Learn · Botanical

Turmeric

A golden spice from the ginger family. Here is the chemistry of what gives it its colour, and why it is paired with black pepper.

In your pack500mg, with 5mg black pepper
FormTurmeric and black pepper
Comes fromThe root of Curcuma longa
Key moleculeCurcumin

The basics

What it is

Turmeric is the dried and ground underground stem, or rhizome, of Curcuma longa, a plant in the ginger family. It has been used as a spice and a dye in South Asia for thousands of years.

Its deep yellow colour comes from a group of compounds called curcuminoids. The main one is curcumin.

The basics

What it does

There is no authorised health claim for turmeric or curcumin in Great Britain, so we do not make one. Turmeric is available as an option in VeraCustom for people who want it in their routine.

What we can do is explain the chemistry: what is in turmeric, and what happens to it in your body.

The basics

How to take it

Dose - 500mg of turmeric with 5mg of black pepper a day

When - with a meal

Curcumin dissolves in fat far better than in water, so taking it with food makes sense. Turmeric supplements can interact with some medicines, including blood thinners, so check with your GP or pharmacist first if you take any regular medication.

A little deeper

Why black pepper?

Curcumin is poorly absorbed. It barely dissolves in water, and what does get through the gut wall is quickly tagged for removal: enzymes in the gut wall and liver attach a sugar acid to it, which makes it water-soluble and easy to excrete.

What happens to curcumin after you swallow itA three step flow. Curcumin is swallowed, the gut wall and liver attach glucuronic acid to it, and the tagged, water-soluble form leaves the body in bile and urine. Piperine from black pepper slows the tagging step.Curcuminswallowed, poorly soluble in watergut wall and liver attach glucuronic acidCurcumin glucuronidetagged with a sugar acid, now water-solublecarried awayOut of the bodyin bile and urinePiperine from black pepperslows the tagging step.
Curcumin is tagged and removed quickly. Piperine, the compound that makes black pepper taste hot, slows the tagging enzymes.

In one small study in healthy volunteers, taking 20mg of piperine with 2g of curcumin raised the amount of curcumin measured in the blood about twentyfold. That is a finding about absorption, not about any effect on health.

A little deeper

The molecule

Curcumin is a symmetrical molecule: two identical rings joined by a seven-carbon bridge.

Skeletal structure of curcuminTwo six-membered aromatic rings, each carrying an OH group and a methoxy group, joined by a seven-carbon chain that contains two carbon to carbon double bonds and two carbon to oxygen double bonds.HOOCH3OOOHOCH3Diketone bridge
Curcumin. The long run of alternating single and double bonds absorbs blue light, which is why turmeric looks yellow.
Formula
C21H20O6
Molar mass
368.4 g/mol
Systematic name
(1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5-dione
As a food colour
E100

The same structure makes curcumin a natural pH indicator. It is yellow in acid and turns red-brown in alkali, which you can see by adding a little bicarbonate of soda to turmeric in water.

A little deeper

Piperine, from black pepper

Piperine is the molecule responsible for the heat of black pepper. It makes up a few percent of the weight of a peppercorn.

Skeletal structure of piperineAn aromatic ring fused to a small ring containing two oxygens, joined by a four-carbon chain with two double bonds to a carbon double-bonded to oxygen, which is bonded to the nitrogen of a six-membered ring.OOONPiperidine ring
Piperine.
Formula
C17H19NO3
Molar mass
285.34 g/mol
Systematic name
(2E,4E)-5-(1,3-benzodioxol-5-yl)-1-(piperidin-1-yl)penta-2,4-dien-1-one

For the curious

Going deeper

Open any of these for more detail. None of it is needed to take it well, it is here if you want it.

How much curcumin is in turmeric

Turmeric powder is mostly starch and fibre. Curcumin makes up only a few percent of its weight, about 3% on average in one analysis of pure turmeric powders.

Curcumin has two close relatives in turmeric, demethoxycurcumin and bisdemethoxycurcumin. Each is curcumin with one or both of its OCH₃ groups missing.

Keto and enol

The middle of the bridge can exist in two forms that swap back and forth. In the keto form, drawn above, there are two C=O groups with a CH₂ between them.

In the enol form, a hydrogen moves from that carbon to one of the oxygens. This creates an unbroken run of alternating bonds from one ring to the other. In solution, curcumin is mostly in the enol form.

A difficult molecule to test

Curcumin has been studied a great deal in the laboratory, but it is a hard molecule to test fairly. It is unstable, it glows under the light that many tests use, and it sticks to proteins in general, all of which can give false signals.

A detailed review by medicinal chemists in 2017 set out these problems. It is listed in the sources below.

Quick facts

  • There is no authorised health claim for turmeric or curcumin in Great Britain, so we do not make one.
  • Curcumin is the food colouring E100.
  • Turmeric belongs to the ginger family.
  • Piperine is what makes black pepper taste hot.
  • If you take regular medication, check with your GP or pharmacist before taking a turmeric supplement.

Sources

  1. Great Britain nutrition and health claims register, GOV.UK
  2. Shoba G et al. Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta Med. 1998;64(4):353-356
  3. Tayyem RF et al. Curcumin content of turmeric and curry powders. Nutr Cancer. 2006;55(2):126-131
  4. Nelson KM et al. The essential medicinal chemistry of curcumin. J Med Chem. 2017;60(5):1620-1637
  5. Curcumin, PubChem compound summary, CID 969516
  6. Piperine, PubChem compound summary, CID 638024

Food supplements should not replace a varied, balanced diet and a healthy lifestyle. Speak to your GP before use if you are pregnant, breastfeeding, taking medication or have a medical condition.

Where you'll find it

Packs with turmeric

VeraCustom

Add turmeric to a box you build yourself. From £11.99 per 28 days