Best Protein Powder: Whey, Casein, and Plant-Based Compared
A science-backed comparison of whey, casein, and plant-based protein powders - what to look for, how they differ, and which is best for your goals.
Protein powder is one of the most popular supplements worldwide - and for good reason. It is a convenient, affordable way to boost your protein intake when whole foods are not enough. But with hundreds of options on the market, how do you choose?
Types of Protein Powder
Whey Protein
Whey is derived from milk during cheese production. It is the most studied protein supplement and the gold standard for muscle building.
Key facts:
- Protein per scoop (30g): 24–27g
- Digestion speed: Fast (absorbed within 1–2 hours)
- Leucine content: ~2.5–3g per scoop - the highest of any common protein source
- PDCAAS score: 1.00
Whey comes in three forms:
- Concentrate (70–80% protein) - cheapest, contains some lactose and fat
- Isolate (90%+ protein) - less lactose, leaner, slightly more expensive
- Hydrolysate - pre-digested for faster absorption, most expensive, minimal practical advantage over isolate
The International Society of Sports Nutrition recommends whey protein as an effective supplement for muscle building and recovery (Jäger et al., 2017, JISSN).
Casein Protein
Casein is the other major milk protein (~80% of milk's protein content). It digests much more slowly than whey.
Key facts:
- Protein per scoop (30g): 24–26g
- Digestion speed: Slow (6–8 hours)
- Leucine content: ~2g per scoop
- PDCAAS score: 1.00
Casein is popular as a before-bed supplement because it provides a steady release of amino acids overnight. A study by Res et al. (2012) found that 40g of casein before sleep increased overnight muscle protein synthesis by 22% (Res et al., 2012, Medicine & Science in Sports & Exercise).
Plant-Based Protein Powders
For those avoiding dairy, plant-based options have improved dramatically:
| Source | Protein per scoop (30g) | PDCAAS | Notes |
|---|---|---|---|
| Pea protein | 22–25g | 0.89 | Rich in BCAAs, gritty texture |
| Soy protein isolate | 25–27g | 0.91 | Complete amino acid profile |
| Rice protein | 22–24g | 0.47 | Low in lysine; pair with pea |
| Hemp protein | 12–15g | 0.63 | Lower protein %, high in omega-3 |
| Blended (pea + rice) | 22–25g | ~0.90 | Complementary amino acids |
A pea + rice blend is the most popular plant-based option because the two complement each other's amino acid weaknesses, creating a profile similar to whey.
Research confirms that plant protein can match animal protein for muscle growth when total intake is matched (Hevia-Larraín et al., 2021, Sports Medicine).
What to Look For in a Protein Powder
- Protein per serving - aim for 20–30g per scoop.
- Short ingredient list - protein source, flavouring, sweetener. Fewer fillers is better.
- Third-party testing - look for NSF Certified for Sport, Informed Sport, or USP verification. These certify the product contains what the label says and is free from banned substances.
- Leucine content - at least 2g per serving for effective muscle protein synthesis.
- Digestive tolerance - if you are lactose intolerant, choose whey isolate (very low lactose) or plant-based.
Which Protein Powder Is Best?
| Goal | Best Choice |
|---|---|
| Muscle building (general) | Whey isolate or concentrate |
| Before bed | Casein |
| Lactose intolerant | Whey isolate or pea + rice blend |
| Vegan/plant-based | Pea + rice blend or soy isolate |
| Weight loss | Whey isolate (highest protein per calorie) |
| Budget | Whey concentrate |
There is no single "best" protein powder - the right choice depends on your dietary needs, goals, and preferences.
How Much Protein Powder Should You Use?
Protein powder is a supplement, not a replacement for whole foods. Most people benefit from 1–2 scoops per day to fill gaps in their diet. The bulk of your daily protein should still come from foods like chicken, eggs, beef, and dairy.
Tips for Getting the Most From Your Protein Powder
- Mix with milk instead of water for an extra 8g of protein per cup.
- Add to oatmeal, pancakes, or baking - not just shakes.
- Time it after training - convenient for a quick post-workout protein hit.
- Use casein before bed for overnight muscle recovery.
- Log your shakes in Protein Pal to keep your daily protein count accurate.
The Bottom Line
Whey protein is the most effective and well-researched option for most people. Casein is excellent before bed. Plant-based blends (pea + rice or soy) are a strong alternative for those avoiding dairy. Whatever you choose, prioritise products with third-party testing, 20+ g of protein per scoop, and minimal fillers.