Protein powder: when it makes sense and how to choose it

What is protein powder and where does it come from?

Protein powder is a food from which almost everything except the protein has been removed, and which is then dried. Most of it comes from milk. The rest comes from soy, peas, rice or other plants.

Milk contains two types of protein. Whey is in the liquid left over when cheese is made, the same liquid you see floating on top of yogurt. Casein is the protein that forms the curds. Whey is available in three forms.

• Concentrate. Gently filtered, so it retains some fat and lactose
• Isolate. More extensively filtered, with more protein per serving and almost no lactose or fat.
• Hydrolysate. The protein is broken into small pieces; it is more expensive and more bitter.

Casein is digested more slowly than whey [1]. That is why it is sold for use before bed, an approach studied mainly in people who do strength training [1].

Powdered plant proteins are made mainly from peas, soy or rice. Per serving, they usually provide slightly less leucine than milk proteins [1]. Leucine is the amino acid that most strongly stimulates muscle formation. That is why many products combine pea and rice proteins, which complement each other . See “Pea protein”.

Do you need to take it if you train?

In most cases, no. A sedentary adult needs about 0.83 g of protein per kilogram of body weight per day [2]. If you train regularly, the International Society of Sports Nutrition puts the reference range at 1.4 to 2 g per kilogram [1]. You can reach this amount through food; powder is simply a convenient way to get there when it is difficult [1].

Here is an example with figures. A 60 kg person who trains would aim for 84 to 120 g per day . For breakfast, two eggs and a glass of milk; at midday, a plate of lentils. With 250 g of whipped fresh cheese as an afternoon snack and 150 g of hake for dinner, the total comes to about 85 g . With bread, vegetables and some nuts, the day falls within the range.

Protein powder solves a logistical problem. If your problem is something else, the tub will not fix it.

Adding powder to a diet that already meets your protein needs contributes little. A review of trials involving strength training found that adding protein helps people gain slightly more muscle and strength [3]. But the benefit stops increasing above about 1.6 g per kilogram per day [3].

Our guide to sports nutrition explains how to distribute protein alongside carbohydrates and water around training. If your goal is to gain muscle mass, the fitness diet guide turns those figures into specific meals.

When might it make sense?

There are situations where it is difficult to get enough from food alone, and powder is one more tool that can help.

• Low appetite due to illness, treatment or age, when a whole meal feels like too much.
• Older adults with sarcopenia, the loss of muscle and strength that comes with age.
• Vegan diets with high requirements, such as for strength or endurance athletes
• Logistics, when you train away from home and your next meal is hours away.

For older adults, the European geriatric nutrition guideline recommends 1 to 1.2 g of protein per kilogram per day [4]. Those who train may need more. If they have kidney disease, the amount is tailored to the individual. Strength training helps preserve muscle [4]. When malnutrition or the risk of it is present, the guideline includes oral nutritional supplements alongside enriching meals [4]. Your doctor or dietitian prescribes them.

Before turning to a tub, in consultations we usually try enriching the foods a person already eats. A beaten egg in vegetable soup, powdered milk in mash or grated cheese over vegetables increases protein without changing the dish.

How to read the label before buying

If you and your dietitian decide it makes sense, the label tells you almost everything you need to know. Check these five things.

1. Protein per serving, as well as per 100 g. Check how much a serving provides [1].
2. Sugars. The less, the better; dessert flavours tend to contain more.
3. Sweeteners. They are authorised, but if they cause intestinal discomfort, look for the unflavoured version.
4. A short ingredients list, with protein first and few items after it.
5. Anti-doping certification if you compete, from an independent programme that tests every batch.

Certification matters if you undergo testing. The International Olympic Committee consensus reports that some supplements contain substances prohibited in sport without listing them on the label [5]. A programme that tests each batch reduces this risk, although it does not eliminate it [5].

The Spanish food safety authority summarises what a supplement must state on its page What do I need to know about food supplements?.

Can I take it if I am lactose intolerant?

It depends on the type and how much lactose you can tolerate. Whey isolate and hydrolysate contain very little, while concentrate contains somewhat more . Plant proteins contain none. In an unflavoured milk protein product, almost all the sugar shown on the label is lactose, and that figure can help you compare products .

How much lactose people can usually tolerate, and which foods contain hidden lactose, is covered in the guide to lactose intolerance.

An allergy is different. If you have a milk protein allergy, neither whey nor casein is suitable, including lactose-free versions . And if you are allergic to soy, check plant protein blends, which often contain it.

Does it cause weight gain or damage the kidneys?

Weight gain depends on the day’s calorie intake. A serving with no added sugar still contains calories. If you add it to what you already eat without removing anything, it adds calories like any other food.

Healthy kidneys tolerate it well. A review of trials in healthy adults found that high-protein diets did not worsen kidney function compared with usual diets [6].

With chronic kidney disease, things are different. Your nephrologist or dietitian will tell you how much protein, potassium, phosphorus and other minerals and ions are suitable for you, depending on your stage [7]. If you have been told that your kidneys filter less effectively, do not take protein powder on your own.

What we see in consultations

• A shake, but no breakfast. Someone has a shake after leaving the gym and skips an entire meal.
• Two or three scoops a day “just in case”. Going beyond what the muscle uses does not build more muscle [3].
• Choosing the biggest tub or the flashiest label. The deciding information is in the ingredients.

Many people who come to see us say they started having a shake because everyone at the gym was taking one. When we review what they eat together, they often find they were already meeting their needs without it.

Homemade shakes with what you have in the fridge

If you like having a shake, you can make one with food. These three ideas take two minutes to prepare in a blender .

Whipped fresh cheese with banana. 250 g of whipped fresh cheese, one ripe banana and cinnamon. About 20 g of protein.

Milk with oats and cocoa. A large glass of milk or soy drink with at least 3% protein, two tablespoons of rolled oats and pure cocoa. About 12 g.

Silken tofu with berries. 150 g of silken tofu, a handful of frozen berries and a glass of soy drink. About 14 g. It contains soy, one of the allergens that must be declared on the label.

If you eat a vegetarian diet, the weekly ovo-lacto vegetarian menu spreads protein across the week without needing powder.