Table 1. Observational studies of total protein intake and blood pressure.
| Author, year | respondents | Initial BP (mmHg) | Habitual protein intake | Dietary assess-ment | BP outcome (SBP/DBP) | BP outcome per 25 g/d or 3.5 en% (SBP/DBP) | P-value | Statistical adjustment |
| Cross-sectional studies | ||||||||
| Pellum, 1983[16] | 61 normotensive US adults mean age ∼24 | M: 119/73F: 107/68 | M: 101 g/d; F: 65 g/d (≈14 en%) | 3-d food record | −0.13/… mmHg per g/d | ∼ −3.33/… mmHg per 25 g/d | …/… | Sex, serum HDL, exercise, fat intake |
| Havlik, 1990[13] | 402 male US twins aged 42–56 y | 128/82 | 15 en% ( = 75 g/d) | FFQ | …/+0.11 mmHg per g/d of energy adjusted protein | …/∼ +2.75 mmHg per 25 g/d | NS/0.02 | Weight, serum cholesterol, triglycerides, total energy intake |
| Wang, 2008[20] (PRE-MIER) | 810 untreated pre- or mild hypertensives aged 25–79 y | 135/85 | 16 en% | 2×24 h recall | −0.08/+0.03 mmHg per en% | ∼ −0.28/∼ +0.11 mmHg per 3.5 en% | 0.41/0.73 | Age, sex, race, weight, waist, exercise, education, income, antihypertensive drugs, study site, baseline BP, alcohol, energy intake, intake of Ca and K, urinary creatinine, urinary Na |
| He, 1995[14] | 827 Chinese adults mean age ∼381 | ∼113/70 | ∼12 en% (≈93 g/d) | 3×24-h recall | −3.6/−2.2 mmHg per SD ( = 39 g/d) | ∼ −2.28/∼ −1.38 mmHg per 25 g/d | <0.05/NS | Age, BMI, alcohol, urinary Na, energy intake, resident area |
| Reed, 1985[17] | 6496 Japanese men in Hawaii aged 46–69 y | … | … | 24-h recall | −3 mmHg/−1 mmHg for Q5 (≥122) vs. Q1 (<67 g/d) | ∼ −0.85/∼ −0.28 mmHg per 25 g/d | <0.001/0.03 | Age |
| Umesawa, 2009[19] | 7585 Japanese men and women aged 40–69 y1 | M: 137/83; F: 135/81 | M: 83 g/d;F: 65 g/d | Single 24 h recall | −0.29/−0.42 mmHg per 25.5 g/d | ∼ −0.28/∼ −0.41 mmHg per 25 g/d | NS/<0.05 | age, gender, BMI, smoking, alcohol, community, use of antihypertensive medication, intake of sodium, potassium, and calcium |
| M: +0.07/−0.31 mmHg per 27.4 g/d | M: ∼ +0.06/∼ −0.28 mmHg per 25 g/d | <0.01/NS | age, gender, BMI, smoking, alcohol, community, use of antihypertensive medication, intake of sodium, potassium, and calcium | |||||
| F: −0.61/−0.55 mmHg per 20.6 g/d | F: ∼ −0.74/∼ −0.66 mmHg per 25 g/d | NS/<0.05 | age, gender, BMI, smoking, alcohol, community, use of antihypertensive medication, intake of sodium, potassium, and calcium | |||||
| Masala, 2008[15] (EPIC) | 7601 Italian women aged 35–64 y | 123/79 | … | FFQ | +0.38/+0.60 mmHg per log(g/d) | ∼ +1.22/∼ +1.93 mmHg per 25 g/d | 0.76/0.43 | Age, BMI, waist circumference, smoking, education, physical activity, energy intake |
| Garcia-Palmieri, 1984[12] | 7932 men from Puerto Rico aged 45–64 y | … | … | 24-h recall | SBP: between -0.03 and +0.03 mmHg per g/d depending on subgroup (urban/rural, middle-aged/old age); DBP: … | ∼+0.13/… mmHg per 25 g/d | NS/… | Age, smoking, weight, education, serum glucose, heart rate, intake of milk, fat, carbohydrates, coffee, alcohol |
| Stamler, 1996b[18] (MRFIT) | 11342 US men aged 35–57 y1 | 125/84 | 17 en% | 4–5×24-h recall | −0.06/−0.06 mmHg per en% | ∼ −0.20/∼ −0.21 mmHg per 3.5 en% | <0.01/<0.001 | Age, race, BMI, education, smoking, serum cholesterol, antihypertensive drugs, Na and K intake, alcohol and caffeine intake; corrected for regression dilution bias |
| Prospective studies | ||||||||
| Stamler, 2002[21] | 1714 men, aged 40–55 y1 | 135/87 | 15 en% | FFQ | +0.05/−0.02 mmHg per year per en% | ∼ +0.16/∼ −0.05 mmHg per 3.5 en% | 0.04/0.16 | Age, height, weight (+ change), education, alcohol, smoking |
| Liu, 1996[22] (CARDIA) | 4146 US blacks and whites aged 18–30 y1 | ∼110/69 | ∼15 en% | FFQ | ∼ −0.16/∼ −0.34 mmHg per year per 3 en% | ∼ −0.20/∼ −0.40 mmHg per year per 3.5 en% | NS/NS | Age, BMI, education, exercise, smoking, alcohol, hostility score, use of antihypertensive medication, intake of K and Ca |
| Alonso, 2006[23] (SUN) | 5880 Hispanic, university graduates, mean age ∼36 y | … | ∼18 en% | FFQ | HR (95%-CI) = 0.9 (0.6; 1.4) for Q5 vs.Q1 of energy adjusted protein | NA | 0.51 | Age, sex |
| Multivariable HR (95%-CI) = 0.8 (0.4; 1.4) for Q5 vs. Q1 of energy adjusted protein | 0.26 | Age, sex, BMI, exercise, alcohol, smoking, hypercholesterolemia, intake of total energy, Na, fruit, vegetables, fiber, caffeine, magnesium, potassium, low-fat dairy, MUFA, SFA | ||||||
BP = blood pressure, SBP = systolic blood pressure, DBP = diastolic blood pressure, M = men, F = women, en% = energy percentage; 95%-CI = 95% confidence interval, MUFA = monounsaturated fat, PUFA = polyunsaturated fat, SFA = saturated fat, Na = sodium, K = potassium, Ca = calcium, BMI = body mass index; NS = not statistically significant (p>0.05); … = value not given.
1
Users of anti-hypertensive medication were not excluded.