Protein powder: quality, contaminants, choosing well

By the DieticiansWorldwide.com editorial team · 17 October 2026 · Supplements & industry

Do you actually need protein powder?

Protein powder is a convenience food, not a requirement. It is concentrated protein (from milk, eggs, soya, peas, rice or other sources), dried and usually flavoured, that you mix into a drink or food. It does nothing that the same amount of protein from food cannot do. The real questions are how much protein you need, whether you reach that from meals, and whether a powder is the most practical way to close any gap.

Start with the baseline. The European Food Safety Authority set the Population Reference Intake for protein at 0.83 g per kilogram of body weight per day for healthy adults of all ages, covering both high-quality protein and protein from mixed diets. It found the data insufficient to set an upper limit, and said intakes up to twice that level are regularly eaten by physically active, healthy adults in Europe and are considered safe (EFSA, Dietary Reference Values for protein, 2012).

For a 70 kg adult, 0.83 g/kg is about 58 g of protein a day. Many people in high-income countries already eat more than that from ordinary meals. If you are unsure where you stand, work out your own target first.

Try the free protein calculator

Is the protein boom overdone?

Protein has become the nutrient everyone wants more of, with high-protein versions of everything from yoghurt to crisps. Some of that is marketing. But there are groups for whom the standard reference intake is probably too low, and the debate is really about who those groups are.

Older adults

The PROT-AGE study group, convened by the European Union Geriatric Medicine Society, recommended in 2013 that people over 65 eat at least 1.0 to 1.2 g of protein per kg a day to maintain and regain muscle and function, at least 1.2 g/kg if they are exercising or otherwise active, and 1.2 to 1.5 g/kg for most older adults with acute or chronic illness. It made an exception for people with severe kidney disease not on dialysis, who may need to limit protein (Bauer et al., Journal of the American Medical Directors Association, 2013).

People doing resistance training

A 2018 meta-analysis of 49 trials with 1,863 participants found that protein supplements significantly increased gains in muscle size and strength during at least six weeks of resistance training. The effect was smaller with increasing age and larger in people already trained. Crucially, it found no further gains in fat-free mass once total protein intake went above about 1.6 g/kg a day (Morton et al., British Journal of Sports Medicine, 2018). That figure is the source of the "1.6 g/kg" number you see quoted online; it is a ceiling for benefit in training adults, not a target for everyone.

People taking GLP-1 medicines

GLP-1 medicines such as semaglutide and tirzepatide reduce appetite, and with less food comes less protein. A 2025 joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society listed muscle and bone loss and nutritional deficiencies among the main challenges of GLP-1 treatment, and named preserving muscle and bone through resistance training and an appropriate diet as a priority, supported by counselling from a registered dietitian (Mozaffarian et al., Obesity, 2025). When appetite is very small, a protein drink can be an easier way to get protein in than a large meal. Our guide to GLP-1 weight loss covers this in more detail.

Everyone else

For a healthy adult who eats regular meals with protein foods and is not training hard, the evidence that extra protein beyond the reference intake brings health benefits is weak. A powder will mostly add cost and calories. If weight is a concern, count those calories; our calorie calculator helps you see how a daily shake fits into your total.

How protein quality is measured

Not all protein is equal. Quality depends on whether a protein supplies all nine essential (indispensable) amino acids in the right proportions, and how much of each is actually digested and absorbed.

Two scoring systems are used:

• PDCAAS (protein digestibility-corrected amino acid score) is the older method. It estimates digestibility from total protein digestion across the whole gut and is capped at 1.0 (or 100), so the best proteins all look the same.
• DIAAS (digestible indispensable amino acid score) measures digestibility of each amino acid at the end of the small intestine, which is closer to what the body absorbs, and is not capped.

A 2017 study measured both scores for dairy and plant protein ingredients, using pigs as the model for human digestion. It concluded that PDCAAS may overestimate the quality of several plant proteins (Mathai et al., British Journal of Nutrition, 2017). Its DIAAS values, using the reference pattern for people over three years old, were:

A score of 100 means the protein supplies, per gram, at least the reference amount of its most limiting essential amino acid. Dairy proteins exceed that comfortably; soya comes close; pea protein on its own falls short, mainly because it is low in the sulphur amino acids methionine and cysteine. This is why many plant powders blend pea with rice or other proteins, whose amino-acid profiles complement each other.

Whey versus plant protein for muscle

Quality scores are one thing; real-world results are another. Two meta-analyses reach slightly different conclusions:

• A 2021 meta-analysis of randomised trials found that protein source did not affect changes in absolute lean mass or strength overall, although animal protein had a favourable effect on percentage lean mass, and adults under 50 gained more lean mass with animal protein (Lim et al., Nutrients, 2021).
• A 2025 meta-analysis of 30 trials in Nutrition Reviews found that plant protein led to slightly lower muscle mass than animal protein after the intervention, a small standardised difference of 0.20 (Reid-McCann et al., Nutrition Reviews, 2025).

The fair reading: animal and dairy proteins have a small edge, most visible in younger adults, but the gap is modest. If you prefer plant-based eating, a well-formulated soya or blended plant powder, used as part of a diet with enough total protein, is a reasonable choice. Total daily protein and training matter far more than the powder's source.

Heavy metals: what the 2025 testing found

Contamination is the biggest reason to be selective. Protein powders are sold as dietary supplements in many countries, and the US Food and Drug Administration says it is not authorised to approve dietary supplements for safety and effectiveness before they are marketed (FDA).

In October 2025, Consumer Reports published tests of 23 protein powders and ready-to-drink shakes, with multiple samples of each. More than two-thirds contained more lead in a single serving than its experts' daily level of concern, which is 0.5 micrograms. Plant-based products averaged about nine times as much lead as dairy-based ones and about twice as much as beef-based ones. Dairy products generally had the lowest levels. Consumer Reports noted that the FDA has not set action levels for lead in protein powders or shakes, and it advised against daily use of most of the powders it tested (Consumer Reports, updated January 2026).

In a follow-up published in January 2026, it tested 28 powders and shakes and identified 10 that met its criteria for daily use (Consumer Reports, January 2026).

Two points help put this in context. Consumer Reports' threshold is deliberately cautious, and an occasional shake is a very different exposure from two a day for years. But the World Health Organization says there is no level of lead exposure known to be without harmful effects, and that lead is particularly harmful to young children and women of child-bearing age (WHO, Lead poisoning fact sheet). Daily users, and anyone pregnant, should choose carefully.

Sweeteners, additives and digestion

Most flavoured powders contain sweeteners. Many use non-sugar sweeteners such as sucralose, acesulfame K or stevia. In May 2023, the World Health Organization issued a conditional recommendation against using non-sugar sweeteners to control body weight or reduce the risk of non-communicable diseases. It found no long-term benefit for reducing body fat, and noted possible long-term risks such as type 2 diabetes and cardiovascular disease in observational data. The guidance does not apply to people who already have diabetes (WHO).

That is not a reason to panic about a sweetened shake, but it is a reason not to think of sweetened protein drinks as a weight-loss tool in themselves. Unflavoured powders, which you can mix into porridge, yoghurt or smoothies with fruit, avoid the question.

Other things to check:

• Lactose. Whey protein concentrate contains some lactose; whey isolate contains less. People with lactose intolerance often tolerate isolate better.
• Sugar alcohols and gums. Ingredients such as sorbitol, xylitol and some thickeners can cause wind and loose stools in sensitive people, including many with IBS.
• Added extras. Creatine, caffeine, "fat burners", herbal blends and high doses of vitamins increase cost and the chance of interactions. If you want creatine, take it as a separate product so you control the dose; see our guides to creatine monohydrate and its side effects.

Who benefits from a protein powder

Protein powder is genuinely useful for some people:

For snack ideas that do not involve a shaker, see our list of high-protein snacks. Creatine is also moving from the gym into conversations about women's health and healthy ageing; our guide to creatine for women looks at that evidence.

Is protein powder safe to take every day?

For most healthy adults, a daily serving of a tested product, as part of a total protein intake within the ranges above, is not known to be harmful. EFSA considered intakes up to about twice the reference intake safe for healthy adults. Daily use does raise three issues:

1. Contaminant exposure adds up. This is why Consumer Reports advised against daily use for most products it tested, and why choosing a product with published test results matters most for daily users.
2. It can displace food. A shake replacing breakfast also replaces the fibre, vitamins and minerals that breakfast might have provided.
3. Kidney disease changes the picture. The US National Institute of Diabetes and Digestive and Kidney Diseases says some people with chronic kidney disease may need moderate amounts of protein so waste does not build up in the blood, while too little protein can cause malnutrition, and that people on dialysis may need more protein (NIDDK). If you have kidney disease, do not use protein powder without advice from your renal team or dietitian.

Children and teenagers generally do not need protein powders, and pregnant or breastfeeding women should be especially careful about contaminant exposure.

How to choose a protein powder: a checklist

There is no single "best" protein powder, and DieticiansWorldwide.com does not endorse brands. Use these criteria instead:

1. Decide whether you need one. Check your target and your current intake first.
2. Choose the protein type that suits you. Whey or milk protein for highest quality; soya or a pea-and-rice blend if plant-based.
3. Look for independent testing. Prefer products with batch-specific heavy-metal results published by the brand, or certification from an independent programme. The US Pharmacopeia, for example, says its verification checks that "what's on the label is what's in the bottle" (USP). Our guide to third-party tested supplements compares the main schemes.
4. Check protein per serving and serving size. Compare grams of protein per serving, not per tub.
5. Read the ingredient list. Shorter is usually better; avoid stimulant and herbal blends.
6. Mind the sweeteners and sugar if you use it daily.
7. Limit how often you use it if the product has no published contaminant data.

For more on the wider supplement market and how products are regulated, see our supplements hub.

When to get personal advice

Protein needs depend on age, weight, activity, medical conditions and medicines. A registered dietitian can calculate your target, check what you already eat, and decide whether a powder adds anything. That matters most if you are older, losing weight on a GLP-1 medicine, recovering from illness, pregnant, vegan with high needs, or living with kidney or liver disease. You can book a session with a dietitian through DieticiansWorldwide.com.