How many plants feed the world?

A first (of many, we hope) guest post from our friend and colleague Colin Khoury.

In the field of conservation of plant genetic resources, it is commonly stated that a very limited number of plant species feed the world.1 A number of publications, especially in the 1970’s and 1980’s, provided different angles on how many crops or species provide just how much of the human diet. And there are a lot of ways to try to answer the question. Most of the publications end up with numbers around 7, or 15, or 20, or 30 crops that feed the world. Prescott-Allen and Prescott-Allen (1990) found global aggregate statistical data unsatisfactory in telling the full story for peoples of all countries:

Crops such as fonio, Digitaria exilis Stapf, and quinoa, Chenopodium quinoa Willd., are lost in global production data; but to conclude that they are unimportant is to conclude that the people of Guinea, Gambia, and Bolivia who rely on them are unimportant.

Instead, they worked with national level Food Balance Sheets from FAO, and looked at the question in four ways to determine just how many species make up 90% of the total intake of food weight, calories, protein and fat in each country.

The result is “85 species commodities and 28 general commodities contribute 90% of national per capita supplies of food plants.” After a bit of tinkering, they come up with this final statement: “the total number of species commodities is 82. These consist of 103 species. Fifty-six of the species commodities, consisting of 75 species, account for 5% or more of the national supply of a nutritional category in at least one country.”

Still confused? Well, it’s a difficult question to answer. And answers are often underestimates, as statistical data rarely account well for local markets, home production, etc. Prescott-Allen and Prescott-Allen provide some interesting food for thought2 in working with statistics at the national level, and in doing so perhaps include more species/crops than studies working with global aggregate data.

Has much changed since 1990? A full re-run of their analysis, country by country, is still to be done. But what happens when we aggregate the country statistics from the latest Food Balance Sheets (2007)? Again including the four categories (weight, calories, protein, fat), and counting those crops and food products that comprise 90% of the diet, we find that about 25 crops/species, plus about 7 general commodities, do the job (not listed in any particular order of importance):

Apples
Bananas/ Plantains
Beans
Barley
Cassava
Coconut
Cottonseed
Grapes
Groundnuts
Maize
Millet
Olive Oil
Onions
Oranges, Mandarines
Palm Oil
Potatoes
Rape and Mustard Oil
Rice (Milled Equivalent)
Sorghum
Soyabeans
Sugar Cane
Sunflowerseed Oil
Sweet Potatoes
Tomatoes
Wheat

Beverages, Alcoholic
Beverages, Fermented
Fruits, Other
Oilcrops Oil, Other
Pulses, Other
Sweeteners, Other
Vegetables, Other

A further note, if the alcoholic beverages happened to have caught your eye:3

Average alcohol consumption (= beer + beverages, alcoholic + wine + beverages, fermented) = 70 kcal/cap/day = 3% total calories from plant sources. Alcohol consumption is much higher in some countries, such as Czech Republic: 282 kcal/cap/day, or 11.9% of total calories from plant foods.

Here’s the top 10 countries in providing calories from alcohol: Luxembourg, Ireland, Estonia, Czech Republic, Portugal, Austria, Germany, Lithuania, Bosnia and Herzegovina, Hungary. No surprises there.

Footnotes:
  1. Ah, those meta-narratives! Ed. []
  2. As it were. Ed. []
  3. Don’t look at me. Ed. []

7 Replies to “How many plants feed the world?”

  1. As it happens, I was thinking about these statistics during breakfast. What would happen if we include phylogenetic diversity? If two maize varieties can have more genetic differences than those between me and the average chimpanzee, perhaps this would be important to take into account as well. Just to help to confuse the reader a bit more.

  2. Journalists love this kind of figures. I have for long commented about that. The assumption behind is that we are highly dependent, and that our genetic base is fragile.
    One first objection is that ‘plants’ such as wheat or millets are not one species, but a group of species (2-5 for wheat and more than 10 for millets).
    A second objection is of course that those figures would better be elaborated at a regional or local level. Taro or yams would then spring up.
    A third objection is that only weights of staples are considered. But human nutrition also relies on micronutrients (vitamins,minerals, polyphenols…) and fibers, which are to be found in many other species, for example cabbages, fruits in general…
    Further, if we change the question into ‘how many food crops contribute to the world market?’, then black pepper, vanilla, lettuce and many others will come to the list, as their input in value is much more than their input in weight.
    Coming back to our dependance, I would add that I am quite confident about plants such as wheat or maize, because there are a lot of genetic resources available, and a big scientific community involved. The risk is greater with ‘orphan’ crops.
    Finally, the problem is not ‘which answer de we give to such a question?’, but ‘for what purpose do we ask this question?’.

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