Animal vs Vegan Protein: What is the difference?
Part 2-Chronic Ingestion and its Effects on Building Muscle
Last week I touched on animal vs plant-based protein and their effect on lean muscle mass. To quickly summarise, animal-based protein is superior in stimulating muscle protein synthesis (MPS) when compared to plant-based protein sources, in an acute setting. For a more in-depth explanation you can go back to read blog post number 1 from last week. This week I will focus on comparing the quality of protein sources on lean muscle mass over a chronic period of time (>8 weeks).
Chronic Effects of Protein Sources on MPS & skeletal muscle hypertrophy
Based off the literature from the previous weeks blog, it could be hypothesized that long term ingestion of animal-protein sources would stimulate greater levels of MPS, therefore, leading to greater muscular hypertrophy. The work of Hartman and colleagues (2007) in recreationally trained subjects would support this hypothesis. Over 12 weeks, 56 healthy sedentary male subjects performed 5 RT bouts/week, volume was equated for, and subjects were randomly split into 1 of 3 groups for post-exercise supplementation N=18 milk, N=19 soy, N=19 control (Maltodextrin). Each supplement was isoenergetic (same calories), with soy and milk also being isonitrogenous (same amount of protein). Compared to the control, both soy and milk protein had significantly greater gains in muscle hypertrophy (P<0.05). The cross-sectional area (CSA) of type II muscle fibers was significantly greater (P=0.05) in the milk group compared to the soy group, but no significant difference was observed in type 1 fibers. A rationale for this specific difference in fiber hypertrophy could be that subjects were recreational and early adaptations to RT in this population are neural, rather than hypertrophic (Staron et al.1991; cited in Deschenes and Kraemer, 2002 p.5). Diet was poorly controlled during the 12-week intervention, meaning the lean body mass (LBM) gains made by the soy group could have been attributed to a more omnivorous diet and not solely through the plant-based protein source.
Conversely, Joy and colleagues (2013) found no differences in LBM between either an isonitrogenous rice or whey protein supplementation over 8 weeks a group of 24 resistance trained men (21.3±1.9 years). The subjects had 3 RT bouts per week, equating for volume. There were significant gains in LBM (P<0.01) in both rice protein supplement (N=12) and whey protein supplement (N=12) groups, with no significant difference between the 2 groups. Both groups ingested 48g of protein in their post RT period, leucine content 5.5g for whey group and 3.8g for rice group, where the MPS threshold appears to be at 3g of leucine ingestion in one feeding, whether from a plant source or animal source. This could be viewed as a “ceiling” effect, and once 3g of leucine has been ingested MPS is maximally stimulated (Morton, McGlory and Phillips., 2015; van Vliet, Burd and van Loon, 2015). Both groups significantly improved body composition, strength, and power output, with no significant differences between the groups. The authors concluded that the composition of protein has less relevance when protein is consumed in high doses, breaking the leucine threshold of 3g, throughout a periodized RT program.
Similarly, in Brown and colleagues (2004), no significant difference in LBM gain between 33g soy (N=9) and 33g whey supplementation (N=9) over a 9-week intervention when combined with RT. Subjects were given protein bars, 11g protein/bar, and instructed to ingest 3 bars per day. A limitation of the study is the lack of control over subject’s diet outside of the intervention, meaning subjects potentially ingested an omnivorous diet and therefore stimulated MPS by ingestion of animal and plant-based products to increase the leucine content in their diet. This is further backed by the 33g dose in the study, where 33g of soy protein is <3g leucine, as observed in the work of Gorissen & colleagues (2018) with the authors identifying that 40g of soy protein contains 2.7g of leucine. Subjects in the soy protein group would have to either ingest higher amounts of total protein/day or change the source of protein to other plant or animal-based sources in order to break the 3g leucine threshold. It may also be worth mentioning that one of the authors owns the company that produced the soy protein bars, Dr.Soy, for this study, which is a conflict of interest with the results.
Kalman et al.,2007 assessed LBM in 20 young male subjects (30.7±6.5 years) over a double blind, intervention comparing protein supplementation across four groups, in combination with RT.
- Soy isolate (N=5)
- Soy concentrate (N=5)
- Whey blend (N=5)
- Soy and whey blend 50/50 (N=5).
Training and non-training days included ingestion of 2 boluses of 25g of protein for each group. The researchers found no significant difference between the groups. Limitations include 1) lack of dietary control, as previously mentioned 25g soy protein <3g leucine (Gorissen et al.,2018) it would mean that subjects would require a greater dose or various source of protein to reach MPS. 2) A lack of control of RT volume or recognition of interindividual/group differences in training volume, as it was optional to do either 3 or 4 sets of 8-12 reps meaning 9 exercises X3 sessions per week=27 extra sets X12 (weeks)= 324 potentially extra sets over the intervention.
It appears that in acute settings, the ingestion of animal-based protein sources will exhibit a greater MPS response both at rest and post-RT, in recreationally active, elderly, young, and active adults. The same cannot be stated in a chronic (8 weeks) sense, where the supplementation of plant-based sources appear to equal the efficacy of animal sources. There is only evidence to suggest that hypertrophy of type II muscle fibers respond significantly greater when animal-based sources are ingested instead of plant-based (Hartman et al.,2007). Whilst several limitations are highlighted in each longer-term study (Hartman et al,2007; Brown et al.,2004; Kalman et al.,2007), it appears that the source of protein is redundant when the leucine threshold, >3g, has been breached.
To conclude, animal-based protein sources appear to have a greater acute anabolic response, both at rest and post-RT, but doesn’t seem to have as much of an effect over longer periods (>8-weeks), when plant-based protein is ingested as part of an omnivorous diet. Provided that the leucine threshold has been breached at each feeding and a positive nitrogen balance occurs, the source of protein appears to be less important. Further research is warranted to investigate solely the chronic effects of plant and animal-based protein on MPS at both rest and post-RT in a variety of populations, with more tightly regulated dietary control during the intervention. Individuals who follow a vegan diet can still attain a positive nitrogen balance within their diet, however, may require supplementation in order to achieve their g/kg/day requirement.
My recommendations for a vegan dieter looking to increase protein in their diet is the following
- Variety- Eat various forms of plant proteins in order to get various amino acids into the diet. Rice, lentils, nuts, chickpeas, quinoa, as well as other grains and pulses. This is because plant-based sources are incomplete proteins, they don’t contain all of the essential amino acids, such as in milk or other animal-based sources. By eating a variety of different plant-based proteins you will have a more complete protein profile.
- Supplementation- If struggling with protein ingestion I would invest in a supplement. If possible, try to get a mixed blend of different protein sources, again to try to make a more complete source of protein. Adding a 3g scoop of pure leucine with the protein will also enhance the quality of the protein ingested.
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- Brown, E., DiSilvestro, R., Babaknia, A. and Devor, S. (2004). Soy versus whey protein bars: Effects on exercise training impact on lean body mass and antioxidant status. Nutrition Journal, 3(1).
- Deschenes, M. and Kraemer, W. (2002). Performance and Physiologic Adaptations to Resistance Training. American Journal of Physical Medicine &and Rehabilitation, 81(Supplement), pp.S3-S16.
- Gorissen, S., Crombag, J., Senden, J., Waterval, W., Bierau, J., Verdijk, L. and van Loon, L. (2018). Protein content and amino acid composition of commercially available plant-based protein isolates. Amino Acids, 50(12), pp.1685-1695.
- Hartman, J., Tang, J., Wilkinson, S., Tarnopolsky, M., Lawrence, R., Fullerton, A. and Phillips, S. (2007). Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters. The American Journal of Clinical Nutrition, 86(2), pp.373-381.
- Joy, J., Lowery, R., Wilson, J., Purpura, M., De Souza, E., Wilson, S., Kalman, D., Dudeck, J. and Jäger, R. (2013). The effects of 8 weeks of whey or rice protein supplementation on body composition and exercise performance. Nutrition Journal, 12(1).
- Kalman, D., Feldman, S., Martinez, M., Krieger, D. and Tallon, M. (2007). Effect of protein source and resistance training on body composition and sex hormones. Journal of the International Society of Sports Nutrition, 4(1).
- Morton, R., McGlory, C. and Phillips, S. (2015). Nutritional interventions to augment resistance training-induced skeletal muscle hypertrophy. Frontiers in Physiology, 6:245.
- van Vliet, S., Burd, N. and van Loon, L. (2015). The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein
MPB = Muscle Protein Breakdown
MPS = Muscle Protein Synthesis
BCAA = Branched Chain Amino Acid’s
AA = Amino Acids
FSR = Fractional Synthetic Rate
CSA = Cross Sectional Area
RT = Resistance Training