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Traditional Chinese medicine

Lotus seedNelumbo nucifera

A food seed that the texts use to firm loose stools, in Shen Ling Bai Zhu San; we found no gut trial of it, and one 45-adult trial of an extract for depression.

Botanical name
Nelumbo nucifera
Part used
seed (kernel)
Also called
pinyin Lian zi (莲子); Lotus seed, Nelumbinis semen
Used in
Traditional Chinese medicine
Taken for
Loose stools and diarrhea, Appetite
Sold as
dried seed, powder, extract, pills in formulas, decoction

What is meant by lotus seed

Lotus seed is the seed of Nelumbo nucifera Gaertn., the sacred lotus, an aquatic plant of Asia. In Chinese medicine the drug is Nelumbinis Semen, lian zi, the dried seed kernel. The green embryo at the center of the seed is a separate drug, Plumula Nelumbinis, with its own review, and is not what this page covers.

The seed is also a food: cooked in sweet soups and congee, ground to a paste for filling, or eaten dried. For the gut, it is one of the ten ingredients of Shen Ling Bai Zhu San, a Song-dynasty formula that a review describes as representative for spleen weakness diarrhea, with the symptoms of eating little, loose stools and tired limbs. Beyond that formula we found no gut studies of lotus seed in people. The single clinical trial of a lotus seed extract that turned up in our search tested depression and stress in 45 adults, not digestion.

In the traditions

Traditional Chinese medicine (about TCM)

Lian zi is classed in the Chinese materia medica as sweet, astringent and neutral, entering the spleen, kidney and heart channels. The tradition says it supports the spleen and astringes the intestines, and it uses it for the persistent loose stools, poor appetite and tiredness that the texts attribute to spleen weakness, as in Shen Ling Bai Zhu San, where it works with Chinese yam, coix, poria and lablab bean. The same texts use it for calming the heart and spirit and for steadying the kidney, which are non-gut uses. These are the tradition’s own classifications, taken from the standard English materia medica and a review of the formula, and not findings about the body.

What the plant contains

The sources we read give no composition table for the seed kernel itself. A review of the alkaloids of the lotus plant covers their biosynthesis, pharmacokinetics, bioactivity and safety, and a separate review covers the embryo, which is a different drug. A laboratory study of a seed extract used cell, computer and gas chromatography methods to profile its chemistry and reported anticancer potential. These are preclinical findings, none of them about digestion, and none identifies a compound responsible for the astringent, stool-firming use in the texts.

What has been tested in people

We found no human trial of lotus seed alone for diarrhea, loose stools, or any gut outcome. The one clinical trial of a lotus seed product that turned up was a randomized, double-blind, placebo-controlled study in 45 adults with major depression or other depressive disorders: a standardized water extract of Nelumbinis semen at 2.4 g or 4.8 g a day for two weeks. The 2.4 g group had better depression and stress scores than placebo (P below 0.05). The authors describe the result as preliminary evidence for safety. It says nothing about digestion.

The gut evidence that includes lotus seed is of the formula Shen Ling Bai Zhu San, which has ten herbs, so it cannot be attributed to the seed. A meta-analysis of 14 studies with 1,335 participants with chronic gastritis found the formula beat conventional therapy on the effective rate (risk ratio 1.29, 95% CI 1.21 to 1.37); the authors rate the quality of evidence as not high and the safety data as unclear. A network meta-analysis of five Chinese formulas for ulcerative colitis, 64 randomized trials with 5,456 patients, found formulas added to mesalazine did better than mesalazine alone. A pooled analysis of 26 animal studies of the formula in diarrhea found lower diarrhea scores (standardized mean difference -1.40) but rated the evidence very low. The review of the formula in colitis notes that the formula’s doses follow tradition and are not standardized.

What has not been tested: lotus seed in diarrhea, the formula without lotus seed, and any seed dose for a gut outcome.

StudyDoseWhat it found
Randomized double-blind trial, 45 adults with depressive disorders (lotus seed water extract; not a gut trial) PMID 35805620Nelumbinis semen water extract 2.4 g or 4.8 g a day for 2 weeksDepression and stress scores better than placebo at 2.4 g (P below 0.05); authors call it preliminary evidence of safety
Meta-analysis of Shen Ling Bai Zhu San in chronic gastritis: 14 studies, 1,335 participants (ten-herb formula) PMID 36156925Formula; doses not standardizedEffective rate better than conventional therapy, RR 1.29 (95% CI 1.21 to 1.37); evidence quality not high
Network meta-analysis of five formulas added to mesalazine in ulcerative colitis: 64 randomized trials, 5,456 patients (includes Shen Ling Bai Zhu San) PMID 39109018Formulas; add-on to mesalazineTCM plus mesalazine more effective than mesalazine alone
Meta-analysis of 26 animal studies of Shen Ling Bai Zhu San in diarrhea PMID 36188567Animal dosesLower diarrhea scores (SMD -1.40, 95% CI -2.03 to -0.87); evidence quality very low

Doses used in trials and traditional preparations

No trial of lotus seed for the gut gives a dose. The depression trial gave a standardized water extract of the seed at 2.4 g or 4.8 g a day for two weeks. In the formula trials the dose was that of the formula, and the review of the formula in colitis notes that its doses follow tradition and lack standardization. In the tradition the dried seed is decocted with other herbs, ground into a powder, or cooked into soup or congee as a food. We found no single-herb gram dose that we could tie to a primary source.

Treat these figures as a record of what was studied. Whether any amount of lotus seed suits a particular person is a question for a clinician or pharmacist who knows their history.

Safety

Lotus seed is a food with a long record of use, and the 45-adult trial of a water extract reported what its authors call preliminary evidence of safety over two weeks. The safety issue most specific to the seed is mold: in a survey of 163 commercially available edible and medicinal substances in China, one lotus seed sample contained 10.75 micrograms per kilogram of aflatoxin B1, above the regulatory limits in Europe and China; fungi were found in 92% of the samples overall. That is one sample in one survey and not a finding about every lotus seed. We found no pregnancy or breastfeeding data for extracts. For patent-medicine products, a review of Chinese proprietary medicines in Singapore tabulated excess toxic heavy metals and undeclared drugs reported in some such products between 1990 and 1997, which concerns those products and not lotus seed itself.

Drug interactions

We found no documented drug interaction for lotus seed in the sources read. The depression trial gave a standardized extract to people with depressive disorders but the abstract reports no interaction or adverse event outcome. The formulas lotus seed sits in contain ginseng and licorice, which carry their own interaction records, so an interaction seen with a formula cannot be assigned to the seed.

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Related herbs

TCM Chinese yam Dioscorea oppositifolia (also written Dioscorea opposita) TCM Coix Coix lacryma-jobi var. ma-yuen TCM Poria Wolfiporia cocos (syn. Poria cocos) TCM Atractylodes Atractylodes macrocephala (bai zhu); A. lancea (cang zhu) TCM Codonopsis Codonopsis pilosula

The questions that come up

Is lotus seed the same as lotus seed embryo (lian zi xin)?

No. The green embryo in the seed's center is a separate drug, Plumula Nelumbinis, with its own review and its own traditional uses. This page covers the seed kernel.

Is there evidence lotus seed helps diarrhea?

We found no human trial of lotus seed alone for diarrhea. The gut evidence is of Shen Ling Bai Zhu San, a ten-herb formula, in chronic gastritis and ulcerative colitis, and it cannot be assigned to the seed.

What does TCM say about it?

TCM classes it as sweet, astringent and neutral, entering the spleen, kidney and heart channels, and uses it to support the spleen and astringe the intestines. That is the tradition’s framework.

Can lotus seed carry mold toxins?

One of 163 edible and medicinal substances tested in a Chinese survey, a lotus seed sample, had aflatoxin B1 above regulatory limits. It is a single sample, and it is the reason quality control matters for stored seeds.

Sources