Protein - how much is too much?

 

"Can I have too much protein?"

"How much is too much??"

Hmmm..

How come no body asks me that question about carbs?

I never get that question about bread, pasta or chocolate...?

And those few chardies that always seem to find a way in there a few times a week along with the Chinese, Italian, Indian takeaway...?

But as soon as we start to place our eating habits under a little more scrutiny, protein becomes the topic of concern, particularly, "having too much".

Well guess what? You’ve been having too much for years.

Yep, most Americans & Australians already consume double the recommended daily allowance as part of their normal eating[1,2].

What is a high protein intake exactly?

That's where it gets confusing and inaccurate. The definitions in the scientific literature range from intakes greater than 15–16 % of total energy or as high as 35% of total calories or intakes that merely exceed the RDA of 0.8g/kg/day[1,3].

According to an extensive review of the research by the International Society of Sports Nutrition, “protein intakes of 1.4 – 2.0 g/kg/day for physically active individuals is not only safe, but may improve the training adaptations to exercise training”[4]. That amount is up to two and a half times the RDA.



Concerns about a high Protein diet? Most people consume around double the RDA without knowing it.

More recent long term investigations have confirmed previous work that is, up to 3.3 grams of protein per kilo of body weight per day for one year provided no harmful effects on liver and kidney function - that's over five and a half times the RDA! And it provided no increase in body fat [3-6].

What happens if I consume more than the RDA?

Surprisingly, not much... aside from improve athletic performance and promote healthy aging[1-7]. Increasing protein intake doesn't appear to increase weight or body fat. Also, no research has been able to establish a link of any kind that may suggest a particular protein amount will damage a healthy organ or body.

How much do I need really?

That depends on what you're doing. Probably the most important finding from contemporary research on this topic is that, a higher protein intake won't improve your body composition unless you are engaged in a structured resistance exercise program.



The methods used to help assess protein requirements are constantly improving, as a result protein recommendations are increasing for many populations.

If your goals involve improving health and body composition (more lean tissue & less fat) then the real experts on this topic - the ones that actually complete the research,  suggest 2-3 times the RDA is not only acceptable, it's highly recommended. Up to 35% of your total daily energy intake (rather than the out-dated 10-15%) is recognized as safe and effective [1,7].

Once you start going much higher than that, there is a risk of not obtaining enough nutrition, fiber and fuel from other food sources.

One of the true pioneers of great research on protein requirements, Robert Wolfe and his team, showed clearly when you consume protein-only meals in a fasted state, a big chunk is simply oxidised (converted to blood sugar). So going crazy with very high protein intakes at the expense of other food sources only teaches your body to burn more of it for fuel - gluconeogenesis is the biochem term for the conversion of several key amino acids including the BCAAs to glucose when energy intake is too low.

Our physiology cannot be tricked, it's too clever after around 10,000 years of evolutionary tweaking. 

The bottom line is, the methods used in research to help assess protein requirements are constantly improving, as a result so are the estimated recommendations for protein needs in many populations.

For example, the average protein requirement recommended for women aged above 65 years has increased up to 1.29 grams per kilogram of body weight per day. Another important recommendation is 25-30 gram dose of protein per meal is considered a safe effective strategy that promotes better health, satiety and loss of unwanted weight in over weight adults [1].

If most of us already consume around double the recommended amount - without even knowing it, based on all the information we have, maybe a much better question is "Where does your protein come from, in relation to your health status?"

For example, you could be a 5'9, middle-aged adult with a body mass index (BMI) over 20.

Or you could be the same height, similar BMI but carry only around 10% body fat from lifting weights for the last 15 or so years

Your health status will be very different.

The type of protein consumed and the lifestyle habits of the individuals consuming them is just as important as the actual amount. That's the distinction the longitudinal research on dietary protein intakes has failed to make over the last 50 years in relation to cardiovascular disease, cancers and diabetes.

The good news is, we are starting to see the data from people that do live that second half of the equation.[1,7]





References

1. Introduction to Protein Summit 2.0: continued exploration of the impact of high-quality protein on optimal health. Rodriguez NR. Am J Clin Nutr. 2015 Apr 29.

2. http://mp-body.com/ask_the_dr/carb-delusions

3. A high protein diet (3.4 g/kg/d) combined with a heavy resistance training program improves body composition in healthy trained men and women--a follow-up investigation. Antonio J, Ellerbroek A, Silver T, Orris S, Scheiner M, Gonzalez A, Peacock CA. J Int Soc Sports Nutr. 2015 Oct 20;12:39.

4. The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. Antonio J, Peacock CA, Ellerbroek A, Fromhoff B, Silver T. J Int Soc Sports Nutr. 2014 May 12;11:19.

5. The effects of a high protein diet on indices of health and body composition--a crossover trial in resistance-trained men. Antonio J, Ellerbroek A, Silver T, Vargas L, Peacock C. J Int Soc Sports Nutr. 2016 Jan 16;13:3.

6. A High Protein Diet Has No Harmful Effects: A One-Year Crossover Study in Resistance-Trained Males. Antonio J, Ellerbroek A, Silver T, Vargas L, Tamayo A, Buehn R, Peacock CA. J Nutr Metab. 2016;2016:9104792. Epub 2016 Oct 11.

7. Protein "requirements" beyond the RDA: implications for optimizing health. Phillips SM, Chevalier S, Leidy HJ. Appl Physiol Nutr Metab. 2016 May;41(5):565-72.