It’s easy to take for granted our access to artificial light. There’s rarely a need to keep a fire stoked or light a candle to see through darkness. We can just flip a switch to illuminate a room, reach into our pocket for our flashlight enabled phones – or heck, just read directly from our miniature computer screens. The thing is, there may be a dark side to basking in all this artificial light – particularly our exposure to blue light. What is Blue Light? The visible light spectrum is an actual rainbow of colors – red, orange, yellow,
Listen to your mother when she tells you not to pass on the peas at dinner. Peas have long been hailed as an excellent source of protein, often considered a hypoallergenic, vegan alternative to whey protein supplements (see Dr. Hrkals comparison of pea and whey protein here). New benefits of pea protein hydrosylates as antioxidants, and support for cardiovascular and renal health have come to light in the last few years. Clinical and preclinical research suggests that peptides from pea protein may have some blood pressure lowering effects. Preclinical studies in hypertensive rats found there was a significant reduction in systolic blood pressure after supplementation with a hydrolysed pea protein isolate. When small scale studies in human subjects were conducted a similar albeit less dramatic, effect was found. Since then a number of other human clinical studies have popped up. So how does it benefit the kidneys? Well hypertension increases the pressure and burden on the kidneys.
How does pea protein work?
Scientists have proposed that pea protein affects blood pressure through the RAAS pathway. Within the kidneys lies a trigger for a complex endocrine pathway called the RAAS pathway, to increase blood pressure. A quick overview:
- When there is low blood pressure, the reduction in pressure detected by the kidneys will cause the release of renin
- Renin then causes the conversion of angiotensinogen (which comes from the liver) to angiotensin I
- An enzyme aptly names angiotensin converting enzyme (ACE) found in the lungs and kidneys, converts the angiotensin I into angiotensin II
- Angiotensin II has a number of effects all of which increase blood pressure
- Through increasing sympathetic activity
- Through increasing the secretion of aldosterone – a hormone which increases water and sodium retention by the kidneys
- Constriction of blood vessels which increases blood pressure
- And increasing the secretion of another hormone ADH from the brain causing more water to be reabsorbed from the urine
Conventional treatments for high blood pressure target this system, particularly through the inhibition of ACE. The class of drugs called ACE inhibitors, have some adverse side effects and long term consequences. Including a cough, taste disturbances, rashes, hyperkalemia, and renal impairment.
Pea protein offers a natural alternative to ACE inhibition. The most benefits seemed to be derived from hydrolysed, ie. proteins that have been broken down into specific peptides. Ingestion of pea protein was also related to an increase in the nitric oxide response. Which as we have talked about before, results in relaxation and dilation of the blood vessels, thereby reducing blood pressure. Further, pea protein isolates exhibit moderate antioxidant activity.
So go ahead, pass the peas!
Aluko, Rotimi E. Functional Foods and Nutraceuticals. New York, NY: Springer, 2012.
Boschin G1, Scigliuolo GM, Resta D, Arnoldi A.ACE-inhibitory activity of enzymatic protein hydrolysates from lupin and other legumes.Food Chem. 2014 Feb 15;145:34-40. doi: 10.1016/j.foodchem.2013.07.076. Epub 2013 Jul 24.
Li H, Aluko RE. Identification and inhibitory properties of multifunctional peptides from pea protein hydrolysate.J Agric Food Chem.2010 Nov 10;58(21):11471-6. doi: 10.1021/jf102538g. Epub 2010 Oct 7.
Li H, Prairie N, Udenigwe CC, Adebiyi AP, Tappia PS, Aukema HM, Jones PJ, Aluko RE. Blood pressure lowering effect of a pea protein hydrolysate in hypertensive rats and humans.J Agric Food Chem. 2011 Sep 28;59(18):9854-60. doi: 10.1021/jf201911p. Epub 2011 Sep 2.
Girgih AT, Nwachukwu ID, Onuh JO, Malomo SA, Aluko RE. Antihypertensive Properties of a Pea Protein Hydrolysate during Short- and Long-Term Oral Administration to Spontaneously Hypertensive Rats. J Food Sci. 2016 May;81(5):H1281-7. doi: 10.1111/1750-3841.13272. Epub 2016 Apr 1.
Teunissen-Beekman KF, Dopheide J, Geleijnse JM, Bakker SJ, Brink EJ, de Leeuw PW, Serroyen J, van Baak MA.Differential effects of proteins and carbohydrates on postprandial blood pressure-related responses.Br J Nutr. 2014 Aug 28;112(4):600-8. doi: 10.1017/S0007114514001251. Epub 2014 Jun 3.
Vermeirssen V, Augustijns P, Morel N, Van Camp J, Opsomer A, Verstraete W. In vitro intestinal transport and antihypertensive activity of ACE inhibitory pea and whey digests. Int J Food Sci Nutr. 2005 Sep;56(6):415-30.