Rick Wilson – Director of Nutrition and Dietetics at Kings College Hospital for 30 years up to his retirement in 2015, BSc. RD (retired) – looks at some of the considerations and challenges of eating a plant-based diet to benefit the planet.
There is no doubt that our diet and the food and agriculture systems that sustain it are contributing to the environmental emergency the planet now faces. The recent Intergovernmental Panel on Climate Change (IPCC) report ‘Climate Change and Land’ illustrates that in all likelihood our current trajectory will lead to severe, adverse effects on the climate. Change is necessary.
One of the key changes recommended is to reduce our consumption of meat. The evidence in the report shows that the production of meat as a source of protein in our diet is a very inefficient use of land. Plant-based sources of protein can be produced much more efficiently. Switching to a more plant-based diet would help.
The IPCC report does not recommend that we all adopt a vegan diet nor does it recommend that we all become vegetarian. Reducing meat consumption need not entail such drastic changes.
Another key point that has not been emphasised is that we should also try to reduce food waste. If meat is produced and eaten or produced and thrown away the detrimental effects on the environment are the same. Less consumption and less waste are both needed.
The National Diet and Nutrition Survey (NDNS), a survey carried out on behalf of the Department of Health and the Food Standards Agency, is a programme of surveys designed to assess the diet, nutrient intake and nutritional status of the general population aged 1.5 years and over living in private households in the UK. It is the best source of data available on the diet and nutrient intake of the UK population and has some useful considerations for those looking to reduce their impact on the planet by consuming less meat.
The most recent edition of the survey illustrates that the UK diet is adequate in most regards. In women – especially those of childbearing age – intakes of iron are low and put women at risk of iron deficiency anaemia as indicated by low haemoglobin levels. It also showed that a proportion of adult women and older girls had low iron stores as indicated by low levels of plasma ferritin. This is a key area of risk when considering reductions in meat consumption.
There are vegetarian sources of iron and indeed white flour is, by law, fortified with iron in the UK. Mineral iron and iron from plants is not as well absorbed by the human body as haem iron i.e. iron which is found in meat. When reducing meat intake special care must be taken to ensure an adequate iron intake.
Meat is a very good source of high-quality protein. All proteins are made up of a mixture of around 20 amino acids. The best protein for the growth and repair of human tissue would be human tissue! Barring this, meat is the next best quality protein with the necessary mix of amino acids. No single plant-based protein contains the full mix of amino acids we require. To get the full mix it is necessary to eat a wide variety of plant-based protein – each plants’ mix of amino acids complements the others to make up an adequate mix for humans. Grazing animals such as zebra and wildebeest must spend most of their day eating because their diet of grass is of poor quality. Carnivorous animals that prey on the grazers do not have to eat as frequently because their food quality has been enhanced and concentrated for them by the grazers.
Reducing the national consumption of meat and dairy foods in a sustainable way would require careful planning and thought. It is not without risk but the change may well be worth it should it have the desired effect on climate change
By Rick Wilson