Kratom UK Guide: Strains, Extracts & Lab-Tested Quality

What Is Kratom? (Mitragyna Speciosa Explained)

Mitragyna speciosa belongs to the coffee family (Rubiaceae) and grows natively across Indonesia, Malaysia, Thailand, and Myanmar. The leaves contain a range of naturally occurring alkaloids, the two most studied being mitragynine and 7-hydroxymitragynine. For centuries, communities across the region cultivated and traded the plant, and it remains a subject of ongoing scientific and botanical research today.

GreenGuru sources, dries, and packages kratom leaf material strictly as a collector and research specimen. We don't market it as a supplement, food product, or anything intended for ingestion — our role is to supply a consistently tested, traceable botanical product to collectors who value transparency about what's actually in the packet.

Kratom Strains Explained: Red, White, Green & Gold

Kratom is traditionally categorised by vein colour and, in some cases, by curing method. These distinctions come from the plant's natural pigmentation and post-harvest processing, and they're the main way collectors compare batches:

• Red vein — leaves left to mature longer before harvest, typically slow-dried.
• White vein — younger leaves, dried quickly to preserve a lighter colour.
• Green vein — harvested and dried at a mid-point between red and white processing.
• Gold vein — leaf that undergoes an extended fermentation or curing step, giving it a distinct appearance and profile.

Beyond colour, kratom is also classified by regional origin, which is where names like Bali, Borneo, and Jonkkong come from.

Bali Kratom

Named after the island of Bali, this is one of the most widely traded regional varieties and the most common starting point for collectors comparing origins. GreenGuru carries Bali across all four vein colours in both powder and tablet form, including Green Bali, Red Bali, White Bali, and Gold Bali.

Borneo Kratom

Sourced from the island of Borneo, this origin is known among collectors for a denser leaf structure and a distinct alkaloid ratio compared to Bali material. Available as Green Borneo, Red Borneo, White Borneo, and Gold Borneo.

Jonkkong Kratom

A rarer, less widely stocked regional variety that specialist collectors seek out specifically because it's harder to source reliably tested batches of. GreenGuru stocks Green Jonkkong, Red Jonkkong, White Jonkkong, and Gold Jonkkong.

Kratom Formats: Powder, Capsules & Tea

Beyond origin and vein colour, kratom is available in a few standard formats. Each is the same underlying material, processed differently for handling, storage, and study purposes.

Kratom Powder

The most common format: dried leaf ground to a fine, consistent texture. Powder is the base material most collectors start with, since it's the closest form to the raw dried leaf and the easiest to compare batch-to-batch. Browse the full kratom powder range.

Kratom Capsules

The same lab-tested powder, portioned into standardised capsules. Capsules are popular with collectors who want consistent, pre-measured units for cataloguing or comparison purposes, without handling loose powder. See the kratom tablets and capsules range.

Kratom Tea

Historically, dried kratom leaf was prepared as an infusion in parts of Southeast Asia, similar to other traditional herbal teas from the region. GreenGuru's fruit-flavoured kratom line — including cherry, apple, and lemon/lime variants — reflects this traditional format for collectors interested in the plant's cultural and ethnobotanical history. Explore the fruit kratom range.

What Is 7-OH (7-Hydroxymitragynine)?

7-hydroxymitragynine (7-OH) is one of the two principal alkaloids naturally occurring in Mitragyna speciosa, alongside mitragynine. It's present in the raw leaf only in trace amounts — most 7-OH products on the market, including GreenGuru's, are concentrated extracts specifically formulated to isolate and standardise this compound for research and collector purposes.

What's the difference between kratom and 7-OH? Standard kratom powder or capsules contain the full natural alkaloid spectrum of the dried leaf, with mitragynine as the dominant compound. 7-OH products are extracts, processed to concentrate the 7-hydroxymitragynine fraction specifically, at a stated, tested purity.

GreenGuru's 7-OH line includes several formats, each independently tested and clearly labelled with alkaloid content:

• 7-OH Kratom Strips — a fast-dissolving strip format, 20 mg of 7-hydroxymitragynine per strip, one strip per pack.
• 7-OH Kratom Extract, 96% purity — a concentrated powder extract.
• 7-OH Kratom Tablets, 7.5 mg and 15 mg — pure 7-hydroxymitragynine tablets in two strengths.
• Mitragynine Extract, 98% purity — for collectors specifically comparing mitragynine-dominant material against 7-OH-dominant extracts.

As with every product on GreenGuru, 7-OH items are sold strictly as collector and research specimens, with lab documentation available for each batch.

Lab Testing & Quality: How GreenGuru Verifies Purity

The single biggest quality risk in the kratom market is unverified material — batches with no independent testing, inconsistent alkaloid content, or contamination that only shows up under proper laboratory analysis. GreenGuru's approach is built around closing that gap:

• Heavy metal screening is carried out by an accredited laboratory at the State Veterinary Institute, testing every batch for mercury, lead, cadmium, and arsenic.
• Mycotoxin and pesticide screening, along with alkaloid (mitragynine) content verification, is carried out at VŠCHT Prague (the University of Chemistry and Technology), one of the leading analytical chemistry institutions in Central Europe.
• Results are batch-specific, not a one-off certificate reused across an entire product line.

Full documentation and methodology are published on our laboratory tests page. This is the page we'd point any collector to first if they want to verify a claim before buying.

Buying Kratom in the UK: What to Check

If you're comparing suppliers, a few checks separate a transparent collector-grade source from a generic listing:

1. Batch-specific lab reports, not a single generic certificate applied to every product on the site.
2. Independent, accredited labs — ideally named, not just "third-party tested" with no further detail.
3. A full contaminant panel — heavy metals, mycotoxins, and pesticides, not just an alkaloid percentage.
4. Clear alkaloid content stated per product, especially for concentrated extracts like 7-OH.
5. Transparent labelling that the product is sold as a collector or research specimen, not marketed for consumption.

GreenGuru publishes all of the above for every strain, format, and extract listed on the site, alongside shipping and payment details for UK orders and volume discounts for collectors and researchers ordering in bulk.

Frequently Asked Questions

What is kratom used for? Kratom (Mitragyna speciosa) has a long history of traditional cultivation and use across Southeast Asia. GreenGuru sells it strictly as a collector and research specimen for botanical study, not as a product intended for consumption.

What's the difference between kratom and 7-OH? Standard kratom contains the full natural alkaloid profile of the dried leaf. 7-OH products are concentrated extracts isolating 7-hydroxymitragynine specifically, at a tested, stated purity — a different product category from raw leaf powder or capsules.

Is kratom lab tested? Every GreenGuru batch is tested for heavy metals (mercury, lead, cadmium, arsenic) at an accredited State Veterinary Institute laboratory, and for mycotoxins, pesticides, and mitragynine content at VŠCHT Prague. Full results are published on our laboratory tests page.

What kratom strain is right for me? That depends on what you're comparing as a collector — origin (Bali, Borneo, Jonkkong) and vein colour (red, white, green, gold) are the two main variables. Many collectors start with Bali across the four colours as a baseline before comparing other origins.

How is kratom powder different from capsules? They're the same lab-tested material. Powder is the raw ground leaf; capsules are the same powder portioned into standardised, pre-measured units for easier handling and cataloguing.