saudigastro.com/patients/oral-nutrition-supplements-protein-powders
This article is educational and does not replace your doctor's advice. Seek urgent care for any red-flag symptoms.
Drug class
Dietary supplement / medical nutrition product
Examples
Ready-to-drink or powdered oral nutrition supplement (ONS) drinks and puddings, high-protein or diabetes-specific formulas, whey, casein, soy, pea or rice protein powders, meal-replacement shakes. Brand names are only examples of product types.
How it works
Malnutrition (not getting or not absorbing enough energy, protein and nutrients) is common in gut, liver, pancreatic and cancer disease and increases complications and hospital stay. ESPEN (European Society for Clinical Nutrition and Metabolism) guidelines advise screening for malnutrition, first using food-based measures (small frequent meals, fortifying ordinary food), and adding oral nutrition supplements when food alone is not enough; a dietitian should guide this. Systematic reviews show ONS increase intake and weight and, in malnourished patients, can reduce complications. Protein powders are different: they are sold as food or sports supplements, not tested as medical products, and ordinary healthy people who eat adequate protein from food gain little from them. Whey is a milk protein digested quickly, casein is a milk protein digested slowly, and soy, pea and rice proteins are plant alternatives; no type is proven to be best for gut disease.
What it treats
- Disease-related malnutrition or unplanned weight loss, with a dietitian’s plan (GOOD evidence for ONS in malnourished patients)
- Cirrhosis: ESPEN 2019 advises against restricting protein, and recommends regular meals with a late-evening snack; supplements are used if food intake is low
- Before and after surgery, during cancer treatment, and in older adults with frailty or sarcopenia (loss of muscle), under professional guidance
- Short bowel, severe Crohn’s disease or pancreatic insufficiency, when advised by the team; exclusive enteral nutrition in children with Crohn’s is a supervised treatment, not a product to self-start
- Protein powders and shakes for bodybuilding or “gut health” in otherwise healthy people: LIMITED benefit, and not needed if you eat enough protein
How to take it
Use ONS as a supplement to, not a replacement for, meals, in the amount and at the times your dietitian recommends (often between meals so they do not reduce appetite for the main meal); sip slowly and serve chilled if the sweetness is a problem. Check lactose content, sugar and the energy and protein per serving on the label. Very underweight people who have barely eaten for days must start feeding slowly under supervision because of the risk of refeeding syndrome (dangerous shifts in blood salts); NICE and ESPEN describe this. For protein powders, choose a product whose label lists all ingredients, avoid those promising rapid muscle gain or fat loss, follow the label and your doctor’s or dietitian’s advice, and do not take them in place of meals. Buy only products registered with the SFDA from pharmacies or reputable stores.
Common side effects
- Bloating, gas, nausea or feeling too full to eat meals
- Diarrhoea, particularly with lactose (whey concentrate and milk-based ONS), sugar alcohols (sorbitol, xylitol) or sweeteners
- Constipation with low-fluid or low-fibre products
- Taste fatigue, and higher blood sugar with sugary formulas in people with diabetes
Serious side effects — call your doctor
Swelling of lips or throat, wheeze, hives or vomiting soon after a product containing milk, soy or other allergens
Possible food allergy or anaphylaxis. Call emergency services now.
Yellow eyes or skin, dark urine, severe itching, or marked tiredness after starting a muscle-building or “fat-burning” powder
May be liver injury from an adulterated or herbal product. Stop it and see a doctor urgently, and bring the product.
Swollen legs, much less urine, or foamy urine in someone with kidney disease taking high-protein products
A high protein load may strain damaged kidneys. Stop the product and contact your kidney doctor promptly.
Confusion, marked sleepiness or a change in behaviour in someone with cirrhosis
Could be hepatic encephalopathy. Go to the emergency department; do not simply cut protein, because restricting it is not advised.
Persistent vomiting, severe weakness, muscle cramps or heart palpitations when restarting feeding after a long period of poor intake
Could be refeeding syndrome (dangerous changes in blood salts). Seek urgent medical care.
Interactions
Kidney disease: very high protein intake may be unsuitable for people with chronic kidney disease, so ask your kidney team before using protein powders; some renal formulas are low in potassium and phosphate. Liver disease: in cirrhosis, adequate protein is protective and ESPEN advises against restricting it, but many sports powders contain herbal, “thermogenic” or hidden ingredients that can injure the liver; use dietitian-selected products only. Contaminants: independent laboratory studies of sports supplements have found heavy metals (such as lead, cadmium and arsenic), undeclared stimulants and even anabolic steroids, because supplements are not tested like medicines; third-party certification marks (for example NSF Certified for Sport or Informed Sport) reduce but do not eliminate the risk. Lactose: whey concentrate contains lactose, whey isolate has less, and plant proteins are lactose-free but may contain fermentable carbohydrates and sweeteners. Diabetes: choose diabetes-specific formulas and count the carbohydrate. Some products contain vitamin K or minerals that affect warfarin or other medicines; show the label to your pharmacist.
Monitoring
Your team will track weight, appetite, grip strength, and blood tests (for example albumin is not a reliable marker alone; electrolytes, kidney and liver tests are used as needed). Review the need for ONS regularly, since the goal is to restore eating and stop supplements when weight and intake recover.
When and how to stop
Stop ONS when you are eating enough and weight is stable, as advised by your dietitian. Stop any protein or sports product at once if you develop jaundice, dark urine, severe itching, palpitations, or allergy symptoms, and do not restart without medical advice.
Pregnancy & breastfeeding
Pregnant and breastfeeding women should not use sports or “fat-burning” products. Prenatal nutrition or an ONS can be used when a doctor or dietitian advises it.
In the Saudi context
Many protein powders and gym supplements are sold in gyms, social media shops and online, and some are not registered. The SFDA regulates food and dietary supplements and requires registration or notification before sale; check for the SFDA registration information and buy from licensed pharmacies and stores. Prescribed ONS may be supplied through hospital pharmacies or dietitian clinics. In Ramadan, an ONS taken at iftar and suhoor can help people with malnutrition, but discuss timing with your dietitian, especially if you have diabetes.
Questions to ask your doctor
Save this list or print it before your appointment — doctors appreciate prepared patients.
- Am I malnourished, and would a prescribed supplement help me?
- Which product, how many servings and when, and for how long?
- Are protein powders safe with my kidney, liver or diabetes?
- I am lactose intolerant: which options suit me?
- How do I know a gym supplement is registered and safe?
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Status: Approved for publication by SGA; individual clinician review is ongoing · Published 24/04/2026
For general education only; it does not replace your doctor’s advice. Individual clinician review of this guide is ongoing. SGA clinician? Review this guide