GLP-1 and GIP natural supplements are increasingly marketed for blood glucose control and weight management, but do they work? Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are naturally occurring hormones that regulate appetite, insulin secretion, and metabolism. Whilst pharmaceutical GLP-1 receptor agonists such as semaglutide are proven treatments for type 2 diabetes and obesity, some people seek natural alternatives through dietary supplements. This article examines the evidence for natural compounds that may influence GLP-1 and GIP activity, their safety considerations, and when to consult your GP about metabolic health concerns.

What Are GLP-1 and GIP Hormones?

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are naturally occurring hormones known as incretins, produced in the gastrointestinal tract in response to food intake. These hormones play crucial roles in regulating blood glucose levels, appetite, and metabolic function.

GLP-1 is secreted primarily by L-cells in the distal small intestine and colon. Its main actions include:

• Stimulating insulin secretion from pancreatic beta cells in a glucose-dependent manner

• Suppressing glucagon release, which reduces hepatic glucose production

• Slowing gastric emptying, which moderates post-meal glucose spikes

• Promoting satiety through central nervous system pathways, thereby reducing appetite

GIP is released by K-cells in the proximal small intestine and shares some functions with GLP-1, particularly in enhancing insulin secretion after meals. GIP may also influence fat metabolism and bone health, though these effects are still being investigated in humans. Together, these incretins contribute significantly to insulin secretion following oral glucose intake, a phenomenon known as the incretin effect.

In individuals with type 2 diabetes, the incretin effect is often diminished, with GIP's insulinotropic effect more markedly reduced than GLP-1's. Additionally, native GLP-1 is rapidly degraded by the enzyme DPP-4, limiting its therapeutic potential in its natural form.

This understanding has led to the development of GLP-1 receptor agonists (such as semaglutide and liraglutide) and dual GIP/GLP-1 receptor agonists (such as tirzepatide) as pharmaceutical treatments. These medications mimic or enhance the action of natural incretins and are prescribed for type 2 diabetes management and, in some cases, weight management. Understanding how these hormones function naturally has prompted interest in whether dietary supplements or lifestyle interventions might support their endogenous production or activity.

Natural Supplements That May Support GLP-1 and GIP

Several natural compounds and dietary supplements have been investigated for their potential to influence GLP-1 and GIP secretion or activity. It is important to note that whilst some preliminary evidence exists, natural supplements are not substitutes for prescribed medications and should not be used as such without medical guidance. NICE does not recommend supplements for incretin enhancement in type 2 diabetes management.

Berberine is a plant alkaloid found in several herbs, including barberry and goldenseal. Some research suggests berberine may improve insulin sensitivity and glucose metabolism, with animal studies indicating potential effects on GLP-1 secretion. However, human evidence remains limited and inconsistent.

Curcumin, the active compound in turmeric, has been studied for its anti-inflammatory and metabolic effects. Preliminary research suggests it may influence incretin hormone pathways, though clinical evidence supporting meaningful GLP-1 or GIP enhancement in humans is lacking.

Omega-3 fatty acids (found in fish oil) have been investigated for various metabolic benefits. Some studies suggest omega-3 supplementation may modestly affect GLP-1 levels, though results are mixed and clinical significance uncertain.

Dietary fibre supplements, particularly soluble fibres such as:

• Psyllium husk (requires adequate fluid intake; may pose choking risk in those with swallowing difficulties)

• Glucomannan (must be taken with sufficient water to avoid choking or oesophageal/intestinal obstruction)

• Inulin and other prebiotics

These may indirectly support incretin secretion by slowing carbohydrate absorption, promoting beneficial gut bacteria, and stimulating L-cells in the intestine. Fermentation of fibre by gut microbiota produces short-chain fatty acids, which may stimulate GLP-1 release.

Chromium picolinate is sometimes marketed for blood sugar support, though evidence for direct effects on GLP-1 or GIP is minimal. Similarly, green tea extract (which carries rare but serious liver injury risk at high doses) and cinnamon (particularly cassia cinnamon, which contains coumarin) have been studied for metabolic effects, but there is no robust evidence they meaningfully enhance incretin hormone activity in humans.

Evidence for Natural GLP-1 and GIP Support

The scientific evidence supporting natural supplements for enhancing GLP-1 and GIP activity is limited and largely preliminary. Most studies have been conducted in animal models or small human trials with high risk of bias, and findings often lack replication in larger, well-controlled clinical studies.

Berberine has shown promise in some trials for improving glycaemic control in type 2 diabetes, with mechanisms possibly involving improved insulin sensitivity and altered gut microbiota. However, whether these effects are mediated through GLP-1 or GIP pathways remains unclear. A systematic review of berberine trials found modest glucose-lowering effects, but the quality of evidence was generally low, and direct measurement of incretin hormones was rarely included.

Fibre supplementation has more consistent, though modest, evidence. Studies indicate that increased dietary fibre intake can improve post-meal glucose responses and may increase GLP-1 secretion. The mechanism likely involves slower nutrient absorption and stimulation of intestinal L-cells. However, the magnitude of effect is considerably smaller than that achieved with pharmaceutical GLP-1 receptor agonists.

Probiotics and prebiotics have generated interest due to their effects on gut microbiota composition. Some research suggests certain bacterial strains may influence incretin secretion, but evidence remains exploratory. The gut microbiome's role in metabolic health is complex, and it is premature to recommend specific probiotic supplements solely for GLP-1 or GIP enhancement.

Critically, no natural supplement has been shown to replicate the clinical benefits of prescribed GLP-1 or GIP receptor agonists for diabetes management or weight loss. In the UK, food supplements are regulated as foods by the Food Standards Agency and Trading Standards, not as medicines by the MHRA. This means their quality, purity, and efficacy are not held to the same standards as licensed pharmaceuticals. Some herbal medicines may have Traditional Herbal Registration (THR) through the MHRA, but this does not verify efficacy. Patients should be cautious of marketing claims suggesting natural supplements can replace prescribed treatments.

Safety and Interactions with Prescribed Medications

Whilst natural supplements are often perceived as safe, they can cause adverse effects and interact with prescribed medications. Anyone considering supplements, particularly those with existing health conditions or taking medications, should consult their GP or pharmacist first.

Berberine can lower blood glucose and may potentiate the effects of diabetes medications, including metformin, sulfonylureas, and insulin, potentially causing hypoglycaemia. It may also interact with medications metabolised by cytochrome P450 enzymes, affecting drug levels of various medications including statins and anticoagulants. Berberine should be avoided during pregnancy and breastfeeding due to potential risks including neonatal jaundice.

Fibre supplements are generally well-tolerated but can cause gastrointestinal symptoms such as bloating, flatulence, and altered bowel habits, particularly when introduced rapidly or in high doses. They may also reduce absorption of certain medications if taken simultaneously. Levothyroxine should be taken at least 4 hours apart from fibre supplements. For other medications, it is advisable to take fibre supplements at least two hours apart unless otherwise advised by your prescriber.

Glucomannan and psyllium require adequate fluid intake to prevent choking or intestinal obstruction. They should be avoided by people with swallowing difficulties or gastrointestinal strictures.

Omega-3 supplements at high doses (typically above 3g daily) may increase bleeding risk, particularly in individuals taking anticoagulants (such as warfarin) or antiplatelet agents (such as aspirin or clopidogrel). Patients should inform their healthcare provider before starting omega-3 supplementation if they are on such medications.

Chromium supplements may affect blood glucose levels and should be used cautiously in individuals with diabetes. There have been rare reports of kidney and liver damage with high-dose chromium use.

Green tea extract in concentrated form has been associated with rare but serious liver injury. Stop taking it and seek medical advice if you develop symptoms such as abdominal pain, dark urine, or yellowing of the skin or eyes.

Quality and contamination concerns are important considerations. Purchasing supplements from reputable sources and looking for third-party testing certifications can help mitigate these risks, though it does not eliminate them entirely.

If you experience any suspected adverse reactions to supplements, report them through the MHRA Yellow Card scheme, which monitors the safety of medicines and supplements.

When to Speak with Your GP About GLP-1 and GIP

It is important to have an open conversation with your GP before starting any supplement regimen, particularly if you are considering natural products to support metabolic health or blood glucose control. You should definitely speak with your GP if:

• You have been diagnosed with type 2 diabetes or non-diabetic hyperglycaemia (pre-diabetes) and are considering supplements as an alternative or addition to prescribed treatment

• You are currently taking medications for diabetes, as supplements may interact and alter blood glucose control

• You are taking any prescribed medications, particularly anticoagulants, immunosuppressants, or medications with narrow therapeutic windows

• You are experiencing symptoms of poor glucose control, such as excessive thirst, frequent urination, unexplained weight loss, or fatigue

• You are interested in pharmaceutical GLP-1 or GIP receptor agonists for diabetes management or weight loss

Seek urgent medical help via NHS 111 or 999 if you experience:

• Severe dehydration

• Abdominal pain with vomiting

• Deep or rapid breathing

• Confusion or drowsiness These could indicate a serious hyperglycaemic emergency requiring immediate treatment.

NICE guidelines (NG28) recommend a structured approach to type 2 diabetes management, beginning with lifestyle interventions (diet and physical activity) and progressing to pharmacological treatments as needed. If you are struggling with weight management or glucose control, your GP can assess whether you meet criteria for NHS-funded GLP-1 receptor agonist therapy under relevant NICE technology appraisals (such as TA875 for semaglutide or TA664 for liraglutide for weight management), which is considerably more effective than any natural supplement. Eligibility depends on specific criteria and local NHS commissioning arrangements.

Never obtain GLP-1 or GIP medicines without a prescription or from unregulated sources, as this poses serious health risks.

Your GP can also provide evidence-based guidance on lifestyle modifications that naturally support incretin function, such as:

• Adopting a diet rich in whole foods, vegetables, and dietary fibre

• Achieving and maintaining a healthy body weight

• Engaging in regular physical activity

• Optimising sleep and stress management

These interventions have robust evidence for improving metabolic health and may naturally enhance GLP-1 and GIP secretion without the need for supplements. If you have concerns about your metabolic health or are considering supplements, your GP is best positioned to provide personalised, evidence-based advice tailored to your individual circumstances and medical history.

Frequently Asked Questions