Short answer
Usually, but check. Whey is the liquid left over from making cheese, so its ruling follows the rennet used. Whey from cheese made with microbial or plant rennet is halal, and many Hanafi muftis also allow whey from animal rennet on Imam Abu Hanifa's view. Protein powders can also contain gelatin, collagen or alcohol-based flavours, so read the whole label.
Following Imam Abu Hanifa, rennet from an animal not slaughtered properly stays pure, so whey made with it is halal on his view, which many Hanafi muftis allow. Halal-certified whey, or whey from microbial rennet, is the more cautious choice.
Other madhhabs
- Shafi'i
- Rennet from an animal not slaughtered properly is impure, so whey from cheese made with it is not eaten.
- Maliki
- Rennet from an animal not slaughtered properly is impure, so whey from cheese made with it is not eaten.
- Hanbali
- The main view agrees with the Shafi'is, though some Hanbali scholars held such rennet pure.
Explanation
When milk is curdled to make cheese, the solid curds become cheese and the watery part is whey. It is filtered and dried into whey protein concentrate, isolate or hydrolysate. Casein, another milk protein, comes from the curds.
Cheese is curdled with rennet: enzymes that can come from microbes, from plants, from fermentation, or from the stomachs of calves. Much of the cheese made today uses microbial or fermentation-produced rennet, but whey makers do not always say. Acid whey from Greek yoghurt uses no rennet at all. The Hanafi discussion of animal rennet is in is rennet halal.
Other ingredients to check in protein powders and bars:
- gelatin in capsules or some blends;
- collagen in protein and beauty blends;
- flavourings with an alcohol carrier (see ethanol in food);
- enzymes added for digestion.
Halal-certified protein powder settles the question. Without it, choose whey that states microbial or vegetarian rennet, or an unflavoured isolate from a maker who confirms its sources. Pea, soy and rice protein and egg-white protein are halal.
The evidence
Quran, Surah An-Nahl 16:66
وَإِنَّ لَكُمْ فِى ٱلْأَنْعَٰمِ لَعِبْرَةًۭ ۖ نُّسْقِيكُم مِّمَّا فِى بُطُونِهِۦ مِنۢ بَيْنِ فَرْثٍۢ وَدَمٍۢ لَّبَنًا خَالِصًۭا سَآئِغًۭا لِّلشَّٰرِبِينَ ﴿٦٦﴾
And indeed, for you in grazing livestock is a lesson. We give you drink from what is in their bellies - between excretion and blood - pure milk, palatable to drinkers.
Milk and what comes from it are a blessing.
Where the ruling is recorded
- Bada'i al-Sana'i, Kitab al-Taharah, on the parts of carrion that are pure. Abu Hanifa's view that rennet from carrion is pure, and his students' view.
- al-Majmu' (Nawawi), Kitab al-Taharah, on impurities. The Shafi'i view that rennet from carrion is impure.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.