Kohlrabi | whatsinit

About

What it is and where it shows up.

Kohlrabi (Brassica oleracea var. gongylodes) is a biennial herbaceous vegetable of the Brassicaceae (mustard) family that produces a swollen bulb-like stem eaten raw or cooked. It is consumed as a food vegetable and is rich in antioxidant vitamins C and E, carotene, dietary fibre, and bioactive glucosinolates such as sulforaphane and isothiocyanates.

Safety summary

The regulatory and scientific consensus.

Kohlrabi is widely regarded as safe for the general adult population with no established ADI; it contains glucosinolates that are associated with reduced cancer risk but may theoretically affect thyroid function at very high intake, though animal studies show kohlrabi has a high thyroid safety profile due to its low progoitrin content. No major regulatory body has placed restrictions on its consumption as a whole food. High intake of kohlrabi sprouts (not typical dietary portions) has been associated with reduced white blood cell counts and adverse liver function markers in rat studies, an effect attributed to elevated glucosinolate intake.

Regulatory landscape

What food-safety regulators have decided.

Jurisdiction	Status	Note
EFSA (European Food Safety Authority) (European Union)	Approved	Kohlrabi is classified as a conventional vegetable food; pesticide maximum residue levels (MRLs) apply under EC Regulation 396/2005. No ADI or additive restriction has been established.source
FSSAI (Food Safety and Standards Authority of India) (India)	Approved	Kohlrabi is a whole vegetable food regulated as a fresh produce item under the Food Safety and Standards Act, 2006 and associated regulations; no specific maximum intake or additive restriction applies.source
FDA (Food and Drug Administration) (United States)	Approved	Kohlrabi is a whole, unprocessed vegetable recognized as a conventional food; no additive status or intake restriction. Subject to standard produce safety regulations under FSMA.source

Who should approach with care

Whose guidance would steer them away.

Thyroid Disease — Kohlrabi contains glucosinolates which can theoretically exert goitrogenic effects; although animal studies show its progoitrin content is low and thyroid safety profile is high, individuals with pre-existing hypothyroidism or iodine deficiency should exercise caution with very large or concentrated (sprout/juice) intake.

Diabetes — Knol-khol juice has demonstrated a statistically significant hypoglycaemic effect in a pilot clinical trial, so diabetic patients on blood-glucose-lowering medications should consult a doctor before using concentrated forms to avoid additive blood sugar lowering.

Liver Disease — High intake of kohlrabi sprouts was associated with adverse liver function markers in rats, likely due to elevated glucosinolate levels; patients with existing liver disease should avoid consuming large quantities of sprouts or concentrated preparations.

Research citations

The sources behind this verdict.

1PubMed. The Impact of Kohlrabi Sprouts on Various Thyroid Parameters in Iodine Deficiency- and Sulfadimethoxine-Induced Hypothyroid Rats, 2022. pmc.ncbi.nlm.nih.gov
2PubMed. Glucosinolates From Cruciferous Vegetables and Their Potential Role in Chronic Disease: Investigating the Preclinical and Clinical Evidence, 2021. pmc.ncbi.nlm.nih.gov
3PubMed. Immediate effect of bitter gourd, ash gourd, Knol-khol juices on blood sugar levels of patients with type 2 diabetes mellitus: A pilot study, 2017. pmc.ncbi.nlm.nih.gov
4PubMed. Anti-Diabetic and Anti-Inflammatory Effects of Green and Red Kohlrabi Cultivars (Brassica oleracea var. gongylodes), 2015. pmc.ncbi.nlm.nih.gov
5PubMed. Glucoraphanin and 4-hydroxyglucobrassicin contents in seeds of 59 cultivars of broccoli, raab, kohlrabi, radish, cauliflower, brussels sprouts, kale, and cabbage, 2004. pubmed.ncbi.nlm.nih.gov

Independently researched5 citations