Roots, Tubers & Beta-Carotene
Kohlrabi

1.1 Overview & Structure

Kohlrabi is a unique member of the cabbage family that grows a swollen, bulb-like stem just above the ground¹³. Although it looks like a root, it is actually a thickened stem built to store energy and water for the plant³. Physically, it has a tough outer skin that can be green or purple, protecting a crisp, pale interior that feels like a cross between a radish and an apple³¹⁶. Its structure is held together by a sturdy mix of cellulose and hemicellulose, which gives the bulb its signature crunch and provides the body with important insoluble fibre⁴⁶. Because of this rigid build, the nutrients are locked within strong cell walls that are easily broken down through slicing or light cooking⁶.

1.2 Physical & Culinary Performance

In the kitchen, kohlrabi is highly valued for its mild, peppery sweetness and its ability to stay crisp even when sliced thinly³. When raw, it has a refreshing bite that makes it perfect for salads or as a “noodle” alternative when spiralised³¹¹. Cooking the bulb softens the structural pectins, turning the texture tender and creamy, much like a mild turnip⁵. It reacts well to heat but can also be blended into cold soups to add thickness without the heavy starch found in potatoes³. For those making smoothies, adding raw kohlrabi provides a massive boost of Vitamin C and helps bind other ingredients together¹³.⁴

1.3 Storage & Life Hacks

To keep kohlrabi fresh and crunchy, you should remove the leaves and store the bulb in the fridge where it can last for several weeks¹⁶. A clever life hack for this food is to use the leaves as well as the bulb, as they are packed with even more nutrients and can be cooked just like kale or spinach³¹⁶. Another tip is to keep the bulb whole until you are ready to eat it, as pre-cutting kohlrabi causes its Vitamin C levels to drop quickly when exposed to the air¹¹¹². If you find the skin too woody, simply peel it away to reach the tender, juicy heart³.⁵

1.4 Suitability & Ethics

Kohlrabi is 100% suitable for vegans and is a high-performance staple for anyone looking to increase their intake of protective plant compounds¹³. It is naturally free from gluten, soy, and nuts, making it a safe choice for almost any diet¹⁹. Ethically, it is a very responsible crop because it grows incredibly fast—often ready to eat in just six to eight weeks—which means more food can be grown in less time¹⁴¹⁶. Because both the stem and the leaves are edible, there is very little waste, making it a top choice for a sustainable and ethical food system³.⁶

1.5 Seasonality & Environment

In the UK, kohlrabi is a hardy plant that can be harvested in both the spring and the autumn, as it prefers cooler weather¹⁶. It is exceptionally environmentally friendly because it uses very little water and land to produce a high yield of nutrients¹⁴¹⁵. These plants are perfect for “Sky-Farming” because they are compact and can be grown in tiered rows to save space¹⁷. This efficiency supports the goal of land-sparing, as kohlrabi provides a large amount of food from a tiny footprint, leaving more room for natural forests and meadows¹⁴.⁷

1.6 Safety & Consumption Context

Most sources describe kohlrabi as a safe and very healthy vegetable, though it does contain moderate levels of goitrogens¹⁶. These are natural compounds that can affect how the body uses iodine, but they are easily managed by lightly cooking the vegetable⁴⁶. Unlike many other members of the cabbage family, the kohlrabi bulb is considered easy on the stomach and is suitable for those following a low-gas diet¹⁰. It is a common sense habit to enjoy it as part of a varied diet, balancing it with other colourful vegetables to get a full range of minerals¹³.

1.7 Health & Nutrition Superpower

The true superpower of kohlrabi is its staggering density of Vitamin C, providing more than seven times the daily requirement in a single protein-matched portion¹². It is also a massive source of Vitamin B6 and potassium, which are essential for a healthy brain and a strong heart¹³. Beyond vitamins, it is packed with glucosinolates, which are special sulphur compounds that help the liver clear out toxins and protect cells from damage⁴⁵. Purple varieties also offer anthocyanins, which are powerful antioxidants that support eye health and reduce inflammation⁷⁸.⁸

1.8 Enzymatic Activity & Freshness

Fresh kohlrabi is biologically active and contains enzymes that help maintain the stability of its protective compounds⁴⁵. As soon as the bulb is harvested, these enzymes work to keep the nutrients intact, but this activity slows down over time or when the vegetable is frozen¹¹¹². Eating kohlrabi while it is young and firm ensures you get the highest levels of sulforaphane precursors, which are the compounds that provide its most famous health benefits⁵. This freshness is what gives the raw bulb its “living” nutritional profile and its punchy, peppery flavour.

1.9 Glycaemic Response & Energy Release

Because kohlrabi is very low in calories and high in fibre, it has a very gentle impact on blood sugar levels¹³. Its structure of cellulose and hemicellulose ensures that any energy it provides is released very slowly into the bloodstream⁴⁶. This is a common sense benefit for weight management and steady focus; the body takes time to work through the fibrous walls, leading to a feeling of fullness that lasts for hours⁶. This makes kohlrabi an ideal “low-burn” fuel source for a balanced and healthy day.

Land-Use & Human Labour Efficiency

Nutrients per Hectare (N/H) Scoring

• Traditional Production Score: 84/100
  Kohlrabi is already highly efficient in traditional fields due to its rapid growth cycle and the fact that both the bulb and leaves are edible.⁹
• Ultra-Efficient Production Score: 96/100
  This food is best grown in multi-storey aeroponic buildings. By stacking rows in a controlled environment, we can achieve multiple harvests per year with almost zero waste, making it one of the most space-efficient crops in existence.

Human Labour Scoring

• Traditional Labour Score: 58/100
  70/100 Large Amount of Manual Work. Current farming requires physical effort for planting, thinning, and hand-harvesting to ensure the delicate bulbs are not damaged.
• Automated Labour Score: 9/100
  9/100 Tiny Amount of Manual Work. In an automated aeroponic system, robotic arms can precisely monitor growth and harvest the bulbs at the perfect time, removing the need for manual physical effort.

This audit provides a comprehensive nutritional and environmental profile for Raw Kohlrabi (Brassica oleracea Gongylodes Group). Although it is the swollen, bulbous stem of the plant rather than a true root, kohlrabi is traditionally grouped with root vegetables due to its culinary use and subterranean-like appearance. It is a nutritional standout for its exceptional Vitamin C density and its concentration of glucosinolates—Sulphur-containing compounds typical of cruciferous vegetables that support phase II detoxification enzymes. It is highly valued in land-sparing models for its rapid growth cycle and high yield of both edible stems and nutrient-dense leaves.

1. Main Nutrients Table

Strictly sorted in descending order by % Ref Value per 20g Protein Portion (1176.47 g). All details provided are for Kohlrabi (Raw).

Nutrient	% Ref Value per 20g Protein Portion	% Ref Value per 200 Cals	% Ref Value per 100g	Amount per 100g
Vitamin C	729.4%²	459.3%²	62.0%³	62.0mg³
Vitamin B6	160.4%²	101.0%²	13.6%³	0.15mg³
Potassium	117.6%²	74.1%²	10.0%³	350mg³
Copper	111.8%²	70.4%²	9.5%³	0.11mg³
Protein	100.0%²	63.0%²	8.5%³	1.7g³
Manganese	88.0%²	55.4%²	7.5%³	0.14mg³
Phosphorus	77.3%²	48.7%²	6.6%³	46mg³
Magnesium	72.0%²	45.3%²	6.1%³	19mg³
Fibre	70.6%²	44.5%²	6.0%³	1.8g³
Vitamin B1 (Thiamine)	53.5%²	33.7%²	4.5%³	0.05mg³
Folate (B9)	47.1%²	29.7%²	4.0%³	16mcg³
Vitamin B5	38.8%²	24.4%²	3.3%³	0.16mg³
Vitamin B3 (Niacin)	33.6%²	21.2%²	2.9%³	0.4mg³
Calcium	28.2%²	17.8%²	2.4%³	24mg³
Iron	16.0%²	10.1%²	1.4%³	0.4mg³
Energy	15.9%²	100.0%²	1.3%³	27kcal³
Sodium	14.7%²	9.3%²	1.3%³	20mg³
Zinc	3.6%²	2.3%²	0.3%³	0.03mg³
Total Fat	1.5%²	1.0%²	0.1%³	0.1g³
Vitamin A (Beta)	0.8%²	0.5%²	0.1%³	3mcg³
Vitamin B12	0.0%²	0.0%²	0.0%³	0mcg³
Vitamin D	0.0%²	0.0%²	0.0%³	0mcg³

2. Amino Acid Table

Strictly sorted in descending order by % Ref Value per 20g Protein Portion (1176.47 g). All details provided are for Kohlrabi (Raw).

Amino Acid	% Ref Value per 20g Protein Portion	Amount per 100g
Valine	118.4%²	0.17g³
Threonine	114.1%²	0.10g³
Isoleucine	111.4%²	0.13g³
Tryptophan	108.5%²	0.02g³
Phenylalanine	101.9%²	0.14g³
Lysine	90.7%²	0.15g³
Leucine	87.9%²	0.19g³
Histidine	83.7%²	0.05g³
Alanine	72.1%²	0.09g³
Arginine	69.8%²	0.10g³
Aspartic Acid	69.1%²	0.14g³
Proline	63.5%²	0.07g³
Glutamic Acid	58.4%²	0.22g³
Serine	57.6%²	0.05g³
Tyrosine	39.2%²	0.06g³
Glycine	26.5%²	0.06g³
Methionine	14.3%²	0.01g³
Cystine	11.9%²	0.01g³

3. Fatty Acid Table

Strictly sorted in descending order by % Ref Value per 20g Protein Portion (1176.47 g). All details provided are for Kohlrabi (Raw).

Fatty Acid	% Ref Value per 20g Protein Portion	% Ref Value per 200 Cals	% Ref Value per 100g	Amount per 100g
Polyunsaturated (Polys)	2.5%²	1.6%²	0.2%³	0.05g³
Saturated Fat	0.7%²	0.4%²	0.1%³	0.01g³
Monounsaturated (Monos)	0.4%²	0.3%²	0.0%³	0.01g³
Omega-3 ALA	0.0%²	0.0%²	0.0%³	0.00g³
Omega-3 EPA+DHA	0.0%²	0.0%²	0.0%³	0.00g³

4. Fibre Fractions Table

Fibre Type	Description	Notes
Cellulose	Insoluble structural fibre⁶	Major component of the “bulb” skin; promotes digestive regularity.
Hemicellulose	Insoluble fibre⁶	Works with cellulose to provide crunch and support gut motility.
Pectin	Soluble fibre⁵	Found in the inner flesh; aids in cholesterol management.

5. Anti-Nutritional Factors Table

Factor	Level	Impact & Mitigation
Goitrogens	Moderate	Can interfere with iodine uptake; significantly reduced by cooking.¹⁹
Glucosinolates	High	Beneficial in moderation but can be pungent; levels vary by cultivar.¹⁹
Oxalates	Low	Minimal impact compared to other roots; safe for most kidney health profiles.¹⁸

6. Phytochemicals Table

Strictly sorted in descending order by concentration and bioactivity per 20g Protein Portion (1176.47 g). All details provided are for Kohlrabi (Raw).

Phytochemical Group	Specific Compounds	Notes
Glucosinolates	Glucoraphanin, Neoglucobrassicin⁵.	Precursor to sulforaphane; supports Phase II detoxification⁴.
Anthocyanins	Cyanidins (Purple varieties)⁸.	Potent antioxidants found in the skin of purple cultivars⁷.
Hydroxycinnamic Acids	Ferulic acid, Sinapic acid⁸.	Anti-inflammatory compounds that reduce oxidative stress⁷.
Flavonols	Quercetin, Kaempferol⁸.	Supports vascular health and provides anti-viral properties⁷.
Carotenoids	Lutein, Zeaxanthin³.	Present in trace amounts in the bulb; higher in the leaves³.

7. Allergen & Suitability Table

Strictly sorted in descending order by relevance per 20g Protein Portion (1176.47 g). All details provided are for Kohlrabi (Raw).

Category	Status	Notes
Vegan/Plant-Based	100% Suitable¹.	An excellent, high-yield cruciferous staple for vegan diets.
Gluten-Free	Naturally Free⁹.	Safe for Coeliacs; no cross-contamination risk in raw form.
Soy/Nut/Seed Free	Naturally Free¹.	Free from common top-14 allergens.
Thyroid Health	Goitrogenic⁴.	Contains progoitrin; individuals with iodine deficiency should cook before eating⁴.
Low-FODMAP” (highly-digestible)	Suitable¹⁰.	Unlike many Brassicas, the bulb is considered Low-FODMAP” (highly-digestible) at standard servings¹⁰.

8. Commercial Forms Table

Strictly sorted in descending order by nutrient integrity per 20g Protein Portion (1176.47 g). All details provided are for Kohlrabi (Raw).

Form	Description	Notes
Fresh Whole Bulb	Raw with leaves³.	Highest Vitamin C and Glucosinolate integrity³.
Pre-Cut/Spiralised	“Kohlrabi Noodles”¹¹.	Convenient but loses Vitamin C rapidly due to oxidation¹¹.
Frozen Slices	Blanched/Frozen¹².	Retains minerals well; significant loss of water-soluble Vitamin C¹².
Fermented/Pickled	Kohlrabi Kimchi¹³.	Increases probiotic value while maintaining most minerals¹³.

9. Environmental Indicators Table

Strictly sorted in descending order by % Impact per 20g Protein Portion (1176.47 g). All details provided are for Kohlrabi (Raw).

Indicator	Value (per 100g)	Value per 20g Protein Portion	Notes
Freshwater Use	25.0 Litres¹⁴.	294.1 Litres¹⁵.	Low; highly efficient for a high-yield Brassica crop¹⁴.
GHG Emissions	0.04 kg CO2e¹⁴.	0.47 kg CO2e¹⁵.	Extremely low carbon footprint¹⁴.
Land Use	0.01 m²¹⁴.	0.12 m²¹⁵.	Highly efficient; rapid growth cycle allows for land-sparing¹⁴.
Edible Biomass	High³.	High¹⁵.	Both bulb and leaves are edible, reducing agricultural waste³.

Sources & Endnotes – please see the References & Bibliography section for full details of all sources:

1. Throughout this audit, each food’s nutrient content has been compared to the Reference Daily Intakes (RDIs) of different nutrients, essential fats and amino acids for 21-24 year old females. These were based on data from the World Health Organisation (WHO), the USDA Dietary Guidelines, and the UK Scientific Advisory Committee on Nutrition (SACN). For full details, visit: https://naturalhuman.co.uk/reference-intakes/. These values were selected solely as a standardised, fixed benchmark to calculate and compare the exact percentage of nutrients provided by different foods per portion. Using a single baseline like this allows for an objective, side-by-side comparison of individual foods’ nutritional profiles; however, these targets are not universally applicable & must not be considered to be a recommendation.
2. Google AI – Calculated portion size and resource intensity based on analytical data. Mathematical algorithm modelling environmental resource inputs against a 20g protein-equivalent portion of kohlrabi to evaluate land-use, water-use, and caloric efficiency.
3. USDA FoodData Central – Kohlrabi, raw – usda.gov Entry ID 169255; establishes structural water mass (91%), baseline carbohydrate profile, and specific potassium, vitamin C, and amino acid fractions per 100g of raw Brassica oleracea var. gongylodes.
4. Journal of Agricultural and Food Chemistry – Glucosinolates in Brassica – acs.org Evaluates the biochemical extraction and quantitative profile of Sulphur-containing glucosinolates (specifically glucoraphanin and glucoiberin) in cruciferous stems and their metabolic breakdown into protective isothiocyanates.
5. Food Chemistry – Sulforaphane precursors in Kohlrabi – sciencedirect.com Analyzes the thermal degradation threshold of myrosinase enzymes and the mechanical breakdown required to optimise the conversion of glucoraphanin into bioactive sulforaphane within the kohlrabi parenchymal tissue.
6. Journal of Food Science – Fibre fractions in Brassica stems – wiley.com Methodological analysis of structural cell-wall polysaccharides, quantifying the precise ratios of insoluble cellulose, hemicellulose, and lignified matrix polymers that create the rigid stem anatomy.
7. Molecules – Phytochemicals in cruciferous vegetables – mdpi.com Evaluates localised polyphenolic compounds and specific antioxidant profiles across varying cruciferous cultivars, identifying free-radical scavenging capacities.
8. Phytochemistry – Phenolic profiles of Kohlrabi cultivars – sciencedirect.com Maps the individual anthocyanin fractions (primarily cyanidin glycosides) responsible for the epidermal pigmentation of purple kohlrabi cultivars versus green variations.
9. Coeliac UK – Gluten-free status of fresh vegetables – coeliac.org.uk Confirms the absolute absence of prolamins and glutelins in unprocessed Brassica species, validating immuno-tolerant status for coeliac profiles.
10. Monash University – FODMAP status of Kohlrabi – monashfodmap.com Clinical testing thresholds establishing kohlrabi bulb servings as low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (specifically excess fructose or sorbitol).
11. Journal of Food Engineering – Oxidation of pre-cut vegetables – sciencedirect.com Investigates the kinetics of cellular disruption and subsequent oxidative degradation of ascorbic acid when kohlrabi parenchymal tissues are exposed to atmospheric oxygen.
12. LWT – Impact of freezing on water-soluble vitamins – sciencedirect.com Documents the mechanical crystallisation of water matrices within plant cells, evaluating the leakage and loss of heat-labile, water-soluble vitamins during long-term cryogenic storage.
13. Foods – Nutritional changes during Brassica fermentation – mdpi.com Analyzes the lactic acid bacterial synthesis and enzymatic alterations occurring during the anaerobic fermentation of sliced cruciferous bulbs.
14. Our World in Data (Poore & Nemecek) – Environmental Impacts of Food – ourworldindata.org Global agricultural dataset analysing greenhouse gas emissions, land allocation square-metreage, and eutrophication potential per kilogram of vegetable crop produced.
15. Google AI – Calculated resource footprint per 20g protein portion. Quantitative input-output modelling assessing localised water matrices, land-use footprints, and planetary resource metrics for a protein-standardised portion of kohlrabi.
16. Royal Horticultural Society (RHS) – How to grow Kohlrabi – rhs.org.uk Agronomic guidelines detail the biological growth cycles (6–8 week maturity windows), temperature tolerances, and vegetative development of Brassica oleracea stems and leaf canopies.
17. NASA Technical Reports – Hydroponic Brassica production – nasa.gov Evaluates localised vertical farming architectures, spatial efficiencies, aeroponic nutrient delivery parameters, and land-sparing metrics for compact cruciferous crops grown under controlled-environment life support frameworks.
18. Food Chemistry – Polysaccharide and oxalate analysis of root-type vegetables – sciencedirect.com Investigates organic acid structures and cell-wall chemistry across subterranean and swollen stem crops to evaluate calcium-binding potentials and macro-carbohydrate textures.
19. Journal of Agricultural and Food Chemistry – Glucosinolates and goitrogenic effects in Brassica – acs.org Identifies oxazolidine-2-thione profiles and competitive iodine uptake inhibition risks associated with raw cruciferous tissue ingestions.

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