Optimal Protein Intake for Life

We spend a lot of time talking and debating about carbohydrates and dietary fat in the nutrition world. High carb, low carb, keto, low fat, high fat, healthy fat etc. Protein often gets left out of the conversation as if the correct levels of protein were not only well understood but also easy to obtain from high quality sources. I’ve also noticed a trend in my new patients recently that they have started reducing protein consumption, sometimes unintentionally, in an attempt to improve their health. As a physician optimizing patients in the spaces of longevity, hormone optimization, bone health and weight loss maintenance I want to take the time to explain why we need to take a closer look at our protein consumption. This blog will focus on optimal quantity or protein and leave the question of where to get it from for another day.

The current RDA recommendations for adult protein intake (0.8g/kg) have been accepted as dogma and generally are not questioned in the healthcare space. This number is touted as the optimal level for all adults no matter what their goals are unless a disease state makes this level of consumption concerning and further restriction is then recommended. A simple big picture perspective of this principle should raise red flags. How can every adult from every ethnic background with infinitely unique situations and goals be recommended the same quantity of protein? We have to understand that the RDA is making recommendations not for optimal intake but for MINIMUM levels of intake to prevent disease in the short term. In the space of health optimization short term disease prevention is not our goal. Long term disease prevention, performance optimization, longevity and increased healthspan are what we are interested in.

When I explored the origins of these recommendations I found a significant amount of controversy surrounding how these numbers were obtained and what a better recommendation should be. The nitrogen balance studies used to determine the RDA minimum has been questioned publicly by the Institute of Medicine and other methods are being explored to better identify an appropriate minimum. The concern is that the current approach underestimates protein requirements potentially for every human but certainly for some very important conditions that are prominent in our society today. Newer literature concedes that higher levels of protein (up to 1.6g/kg) should be considered the minimum required intake but not even these levels are not designed for optimal performance, glucose metabolism, longevity or bone health!

Protein consumption is also challenging to openly discuss because it brings with it strong opinions on animals and the environment. I’ll leave these for another day but assume for the sake of this discussion that we can provide a protein to all humans free of ethical questions and equal in quality. In this scenario protein consumption would still be controversial because of the fear around kidney function, bone health, cancer risk and diabetes. The challenge is sorting through the garbage headlines and research funded by interest groups to try to find the truth which as usual lies with the minority, somewhere in the middle. Some nefarious associations and headlines try to undermine protein consumption by trying to tie increased consumption with bone loss and kidney dysfunction. However, the evidence actually points to the opposite. Increased protein consumption actually leads to improved vitamin D and calcium metabolism and improved muscle mass. Both of which will improve bone health and indeed increased protein consumption did result in reduced fractures in a 2019 meta-analysis. The fear of “acid causing” protein has never fundamentally made sense to me and I couldn’t find any substantive literature to support that claim. Kidney function also does not appear to be effected by increased protein consumption and as long as your kidney’s are healthy.

The cancer argument is a larger question. One that requires a short background discussion. When protein is consumed with meals consistently it will increase levels of a hormone called Insulin Like Growth Factor 1 (IGF-1). Several well known authors who champion protein restriction point to this blood marker as “proof” that we should limit consumption. The disparity here is that reduction of IGF-1 in insect models does promote longevity. So the leap is to say that reducing protein consumption in humans which reduces IGF-1 will promote longevity. Like so many hypothesis derived from animal and insect studies this result is not demonstrated in available human studies. In fact the opposite seems more likely to be true, especially as we age. To understand why let’s examine the benefits of increased protein consumption.

The benefits are many but some at the top of my list are improved lean muscle mass, reduced levels of the hormone insulin, improved blood sugar, improved inflammation and decreases in the stress hormone cortisol and lastly a decreased risk for falls and fracture. Many of these improvements are grounded in the capacity of protein consumption to increase or at least maintain lean muscle mass. Muscle is the largest organ by volume in the body. It has the ability to act in locomotion but more importantly acts as a massive component to the metabolism and as an endocrine organ (communication to other organs through hormones). All humans will lose muscle mass as we age unless we fight to prevent it. This battle requires increases in resistance training and protein consumption. Our muscles literally become resistant to the effects of training and nutrition compared to our younger selves but generally we see the opposite recommendations for our aging population.

Metabolically our muscles can help to reduce blood glucose by acting as a large sink for glucose disposal. The skeletal muscle stores five times the glycogen (storage form of glucose) than the liver and more than any other organ in the body. The more muscle you have the easier it is to handle carbohydrates when you eat them. In addition protein consumption compared to carbohydrates increases your muscles sensitivity to the hormone insulin which is responsible for keeping your blood sugar at healthy levels. The more sensitive your body is to insulin the lower levels of the hormone you will see. Low levels of insulin allow for increased use of fat for fuel from adipocytes (fat cells) as well as increases in testosterone and reductions in the stress hormone cortisol! Some of these effects are mediated by the secretion of unique signaling molecules called myokines. These molecules secreted from muscle have a tremendous number of beneficial effects that help in disease prevention and health optimization.

Finally, with all of the potential benefits of exercise and muscle wouldn’t we want to do everything we can to maintain this unique organ? My recommendation to my patients is an overwhelming yes. We must protect the function of the skeletal muscle and give it what it needs to thrive. One of those elements is adequate protein intake from high quality sources. Adequate intake is likely far above the RDA minimum of 0.8g/kg and possibly above the cited levels of 1.6g/kg. If your goal is to increase lean muscle mass (which it should be for everyone) or if you have obesity, heart disease, type 2 diabetes or cancer (>75% of the population over 65) you probably need more protein. I recommend aiming for 1g/pound of body weight or 2.2g/kg as long as your kidney function is adequate and frequently even if it’s not. If you’re not a patient of OHH check with your physician team prior to embarking on this change. Once you realize the power of a diet higher in protein and a life rich in exercise you will do everything you can to maintain it!

Dr. Doug

Doug Lucas
Author: Doug Lucas

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