We’ve all heard about the need to eat a healthy, balanced diet including fruits and vegetables. But what is a vegetable, really? When it comes to putting food on your plate, the answer isn’t as simple as you might think
In a botanical sense, a fruit is defined as the seed-bearing structure of a flowering plant that is formed from the ovary after flowering. There remains no scientific consensus, however, on the question, “What is a vegetable?”
There’s a famous line, “There’s no such thing as a fish” (there’s even a podcast bearing the name). This refers to the fact that the term “fish” has been coined to group together a wide range of water-based animals that do not actually fall within the same scientific classifications.
Similarly, Vegetables have been grouped together in a variety of ways – including by botanic families, colours, and which part of the plant is edible – yet their taxonomy remains disparate.
The influence of place and culture
Perceptions of what counts as a vegetable have been shown to vary across countries, cultures, and communities. One study from the US National Cancer Institute (USNCI), for example, found that Spanish speakers were more likely (and Chinese speakers less likely) than English speakers to consider rice a vegetable.
Cultural definitions are a powerful force. Botanically speaking, nuts in general are classified as fruits, but peanuts are legumes. In a cultural or consumer context, however, it would be rare to make this distinction.
Furthermore, many foods commonly considered as vegetables are actually fruits. Perhaps the most famous example is the tomato, but this also applies to peppers, cucumber, and pumpkin.
A focus on dietary benefits
Vegetables continue to defy classification because there are no unifying characteristics across foods broadly considered to be vegetables.
Most of the discussions in scientific literature focus instead on trying to define vegetables in terms of the dietary benefits they provide. This largely explains why researchers continue to define vegetables very differently.
When it comes to planning a healthy diet, many scientists and health professionals focus on classifying vegetables according to food composition profile – the types of nutrients they provide.
For example, the USNCI study notes that while the US and Australian health departments class potato as a vegetable, the World Cancer Research Foundation has excluded starchy tubers from recommendations to increase vegetable intake. Taking this a step further, the “Fruits & Veggies – More Matters” programme – driven by the US Department of Agriculture and other organisations – considers the preparation method as well, excluding French fries and other fried vegetables.
Maize (corn) and soybeans are considered vegetables. Unsurprisingly, though, products prepared using them (such as maize tortillas, popcorn, tofu, and soy “milk”) are generally not. While classifying these products does not relate directly to the scientific or botanical classification of the original foodstuff, it does further confuse the issue when it comes to the use of vegetables in a healthy diet. According to researchers, this reinforces the vagueness and complexity of the term “vegetable”, as well as the extent to which interpretations of the term may vary.
As long as this focus continues to dominate both the scientific literature and popular culture, the term vegetable will continue to be used predominantly in a culinary and/or nutritional sense. Thus, attempts to define what makes a vegetable a vegetable will be subject to the vagaries of cultural, ethnic, and regional interpretation.
Reaching a consensus
Without any definitive scientific or botanical definition – an unlikely proposition considering the wide diversity of plant types grouped under this umbrella term – this is probably for the best. The first thing that springs to mind when someone mentions vegetables is likely an edible plant linked to a healthy diet, so it makes sense to continue to classify them based on the nutritional benefits they provide.
However, there needs to be some scientific consensus reached about where to draw the line in these classifications. The easiest way to do this is probably to define a vegetable as the edible part of its parent plant, similarly to fruit (although lacking the more precise delineation between most fruits and their parent plants – like a peach and the tree it grows on). Any product containing vegetables or requiring them to be processed, on the other hand, clearly becomes exactly that: a product – not a vegetable in its own right.
