The Protein Paradox - are you consuming enough protein?

Welcome back to Plantforce® Protein Series, if you haven’t checked out part 1, we recommend you familiarize yourself with our introduction. In our previous instalment we covered the basics of protein as a macronutrient and why it’s essential. As plant-based diets are becoming increasingly popular, our aim in this essential guide is to equip you with the knowledge to make informed decisions regarding your protein source and overall intake to not just survive, but to thrive on a plant-based diet.

In this instalment, we investigate the Population Reference Intake (PRI) and begin to question the nutritional science to see if this recommendation is suitable for our individual needs and plant-based diets. Firstly, one general misconception is that all sources of protein is created equal and that every individual will eat a mix of plant and animal-based products. We breakdown this recommendation by focusing on the overlooked factors, such as dietary protein quality, digestibility and the difference in plant and animal sources of protein. Taking these factors into consideration we can make informed choices regarding protein supplementation and delve into the scientific data which will elucidate the best road forward for optimising protein intake.

What is the current dietary reference for protein?

The current dietary reference is the Population Reference Intake (PRI) for healthy adults that has been established by European Food Safety (EFSA). Protein requirement in healthy adults is defined as an intake of dietary protein that is sufficient to achieve body protein equilibrium (zero balance) in a healthy individual. Large public health organisations such as EFSA provide population-based recommendations for protein as part of their mission to improve global health. The PRI for protein in healthy adults is 0.83g protein/per kg body weight/per day.

For example Mike (80kg) would need 66.4g of high quality protein daily to meet EFSA recommendation. (1)
 
For example Mary (62kg) would need 51.5g of high quality protein daily to meet EFSA recommendation. (1)

The International Society of Sports Nutrition (ISSN) has recommended protein intake to be anywhere between 1.4-2.0g/kg for a range of different athletes in various sports. Additionally, there are also sport specific recommendations. If interested in further and detailed reading, click this link. 

Reverting back to the previous example used to illustrate the amount of protein needed to meet the PRI, they would need both to adopt a high protein diets to adhere to ISSN guidelines, see the breakdown below.

Mike the athlete (80kg) would need somewhere between 112-160g of protein to optimize recovery from training and promote growth of muscle mass when calorie intake is sufficien. (2)

Mary the athlete (62kg) would need somewhere between 87-124g of protein to optimize recovery from training and promote growth of muscle mass when calorie intake is sufficient (2) 

Simplistic Overview of Protein Requirements:

Issues with PRI suiting your individual needs:

1. Recommendations for healthy adults are generally derived from studies conducted mainly in younger adults which is problematic for several reasons. Compared with younger adults, the muscles of older adults are less sensitive to smaller doses of protein and appear to require a greater amount of protein to fully stimulate muscle protein synthesis (MPS). (3)

2. The PRI is only to prevent protein deficiency and maintain whole-body protein balance, it’s not necessarily optimal for thriving, particularly for athletes who train hard regularly and have a higher protein demand due to the increased utilization of AA during exercise and muscle breakdown as a by-product of intense exercise. (4)

3. One method used to calculate whole body protein status is nitrogen balance. This requirement has been derived from methodology that has limitations in accuracy. This results in protein requirements to be UNDERESTIMATED which results in an inexact public health recommendation. (5) (See below for our Protein Turnover and Nitrogen Balance explanation).

4. The 0.83g/kg/bw recommendation is derived from data using a variety of protein sources including animal protein. The PRI assumes that an individual’s diet will consist of some “high quality” protein (e.g. meat, eggs). Animal protein is considered as high-quality protein as it contains a balanced amino acid profile and has the superior bioavailability than any plant protein source. Whereas, some or even most proteins of plant origin have lower protein quality as a consequence of several essential amino acids being inadequate for optimal muscle building.

5. It’s crucial to consider that your individual needs are dynamic and ever changing and your specific intake should be personalised and tailored to you. The intake for a bodybuilder is not comparable to a sedentary desk worker or even an infant to an adolescent, your requirements are unique to your biology and lifestyle. While public health guidelines are a decent reference, they are just that a “guideline”, to identify what works for you best as an individual is the goal.

Considerations for plant-based diets

Plant based diets have gained popularity worldwide, sourcing environmentally friendly and cruelty free animal protein alternatives is becoming a necessity to decrease our global carbon footprint. A plant-based diet promotes healthy eating and can be nutritionally sufficient and, in some cases, superior to its omnivore or mixed diet counterpart. It is advisable for an individual transitioning from an mixed diet to pay careful consideration to quality and variety of protein sources especially if they participate in regular physical activity.

Vegan athletes on average consume less protein compared to those that consume animal protein. The digestibility and bioavailability of protein in plant foods is inferior to meat, fish and dairy products. (6) Therefore, this increases the recommended intake due to the reduced amount available for absorption and lower overall protein content in the diet. Hence, vegetarians and more specifically vegans need well thought out food-based guidelines for protein, 0.83g/kg/bw would not be sufficient here as all protein sources would be derived from plants.

A common concern for individuals who partake in physical activity and adopt a plant-based diet is consuming enough “high quality” protein to support muscle growth and recovery. Plants are lower in overall protein content and therefore require a greater absolute amount to meet bodily needs compared to animal sources. It is rare to find the full spectrum of essential amino acids in adequate quantities from plant-based foods. The amino acid profile and digestibility of many plant proteins suppress their ability to support tissue repair.

Although, meeting your protein requirements on a plant-based diet requires more attention to detail, these targets can be easily met with correct preparation and planning. Incomplete protein sources can easily be combined to complement each other’s inadequacies. For example; pea protein isolate and rice protein isolate that complement each other’s AA profile is an efficacious strategy to obtain a “complete” AA profile.

Benefits of plant-based protein powders

Plant proteins generally have lower digestibility, with the exception of plant-based protein powders as most antinutrients that hinder absorption are removed in the production process. Protein supplements can be as effective as some complete animal-based proteins, which is demonstrated in studies supplementing rice and pea protein powders vs whey protein. The results showing similar muscle hypertrophy for both groups in the respective studies. 

Supporting your diet with higher digestible plant protein powders daily provides reassurance that you ingest an adequate amount of high quality proteins. See Table 2 for our Plantforce® Synergy Blend AA profile and relevant comparisons. (7)

Protein Turnover & Nitrogen Balance Explained:

Protein Turnover is a set of processes where there is simultaneous breakdown and synthesis of protein. The balance between Muscle Protein Breakdown (MPB) and Muscle Protein Synthesis (MPS) is known as Net Protein Balance (NPB) which defines the protein turnover concept. For a simplistic breakdown of this concept see bullet points below.

• If synthesis is greater than breakdown, it will result in muscle mass accretion – net POSITIVE protein balance. (Anabolic State)
• If breakdown is greater than synthesis, there will be a decrease in the amount of tissue. We will have a net NEGATIVE protein balance – where we are losing muscle tissue. (Catabolic State)
• If breakdown equals synthesis, there will be no change in the amount of tissue mass lost or gained, although there is replacement of old damaged proteins with newly synthesised proteins. We are fulfilling the body’s basic needs resulting in net protein balance.

Fats and carbohydrates contain carbon, hydrogen and oxygen. Protein contains nitrogen as an additional element. The nitrogen we ingest via the diet is derived from protein. It’s fairly easy to measure nitrogen in urine and faeces, which allows us to calculate nitrogen excretion and subsequent nitrogen balance.

Current public health protein recommendations are based on data from Nitrogen Balance studies which attempts to determine protein requirements by measuring the amount of nitrogen that is ingested (food) and the amount that is excreted (via sweat, urine, feces, hair, and skin). (5) There is a universal conversion factor to convert protein to nitrogen which is based on an assumption that the average nitrogen content in all protein sources is 16% and is protein-bound, this should immediately raise a red flag as we know foods are complex and  rarely have the exact same structure.

Despite many studies documenting that this leads to an overestimation of the protein content in most foods and, in particular, plant foods this method is still utilised for public health recommendations. (8) Therefore, in conclusion the nitrogen balance method tends to underestimate nitrogen losses due to the difficulty in quantifying all routes of nitrogen excretion (skin hair, nails, various bodily secretions, breath, changing size of urea body pool etc.). Nitrogen balance is calculated below. Nitrogen in through food minus nitrogen excreted through the aforementioned routes is how balance is calculated.

Conclusion

Those who consume animal protein in their diet hit their protein requirements without paying much attention to food sources or intake, however vegans and vegetarians may need specific attention to their protein sources, as we know now not all protein sources are created equal.
 
There is accumulating evidence for the consumption of protein above the RDA, for multiple subgroups in order to improve health status. It’s an extremely important for maintaining and supporting human health. Protein enables appropriate body composition to be achieved and maintained, but also to enable long-term health and well-being in terms of reduced risk of multifactorial diseases that currently affect a high proportion of the population. Muscle mass has an important role to play in keeping degenerative diseases such as osteoporosis and sarcopenia at bay.
 
Finally, see table 4 & 5 below for our protein recommendations for adults whether you are sedentary or active, stratified by the lower end and higher end of our recommended ranges. 

Sedentary Adults

Active Adults

Do you need extra protein? Healthy eating is easy with our Plantforce® Synergy Protein, available in four delicious natural flavours. It has a similar amino acid profile to whey protein but it’s vegan, 100% hypoallergenic and RAW! Backed by nutritional science, it’s ultra-clean blend provides your daily amino acids making it add extra protein to plant-based meals.

References:

1. Carlo Agostoni, Jean-Louis Bresson, Susan Fairweather-Tait, Albert Flynn, Ines Golly, Hannu Korhonen, Pagona Lagiou, Martinus Løvik, Rosangela Marchelli, Ambroise Martin, Bevan Moseley, Monika Neuhäuser-Berthold, Hildegard Przyrembel, Seppo Salminen, Yola H van L and HV. Scientific Opinion on Dietary Reference Values for protein. EFSA J. 2012;10(2):2557. doi:10.2903/j.efsa.2012.2557 
2. Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14(1):20. doi:10.1186/s12970-017-0177-8 
3. Churchward-Venne TA, Holwerda AM, Phillips SM, van Loon LJC. What is the Optimal Amount of Protein to Support Post-Exercise Skeletal Muscle Reconditioning in the Older Adult? Sport Med. 2016;46(9):1205-1212. doi:10.1007/s40279-016-0504-2 
4. Wu G. Dietary protein intake and human health. Food Funct. 2016;7(3):1251-1265. doi:10.1039/C5FO01530H 
5. Pencharz PB, Ball RO. DIFFERENT APPROACHES TO DEFINE INDIVIDUAL AMINO ACID REQUIREMENTS. Annu Rev Nutr. 2003;23(1):101-116. doi:10.1146/annurev.nutr.23.011702.073247 
6. Venderley AM, Campbell WW. Vegetarian diets: Nutritional considerations for athletes. Sport Med. 2006;36(4):293-305. doi:10.2165/00007256-200636040-00002 
7. van Vliet S, Burd NA, van Loon LJ. The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption. J Nutr. 2015;145(9):1981-1991. doi:10.3945/jn.114.204305  
8. Schwingshackl L, Hoffmann G. Comparison of High vs. Normal/Low Protein Diets on Renal Function in Subjects without Chronic Kidney Disease: A Systematic Review and Meta-Analysis. Sands JM, ed. PLoS One. 2014;9(5):e97656. doi:10.1371/journal.pone.0097656