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BSN Syntha 6 vs. Optimum Nutrition 100% Casein Gold Standard Protein

What is BSN Syntha 6?

Syntha 6 is one of the most popular protein supplements from BSN. Having a noticeably higher than average caloric content, Syntha 6 is an ideal supplement for several fitness goals including lean mass gains and weight loss meal replacement.



  • 22 grams of protein per serving
  • Offers a variety of protein types for varying speeds of protein digestion (Whey Protein Concentrate, Whey Protein Isolate, Calcium Caseinate, Micellar Casein, Milk Protein Isolate, Egg Albumin, And Glutamine Peptides)
  • Also includes fatty acids, fibre, and carbohydrates


Why You Should Use BSN Syntha 6

Syntha 6 is an ideal protein supplement for anyone who wants to pack on solid lean muscle mass and has no restrictions on carbohydrates in their diet. You'll immediately notice that Syntha 6 has 200 calories per serving and this number is higher than most other protein supplements including Optimum Nutrition Casein Protein, which only has 120 calories.


These extra calories are coming from a combination of protein, fatty acids, and complex carbohydrates, making this ideal as a lean mass gainer or someone who wants to pack on muscle and minimize fat gain. Syntha 6 is also a great option for meal replacement when your goal is weight loss.


Syntha 6 utilizes a protein matrix, which consists of several types of protein sources. This is excellent for ensuring amino acid release over the course of several hours. Amino acids are the building blocks of muscle tissue and promote protein synthesis, lean mass growth, and recovery. (1-6)


Casein from Optimum Nutrition also offers an extended amino acid release; however, Syntha 6 provides an immediate supply of aminos from whey isolate. Casein, on the other hand, takes more time to start breaking down.


Things to Watch Out for With BSN Syntha 6

If you are on a low-carbohydrate diet, Syntha 6 may interfere with that as it contains 15 grams of carbohydrates per serving.


The only other issue with BSN Syntha 6 would be nutritional preferences. If you are someone who wants to avoid artificial flavouring, fillers, and sweeteners at all cost, then Syntha 6 may pose a problem as it contains all of these things. Then again, you'll be hard pressed to find a supplement in this industry that doesn't contain those things. Even Optimum Nutrition Casein has artificial sweeteners; however, it has less additives than Syntha 6.



What is Optimum Nutrition 100% Casein Gold Standard Protein?

Optimum Nutrition Casein is a leading brand of casein protein, primarily used by those who want to protect muscle mass and support its growth. O.N. Casein can also be useful for anyone who is looking to curb their appetite and support a healthy weight loss due to its slow digestion rate.



  • Provides 24 grams of protein
  • Ideal for low carbohydrate diets with only 3 grams per serving – With the 1 gram of fiber, the net carb content would only be 2 grams per serving
  • Slowest rate of digestion, which allows for extended release of muscle building amino acids

Why You Should Use Optimum Nutrition 100% Casein Gold Standard Protein

Once exclusively used by bodybuilders, casein protein has become a fitness staple for those who are muscle-focused. Optimum Nutrition 100% Casein Gold Standard Protein is a unique supplement in that it is designed to take hours to digest. This means that the amino acids that you need for muscle maintenance and growth are going to be released over the course of several hours as opposed to one quick shot like with an isolate.


The 120-calorie serving makes O.N. Casein ideal for muscle building especially for those on a low carb diet.


Things to Watch Out for With Optimum Nutrition 100% Casein Gold Standard Protein

Due to the extremely slow digestion rate, Optimum Nutrition 100% Casein Gold Standard Protein would not be a great choice for immediate post-workout nutrition. BSN Syntha 6 features whey isolate in its protein matrix, making it the better choice for an immediate post-workout shake.



Both of these protein brands are excellent choices for muscle building and weight loss. It is not a question of quality, as they are both of elite equality; rather, it is a question of nutritional timing.


BSN Syntha 6 can be used at any point throughout the day; however, we wouldn't recommend using it at night because of the higher caloric content. In this case, Optimum Nutrition Casein would be the better choice. It will release amino acids throughout the night and it only has 120 calories per serving, helping you to promote muscle growth and avoid fat gain.


If you're serious about your fitness goals, you can use both of these supplements to support your results.



  1. Tsutsumi R, Tsutsumi YM. Peptides and proteins in whey and their benefits for human health. Austin J Nutri Food Sci 2014;1(1): 1002
  1. Blomstrand E, Eliasson J, Karlsson HK, Köhnke R. Branched-chain amino acids activate key enzymes in protein synthesis after physical exercise. J Nutr. 2006 Jan;136(1 Suppl):269S-73S.
  1. Norton, Layne, Layman, Donald. Leucine Regulates Translation Initiation of Protein Synthesis in Skeletal Muscle after Exercise. J. Nutr. February 2006 vol. 136 no. 2 533S-537S.
  1. Negro M, Giardina S, Marzani B, Marzatico F. Branched-chain amino acid supplementation does not enhance athletic performance but affects muscle recovery and the immune system. J Sports Med Phys Fitness. 2008 Sep;48(3):347-51.
  1. Mourier A, Bigard AX, de Kerviler E, Roger B, Legrand H, Guezennec CY. Combined effects of caloric restriction and branched-chain amino acid supplementation on body composition and exercise performance in elite wrestlers. Int J Sports Med. 1997 Jan;18(1):47-55.
  1. De Lorenzo A, Petroni ML, Masala S, Melchiorri G, Pietrantuono M, Perriello G, Andreoli A. Effect of acute and chronic branched-chain amino acids on energy metabolism and muscle performance. Diabetes Nutr Metab. 2003 Oct-Dec;16(5-6):291-7.
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