Calendula Polysaccharides: What the Lab Studies Tested

Calendula flowers do contain polysaccharides, and in the 1980s German researchers tested fractions of them on immune cells in the laboratory. That is the whole basis for the phrase "immune-boosting component," and it does not carry over to an infused oil. Those polysaccharides came from water or alkali extracts of the flowers, and they are water-soluble sugars. The oil we make is a different kind of extraction, so we do not describe our oil as an immune product, and this page explains why.

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What was actually extracted

A 2022 phytochemical review traces the polysaccharide work on calendula to the mid-1980s and notes it concerns the flowers only. When researchers extracted C. officinalis flowers with 0.5 M sodium hydroxide, they isolated three neutral polysaccharides: a rhamnoarabino-3,6-galactan of about 15 kDa and two arabino-3,6-galactans of about 25 and 35 kDa, at yields of 0.08, 0.04 and 0.05 percent of the flower (Olennikov and Kashchenko, Molecules, 2022). Water extracts gave acidic polysaccharides with 24.1 to 57.2 mol percent uronic acids, according to the same review.

The EU herbal assessment report, written when the committee reviewed the old literature, summarises the testing this way. Polysaccharide fractions of molecular weight 25,000 to 500,000 "showed significant immunostimulating activity in the granulocytes and carbon clearance tests" (Wagner, 1985), and isolated polysaccharides stimulated phagocytosis by human granulocytes (Varljen, 1989), both as quoted by the committee (EMA/HMPC assessment report, 2008). The same report lists water-soluble polysaccharides at up to 15 percent of the herb, a textbook figure. We have read these studies through the EMA's and the review's summaries rather than the original papers, so we only repeat what those two documents report.

Three jumps the headline makes

"Immune-boosting" needs three steps that the evidence does not take. Here they are in order, with the reasoning labelled as ours.

  1. From immune cells in a dish or an animal test to a person. The assays above measured granulocyte activity and carbon clearance in laboratory systems. The reviews and the EMA text we read report no trial that showed a change in anyone's immune function after using calendula on the skin.
  2. From a water or alkali extract to an oil. The tested material was isolated fractions from those extracts. Reasoning from the fact that polysaccharides are water-soluble sugar chains, we would not expect much of them in an oil infusion. Nobody, as far as we found, has measured polysaccharides in a calendula oil, so this is an inference and not a measurement. The EU herbal monograph describes the oil preparation as a 1:10 extract in a fatty vegetable oil such as olive oil (EMA/HMPC, 2018), which is a very different solvent from 0.5 M sodium hydroxide.
  3. From immune stimulation to skin. Even if a fraction stimulates a white blood cell in vitro, that says nothing about what happens when an oil sits on the outer layer of skin.

The regulators took a similar view of the clinical side. EMA's public summary says calendula flower is accepted for minor skin and mouth or throat complaints on traditional use, and that clinical studies were considered "but did not support firm conclusions because of design problems" (EMA, Calendulae flos summary, 2018). That is a sober place to start from, and it is a long way from "boosts immunity."

Why the claim keeps circulating

Part of the reason is how calendula research gets summarised. The 2022 review counted twelve review articles on calendula published between 2006 and 2022 and observed that all of them aimed to generalise the pharmacological activity of calendula extracts, at the expense of information on chemical composition (Olennikov and Kashchenko, Molecules, 2022). In that style of summary, "extract" becomes "calendula," and "calendula" becomes "calendula oil." Each step drops the detail that matters here: which compound, from which solvent, tested on what.

You can protect yourself from that drift with three questions for any product page that cites immune or polysaccharide benefits:

Applied to the polysaccharide story, the answers are: water and alkali extracts, laboratory immune-cell assays, and no measurement in oil that we could find.

What this means if you are choosing an oil

When we explain what goes into our oil, we start from process. We buy dried flowers, infuse petals that have been separated by hand from whole dried flower heads, and extract calendula alone before bringing the extract into a carrier oil. Nothing else is added. Our batch paperwork covers physical assays, chemical assays and contaminant screening, and we do not publish a polysaccharide number, nor would you expect to find one on any infused oil's certificate. If a seller quotes a polysaccharide percentage for an oil, ask which method measured it and in what material. A figure that came from the dried flower is not a figure for the bottle.

What a calendula oil can be described by, honestly, is the colour and the lipid-soluble side of the flower: carotenoids and the faradiol esters. Even there, the published figures are for flowers and extracts, not for oil in a bottle. Our articles on carotenoids and faradiol go through what is known and what is not.

One more regulator is worth a line, because it speaks to what cosmetic oils are judged on. The Cosmetic Ingredient Review panel, assessing calendula-derived cosmetic ingredients in 2010, noted they may contain carbohydrates among many other classes of compounds, and concluded they were safe in cosmetics at the concentrations and practices described in its report (Andersen et al., Int J Toxicol, 2010). That is a safety judgement about use on skin. It makes no claim about immune effects, and we read it the same way.

If the polysaccharides are what you want

Then an oil is the wrong product, and we say so plainly. The preparations the EU monograph lists for the flower are water and alcohol based: a warm infusion of 1 to 2 g of flowers in 150 ml of water for mouth and throat use, tinctures, and semi-solid products. Those are traditional medicinal products with their own age limits. The monograph does not recommend them for children under 6 (skin) or under 12 (mouth and throat), and says safety in pregnancy and breastfeeding has not been established. A pharmacist or herbalist can tell you what is sold in your country, and we do not sell any internal product.

The other limit applies to every calendula product, including ours. Calendula is in the Asteraceae family, and the EU monograph lists hypersensitivity to Asteraceae plants as a contraindication. If you react to daisy-family plants, skip it, and see a dermatologist or allergist if you are unsure. For anyone else, patch test first.

So the short version: polysaccharides are a real part of the flower, they were studied in immune-cell assays decades ago, and a calendula oil is not the way to get them. If you want to know what our oil is, the process page at where it comes from is the honest answer.

Calendula oil bottle

Calendula Oil

Nature's Golden Botanical, bottled: small-batch calendula oil in sizes from 0.5 oz to bulk.

From $13.99

Shop Calendula Oil →

Sources & Further Reading