Zeaxanthin in Sea Buckthorn: The Carotenoid Behind the Colour

By Dr. Raj Dhadwal

Sea buckthorn, also spelled seabuckthorn, is orange, and the compound behind that colour may not be the one most people assume. Beta-carotene gets the credit because it is the carotenoid everybody has heard of. In the one wild Romanian population with a full published breakdown, the largest single carotenoid was zeaxanthin, a different molecule from beta-carotene. If you searched the compound name against the berry, here is what that composition data says.

In the measured Romanian wild population, zeaxanthin was the largest single carotenoid, reported at 8.61 mg per 100 g of fresh berry against 4.14 mg for all-trans-beta-carotene and 1.80 mg for lutein, mostly in esterified form.

Zeaxanthin, beta-carotene and lutein: what is the difference?

Carotenoids split into two families. Carotenes are pure hydrocarbons: carbon and hydrogen, nothing else. Xanthophylls carry oxygen atoms on the ring ends, which makes them more polar and changes how they behave in a fruit and in a fat.

Beta-carotene is a carotene. It is symmetrical and carries no oxygen on the rings, which is why it is the carotenoid most often named on a composition table.

Zeaxanthin and lutein are both xanthophylls, and they are structural isomers of one another. Identical molecular formula, identical mass, and one double bond in a different position on one of the end rings. That single bond is the entire chemical difference between them, and it is enough to change their colour slightly and their polarity, which in turn changes how each one behaves in an oil and on an analytical column.

How much zeaxanthin does sea buckthorn carry?

A study of wild-type Hippophae rhamnoides harvested in Cluj County, Romania, published a full carotenoid breakdown for the saponified berry extract, and it is the clearest single set of figures available.

Carotenoid	Amount, mg per 100 g fresh berry	Share of total carotenoids
Zeaxanthin	8.61	42.62 percent
all-trans-beta-carotene	4.14	20.52 percent
all-trans-lutein	1.80	8.93 percent
all-trans-gamma-carotene	1.65	8.15 percent
beta-cryptoxanthin	0.94	4.64 percent
Total carotenoids	20.19	100 percent

Figures from a study of Romanian wild-type sea buckthorn, PMC10254770.

In that dataset zeaxanthin is close to half of all carotenoid measured, and more than double the beta-carotene. That is unusual. In most orange fruit and vegetables beta-carotene leads comfortably.

These figures come from one origin and one wild population, and are not a species-wide value. A separate source, the Norwegian Food Composition Table, publishes 860 micrograms of beta-carotene per 100 g of raw sea buckthorn, which is roughly a fifth of the Romanian figure. Sea buckthorn composition varies very widely by subspecies, altitude and ripeness, and no single number describes the species. The tocopherol side of the same fraction is covered in carotenoids and tocopherols in sea buckthorn.

How does it compare with other zeaxanthin sources?

Published zeaxanthin values sit on different bases, and mixing them into one ranked column produces a comparison that is not real. The sections below keep them apart. Values in the second and third tables come from a review of dietary zeaxanthin occurrence, in micrograms per gram, the unit the review uses.

Fresh berry, per 100 g fresh weight

Food	Zeaxanthin	Source
Sea buckthorn, Romanian wild population	8.61 mg per 100 g	PMC10254770

That is the only fresh-weight whole-berry figure in the sources used here. The comparison foods below are reported on dry weight, so they cannot be set against this row.

Dried material, micrograms per gram dry weight

Food	Zeaxanthin, micrograms per gram dry weight
Goji berry (wolfberry)	1,231.1
Sea buckthorn berries	193 to 424
Orange pepper	62.0
Corn	10.31
Egg yolk, raw	1.5
Spinach	0.7

Oil, per gram of oil

Material	Zeaxanthin, micrograms per gram
Sea buckthorn oil, cold-pressed	2,312.2

Carotenoids concentrate in the lipid fraction, so figures per gram of oil are high and are not comparable to whole-food figures. The review reports this row on a fresh weight basis for the oil, a different basis again, which is why it stands on its own.

Within the dry-weight table, goji is the famous zeaxanthin berry and it earns the reputation, carrying roughly three to six times what sea buckthorn berries carry and leading every other food in that list.

Spinach is on the list because people expect it to be, and its zeaxanthin figure is very low. Spinach is a lutein food, not a zeaxanthin food, and databases that report the two combined obscure that completely. If a table gives you a single lutein-plus-zeaxanthin number, it is not telling you which one you are getting.

What does esterified mean, and why does it matter here?

In most fruit that carries xanthophylls, the molecule does not float free. It is attached to a fatty acid, usually palmitic acid, forming a mono-ester or a di-ester. In goji berries the dominant form is zeaxanthin dipalmitate. The Romanian sea buckthorn study reports that zeaxanthin in the unsaponified berry extract was mostly in the esterified form, with beta-cryptoxanthin mostly esterified as well.

This has two practical consequences.

The first is measurement. Most analytical methods saponify the extract first, hydrolysing the esters back to free zeaxanthin before quantification. That is what the 8.61 mg per 100 g figure above represents: total zeaxanthin after the esters were cleaved. A method that measures free zeaxanthin without saponification will return a much lower number from the same fruit, and comparing across those two method families is a common source of contradictory published values.

The second is stability. A study of sea buckthorn pomace tracked carotenoids across 30 days of storage and found zeaxanthin esters to be the most stable compounds under all conditions tested, retaining 66 to 79 percent, while free zeaxanthin fell to about 46 percent in wet storage and 50.7 percent when dehydrated. Esterified forms were more stable in that storage study.

What do heat and light do to it?

Carotenoids are long conjugated chains, and the same double-bond system that produces the colour is what makes them vulnerable. Heat, light and oxygen all degrade them, and the degradation shows up as colour loss before anything else.

The 30-day storage study gives real numbers for the direction. Total carotenoids in wet sea buckthorn material retained 76.15 percent at 4 degrees Celsius, 64.40 percent at 25 degrees Celsius, and 75.80 percent in dehydrated material held at 25 degrees Celsius. Beta-carotene specifically retained 54 to 72 percent depending on the method, with the worst result in room-temperature wet storage.

Cold matters more than dry: refrigeration outperformed room temperature by more than ten percentage points on the same material. And drying is not free but is not catastrophic either, since dehydrated material at room temperature landed close to refrigerated wet material. Related handling questions are covered in does sea buckthorn need refrigeration.

What is not published is a retention figure for any specific commercial process applied to a specific commercial product. Pasteurisation temperatures, hold times and packaging oxygen barriers all move the number, and manufacturers do not publish before-and-after carotenoid assays. Anyone quoting a retention percentage for a named product is not reading it off a study.

Where this sits in a whole berry

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Carotenoids are fat-soluble and travel with the pulp oil, which is why the pressing method decides whether they are in a finished product at all. For the wider profile see sea buckthorn nutrition facts.

Frequently asked questions

Is zeaxanthin or beta-carotene the main carotenoid in sea buckthorn?
In the measured Romanian wild population, zeaxanthin, at 42.62 percent of total carotenoids against 20.52 percent for all-trans-beta-carotene.

Does sea buckthorn have more zeaxanthin than goji?
No. On a dry weight basis goji berries are reported at 1,231.1 micrograms per gram against 193 to 424 for sea buckthorn berries.

What is the difference between zeaxanthin and lutein?
They are structural isomers with the same formula and mass, differing only in the position of one double bond on one end ring.

Does cooking destroy the zeaxanthin in sea buckthorn?
Published storage data shows losses with heat and time rather than complete destruction, and esterified zeaxanthin held up better than the free form in storage. No figure exists for any specific cooking method applied to this berry.

The short version

Zeaxanthin is a xanthophyll, an oxygen-bearing carotenoid, and it is a structural isomer of lutein differing by the position of one double bond. In the measured Romanian wild population it was the largest single carotenoid at 8.61 mg per 100 g of fresh fruit, 42.62 percent of the total, ahead of beta-carotene at 4.14 mg and lutein at 1.80 mg. It sits mostly in esterified form, which both complicates measurement and makes it more stable in storage than free zeaxanthin. Goji is the richer whole-food source on a dry weight basis, while figures per gram of cold-pressed sea buckthorn oil are higher again because carotenoids concentrate in the lipid fraction, on a basis whole-food figures cannot be ranked against. Heat, light and storage time each reduce measured zeaxanthin, and cold, dark storage reduced it least in that study.