New UC Davis study of how increased vegetable intake may lower blood pressure

According to a recent Nutrition Journal article,"The use of a commercial vegetable juice as a practical means to increase vegetable intake: a randomized controlled trial," and an October 11, 2010 Health Studies Journal article, "Increased Vegetable Intake Associated with Lowering Blood Pressure," a new study conducted at the University of California-Davis (in the Sacramento-Davis regional area) investigated whether the use of commercial vegetable juice was an effective way to increase daily intake of vegetables in adults. The 12 week, randomized, controlled, parallel-arm study included healthy volunteers aged 40 to 65 years.

Participants in the study received education on the DASH diet and 0, 8 or 16 ounces of vegetable juice daily. It was found that without the addition of vegetable juice, the participants’ vegetable intake was lower than the 2005 Dietary Guidelines.

Consumption of vegetable juice helped the participants reach the recommended daily intake. The results also revealed that the subjects who were pre-hypertensive at the start of the study showed significant decreases in blood pressure over the course of the study.

The researchers found that the participants drinking the vegetable juice enjoyed the juice and felt that they were doing something healthy for themselves by drinking it, which is important for developing long-term healthy eating habits. These findings suggest that drinking one to two cups of vegetable juice per day is an effective way to fill the daily vegetable dietary gap for healthy adults and it may also reduce blood pressure in pre-hypertensive adults. For further information, read the abstract of the study, "The use of a commercial vegetable juice as a practical means to increase vegetable intake: a randomized controlled trial." Authors are: Shenoy SF, Kazaks AG, Holt RR, et al. Nutrition Journal, September, 2010;9(1):38.

Recommendations for daily dietary vegetable intake were increased in the 2005 USDA Dietary Guidelines as consumption of a diet rich in vegetables has been associated with lower risk of certain chronic health disorders including cardiovascular disease, according to the abstract of the study. But vegetable consumption in the United States has declined over the past decade.

As a result, the gap between dietary recommendations and vegetable intake is widening. The primary aim of the UC Davis study focused on determining whether drinking vegetable juice is a practical way to help meet daily dietary recommendations for vegetable intake consistent with the 2005 Dietary Guidelines and the Dietary Approaches to Stop Hypertension (DASH) diet. The secondary aim is to assess the effect of a vegetable juice on measures of cardiovascular health.

Scientists conducted a 12-week, randomized, controlled, parallel-arm study consisting of 3 groups of free-living, healthy volunteers who participated in study visits at the Ragle Human Nutrition Research Center at the University of California, Davis. All subjects received education on the DASH diet and 0, 8 or 16 fluid ounces of vegetable juice daily. Assessments were completed of daily vegetable servings before and after incorporation of vegetable juice and cardiovascular health parameters including blood pressure.

Without the juice, vegetable intake in all groups was lower than the 2005 Dietary Guidelines and DASH diet recommendations. The consumption of the vegetable juice helped participants reach recommended intake. In general, parameters associated with cardiovascular health did not change over time. However, in the vegetable juice intervention groups, subjects who were pre-hypertensive at the start of the study showed a significant decrease in blood pressure during the 12-week intervention period.

The problem with this study is that the participants were pre-hypertensive. What if older hypertensive individuals drank vegetable juice? Would their blood pressure also be lowered? That wasn't covered in the study. But you can use common sense and at least add more vegetables and vegetable juice to your diet instead of what people usually get in restaurants--overcooked or deep-fried veggies.

How did the participants close the dietary gap and get enough vegetables? Including 1-2 cups of vegetable juice daily was an effective and acceptable way for healthy adults to close the dietary vegetable gap. Increase in daily vegetable intake was associated with a reduction in blood pressure in subjects who were pre-hypertensive at the start of the trial. You can research the trial information at: Clinicaltrials.gov NCT01161706

How about making a soup of pureed butternut squash, kale, and bok choy for example? And drinking some home-made vegetable juices, green juices from leafy dark green vegetables and carrots or cranberries, blueberries, and cherries? Or organic strawberries and a banana? Is it the potassium and magnesium in the vegetable juices that helps? What older folks want to know is whether blood pressure will be lowered in those with hypertension who don't take prescription drugs which may not work for some.

When will studies focus on people over age 65 or 70 with genetic hypertension who are vegans? Consider the fact that young, healthy or pre-hypertensive people usually are recruited for clinical trial studies. But the question nutritionists want to know is whether there will be benefit also to older people who already have hypertension not helped by medicines? How much will vegetable juices help that population demographic?