To start us on a nutritious path for 2022, Professor Jennie Macdiarmid of the Institute of Applied Health Sciences at the University of Aberdeen speaks to Flora IP about the intersections of food, nutrition and the environment. Jennie Macdiarmid is a Professor of Sustainable Nutrition and Health as well as the Interim Director of the Interdisciplinary Challenge on Health, Nutrition and Well-being at the University of Aberdeen. Her research focuses on food and nutrition security alongside the impact of diets on climate change and land use. This includes understanding how to change dietary habits to be healthier and more environmentally sustainable.
Flora IP (FI): What is a healthy diet?
Professor Jennie Macdiarmid (JM): To have a healthy diet, you need to make sure that your food does not have excessive amounts of fat, sugar or salt, and that it has plenty of fibre including fruits and vegetables. You can have small amounts of meat, a lot of carbohydrate foods: pasta, rice and potatoes, and fruit and vegetables, along with small amounts of dairy products. This combination of food will give you a reasonably healthy diet. A more detailed explanation of healthy diets is provided in the Eat Well Guide available on the NHS website. It delineates the recommendations for a healthy diet and the proportion of food to eat. The Eat Well Guide is a great resource on what constitutes a healthy diet.
FI: Please discuss the benefits and shortcomings of vegetarianism, veganism and whole food plant-based diets?
JM: All these diets are predominately plant-based. Vegetarianism and veganism exclude all meat, a plant-based diet includes some meat, but only small amounts. Vegetarianism, veganism and whole food plant-based should, in theory, be very healthy diets, if you have the right sort of foods. However, you can have a very unhealthy vegetarian diet. It could be all processed foods or a lot of fat and a lot of sugar. We cannot assume that vegetarian diets are always healthy. Traditionally, we had vegetarian diets that were made up of predominantly whole foods: a lot of vegetables, fruits and pulses, all of which are part of a good healthy diet. What we are seeing now is more processed food that is vegetarian and vegan. We have a lot more ready meals and highly processed foods. All these products can be high in salt, fat and sugar. We need to be careful that we are not moving towards a vegetarian or vegan diet that is highly processed because that is less healthy.
The one vitamin that you cannot get in a vegan diet is Vitamin B 12 because it comes from animal products and is not found in any plant-based foods; vegans have to take Vitamin B 12 supplements. Any diet can be healthy or unhealthy however it is framed. You could have a meat diet that is healthy; you could have a vegetarian diet that is also healthy. At the same time, you could have a meat-based diet that is unhealthy and a vegetarian diet that is unhealthy. You have got to look at what the diet is made up of, not just assume that it is healthy because it is vegetarian or vegan.
For instance, you can have a healthy diet with meat in it. Small quantities in diets are perfectly healthy. It is not the case that we must avoid all meat for health reasons. In fact, some meat provide important nutrients in forms that are more available than from plant-based foods. For example, the type of iron in meat is more readily absorbed than if it comes from a plant-based food. In short, healthy foods are not black and white. A whole food plant-based diet, which only has a small amount of meat is probably the healthiest diet you can get.
FI: When you say meat, what type are you referring to?
JM: In terms of iron, it would be red meat. But it can be high in saturated fat. Poultry will be less high in saturated fat, and also a good source of protein. There are recommendations for a maximum amount of red meat and processed meat you should eat in a week, based on the risk of colon cancer. There are suggestions within the Eat Well Guide about how much meat to eat.
FI: What types of diets are environmentally sustainable?
JM: Meat has the highest environmental impact; red meat has the highest and then poultry. A diet without any meat or animal-based product will be the most environmentally sustainable. However, we must balance that with nutrition because we do not want to end up with a diet that generates health problems. That is, a diet that is environmentally sustainable but nutritionally deficient. The important thing here is to make sure that you are considering the environment and health impacts at the same time. If you consider health or nutrition alone, then you may end up with issues around environmental sustainability. If you consider sustainability alone, you may lose out on some of the nutrients. You must combine both. A whole food plant-based diet is the healthiest and the most environmentally sustainable. That is why the research-based recommendations are now to move towards a more whole food plant-based diet.
FI: Please expand on why meat-based diets are detrimental to the environment.
JM: Ruminants: cows, sheep and goats, produce methane as part of their digestive processes. Methane is a potent greenhouse gas. If you think about carbon dioxide having global warming potential of 1, methane is about 25 potent in terms of warming. One of the reasons we are told to reduce red meat consumption from ruminants is because of their increased adverse impacts on the environment. Eating less meat will result in producing less meat as well. This is particularly important in high-income countries because we produce huge amounts of meat and cattle through industrial/intensive farming. In lower-income countries, it is argued that production in smaller numbers provide the required nutrients for populations with nutrient deficiencies, and could benefit the soil for other food production. Dairy also comes from ruminants so the same issues raised about eating meat apply to cheese and milk, etc. Again, when we are looking at all of these and saying we should reduce our consumption, we need to ensure that we are getting enough nutrients. For instance, we must ensure that we are getting enough calcium. What we are recommending is a reduction not an elimination of all these foods.
FI: What about plant-based substitutes for dairy? Are they as nutritious or do they miss some of the important nutrients contained in the animal-based counterpart?
JM: If they are plant-based, they would not have Vitamin B 12 in them. A lot of these plant-based alternatives are fortified. A lot of them have oil added to them. But we must be careful about the substitutes we choose. For instance, if we were to stop consuming cow milk and substitute it with almond milk – the parts of the world where we grow almonds now are water scarce, which means we are putting a lot of strain on the environment to produce almonds. In other words, we could have unintended adverse consequences because increased production will be problematic for the environment. Similarly, there is a growing appetite for coconut products – like coconut milk and coconut water etc. One of the issues with that is – when we scale it up, how are we going to get enough coconut trees to produce the volumes required? We are talking about very large-scale farms. We need to consider the environmental impacts of the substitutes that we choose.
FI: What are the impacts of climate change on food and nutrition security?
JM: Climate change is having a huge impact, particularly in low-income countries. Climate change is causing more extreme weather events. We are seeing a lot more drought, a lot more flooding. As soon as you have these two extremes, your food production is going to be limited. As we see more of these extremes, we are going to get more problems with food production. Once it gets up to a certain temperature, the crops that you can produce change. But also, where people are working on land, for example, once it gets above a certain temperature, it is not possible to go out and do physical work. There are lots of things unfolding from a climate change perspective that will exacerbate foods security. We need to consider how to limit climate change/ global warming, which we are trying to do. Also, how we can adapt to it in some ways?
FI: Food security and food sovereignty in low-income countries are predominantly sustained by smallholder farmers that adopt sustainable agro-ecological practices such as mixed cropping. Please share your thoughts on these farming systems from an environmental or climate change perspective?
JM: We (Global North countries) have moved much away from those farming systems, which are more sustainable – looking after the land also enriches the soil. We have moved to huge mono-cropping systems that can be detrimental to the land and soil. Agro-ecological farming systems are more sustainable and better for the land and soil than the increasing trend towards monocropping. Agro-ecological farming should be encouraged.
FI: What should we pay attention to when we shop for food?
JM: Again, we should adopt a holistic approach to shopping, it is difficult to say any one thing. What should we be buying to make up a healthy sustainable diet? A lot of people talk about food miles. But that is a difficult term because the concern should not solely be the distance food has travelled. We should consider the mode of transport. If you have transported food by airplane, it is going to have a much bigger environmental impact than if you brought it in by boat. We only airfreight a very small amount of food, about 1 per cent of our highly perishable foods. When people talk about food miles, it is a bit misleading, because it is the mode of transport that matters.
Also, when we talk about seasonality, it very much depends on where the food is globally seasonal. If we bring in food by boat grown somewhere in a natural seasonal environment, then actually that is not as big a problem as if we eat food produced locally using a lot of energy to produce it out of season. There is some messaging around which is quite confusing, which makes it hard for consumers to decide what to buy. This is where the retailers need to take some responsibility to source food from sustainable production systems because it is difficult for a consumer to know how food sold in markets/supermarkets is sourced. The food label may say that your tomatoes are grown in Spain, but you do not know under what conditions they were grown. Producers and retailers must take responsibility for ethical production and sale of food.
In addition, plastic has a huge impact on the environment as we use a huge amount of plastic packaging in our food systems. We must investigate how to find other packaging materials that are environmentally sustainable. We must remember that food packaging plays an essential role in food safety, to prevent contaminants. It also plays a vital role in limiting food waste as packaging can extend the shelf life of food. However, as there are alternatives, we must move away from plastics because of their negative effects on the environment. This is where, as an industry, we need to explore what packaging we can develop that will be sustainable and have less detrimental environmental impacts than plastics.
FI: What changes to the food, nutrition and agricultural ecosystem would you like to see in the world?
JM: I would like to see a much more joined-up approach. At the moment, the food system is in segments. But we are starting to talk about a food systems approach, from agriculture, production to consumption. While we may produce nutrient sensitive and nutrient dense commodities, it may undergo a processing system that takes out a lot of those nutrients, or completely changes the product that we end up eating. Whereas, if we have a joined-up system, we will have feedback across the food value chain. I would like to see proper transformation of the food system with health and environment at its centre. A food system that will have a low environmental impact but produce healthy diets.
Attendant pertinent questions would include – How do we achieve that? What do we need to do economically? What about subsidies? How do we make healthy food affordable and accessible for people? The big thing is really making sure that we are working within a food system that caters to all these elements, which requires bringing people from different disciplines together. For instance, people working at the consumption level understanding the connections between healthy food and agriculture. Then people working at the production level understanding why the food system is trying to move in a certain way to become more sustainable and what that means for the consumer. This is all anchored on having a joined-up approach.
What we do not want is a fragmented system that is expensive or that fosters inequalities. In the past, we have tended to work in silos, which is partly what has caused a lot of the problems we are currently tackling. We want to ensure that we also end up having an economic system that is profitable for food that is healthy and has minimal environmental damage. There is a lot to do now to really rethink our food system and strategise on how to move it towards a healthier system for both the planet and for people. However, we must consider this in the context of our complex global food system, where there can be unintended consequences. This is the reason why we must adopt a holistic and joined-up food systems position, because if we do not, we would not think of, for example, the consequences of subsidies. Subsidies must be properly thought through, because subsidising food production in one country may have negative consequences in another as globalisation and multilateralism have facilitated international trade. Obviously, legislation for food will be important. Within the legal landscape for food, we need to think not just economics, we also must think longer term – How does our proposal affect the environment? It will require a big shift because we are not near there now. This is a goal to aspire to, and hopefully, get things moving in the right direction.
