production in 2017, the average carbon footprint of milk was 0.8kg CO₂-equivalents (versus a global average of 2.5kg).

However, dairy emissions are mainly made up of methane produced as part of a cow’s digestive system. As Parliamentary Commissioner for the Environment Simon Upton observes in a recent report, methane is a more potent greenhouse gas than carbon dioxide because it amplifies the warming in the carbon cycle.

Effluent management

Dairy farming’s expansion has also had a significant effect on our waterways. In September, the government released its Action for healthy waterways consultation document, which proposes restricting further intensification of dairying as well as reducing nitrogen contamination (livestock effluent is the primary source) and excluding stock from all waterways.

Dr Mackle said farmers had already taken steps to reduce their footprint. “Nearly 100% of farms have been assessed by farm effluent management practices, 98% of waterways more than one metre wide and 30cm deep have been fenced off from dairy cattle, and 10,396 nutrient budgets have been prepared so farmers can plan nutrient applications and manage losses,” he said.

Action for healthy waterways acknowledges progress has been made but points out there are still tens of thousands of kilometres of unfenced streams across the country. Mandatory farm management plans are among proposals to fix this.

Last month Land, Air, Water Aotearoa updated water quality data for more than 1400 river sites. For total nitrogen and e coli, more sites had degraded than improved over the last 10 years. Ammoniacal nitrogen, phosphorus and water clarity showed an improvement over more sites.

Red meat

Red meat, in particular beef and lamb, got roasted by the EAT-Lancet Commission for its environmental impacts. While the report doesn’t recommend we have to ditch red meat altogether, it suggests a daily amount of 14g of beef, lamb and pork combined (with an upper limit of 28g). That’s about 100g a week or 5kg a year.

We’re eating a lot more than that. On average, Kiwis eat 23kg of pork, 17.2kg of beef, 5kg of lamb and 0.7kg of mutton per year. That’s higher than current Ministry of Health recommendations, which state we should limit red meat to no more than 500g per week of cooked red meat (the equivalent of about 750g raw).

So what’s the beef with red meat? When it comes to greenhouse gas emissions, beef and lamb have the highest impact per kilogram. Like dairy, the main culprits are the methane the animals belch out (about 60% of the animal’s total carbon footprint) and the nitrous oxide excreted in to the soil out the other end (15% to 17%).

Beef & Lamb NZ marketing manager Kit Arkwright said the industry here was performing better than average. “The [EAT] recommendations are based on global averages and grain-fed meat production. In comparison, New Zealand has one of the lowest input and most efficient livestock farming systems in the world partly because our animals are grass rather than grain-fed,” he said.

The sector’s contribution to total greenhouse gas emissions has fallen as stock numbers have reduced. Between 1990 and 2017, sheep numbers dropped by 53% and beef by 21% , according to data from the Ministry for the Environment.

Mr Arkwright said the industry’s aiming to be carbon neutral by 2050 and has been investing in projects to reduce emissions through genetics (breeding sheep that emit less methane), feeds and inhibitors (a drug that works in the stomach so the animal emits less methane).

“New Zealand’s grass-fed beef and sheep population won’t be growing in size,” he said.

Pork fares better in terms of greenhouse gas emission. Globally, pork has about a fifth the carbon emissions of beef and lamb.

NZ Pork general manager David Baines said local pork has a smaller carbon footprint than the imported stuff. “As an industry, we employ an environmental specialist to help farmers meet resource management requirements, manage nutrient budgets and develop farm environment plans” he said.

However, more than 60% of the pork we eat is imported. The bulk comes from the northern hemisphere, and 40% from the US and Canada, adding to the product’s food miles.

From a health perspective, processed meat products, such as ham, salami and bacon, have the added downside that they’re high in sodium and saturated fat. The World Cancer Research Fund recommends eating little, if any, processed meat. The International Agency for Research on Cancer classifies processed meat as a carcinogen.

Chicken and eggs

The EAT-Lancet report is more generous when it comes to chicken, noting poultry is associated with better health outcomes than red meat. However, it recommends we still need to cut back to about two eggs a week and 29g of poultry a day (with an upper limit of 58g), which is about 10kg a year.

That’s significantly lower than what we currently consume. Poultry Industry Association of New Zealand executive director Michael Brooks said, although plant-based diets are growing in popularity, this hasn’t impacted chicken and egg sales – New Zealanders eat 42kg of chicken and about 230 eggs each year.

Chicken has a much smaller carbon footprint compared with beef and lamb. Mr Brooks said it’s just 1% to 2% of our agricultural emissions, but acknowledges it’s still part of the problem. “The main source of poultry’s contribution is from the growing and transportation of grains,” he said.

Seafood

Seafood also gets a better write-up from the EAT-Lancet report, mainly for its omega-3 content and its association with a reduced risk of heart disease. The report suggests we can eat about 28g a day (with a higher upper limit of 100g), which works out about 200g a week.

Data from the latest adult nutrition survey shows 42% of people eat frozen fish or seafood once a week and 29% eat canned fish or other seafood at least once a week.

On average, fish has a similar carbon footprint to chicken and eggs. However, the EAT-Lancet report notes emissions, along with other environmental effects, can vary widely depending on the species and fishing method.

A 2017 review in the Journal of Cleaner Production picked out prawns and shrimps as having a relatively high carbon footprint (7.8kg CO₂e) compared with tuna (2.15kg CO₂e).

Over-fishing has also significantly depleted some fish stocks and caused harm to marine ecosystems.

What's the carbon footprint of plants?

Grains, nuts, legumes

Cereal crops generally have a low carbon footprint. The exception is rice that is grown in paddies and often requires irrigation. It also generates high levels of methane.

Most grains, nuts and legumes we eat in New Zealand are imported – the cost of transporting them adds to their carbon footprint.

Some Kiwi farmers are diversifying their crops. Central North Island Farmers Dan and Jacqui Cottrell grow quinoa. Unlike most plants, quinoa is a complete protein (it contains all the amino acids we need). Limited studies have been done on the environmental impacts of quinoa but Mr Cottrell said all imported quinoa comes from Peru.

“When you factor in the quinoa travelling overland in Peru, then shipped to New Zealand, we are confident New Zealand-grown quinoa has lower emissions,” he said.

Fruit and vege

There’s no disputing the health benefits of eating five-a-day. But is there a “greener” choice of greens?

Your best options are field-grown vege such as onions, potatoes and carrots. Brassica, such as broccoli and cauliflower, also have a low impact.

In the fruit bowl, more robust fruit such as apples and pears rule the roost. Produce that’s fragile such as spinach and berries have a higher footprint.

It’s best to eat produce that’s in season and local. Hot-house tomatoes have more than four times the carbon footprint of conventionally grown tomatoes and hot-house strawberries double that of field-grown berries. Buying local reduces the air miles associated with overseas produce.