Protein and nitric oxide supplements promote muscle growth and strength, although each does so in a different way. They complement each other nicely, and if you are healthy enough to consume both of these supplements, you can take them together. Taking more than one supplement at a time is referred to as "stacking" in the bodybuilding community. Consult your doctor to see if these supplements are safe for you to consume.
A few of the most widely available protein supplements include whey, casein, soy and egg protein powders and bars. Whey protein powder offers the highest biological value of any protein supplement, according to McKinley Health Center at the University of Illinois, so it's a good choice if you are not allergic to milk. Soy protein powder is a viable alternative to whey for those who may be lactose intolerant or vegetarian. Protein supplements help to build, repair and maintain lean muscle mass. These supplements are generally safe to take alongside most other supplements on the market.
Nitric oxide, or NO, supplements are designed to increase blood flow for better muscle pumps and amino acid delivery to your muscle tissue. It makes sense that increasing blood flow would help deliver the amino acids -- building blocks of protein -- to your muscle. However, Dr. Mike Roussell, Ph.D. of Bodybuilding.com, states there is little proof behind the efficacy of NO supplements. He says most NO supplements contain the active ingredient L-arginine, which is an amino acid found in dairy, wheat products and animal-based sources of protein. The L-arginine enters the body and is converted to NO. Dr. Roussell suggests avoiding NO supplements, since most people get enough in their current diets and the scientific evidence behind its effectiveness is weak, as of 2011.
According to Dwayne Jackson, Ph.D. and Jim Stoppani, Ph.D. of Muscle and Fitness, stacking protein and NO supplements is a safe and effective for building muscle. They believe arginine supplements, the main ingredient in NO supplements, are effective, which is contrary to Dr. Roussell's belief. Jackson and Stoppani do agree, however, that NO/arginine supplements may not work well for everyone. That said, taking both protein and NO supplements do appear to be safe for healthy adults to consume as part of a consistent resistance training program.
The main concern associated with protein supplementation is consuming too much protein throughout the day. A healthy adult can process up to 0.91 g of protein per lb. of bodyweight. For example, a 170-lb. person may eat up to 154 g of protein per day. Exceeding this recommendation puts you at a higher risk of weight gain and puts extra strain on your liver and kidneys. Arginine, or NO, supplements may lower your blood pressure, so do not take them if you already take medications for low blood pressure.