phytochemical
Meaning of phytochemical: A neutral word for plant chemistry, covering pigments and flavors that may help, others that do nothing, and a few that are poisons.
Definition of phytochemical
A phytochemical is any chemical compound made by a plant. In nutrition the word usually means the thousands of plant compounds not classed as nutrients, since the body does not need them to survive, but which give fruit and vegetables their color, smell and bitterness and may affect health. Caffeine, the red pigment of tomatoes and the sulfur compounds in garlic are examples.
How does it differ from a nutrient?
A nutrient is something the body cannot make and cannot do without. Remove vitamin C from a diet and scurvy follows. Phytochemicals fail that test: no deficiency disease is known for any of them, which is why some writers prefer phytochemical to the friendlier word phytonutrient. The distinction is about necessity, not usefulness. Traditional nutrients such as protein, fat, vitamins and minerals have defined requirements, while phytochemicals have none and no intake has been set for them.
What are the main groups?
| Group | Found in |
|---|---|
| Polyphenols | Tea, cocoa, berries, olive oil |
| Carotenoids | Carrots, tomatoes, leafy greens |
| Glucosinolates | Broccoli, cabbage, mustard |
| Plant sterols | Nuts, seeds, vegetable oils |
| Alkaloids | Coffee, tobacco, nightshades |
The groups overlap and the total runs into the thousands, so any list of this kind is a sample rather than a catalogue.
Are they all good for health?
No, and assuming that plant means safe is the commonest misreading of the word. Plants make these compounds largely to defend themselves against insects and grazing animals, so bitterness and toxicity are part of the design. Nicotine, the solanine in green potatoes and the heart-active compounds of foxglove are all phytochemicals. Whether a diet rich in fruit and vegetables tracks with better health is also a separate question from whether one compound, extracted and sold as a capsule, does anything, and trials of isolated compounds have often failed to reproduce what was seen with whole foods. A label such as organic food describes how a plant was grown, not which compounds it contains.
Also known as
Used in a sentence
Fruits, vegetables and whole grains supply a wide range of phytochemicals.
Good to know
Phytochemical is a descriptive term rather than a claim of benefit, and it covers plant poisons such as nicotine and solanine alongside the compounds studied for possible protective effects.
Word origin
Where “phytochemical” comes from
The prefix phyto- comes from the Greek phyton, meaning a plant, joined to chemical.