The place of animal products in a more sustainable diet

Abstract

Twitter @StephanPetersNL. Replacing animal-based foods with plant-based foods does not necessarily lower a diets carbon footprint. The nutritional value of food should be taken into account, as well as affordability. Modeling with the quadratic program Optimeal® helps to understand the ecological impact of changing food choices in a healthy diet, and the impact on food prices. Key messages
• Replacing animal products with plant-based alternatives does not automatically result in a healthy alternative diet
• Eating according to the food-based dietary guidelines can increase grocery costs
by 20%
• Eating less meat can reduce the carbon footprint by 20%, but grocery costs increase by up to 10%
• Eating less dairy can reduce the carbon footprint by maximal 7%, but grocery costs increase by 35%
• Eating more bread reduces both the carbon footprint and the costs on groceries Sustainable diets RESEARCH This article was published in Dutch in Voeding Magazine 2-3 | 2020.

Full text

The place of
animal products
in a more sustainable diet
TEXT DR. STEPHAN PETERS AND DRS. JOLANDE VALKENBURG (NZO, THE HAGUE), PROF.DR.IR. THOM HUPPERTZ
(WAGENINGEN UNIVERSITY RESEARCH, WAGENINGEN, FRIESLANDCAMPINA, AMERSFOORT), LUUK BLOM AND
LIONEL VAN EST (NUTRISOFT, GRONINGEN). IMAGE YUNE (AMSTERDAM)
Replacing animal-based foods with plant-based foods does not necessarily
lower a diets carbon footprint. The nutritional value of food should be taken
into account, as well as affordability. Modeling with the quadratic program
Optimeal® helps to understand the ecological impact of changing food choices
in a healthy diet, and the impact on food prices.
Sustainable diets
RESEARCH
This article was published in Dutch in Voeding Magazine 2-3 | 2020.
The calculations are based on LCA-analyses, prices and food compositions of products from the Netherlands.
ons per kilogram of product on the basis of
life-cycle analyses. Using a LCA, the CO2
emissions of a product in all phases of its
life cycle are mapped out. This includes the
raw materials used, packaging, transport,
storage, consumer maintenance and waste
disposal. This is also called the “cradle-to-
grave” analysis, the environmental impact
of a product from its inception to its end.
For each phase of a product’s life, aspects
of the environmental impact can be calcu-
lated, such as land use, water use and CO2
quence, simply leaving out animal pro-
ducts can lead to nutrient deficiencies.
Moreover, the change towards a more
plant-based diet can also have significant
consequences for the costs of your groceries.
In this article, we explain how this works.
Cradle to grave
Scientists and policy-makers have long held
on to the paradigm “eat more plant-based
and less animal-based”. This rule arose
mainly as a result of calculations of emissi-
It is often assumed that you can
reduce the negative eects of your
diet on the environment by eating
more plant-based products and less
animal-based products. This rule
does not always apply, because it
does not take sucient account of the
health aspects of your diet. This may
sound contradictory, because eating more
vegetable products is more beneficial to
our health. But animal products also play
an important role in our health. In conse-
1

emissions. The ultimate LCA value of a
food product is the sum of the CO2 (or other
ecological variable) footprint of each stage
in the life cycle of a food product.
CO2 emissions per kg of
product
Based on LCAs, an overview can be made
of the carbon footprint of food products.
These are often expressed in terms of
CO2 emissions per kilogram of product
(figure 1). The figure shows that products
of animal origin are responsible for most
of the CO2 emissions per kilogram of
product. However, a representation of
CO2 emissions per kilogram of product
does not take into account the quantity
and quality of nutrients in the product.
This means the CO2 emissions of a food
does not tell the whole story, because the
nutritional value is not taken into account.
Reducing or eliminating animal-based
foods from your diet can have negative
consequences on nutrient intake.
To avoid deficiencies, those nutrients
must be compensated for by other foods.
Less animal-based foods:
compensation
In an average Dutch person’s diet, animal
products are an important source of protein,
minerals and vitamins (figures 2 and 3).
Animal products contribute significantly
to the intake of important nutrients, such
as high-quality protein, vitamins A, B2
and B12, calcium, magnesium, zinc and
(in the case of meat) heme iron. These
nutrients are not naturally, or often,
found in plant products. Omitting animal
products from the diet therefore can have
major consequences for nutrient intake.
Plant-based alternatives
On first sight, a way to eat more sustain-
ably is to replace animal products with
plant-based products that are positioned
as alternatives. For example: replacing
meat with a meat substitute and milk with
plant-based drinks that are marketed as
possible alternatives. This seems plausible
because a number of these alternatives are
enriched with vitamins and minerals.
Nevertheless, the one-to-one replacement
of animal products with plant-based alter-
Calcium (mg)
Phosphorus(mg)
Potassium(mg)
Kalium (mg)
Copper(mg)
Magnesium (mg)
Sodium(mg)
Selenium (mg)
Iron(mg)
Heme iron (mg)
Zinc (mg)
Eggs Meat Dairy
0 10 20 30 40 50 60 70 80 90 100
Sources of minerals
VCP 2012-2016, ages 1-79
Bronnen van vitamines
VCP 2012-2016, 1-79-jarigen
Figure 2. Share of eggs, meat and dairy in
the mineral intake of the average Dutch person,
according to the Dutch Food Consumption
Survey 2012-2016 1-79 year olds.
Beef rump steak
Gouda cheese 48+
Pork shoulder chops
Chicken fillet
Pangasius
Chicken egg
Herring
Tomato raw
Whole milk
Yoghurt full fat
Chickpeas
Banana
Bread whole meal
Sojadrink
0
5
10
15
20
25
30
35
40
45
50
CO2eq / kg
Figure 1: Carbon footprint per kilogram of food product.
Key messages
• Replacing animal products
with plant-based alternatives
does not automatically result
in a healthy alternative diet
• Eating according to the
food-based dietary guidelines
can increase grocery costs
by 20%
• Eating less meat can reduce
the carbon footprint by 20%,
but grocery costs increase
by up to 10%
• Eating less dairy can reduce
the carbon footprint by
maximal 7%, but grocery
costs increase by 35%
• Eating more bread reduces
both the carbon footprint
and the costs on groceries
2

natives still leads to potential shortages of
various nutrients. The Dutch Institute of
Public Health (RIVM) has made model
calculations for this purpose. Figure 4
shows the eects on nutrient intake when
dairy and meat are replaced by products
that are recommended as alternatives in
nutritional advice or are available in the
supermarket (figure 4). The RIVM came to
the following conclusions:1,2
1. 30% substitution of animal products
can lead to a 14% reduction in the
CO2-eq footprint and 100% substitution
leads to a 40% reduction in the CO2-eq
footprint;
2. Replacing animal products with
“plant-based alternatives” can lead to
a potential shortage in intake of zinc,
vitamin B1 (thiamine), A and B12 and
calcium.
In short, simply leaving out animal products
leads to potential nutrient deficiencies and
replacing animal products with plant-based
alternatives does not automatically lead to
a healthy alternative diet. The substitution
is not as “nutrient neutral” as one might
expect.
Ideally, model calculations should show
how you can fully compensate for the missed
nutrients with other foods, when you reduce
or omit certain products from your diet.
If the calculated alternative diet ensures
that all nutrients are compensated for,
a more nutritionally complete picture is
generated of changes in the diet.
Programming with Optimeal® oers
this unique option.
Calculating with Optimeal®
Based on quadratic programming in
the Optimeal® program, the eects of
increasing or decreasing products or
product groups (of animal or vegetable
origin) on CO2 emissions can be calculated.
Optimeal® can also be used to calculate
the eect of a change in diet on the costs
of groceries. In its calculations, Optimeal®
uses dierent datasets of 208 commonly
consumed foods in the Netherlands and
combines them:
- Nutrient composition
- Supermarket price
- CO equivalent (CO2-eq) impact based
on life-cycle analyses (LCAs)
Optimizing for health
Optimeal® is a mathematical program
that makes calculations using quadratic
programming. In simple terms, this means
that the LCA data of 208 products are
combined with their nutrient composition.
In our calculations, Optimeal® depicts
the dietary pattern by subdividing these
208 products into 12 product groups.
The starting amount of each product
group in grams is approximately what
the average Dutch person eats (according
to the Food Consumption Survey of the
Dutch Institute of Public Health, RIVM).
The first step is to “optimize” this starting
diet. Once optimized, the starting diet will
meet all recommendations for vitamins,
minerals, saturated fat, salt, etc. as set out
in the Dutch food-based dietary guidelines.
This optimized diet creates an optimal
starting point. Optimeal® can then cal-
culate an alternative healthy diet when
increasing or decreasing the quantity of
a product group.
To show how this works in practice, we
will take meat as an example. In the
Netherlands, the Dutch eat about 150
grams of meat per day (sum of all types
of meat) on average. If we reduce the
amount of meat in Optimeal®, the program
calculates which nutrients you lose. In the
30% change 100% change
% change from reference
-40
-30
-20
-10
0
10
20
30
40
Protein
*
SFA
Fibre
Ca
Fe
Zn
Vitamin A
Thiamin
Vitamin B12
Vitamin D
**
*
*
*
*
*
*
*
*
*
*
Figure 4. Percentage change in nutrient intake after replacing 30% and 100% dairy and meat
with plant-based alternatives.
Retinol activity eq. (µg)
Retinol (µg)
Vitamin B1 (mg)
Vitamin B2 (mg)
Vitamin B3 (mg)
Vitamin B4 (mg)
Folic acid (µg)
Folate Equivalents (µg)
Vitamin B12 (µg)
Vitamin C (mg)
Vitamin D (µg)
Vitamin E(mg)
Vitamin K1 (µg)
Eggs Meat Dairy
Sources of vitamins
VCP 2012-2016, ages 1-79
0 10 20 30 40 50 60 70 80 90 100
Figure 3. Share of eggs, meat and dairy in the intake of vitamins by the average Dutch person,
according to the Dutch Food Consumption Survey 2012-2016 1-79 year olds.
Sustainable diets
RESEARCH
3

case of meat, this is a decrease in, among
other nutrients, protein, vitamin B12 and
iron. To compensate for these lost
nutrients, Optimeal® looks for products in
the other foods in the 11 groups that can
provide these nutrients. Optimeal® selects
these foods and, using quadratic program-
ming, strives to find an alternative diet that
is as similar as possible to the starting diet.
Working in this way Optimeal® ensures that
the alternative diet always complies with
the dietary guidelines and that it is recog-
nizable and acceptable to the average
Dutch person. Decreasing meat in
the diet and compensating for it
using Optimeal® results in a
decrease of the CO2-footprint
of the diet, but it makes the
diet also more expensive.
First results
On average, the Dutch do not eat accor-
ding to the food-based dietary guidelines.
In order to make good calculations within
Optimeal®, we first “optimized” the
average Dutch diet to a healthy diet that
meets all recommendations for vitamins,
minerals, macro nutrients and saturated
fat, among others, according to the
food-based dietary guidelines. This
optimized diet had the same CO2 foot-
print as the average Dutch diet. Interes-
tingly enough, this optimized diet is 20%
more expensive than the average Dutch
diet. In other words: if the average Dutch
person eats according to the food-based
dietary guidelines, he or she will spend
about 20% more on groceries than they
do currently.
CO2 emissions and price
effects
With Optimeal® we can calculate an
alternative diet in a nutritionally sound
way and see the eect of that change in
the carbon footprint and price of the
supermarket groceries. The results in
table 1 show results of calculation with
Optimeal® in which the amount of the
given food group was reduced by 33%,
66% and 100% respectively. In these
calculations, the lost nutrients were
compensated for according to the
principle of quadratic programming.
Results from Optimeal®
We started this article with the question
of whether it is ecologically better to eat
fewer animal products and more vegetable
products. The results from the calculations
with Optimeal® in table 1 clearly and
reliably show when this is the case and
when it is not.
The most important results are:
- Eating less meat results in a diet with a
lower carbon footprint of 20%, but the
costs in the supermarket increase by up
to 10%.
- Eating less fruit and vegetables reduces
the carbon footprint by up to 5%.
Doubling fruit and vegetable intake
increases the CO2 footprint by 7%
and grocery costs by 8% (not shown
in table 1).
- Reducing dairy intake reduces the carbon
footprint by maximal 7%, but grocery
shopping becomes more expensive by
35%.
- Eating less bread and whole grain
products increases the carbon footprint
up to 5%, but grocery costs also rise by
around one-fifth. Conversely (not shown
in table 1), eating more bread reduces
both the carbon footprint and the costs.
Similar calculations have been carried out
previous.3 Our calculations were similar
but with more product groups and added
grocery prices.
Optimeal
®
ensures that the
alternative diet always complies
with the dietary guidelines
CO2 emissions per % decrease
in product group
Grocery price per % decrease
in product group
33% 66% 100% 33% 66% 100%
Vegetables -1 -2 -2 -1 -1 -1
Fruit -2 -3 -5 -2 -4 -5
Meat -11 -18 -21 0 +3 +10
Fish +1 +3 +6 -1 -2 -1
Dairy -2 -4 -7 +4 +17 +35
Beans/legumes 0 -1 -1 0 0 1
Nuts/seeds -1 -1 -2 0 0 0
Bread/whole grain +1 +3 +5 +5 +16 +18
Potatoes/rice/pasta -1 -1 -2 0 +1 +1
Fats +1 +5 +9 +1 +2 +3
Candy/snacks +1 +3 +9 +3 +6 +17
Beverages (excl. milk) -2 -3 -4 -1 -2 -3
Table 1. Effect on CO2 emissions and the price of groceries when reducing the quantity of a product group and compensating for it based on quadratic
programming with Optimeal®.
4

Discussion
According to the Food and Agriculture
Organization of the United Nations (FAO),
there are four important preconditions for
a sustainable change in diet. Any new diet
must be i healthy, ii aordable, iii acceptable
and iv ecologically beneficial. There is a
very complex correlation between these
factors. For a desired change to be success-
ful, a balance must be found between
these four preconditions. Calculations
with Optimeal® bring together these
factors, because it calculates alter native
diets that are as i healthy (i.e. they contain
as many nutrients) as the starting diet.
It then provides insight into the ii price
and iii ecological eects. Through the
principle of quadratic programming,
the mathematical model ensures that
the calculated alternative dietary pattern
comes as close as possible to what the
consumer is used to, making it the most
iv cultural acceptable alternative.
Based on the calculations, the paradigm
“eat less animal- and more plant-based
products” can also be tested. The calcula-
tions show that the paradigm is too general
and does not always apply. The fact that
fewer animal products cause less environ-
mental impact of the diet is true for meat,
but not for dairy and fish. That more vege-
table products cause less environmental
impact applies to bread/whole grain pro-
ducts, but not to fruit and vegetables. The
impact of dietary changes can be viewed in
the interactive online tool (see box). In
these calculations using quadratic pro-
gramming, no food groups were excluded
as alternatives. This means that Optimeal®
can choose any possible alternative (also
animal based) to replace a food group to
achieve a healthy diet that is as sustainable
as possible. For example, when replacing
dair y, Optimeal® mainly chooses vegetables
as an alternative, because after dairy,
vegetables are the most important source
of calcium. If dairy were to be completely
omitted from the diet, calculations with
Optimeal® show that the consumer would
need to consume 538 grams of vegetables
every day.
Conclusion
The paradigm “eat fewer
animal products and more
vegetable products” is of little use to
anyone who strives for a more sustainable
diet that is also healthy. Animal products
contain many nutrients and cannot be
replaced by plant-based products on a
one-to-one basis. To determine a more
sustainable diet, it is necessary to take
into account the quantity and quality
of nutrients in food. This can be done
with the Optimeal® calculation program.
Through quadratic programming,
Optimeal® combines the LCA data
(including carbon footprint) with the
nutrient composition and the supermarket
price of 208 products. Calculations with
Optimeal® show that eating less meat
has a favorable eect on environ-
mental impact and that grocery
costs for the consumer increase
slightly. Eating less dairy hardly
reduces the carbon footprint, and
groceries become significantly more
expensive. The conclusion is that policy
and nutritional advice on more sustainable
eating must be based on both CO2 emissions
and health aspects. In addition, advice on
sustainable dietary changes should take
consumer costs into account.
When replacing dairy, the consumer
would need to consume 538 grams
of vegetables every day
Sustainable diets
RESEARCH
References
1 Seves, S.M. et al. (2017) Are more environmentally sustainable diets with less meat and dairy nutritionally adequate?
Public Health Nutr 20 (11), 2050-2062.
2 Temme, E.H., Bakker, H.M.E., Seves, S.M., Verkaik-Kloosterman, J., Dekkers, A.L., van Raaij, J.M.A., Ocké, M.C. (2015)
How may a shift towards a more sustainable food consumption pattern affect nutrient intakes of Dutch children?
Public Health Nutr 18 (13), 2468-2478.
3 Kramer, G.F. et al. (2017) Decreasing the overall environmental impact of the Dutch diet: how to find healthy and
sustainable diets with limited changes. Public Health Nutr 20 (9), 1699-1709.
Interactive tool
The effect on CO2 emissions and grocery costs when reducing a food group by 33%,
66% and 100%, while compensating for lost nutrients through quadratic program-
ming, is shown in table 1. With the online tool at https://www.nzo.nl/en/ nutrition/
sustainable-diets/ more calculations with Optimeal® can be viewed. By moving the
cursor up or down a food group in the interactive tool, an alternative food pattern is
shown that is just as healthy, calculated with Optimeal®. The columns on the right
of the figure show the effect on the carbon footprint and the costs of groceries.
5