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Further reasons to try to consume foods and beverages from glass containers and avoid cans and plastic bottles. Note that the BPA caused changes within 2 hours, and that BPA-free alternatives may be no better than BPA. Some researchers are speculating whether the high incidence of hypertension is linked to the prevalence of BPA in our environment. From Medical Xpress:

Cans lined with Bisphenol A may increase blood pressure

Drinking or eating from cans or bottles lined with Bisphenol A (BPA) could raise your blood pressure, according to new research reported in the American Heart Association's journal Hypertension. BPA, a chemical used as an epoxy lining for cans and plastic bottles, is everywhere, and its consumption has been associated with high blood pressure and heart rate variability. Previous studies have shown that BPA can leach into foods and drinks.

"A 5 mm Hg increase in systolic blood pressure by drinking two canned beverages may cause clinically significant problems, particularly in patients with heart disease or hypertension," said Yun-Chul Hong, M.D., Ph.D., study author... "A 20 mm Hg increase in systolic blood pressure doubles the risk of cardiovascular disease."

In this study, researchers conducted a randomized crossover trial recruiting 60 adults, mostly Korean women, over the age of 60 from a local community center. Each trial member visited the study site three times and was randomly provided with soy milk in either glass bottles or cans. Later urine was collected and tested for BPA concentration, blood pressure and heart rate variability two hours after consumption of each beverage.

Urinary BPA concentration increased by up to 1,600 percent after consuming canned beverages compared to after consuming the glass-bottled beverages.. Soy milk was the ideal beverage for the test because it has no known ingredient that elevates blood pressure, researchers said.

UPDATE: The NY Times has a nice write-up of this research with further details:

BPA in Cans and Plastic Bottles Linked to Quick Rise in Blood Pressure

A single instance of increased blood pressure may not be particularly harmful. But the findings suggest that for people who drink from multiple cans or plastic bottles every day, the repeated exposure over time could contribute to hypertension, said Dr. Karin B. Michels, an expert on BPA who was not involved in the new research.

BPA has been used since the 1960s to make countless everyday products like plastic bottles, food containers, contact lenses, and even sippy cups and baby bottles. The chemical can leach into food, and studies show that the vast majority of Americans who are tested have BPA in their urine.

The chemical is an endocrine disrupter that can mimic estrogen. In 2012, the Food and Drug Administration said BPA could no longer be used in baby bottles and children’s drinking cups. Canadian regulators formally declared BPA a toxic substance in 2010 and banned it from all children’s products.

Because of growing consumer concerns, some bottles and packaged food products now carry “BPA free” claims on their labels. However, these products often contain chemically similar alternatives – like bisphenol S. One study in the journal Environmental Health Perspectives found that plastic products advertised as BPA-free still leached chemicals with estrogenic activity – and some of these chemicals were even more potent than BPA.

Think lifestyle changes, not medications. From Medical Daily:

Mild Hypertension Should Be Treated With Advice On Lifestyle Changes, Not Medication

In 2013, Dr. Iona Heath, a retired general practitioner published an article in the Journal of  the American Medical Association, in which she spoke about the side effects of overtreatment and overdiagnosis of mild hypertension. Now, in a new study, researchers revisit this idea, saying that unnecessary treatment of mild hypertension in low-risk patients is harming them and putting a burden on health care resources. They also argue that there's a need to reexamine criteria for diagnosing hypertension and treating blood pressure. 

About 40 percent of the world’s population, including 67 million American adults, have hypertension. Over half are classified as having mild hypertension. 

More than half of people with mild hypertension are treated with drugs, but there has been no evidence to suggest that blood pressure-lowering drugs prevent heart attacks. Instead of prescribing drugs to control mild hypertension, the authors urge clinicians to recommend healthier lifestyles to patients, which include exercising, quitting smoking, and decreased alcohol consumption. They also urge clinics to improve the accuracy of blood pressure-measuring instruments and to inform patients about measuring blood pressure at home. 

From Medical Xpress:

Experts raise concern over unnecessary treatment of mild hypertension in low risk people

Lowering the drug threshold for high blood pressure has exposed millions of low-risk people around the world to drug treatment of uncertain benefit at huge cost to health systems, warn US experts in BMJ today. Dr Stephen Martin and colleagues argue that this strategy is failing patients and wasting healthcare resources.

Over half of people with mild hypertension are treated with medication. Yet treating low risk mildly hypertensive patients with drugs has not been proven to reduce cardiovascular disease or death. The authors argue that overemphasis on drug treatment "risks adverse effects, such as increased risk of falls, and misses opportunities to modify individual lifestyle choices and tackle lifestyle factors at a public health level."

And for those over 65 the levels can be even higher. From Science News:

'Mild' control of systolic blood pressure in older adults is adequate: 150 is good enough

A broad review of the use of medications to reduce blood pressure has confirmed that "mild" control of systolic pressure is adequate for adults age 65 or older -- in the elderly, there's no clear benefit to more aggressive use of medications to achieve a lower pressure. Historically, most medical practitioners tried to achieve control of systolic pressure -- the higher of the two blood pressure readings -- to 140 or less. Recently changed guidelines now suggest that for adults over 60, keeping the systolic pressure at 150 or less is adequate, and this extensive analysis confirms that.

Two studies about blood pressure and how it can be easily changed without medications. From Science Daily:

Small weight gain can raise blood pressure in healthy adults

Gaining a few pounds can increase blood pressure in healthy adults, researchers report. Increased fat inside the abdomen led to even larger increases in blood pressure, their study results showed. Many people understand the health dangers of large amounts of extra body weight, but researchers in this study wanted to see the impact of a small weight gain of about five to 11 pounds.

At the beginning of the eight-week study, a 24-hour monitor tested the blood pressure of 16 normal weight people. Their results were compared to 10 normal weight, healthy people who maintained the same weight over the eight weeks. Researchers found: -Those who gained weight had a systolic blood pressure (top number) increase from an average 114 mm Hg to an average 118 mm Hg. -Those who gained more weight inside their abdomen had a greater blood pressure increase. -A five to 11 pound weight gain didn't change cholesterol, insulin or blood sugar levels. The study was conducted in healthy people ages 18-48. 

From Science Daily:

Restricting calories may improve sleep apnea, blood pressure in obese people

Restricting calories may improve sleep apnea and reduce blood pressure in obese adults. Those who restricted their calories had higher levels of oxygen in their blood and a greater reduction in body weight, a study has demonstrated.

 "Losing weight was most likely the key to all the benefits observed in the calorie-restricted group. A greater reduction in systolic blood pressure can be explained, at least partially, by the reduction in body weight that was associated with reduction in obstructive sleep apnea severity and sympathetic nervous system activity." Systolic blood pressure is the top number in a blood pressure reading, which measures the force of the blood in the arteries when the heart is contracted.