I recently grew my own home-grown carrots, and the resulting crop was a little bit bitter. It got me wondering: are bitter carrots safe to eat?
Bitter Carrots Cause
A little google revealed a fantastic paper by Tian et al 2024 which says that the cause of bitter carrots is as follows:
Terpenoids such as α-terpinene, β-myrcene, β-caryophyllene usually contribute to the bitter flavor of fresh carrots. (1)
The question is -
Is it safe to eat bitter carrots?
I asked chatGPT, and got these answers:
α-Terpinene: In large amounts, α-terpinene can cause irritation to the gastrointestinal tract, and it might lead to symptoms like nausea, vomiting, or diarrhea. High doses can be toxic and have been shown to cause liver and kidney damage in animal studies.
β-Myrcene: Consumption of large quantities of β-myrcene can cause sedation and muscle relaxation. Some animal studies suggest potential for liver toxicity and other adverse effects at high doses.
β-Caryophyllene: Generally considered safe in typical dietary amounts. However, consuming it in excessively large amounts could potentially cause gastrointestinal distress and other adverse effects. It is also noted for its anti-inflammatory and pain-relieving properties, which are beneficial at controlled doses but could potentially lead to unwanted effects if overconsumed.
The question is, how much is too much? How much carrots would you need to consume to eat these terpenoids in dangerous levels?
I asked chatGPT:
” Given that α-terpinene, β-myrcene, β-caryophyllene can be dangerous to eat in large amounts; how much carrots by weight (in grams or kg) would be toxic to eat, if they contain α-terpinene, β-myrcene, β-caryophyllene?”
Here was the answer:
To determine the potential toxicity of carrots based on their content of α-terpinene, β-myrcene, and β-caryophyllene, we need to know the concentration of these compounds in carrots and their toxic doses. Here’s the approach we need to take:
1. Determine the concentration of each compound in carrots:
The concentrations of these compounds in carrots can vary, but we will use typical values from available research. For example, essential oil compositions or specific studies on carrot phytochemicals.
2. Establish the toxic doses of each compound:
Toxicological studies and safety data sheets provide information on toxic doses, usually given as LD50 (the lethal dose for 50% of the population).
Concentrations in Carrots
Typical concentrations of these compounds in carrots might be:
· α-Terpinene: Approximately 0.5 mg/kg in fresh carrots.
· β-Myrcene: Approximately 0.2 mg/kg in fresh carrots.
· β-Caryophyllene: Approximately 0.1 mg/kg in fresh carrots.
These values are rough estimates, as exact concentrations can vary.
Toxic Doses
Toxic doses for these compounds (estimated from various sources and animal studies) might be:
· α-Terpinene: LD50 (oral, rat) = 3700 mg/kg (5)
· β-Myrcene: LD50 (oral, rat) = 4900 mg/kg (6)
· β-Caryophyllene: LD50 (oral, rat) = 5000 mg/kg (7)
Calculation
Let’s calculate the approximate amount of carrots needed to reach toxic levels for a 70 kg adult.
1. α-Terpinene:
o Toxic dose = 3700 mg/kg × 70 kg = 259,000 mg = 259 g
o Amount in carrots = 0.5 mg/kg
o Carrots needed = 259,000 mg / 0.5 mg/kg = 518,000 kg
2. β-Myrcene:
o Toxic dose = 4900 mg/kg × 70 kg = 343,000 mg = 343 g
o Amount in carrots = 0.2 mg/kg
o Carrots needed = 343,000 mg / 0.2 mg/kg = 1,715,000 kg
3. β-Caryophyllene:
o Toxic dose = 5000 mg/kg × 70 kg = 350,000 mg = 350 g
o Amount in carrots = 0.1 mg/kg
o Carrots needed = 350,000 mg / 0.1 mg/kg = 3,500,000 kg
Conclusion
Based on these calculations, an individual would need to consume extremely large amounts of carrots—ranging from hundreds of thousands to millions of kilograms—to reach toxic levels of these compounds. Therefore, in practical terms, it is virtually impossible to consume a toxic dose of α-terpinene, β-myrcene, or β-caryophyllene from eating carrots alone.
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In addition, ChatGPT tells me: cooking can affect the levels of volatile compounds like α-terpinene, β-myrcene, and β-caryophyllene in carrots.
Heat can cause them to evaporate, leading to a reduction in their concentration. The extent of the reduction depends on the cooking method, with steaming generally preserving more of these compounds compared to boiling or roasting.
References:
(1) Tian et al 2024 , A comprehensive review on botany, chemical composition and the impacts of heat processing and dehydration on the aroma formation of fresh carrot , Food Chemistry: X, Volume 22, 30 June 2024, 101201,
https://www.sciencedirect.com/science/article/pii/S2590157524000889
(2) M. Kramer, G. Bufler, D. Ulrich, M. Leitenberger, J. Conrad, R. Carle, D.R. Kammerer, Effect of ethylene and 1-methylcyclopropene on bitter compounds in carrots (Daucus carota L.)
Postharvest Biology and Technology, 73 (2012), pp. 28-36, 10.1016/j.postharvbio.2012.05.009
(3) S. Kreutzmann, A.K. Thybo, M. Edelenbos, L.P. Christensen, The role of volatile compounds on aroma and flavour perception in coloured raw carrot genotypes
International Journal of Food Science & Technology, 43 (9) (2008), pp. 1619-1627, 10.1111/j.1365-2621.2007.01662.x
(4) L.M. Negri Rodríguez, R. Arias, T. Soteras, A. Sancho, N. Pesquero, L. Rossetti, …, N. Szerman Comparison of the quality attributes of carrot juice pasteurized by ohmic heating and conventional heat treatment
LWT, 145 (2021), 10.1016/j.lwt.2021.111255
(5) PubChem – α-Terpinene (similar to gamma terpinene) – https://pubchem.ncbi.nlm.nih.gov/compound/7461
(6) PubChem – β-Myrcene https://pubchem.ncbi.nlm.nih.gov/compound/31253#section=Non-Human-Toxicity-Excerpts
(7) PubChem – β-Caryophyllene https://pubchem.ncbi.nlm.nih.gov/compound/5281515