9.4 What are the synergies and trade offs and overall implications for health?

Current diets generate high environmental impacts and are often not healthy. There is a need to identify diets that are good for health but have low environmental impacts. Is it possible to define diets that deliver both health and environment benefits?

9.4.1 ‘Win-wins’ are possible, if not inevitable

Win-wins are possible, if not inevitable

Tilman and Clark (2014).
Non-meat and lower-meat diets generally have lower GHG and land use impacts and are associated with reduced incidence of some important chronic diseases


Chapter 7 discusses the links between eating patterns and health, including the links between higher consumption of red and processed meats and sugars, and obesity, Type II diabetes, coronary heart disease and other non-communicable diseases.

This study identified associations between lower GHG-emitting diets such as a Mediterranean diet, pescetarian diets, and vegetarian diets and reductions in the incidence of such non-communicable diseases. It is important to note that there are also other important non-diet related lifestyle and socio-economic influences on the incidence of such diseases (see Chapter 7).

The study does, however, highlight the potential for eating patterns to achieve win-wins – to contribute to both good health and lower environmental impacts.

Lower impact eating patterns can be consistent with good health

As the studies in this chapter show, diets consisting of less food from livestock and more of the appropriate fruit and vegetables have lower environmental impacts and are consistent with good health. These diets have also been associated with reduced risk of certain negative health outcomes.

More research is needed to understand the characteristics of SHEPs for environmental impacts other than GHGs, such as the sustainability of water use, impact on biodiversity and so forth.

Given the caveats already discussed, a lower environmental impact diet that is also healthy might look like this:

  • Sufficient calories to meet energy needs and nutrient diversity
  • Based around tubers, whole grains, fruit and vegetables (mainly field grown, resistance to spoilage, and not requiring energy-intensive transport).
  • Meat eaten sparingly, if at all, and all parts consumed
    • Includes offal (which is generally nutrient rich) but may also include fattier cuts – since overall meat intakes are very reduced overall dietary quality does not suffer unduly.
  • Dairy products in moderation or replaced with fortified plant-based alternatives
  • Unsalted seeds and nuts
  • Small quantities of fish, from certified sources
  • Very limited quantities of processed foods high in fats, sugars and salt

These general principles may not be applicable to all individuals in all parts of the world. In that sense, while we understand what SHEPs might look like, there is no single ‘ideal’ SHEP.

9.4.2 Sustainable healthy eating patterns are context specific

Sustainable, healthy eating patterns (SHEPs) are context specific – there is no single ‘ideal’ SHEP

  • As shown above, synergies are possible for healthy and low impact eating patterns. Our understanding of diets that are healthy, less GHG-intensive and place less stress on water and land use is growing.
  • But we have less understanding of the relationship among the environmental, societal and economic dimensions of sustainability.
  • There is no ideal SHEP – the ‘ideal’ is contextual.
    • Different age-groups and social groups have different nutritional needs.
    • Important differences in nutritional requirements exist between high and low income countries and among populations within countries.
  • ‘Sustainable’ depends on which aspect we focus on, for example:
    • GHG emissions
    • Water stress
    • Land-use
    • Animal welfare
    • Human welfare (for example farmers’ livelihoods)
    • Other socio-economic and cultural factors.

9.4.3 There are trade-offs between health, environmental and socio-economic considerations

Trade-offs between health, environment and socio-economic aspects exist

Trade offs can exist between health and the environment. For example:

  • Shifts in eating patterns towards certain fruit and vegetables might increase nutritional quality but also increase water stress if this increases production requirements in water scarce areas.
  • Food processing can be a way of improving resource efficiency (e.g. sausages make use of less appealing body parts) but at a cost to health (e.g. due to the addition of salt).

Trade-offs can exist between environmental impacts. For example:

  • Some fish have a lower GHGs than meat but increased fish consumption could put extra pressure on fish stocks and marine biodiversity.
  • Most fruits and vegetables have lower GHGs than meat, but increased consumption of fruits that are grown in warm but water scarce regions could exacerbate water stress – or there may be pesticide issues to consider.

Trade-offs can exist between environmental impacts and social and economic aspects of sustainability. For example:

  • Changes in livestock farming practices that lead to reduced GHGs might have negative consequences for animal welfare.
  • A reduction in livestock production may negatively impact jobs and livelihoods or may undermine food security or local food cultures and traditions

Win-wins are possible if not inevitable. It is possible to define diets that deliver both health and environment benefits, but there are many possible trade-offs that must be considered.

Care and planning is needed to ensure micronutrient adequacy (e.g. iron, calcium, vitamin B12, zinc) – otherwise there is a risk of deficiency.

Animal products are important sources of protein and essential micronutrients both in high and low income contexts. Removing them completely from the diet without care could increase the risk of deficiency.

However, well-planned and diverse plant-based diets can have lower environmental impacts than those containing meat. They can also be nutritionally adequate, containing the full range and quantity of essential micro- and macro-nutrients.

In summary, diets lower in animal products can be nutritionally adequate and carry lower environmental impacts.

The ‘need’ for animal products depends on the context of consumption (see later in the chapter).

9.4.4 Possible outcomes

Towards sustainable and healthy diets

Diets can be seen as:

  • “lose-lose”: high impact / unhealthy (more common in rich and emerging countries)
  • “win-lose”: low impact / unhealthy (more common in poor countries)
  • “lose-win”: high impact / healthy (mainly in rich countries)
  • “win-win”: the “ideal” that is low impact and healthy.

As this chapter has shown there is an acknowledgement that, in high income countries at least, this would include lower levels of animal products and higher levels of appropriate fruit and vegetables (see Chapter 3  for more on the relative GHGs of food types). Proteins can be obtained from other sources, not just from animal products, especially legumes and pulses. Fish should be limited to certified sustainable stocks (see Chapter 5) and food waste should be minimised.