Taking 10 grams of L-citrulline daily for four weeks increases blood flow and vessel dilation in the forearms of hypertensive postmenopausal women during handgrip exercise.

In hypertensive postmenopausal women, increases in blood flow to the forearm during hand exercise after taking L-citrulline are linked to improved dilation of the brachial artery, suggesting that the lining of blood vessels plays a role in how blood flow responds to exercise.

Taking 10 grams of L-citrulline daily for four weeks leads to a small increase in oxygen levels and a decrease in deoxygenated hemoglobin in the forearm muscles of hypertensive postmenopausal women during handgrip exercise, suggesting changes in how oxygen is delivered and used in that tissue.

Taking 10 grams of L-citrulline daily for four weeks lowers aortic systolic blood pressure by 4 mmHg in postmenopausal women with hypertension, without altering aortic stiffness, suggesting a direct effect on blood vessel tone.

Taking 10 grams of L-citrulline daily for four weeks leads to a measurable improvement in blood vessel function and a small reduction in blood pressure in women with high blood pressure who have gone through menopause.

Taking citrulline supplements may help improve blood flow and allow more repetitions during high-repetition, short-rest workouts, but it does not cause measurable increases in muscle size over time.