Sustainable Dietary Protein

The following is a short briefing paper I created in (successful) application for an internship at the Parliamentary Office of Science and Technology (POST). This office produces (amongst other things) POST notes which provide parliamentarians with concise, timely information on various topics. Sustainable production of necessary dietary components is something I find fascinating and I chose to explore protein a bit further. I hope you enjoy it!

On 13 May 2013 the FAO released a new book: "Edible Insects: future prospects for feed and food security". There is growing concern regarding sustainable protein production for a growing population. This document addresses the role of protein in our diet, and the UK’s ability to produce it in the future.

Background

Protein is required in the human diet for growth and replacement of all cells in the body. Proteins are made from amino acids, which are present in all living things. There are 24 amino acids in the human body, 16 of which can be synthesised by healthy adult cells. The remaining 8 must be supplied from the diet, and are termed 'indispensable'.

Red and white meats, eggs, cheese, fish, nuts and beans are considered to be the 'high quality' proteins as they contain all 8 indispensable amino acids. 'Poor quality' proteins are those lacking at least 1 amino acid including wheat, rice, and maize. Their incomplete protein profile can be overcome by eating complementary proteins e.g. a meal of beans (pulse) on toast (cereal) gives protein of equal quality to meat, meaning a vegetarian diet can supply an adequate profile of indispensable amino acids (1).

Recommended Protein Consumption

The recommended daily allowance of protein is 55 g for an average adult (2). The National Diet and Nutrition Survey (NDNS) (3) found that the average adult consumption of protein was actually above this, with men consuming an average of 85.1 g day^-1 and women 64.4 g day^-1 (Table 1).

Table 1. Dietary protein intake for UK population

	Boys (4-18)	Men (19-64)	Men (65+)	Girls (4-18)	Women (19-64)	Women (65+)
Median daily protein intake (g) (3)	63.0	85.1	77.0	55.9	64.4	63.3

Consumption of up to 2-3 times the recommended guideline of protein is considered harmless; however once the body's protein needs are met excess protein is simply used for its calorific value, and surplus to requirements will be stored as fat. 

UK Protein Requirement and Production

Based on results from the NDNS and population estimates (4) it can be estimated that each year the UK requires almost 1.5 million tonnes of red meat, 700,000 tonnes of white meat, 500,000 tonnes of fish, and 300,000 tonnes of pulses. Currently the UK imports around 90% of meat consumed, but its self-sufficiency in producing beef stands at 80%, sheep at 65%, pork at 60-70% and poultry 88% (5). These figures are however in steady decline.

A food security analysis found that the UK is able to produce sufficient calories from arable, horticulture and livestock farming to provide the population with a healthy (if restricted) diet in a crisis situation (6). In reality it is unlikely the UK would act in isolation from the global market, and consumers are likely to demand a greater supply of high quality products over time, so the demand for meat is unlikely to fall.

Sustainability of meat production

The concerns surrounding future meat production include: production of cereals for animals that could instead be used for human consumption, environmental degradation from agricultural practices (POSTnote 418) greenhouse gas emissions, and concerns for animal welfare in more efficient 'intensive' systems (POSTnote 404). There are also serious concerns regarding the sustainability of fish stocks (6).

Table 2. Efficiency of animal-sourced protein production (7)

	Cricket	Poultry	Pork	Beef
Feed conversion ratio (kg feed: kg live weight)	1.7	2.5	5	10
% edible weight	80-100	55	55	40
g protein per kg edible weight	154-205	200	150	190

Production of meat is very inefficient in energy terms. The argument for the incorporation of insects into our diets centres on this inefficiency. For example, 5 kg feed is required to produce 1 kg pork (see Table 2), whereas crickets require only 1.7 kg feed per kg live weight. In addition more of the organism is edible (having no bones) and they provide protein equal to red or white meat. In all they are a much more efficient source of protein. While pulses are an even more efficient and lower-cost form of protein production, in the UK their consumption is 5 times lower than that of red meat. Considering this preference for red meat as a protein source it seems unlikely insects would be accepted as a protein alternative. 

Between January 2007 and December 2008 the cost of beef rose 21 %, lamb 16 %, poultry 23 % and fish 15% (6). As the cost of animal feed is linked to the price of nitrogen fertiliser – which is in turn linked to oil prices – it is likely that the price of meat to the consumer will continue to rise in coming years.

Conclusions

Owing to consumer preference it is unlikely that insects will form part of our diets in the near future. Sustainable production of protein is still a concern, and it is likely that pressure from rising food costs may yet force a reduction in the consumption of meat. Farming of insects for the global market may however provide another source of income for UK farmers.

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References

1. G. Wiseman, Nutrition and Health (Taylor and Francis, 2002).
2. FSA, Manual of Nutrition (The Stationery Office, ed. 11, 2008).
3. Department of Health, National Diet and Nutrition Survey: Headline Results from Years 1, 2 and 3 (combined) of the Rolling Programme 2008/09 – 2010/11 (2012) (available at http://transparency.dh.gov.uk/2012/07/25/ndns-3-years-report/).
4. Dataset: Estimates of resident population: number, by age group, annual 2011, MFPHealth and Social Care Information Centre (2012) (available at https://indicators.ic.nhs.uk/webview/).
5. T. Garnett, Meat and Dairy Production & Consumption (2007; http://www.fcrn.org.uk/sites/default/files/TGlivestock_env_sci_pol_paper.pdf).
6. Defra, UK Food Security Assessment: Detailed Analysis (2010; http://archive.defra.gov.uk/foodfarm/food/pdf/food-assess100105.pdf).
7. A. van Huis, Potential of insects as food and feed in assuring food security, Annual review of entomology 58, 563–83 (2013).