Your blood pressure benefits when you eat lots of veggies. A recent study suggests the biggest benefit may come from eating your vegetables raw.
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In the study, researchers from Imperial College in London followed nearly 2,200 people from Japan, People’s Republic of China, United Kingdom and the United States for three years. The researchers wanted to see how the vegetables the people ate would affect their blood pressure.
The researchers also were interested in whether there is a difference in health benefits between eating cooked or raw vegetables.
Results showed that raw vegetables were associated with a lower blood pressure overall.
The researchers did not count cooked white potatoes and sweet potatoes as vegetables because of their high starch content.
What’s the difference between cooked and raw?
What’s the nutritional difference between cooked and raw? When you cook vegetables, you change their chemical composition. Depending on the method, cooking can reduce the amount of antioxidants.
This is especially true for water-soluble and heat-sensitive nutrients, such as vitamin C, glucosinolate and polyphenols. Cooking also can reduce a nutrient’s ease of absorption into the body.
You may lose some nutrient value cooking vegetables. But it’s more important to make vegetables a major part of your diet, says registered dietitian Julia Zumpano.
Ms. Zumpano sees patients in Cleveland Clinic’s Section of Preventive Cardiology. She did not take part in the study.
“Some nutrients are lost in cooking vegetables. More are lost with some forms of cooking than others,” Ms. Zumpano says.
Steaming, blanching is best
Prefer your vegetables cooked, but want the biggest nutritional benefit? Ms. Zumpano recommends steaming or blanching.
With steaming, you suspend the vegetable over boiling water in a covered pot for a few minutes. In blanching, you immerse a vegetable in boiling water for a few minutes, then plunge it into iced or cold water to halt the cooking process.
“With steaming or blanching vegetables, you still maintain most of the nutrients,” Ms. Zumpano says. “You’re just adding that fluid to soften the foundation of the vegetable. So, yes, you certainly maintain the most amount of nutrients in the raw or semi-raw form by blanching or steaming.””
The study notes, however, some research has shown that absorption of other protective compounds, particularly carotenoids, improves when you cook vegetables such as tomatoes.
Other healthy habits help
Assessing the comparative healthfulness of raw and cooked vegetables is complex, the researchers note. The relationships between plant foods and the body, and how they interact, are not completely known.
For example, the researchers also observed that the people who ate more vegetables tended to be older, more educated, less likely to smoke, had lower total energy intake, and lower blood pressure and body-mass index (BMI) than those who ate fewer vegetables.
The people who ate more vegetables also had a diet with higher amounts of raw fruits, low- and fat-free dairy products, fiber-rich cereals and grains, fish and shellfish and less meat compared with people who ate fewer vegetables.
Whole, fresh foods that are naturally low in sodium and eaten in moderation at regular intervals can help to keep your blood pressure readings normal, Ms. Zumpano says. Maintaining a healthy weight also is important, she says.
People with high blood pressure should consider following the DASH diet, which is rich in vegetables and low in sodium, Ms. Zumpano says.