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A team from Jiangnan University in Wuxi and Dong’e Ejiao Co. fed rats a high-fat diet for eight weeks and gave a portion of the animals either regular or selenium-enriched donkey milk in addition. Blood and liver values, gut bacteria, and metabolic products in the feces were measured. The authors report less fat in the liver and an altered gut flora in the groups receiving selenium-enriched donkey milk. However, a careful reading reveals several contradictions in the paper.
Animal study using a disease model (high-fat diet in rats) – no statement about an effect in humans and no recommendation. The study primarily examined selenium-enriched donkey milk. Donkey milk is a food.
Study profile
| Feature | Information |
|---|---|
| Original title | Effect of Selenium-Enriched Donkey Milk on Lipid Metabolism Disorders Induced by a High-Fat Diet |
| Authors | Zhong Q., Cheng J., Huang G. et al. |
| Journal | Foods, 15(10): 1640 |
| Year | 2026 |
| Country | China |
| Study type | Animal study with disease model, supplemented by cell and bacterial cultures |
| Sample | 40 male Sprague-Dawley rats, 5 groups of 8, duration 8 weeks |
| DOI | 10.3390/foods15101640 |
What question did the researchers ask?
The researchers wanted to know whether rats fed a high-fat diet would show changes in their liver and blood values as well as their gut flora if they also received donkey milk with an increased selenium content. Selenium is a trace element; in the enriched milk, it occurred primarily in organic form.
How it was studied
- Five groups: Control with normal feed, high-fat feed alone (HFD), high-fat feed plus 2.6 ml/kg donkey milk (DM), plus 2.6 ml/kg selenium-enriched donkey milk (Se-L), or plus 10.4 ml/kg selenium-enriched donkey milk (Se-H) daily.
- Feed: In the high-fat feed, 45% of the energy came from fat, while in the normal feed, it was 10%. The milk was administered via a gavage tube for eight weeks.
- Measurements: Blood lipids, liver enzymes, liver and abdominal fat tissue sections, gut bacteria (16S sequencing), metabolic products and short-chain fatty acids in the feces, gene and protein levels in the liver.
- Additional experiments: Experiments on a human liver cancer cell line (HepG2) with short-chain fatty acids and a bacterial culture with selenium compounds and lactose.
The results
According to the paper, the high-fat diet significantly altered blood lipids, liver values, and gut flora. In the groups receiving selenium-enriched donkey milk, the authors describe fewer lipid droplets in the liver, more bacteria of the genus Akkermansia, and more short-chain fatty acids in the feces. However, these values are only shown in figures. The paper provides specific numbers primarily regarding the composition of the two milks and the number of altered metabolic products:
| Measurement | Donkey milk | Selenium-enriched donkey milk |
|---|---|---|
| Selenium (mg/kg) | 0.024 ± 0.003 | 0.082 ± 0.021 |
| Calcium (mg/kg) | 8454 ± 18.62 | 9064 ± 44.18 |
| Zinc (mg/kg) | 26.7 ± 3.12 | 28.4 ± 2.13 |
| Lactose (according to the table mg/kg) | 659.04 ± 22.15 | 769.27 ± 24.77 |
| Altered metabolic products in feces compared to HFD | 460 | 389 (Se-L) / 528 (Se-H) |
The milk values were measured in defatted, freeze-dried samples (n = 3). For comparison: there were differences in 2,241 metabolic products between the high-fat and normal feed.
In the rat model with a high-fat diet, the groups receiving selenium-enriched donkey milk differed from the group without milk in several laboratory values. Due to contradictions in the paper and the disease model, no conclusions can be drawn for humans.
Critical assessment
- Confounding factors: Regular donkey milk was only available in the low dose. The Se-H group received four times as much milk and also more selenium.
- Hardly any numbers: Weight, blood lipids, liver values, and gut bacteria are only provided as graphics.
- Contradictions: According to the results section, the SOD enzyme is supposed to have decreased, while according to the discussion, it had increased. The Srebp1c gene increased according to the results section, while according to the discussion, it was inhibited. Discussed measurements such as CD36 do not appear in the methods section.
- Formal issues: The methods state standard errors, while the figures show standard deviations. One evaluation speaks of four instead of five groups. Some units in Table 1 are implausible.
- Hypothesis instead of proof: The chain gut bacteria → fatty acids → energy sensor AMPK → liver was not directly tested; part of it comes from cell culture experiments.
- Unclear test milk: The paper does not describe how the milk was enriched with selenium.
Funding, conflicts of interest, and level of evidence
The work was funded by a program of the Shandong Province and the Chinese National Natural Science Foundation. Three authors (Jie Cheng, Guangyuan Liu, Zhuoru Ren) were employed by Dong’e Ejiao Co., Ltd.; the same company supplied both milks.
Level of evidence: preclinical (disease model in rats plus cell and bacterial cultures) – no statement about effects in humans.
What does this mean for donkey milk as a food?
The study primarily describes a selenium-enriched specialty milk in a disease model. No recommendation can be derived from this for donkey milk as a food. The authors view their results as a basis for functional foods – we expressly do not adopt this classification.
Our research question: How much does the natural selenium content of donkey milk vary between farms and feeding – as a statement of composition?
Frequently asked questions
What is selenium-enriched donkey milk?
Donkey milk with an increased selenium content; in the study, it was 0.082 instead of 0.024 mg/kg. How the enrichment was achieved is not stated in the paper.
What does "disease model" mean here?
The rats were deliberately given a very high-fat diet so that their liver and blood values would change. It was examined whether the groups receiving milk differed from this.
Can this be applied to humans?
No. It is an animal study with a disease model and numerous inconsistencies. No recommendation can be derived from this.
You can find all measurements, interactive graphics, and the complete critical assessment on our research page: Study 84: Selenium-Enriched Donkey Milk in a Rat Model. Further studies in the research archive.
Zhong Q., Cheng J., Huang G. et al. (2026). Effect of Selenium-Enriched Donkey Milk on Lipid Metabolism Disorders Induced by a High-Fat Diet. Foods, 15, 1640. DOI: 10.3390/foods15101640
Summarized and reviewed by the DON DONKEY'S editorial team based on the original publication · As of: October 2026. This summary does not replace the original work.
End of the study summary. The study was conducted independently of DON DONKEY'S® and does not refer to our products. Our donkey milk is a food.
