by Dr. Spencer Nadolsky T-Nation
Here's what you need to know...
• One 6-week study involving college students who drank protein shakes resulted in big drops in blood pressure.
• Another study involving obese patients who drank protein shakes resulted in blood pressure drops similar to those achieved by salt restriction.
• The results probably have to do with both weight loss (from ingesting more protein and fewer calories) and properties in milk that inhibit an enzyme that regulates blood pressure.
High blood pressure, also known as hypertension, is ranked as the leading risk factor for mortality and is slated as the cause for around 13.5% of all deaths (1,2). Treating blood pressure in a regular doc's office usually starts with lowering salt intake. If that doesn't work, you get medicine.
But what if there were another approach that not only brings your blood pressure down, but also lowers your risk of death and helps you look good naked? Recent research shows that milk (whey and casein) protein may be just such an approach.
In epidemiological studies, milk consumption is associated with a decreased risk of hypertension (3). Having an association with decreased risk is great, but can drinking a protein shake with whey and/or casein actually lower blood pressure? The answer is yes.
In one study over 6 weeks, whey protein helped decrease the systolic (top number) and diastolic (bottom number) blood pressures by 8.00 and 8.60 mm Hg respectively in college students with hypertension or pre-hypertension. To give some perspective, salt reduction is shown to decrease systolic and diastolic blood pressures 5-6 and 2-3 mm Hg respectively (4). While this is a small study on whey and not a huge meta-analysis, those are still impressive numbers in favor of drinking the muscle builder's favorite elixir.
In another study, 70 obese (BMI over 30) folks with normal blood pressures were either given 27 grams of whey protein isolate, sodium caseinate (casein), or glucose. After 12 weeks, both the casein and whey groups had decreases in systolic and diastolic blood pressures by about 5 and 2 mm Hg respectively (5), numbers that are still similar to those of salt reduction.
So is it just that protein shakes help with weight loss and therefore blood pressure, or is there another mechanism? It's probably partly due to weight loss, but there's an enzyme called angiotensin converting enzyme that's a key regulator in blood pressure because it's the rate-limiting enzyme responsible for the conversion of angiotensin I to angiotensin II.
Angiotensin II is a potent vasoconstrictor, which increases blood pressure when activated. It just so happens that there are properties in milk protein that INHIBIT this ACE enzyme, which would decrease the amount of angiotensin II and therefore blood pressure (7-10).
This is pretty neat considering some of the best blood pressure medicines out there are actually ACE inhibitors (e.g., lisinopril). Unfortunately the two human trials mentioned above tried to measure the ACE level changes and didn't find much difference. The studies that did show ACE inhibition were done in vitro, which may help explain the contrast.
Even if we're not entirely sure of the exact mechanism, the potency of whey and casein protein shakes as a means to lower blood pressure is definitely worth trying. Heck, it beats eating bland, saltless meals.
1. Kearney PM, Whelton M, Reynolds K, Muntner P, Whelton PK, He J. Global burden of hypertension: analysis of worldwide data. Lancet. 2005;365:217-223.
2. Lawes CM, Vander Hoorn S, Rodgers A; International Society of Hypertension. Global burden of blood-pressure-related disease, 2001. Lancet. 2008;371:1513-1518.
3. Rice BH, Cifelli CJ, Pikosky MA, Miller GD: Dairy components and risk factors for cardiometabolic syndrome: recent evidence and opportunities for future research. Adv Nutr 2011, 2(5):396-407
4. Fluegel SM, Shultz TD, Powers JR, Clark S, Barbosa-Leiker C, Wright BR, et al.: Whey beverages decrease blood pressure in prehypertensive and hypertensive young men and women. Int Dairy J 2010, 20(11):753-760.
5. He FJ ,Li J ,MacGregor GA. Effect of longer term modest salt reduction on blood pressure: Cochrane systematic review and meta-analysis of randomised trials.BMJ 2013;346:f1325
6. Pal S, Ellis V: The chronic effects of whey proteins on blood pressure, vascular function, and inflammatory markers in overweight individuals. Obesity (Silver Spring) 2010, 18(7):1354-1359.
7. Yamamoto N, Takano T. Antihypertensive peptides derived from milk proteins. Nahrung 1999;43:159-164.
8. FitzGerald RJ, Meisel H. Lactokinins: whey protein-derived ACE inhibitory peptides. Nahrung 1999;43:165-167.
9. Mullaly M, Meisel H, FitzGerald R. Angiotensin-I-converting enzyme inhibitory activities of gastric and pancreatic proteinase digest of whey proteins. Int Dairy 1997;7:299-303.
10. Ricci-Cabello I, Herrera MO, Artacho R: Possible role of milk-derived bioactive peptides in the treatment and prevention of metabolic syndrome. Nutr Rev 2012, 70(4):241-255.