White mulberry supplementation as adjuvant treatment of obesity has attracted growing interest as a complementary approach to conventional weight management strategies. Derived from the leaves, fruit and bark of *Morus alba*, white mulberry contains bioactive compounds—particularly 1-deoxynojirimycin (DNJ)—that may influence carbohydrate metabolism and glucose control. However, it is crucial to understand that white mulberry is sold in the UK as a food supplement, not a licensed medicine, and has not undergone the rigorous efficacy and safety assessments required of pharmaceutical obesity treatments. This article examines the evidence, mechanisms, practical use and safety considerations for white mulberry in the context of obesity management.

What Is White Mulberry and How Does It Work for Weight Management?

White mulberry (Morus alba) is a deciduous tree native to Asia, traditionally used in Chinese medicine for various metabolic conditions. The leaves, fruit and bark contain bioactive compounds including flavonoids, alkaloids and polyphenols, with 1-deoxynojirimycin (DNJ) being the most studied constituent for metabolic effects. In recent years, white mulberry supplementation has gained attention as a potential adjuvant therapy for obesity management. It is important to emphasise that white mulberry is sold in the UK as a food supplement and is not a licensed medicine for obesity treatment; it has not been assessed for efficacy or safety by the Medicines and Healthcare products Regulatory Agency (MHRA) in the way that licensed medicines are.

The proposed mechanism of action centres primarily on carbohydrate metabolism. DNJ acts as a competitive inhibitor of alpha-glucosidase enzymes in the small intestine, which are responsible for breaking down complex carbohydrates into absorbable monosaccharides. By inhibiting these enzymes, white mulberry extract may slow the digestion and absorption of dietary carbohydrates, potentially reducing postprandial glucose spikes and subsequent insulin responses. This mechanism is similar to the pharmaceutical agent acarbose, though white mulberry's effect is considerably milder and the potency, standardisation and dose–response relationship are not well established for supplements.

Additional mechanisms have been proposed based on preclinical research, including modulation of lipid metabolism through activation of AMP-activated protein kinase (AMPK) pathways, which may enhance fatty acid oxidation and reduce lipogenesis. Some in vitro and animal studies suggest white mulberry extracts may influence adipocyte differentiation and reduce fat accumulation. However, it is crucial to note that these mechanisms are derived from laboratory and animal models; the clinical relevance in humans remains uncertain and has not been demonstrated in robust clinical trials.

White mulberry should be viewed as a complementary approach rather than a standalone treatment for obesity. NICE guideline CG189 (Obesity: identification, assessment and management) emphasises that effective obesity management requires a comprehensive approach including dietary modification, increased physical activity, behavioural interventions and, where appropriate, pharmacological or surgical interventions. Any supplementation should be discussed with a healthcare professional as part of an individualised treatment plan. It is also important to note that the composition and DNJ content of white mulberry supplements vary widely between products, and effects seen in clinical trials may not generalise across all available supplements.

Clinical Evidence for White Mulberry in Obesity Treatment

The clinical evidence supporting white mulberry supplementation for obesity management remains limited and of variable quality. A systematic review and meta-analysis examining randomised controlled trials of white mulberry's effects on body weight and metabolic parameters identified modest reductions in body weight (approximately 1–2 kg over 12 weeks) and improvements in glycaemic control markers, including fasting glucose and HbA1c levels. However, the authors noted significant heterogeneity between studies, small sample sizes and methodological limitations that preclude definitive conclusions. The clinical significance of such small weight reductions is uncertain, and there is no evidence of durable weight loss beyond the short trial periods studied.

One frequently cited study involved participants with type 2 diabetes who received white mulberry leaf extract (1,200 mg daily) alongside standard care for three months. Results showed statistically significant reductions in fasting blood glucose and postprandial glucose levels compared to placebo, with a modest decrease in body weight. Another trial examining white mulberry extract in combination with dietary restriction demonstrated enhanced weight loss compared to diet alone, though the independent contribution of the supplement remained unclear. Product standardisation and DNJ content were not consistently reported across trials, limiting the ability to compare results or recommend specific formulations.

Key limitations of the existing evidence base include:

• Short study durations (typically 8–12 weeks), providing no data on long-term efficacy or safety

• Small participant numbers, limiting statistical power and generalisability

• Significant variation in extract standardisation, dosing regimens and formulations between studies

• Lack of robust data in diverse populations, with most research conducted in Asian cohorts

• Insufficient reporting of adverse events and safety monitoring

The MHRA does not currently recognise white mulberry as a licensed medicine for obesity treatment in the UK. It is available as a food supplement, which means it is not subject to the same rigorous efficacy and safety standards as pharmaceutical products. Healthcare professionals should counsel patients that whilst preliminary evidence suggests potential metabolic benefits, white mulberry cannot replace evidence-based obesity treatments recommended by NICE. Licensed pharmacological options for weight management include orlistat (NICE CG189), liraglutide 3.0 mg (NICE TA664) and semaglutide 2.4 mg (NICE TA875), where clinically appropriate and in line with eligibility criteria.

How to Use White Mulberry Supplementation Safely

If considering white mulberry supplementation as an adjuvant to conventional obesity management, several practical considerations should guide safe use. Patients should always consult their GP or a registered dietitian before commencing supplementation, particularly if they have existing medical conditions or take prescribed medications.

Dosing regimens in clinical trials have varied widely, typically ranging from 1,000 to 3,000 mg of standardised leaf extract daily, usually divided into two or three doses taken before meals. The rationale for pre-meal timing relates to the proposed mechanism of inhibiting carbohydrate digestion. Products are sometimes standardised to contain a specified percentage of DNJ (commonly 1–3%), though standardisation varies considerably between manufacturers and optimal dosing has not been established. Patients should follow the manufacturer's instructions on the product label and seek advice from their clinician or pharmacist rather than assuming a particular dose is appropriate. In the UK, supplements should comply with food supplement regulations and display clear labelling, including ingredients, DNJ content where standardised, batch numbers and UK contact details. Choosing reputable manufacturers and products with evidence of third-party testing, where available, may help ensure quality.

Practical guidance for patients includes:

• Start with lower doses to assess tolerance, gradually increasing if no adverse effects occur

• Take supplements 15–30 minutes before carbohydrate-containing meals to maximise potential effects on glucose absorption

• Maintain a food and symptom diary to monitor any gastrointestinal symptoms or changes in glycaemic control

• Continue evidence-based lifestyle modifications, including a balanced, calorie-controlled diet and regular physical activity. The UK Chief Medical Officers recommend at least 150 minutes of moderate-intensity activity weekly for adults

• Monitor body weight and waist circumference regularly to assess progress objectively

Patients with diabetes require particular caution, as white mulberry may potentiate the effects of antidiabetic medications, potentially leading to hypoglycaemia. Blood glucose monitoring should be intensified when initiating supplementation, and medication adjustments may be necessary under medical supervision. Similarly, individuals taking medications for other conditions should verify potential interactions with their pharmacist.

When to seek medical advice:

• Persistent gastrointestinal symptoms (diarrhoea, bloating, abdominal discomfort)

• Signs of hypoglycaemia (tremor, sweating, confusion, palpitations)

• Lack of progress after 12 weeks of combined lifestyle modification and supplementation (review with your clinician)

• Development of any unexpected symptoms

It should be emphasised that white mulberry supplementation does not constitute a substitute for medical assessment and management of obesity, which may involve underlying endocrine disorders, medication-induced weight gain or psychological factors requiring specialist intervention.

Potential Side Effects and Drug Interactions

Whilst white mulberry is generally considered well-tolerated in short-term studies, several potential adverse effects and drug interactions warrant consideration. The most commonly reported side effects relate to the gastrointestinal tract and result from the supplement's mechanism of inhibiting carbohydrate digestion. Undigested carbohydrates reaching the colon undergo bacterial fermentation, producing gas and potentially causing bloating, flatulence, abdominal discomfort and loose stools. These effects are typically dose-dependent and may diminish with continued use as the gut microbiome adapts. In clinical trials, gastrointestinal symptoms were reported by a proportion of participants, though discontinuation rates remained low. Patients can minimise these effects by starting with lower doses, increasing gradually and ensuring adequate hydration. Reducing dietary intake of rapidly fermentable carbohydrates (FODMAPs) may also help manage symptoms.

Significant drug interactions to consider include:

• Antidiabetic medications: White mulberry may enhance the glucose-lowering effects of metformin, sulphonylureas, insulin and other antidiabetic agents, increasing hypoglycaemia risk. Patients with diabetes should monitor blood glucose closely and may require medication dose adjustments under medical supervision.

• Acarbose and other alpha-glucosidase inhibitors: Concurrent use is not recommended due to overlapping mechanisms and increased risk of gastrointestinal adverse effects.

• Anticoagulants and antiplatelet agents: Limited evidence suggests white mulberry may possess mild antiplatelet activity, though clinical relevance is unclear. Patients taking warfarin, direct oral anticoagulants (DOACs) or antiplatelet agents should exercise caution. For those on warfarin, INR monitoring should continue as usual; patients should watch for signs of bleeding or bruising and discuss supplementation with their prescriber.

There is insufficient safety data regarding white mulberry use in pregnancy and breastfeeding, and it should be avoided in these populations. Similarly, safety in children and adolescents has not been established. Individuals with pre-existing liver or kidney disease should consult their healthcare provider before use, as metabolic effects and excretion pathways have not been thoroughly characterised.

Contraindications and precautions:

• Known allergy to mulberry or related plants (Moraceae family)

• Severe gastrointestinal disorders (inflammatory bowel disease, malabsorption syndromes) — use with caution due to potential gastrointestinal effects

• Scheduled surgery: many NHS hospitals advise stopping herbal supplements 1–2 weeks before surgery due to potential effects on blood glucose and coagulation. Patients should follow the instructions provided by their preoperative assessment team

Patients should inform all healthcare providers, including dentists and pharmacists, about white mulberry supplementation to ensure comprehensive medication review and avoid potential interactions. The lack of long-term safety data means that prolonged use beyond 12 weeks should be undertaken only with ongoing medical supervision and regular review of treatment efficacy and tolerability.

If you experience any suspected side effects from white mulberry supplementation, you can report them via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or by searching for 'MHRA Yellow Card' in the Google Play or Apple App Store.

Frequently Asked Questions