Thursday, 9 May 2019

The latest deadly superbug — and why it’s not time to panic

Fast-food restaurants deliver filling, inexpensive meals and snacks. But there’s usually a hidden added cost: a wallop of salt (sodium) that isn’t good for cardiovascular health. Even with the current clamor for reducing sodium in the American diet, and industry promising to do just that, the amount of sodium in prepared foods hasn’t changed much since 2005, according to a report published in the latest issue of JAMA Internal Medicine.

Why does sodium matter? Too much of it can increase blood pressure and make the kidneys work harder. High blood pressure is a leading cause of stroke, heart attack, heart failure, kidney disease, and more. Current recommendations urge us to consume less than 2,300 milligrams (mg) of sodium a day, equivalent to about a teaspoon of table salt. The bar is set lower—1,500 mg a day—for those with cardiovascular disease or high blood pressure. Yet the average American takes in about 3,400 mg a day.

Harvard researchers recently conducted a study that assessed the cumulative health effects of excess sodium. They estimated that excess sodium accounts for the 2.3 million deaths each year around the world. The U.S. ranked 19th out of the 30 largest countries, with 429 deaths per million adults due to taking in too much sodium. That represents one in 10 U.S. deaths due to heart attack, stroke, and other cardiovascular diseases.

Counting the milligrams

For the JAMA Internal Medicine study, researchers with the Center for Science in the Public Interest (CSPI) in Washington, DC, evaluated the sodium in 78 foods served at fast food and chain restaurants between 2005 and 2011, collecting nutritional information from the company websites. They did the same for foods plucked from shelves at stores in Washington, DC, and at one Walmart in Elverston, Pennsylvania.

The average sodium in chain restaurant items increased 2.6% between 2005 and 2011. In packaged foods, it fell on average 3.5%. The sodium in some products fell as much as 30%, although a greater number increased by more than 30%.

Food manufacturers have developed lower-sodium foods—none of which were included in the JAMA Internal Medicine study—and have reduced sodium in other products. So far these efforts, plus continuing public education campaigns, have failed to change this sobering fact: the average American still takes in far more sodium that their bodies need.

CSPI, which sponsored the study, has called for tighter government regulation on the sodium content in processed and restaurant foods, including phasing in ever-stricter limits on how much sodium foods may contain.

“Stronger action…is needed to lower sodium levels and reduce the prevalence of hypertension and cardiovascular diseases,” wrote Michael F. Jacobson, Ph.D., and colleagues, the authors of the JAMA Internal Medicine study.

When applied to millions of people, even small changes in sodium consumption can save lives. “The evidence is convincing that substantially reducing sodium intakes from current levels will have significant population benefits,” says Dr. Dariush Mozaffarian, associate professor of medicine at Harvard-affiliated Brigham and Women’s Hospital. “The data justify government intervention to reduce sodium levels in all processed, pre-prepared, restaurant, and other commercial foods.”

How to reduce your sodium

You don’t need to wait for more government regulations to keep the sodium in your diet in check. There is the obvious solution, says Dr. Helen Delichatsios, an assistant professor of medicine at Harvard Medical School. “Eat out less and cook at home more. There is much less sodium in home cooking than in prepared or restaurant foods.” Here are some other options:

    When shopping, check nutrition labels and limit foods that deliver a lot of sodium. The five top processed food sources of sodium are bread and rolls, cold cuts and cured meats, pizza, poultry, and soups. “Better yet, avoid foods with labels, and instead eat real food like fruits, vegetables, legumes, and whole grains,” says Dr. Delichatsios.
    When dining out, ask for information on calories, fat, and sodium. Chain restaurants commonly post the nutritional profile of their products online.
    Cook more. Base your meals on fresh and whole foods that you cook yourself, not processed warm-and-serve products, since they tend to be loaded with sodium. In the last few years, actress Angelina Jolie went public with her double mastectomy to prevent breast cancer. Governor Chris Christie told us his reasons for gastric bypass surgery. And actor Michael Douglas is shining the spotlight on the human papilloma virus (HPV)—the number one cause of mouth and throat cancer. In an interview published in The Guardian newspaper in London, Douglas mentioned that his own throat cancer could have been brought on by oral sex, a common way to become infected with HPV.

There are about 200 different strains of HPV. Some cause common warts when they invade the skin. Others are the cause of sexually transmitted diseases. In fact, HPV is the most common sexually transmitted infection in the United States.

HPV transmitted by sexual contact often doesn’t become active enough to cause symptoms. When it does become active, it tends to invade mucous membranes, such as those covering the lining of the vagina, cervix, anus, mouth, tongue, and throat. An HPV infection can cause warts in and around these tissues.

Most people sexually exposed to HPV never develop symptoms or health problems, and most HPV infections go away by themselves within two years. But the infection can persist and cause long-term problems. These include cervical cancer in women, penis cancer in men, and in both sexes some cancers of the anus and oropharyngeal cancer (cancer in the back of throat, including the base of the tongue and tonsils).

In the past, oropharyngeal cancers were mostly linked to smoking or alcohol abuse. Today, oropharyngeal cancers related to smoking and alcohol are on the decline while those caused by HPV are rising dramatically. Some experts predict that HPV-caused mouth and throat cancers will become more common than cervical cancer by 2020.
Prevention and treatment

Sexual contact, including oral sex and deep kissing, can transmit HPV from one person to another. The likelihood of contracting oral HPV is directly associated with number of sexual partners a person has had.

There are a few ways to prevent HPV-related oral cancer, depending on your age.

Pre-teens, teens, and young adults of both sexes can get vaccinated against HPV. The Centers for Disease Control recommends that young women get vaccinated against the virus to prevent cervical cancer. The CDC also recommends the vaccination for young men for two reasons: to help prevent its transmission to women, and to help prevent some of the 7,000 HPV-related cancers that occur in men each year. The two available vaccines provide excellent protection against sexually transmitted HPV.

Vaccination won’t help older people (those beyond their early 20s) or the millions of people already infected with HPV. The use of condoms can prevent the spread of the virus during penile-vaginal, penile-anal, or penile-oral sex. The use of a dental dam (a thin piece of latex) can help prevent the spread of the virus during oral-vaginal sex.

If you’ve been infected with the virus, diagnosing an HPV-related oral cancer as early as possible greatly improves the chance of cure. See your doctor if you have one or more of these symptoms for more than two to three weeks
Every living thing is constantly aging. It seems universal and inevitable—a law of nature. Just look in the mirror, or check out your family and friends.
Yet in the past decade, a remarkable series of experiments from laboratories all over the world has begun to challenge that “law.” In both simple animals like worms and in more complicated animals like mice, scientists are discovering what causes aging—and how to slow it. The life spans of several simple animals have been extended greatly by simple biological manipulations. More important, during that extra time alive, the animals remain quite strong and fertile.
The latest example of such aging research was just reported in the prestigious scientific journal Cell by two of my Harvard Medical School colleagues. Cardiologist Richard T. Lee (co-editor in chief of the Harvard Heart Letter) and stem cell biologist Amy Wagers and their teams have found a substance that rejuvenates aging hearts in mice. (You can see a video of the researchers discussing their work below.) The discovery could someday lead to a treatment that prevents or reverses the most common kind of heart failure in humans: age-related diastolic dysfunction. There is currently no specific treatment that prevents or reverses this condition.
In diastolic dysfunction, the heart muscle becomes thicker and stiffer. As a result, when blood enters the heart, its muscular walls can’t stretch enough to accept all the blood flowing into it. That means the heart pumps less blood with each beat, making it difficult to circulate blood to every cell in the body. Blood backs up into the lungs, causing difficulty breathing. It also backs up into the rest of the body, causing fatigue and swelling, particularly in the legs and feet. That’s heart failure.

Young helps old

Mice have a similar condition. It develops as the animals get older, just like it does in humans. The team led by Lee and Wagers wondered if something was present in the blood of young mice that kept the heart young. To pursue that possibility, they joined the circulation of an old mouse to that of a young mouse. As a result, the two animals shared the same blood. After 4 weeks, the thickened and stiff heart muscle of the old mouse became dramatically thinner and more flexible.
In other words, it looked like Lee and Wagers’ hunch was right: some substance was present in the blood of young mice that rejuvenates the heart muscle of old mice. Most likely, that substance had been in the blood of the old mice when they were younger, but had decreased as the mice aged.
The team then identified a substance called growth differentiation factor 11 (GDF11) as a good candidate to be the “anti-aging” substance: it was at high levels in the blood of young mice but not old mice. To prove its role, Lee and Wagers gave old mice enough GDF11 so they had the same blood levels of it as young mice. Again, the thickened, stiff heart muscle of the old mice became rejuvenated. So at least in mice, a common kind of aging of the heart could be reversed by a particular anti-aging substance.
Will this discovery in mice offer any help to humans with heart failure? It will take a lot more research to know. It may not work in humans the way it works in mice. It may work in humans, but cause unacceptable side effects. Any beneficial effects might not last.
On the other hand, it also is possible that this substance has anti-aging effects in more organs than just the heart—and not only in mice, but maybe also in humans. So the discovery could have even greater potential than it now appears.
For me, what is important about this study is not whether it will help human health: we just can’t know if it will until much more research is performed.
What I find important is that the work by Lee and Wagers, like a number of studies before it, reveals a remarkable new truth: there are substances naturally present in all living things that cause aging and that retard it. In other words, aging is not a mystical process. Aging is chemistry. By understanding that chemistry, we may someday be able to slow aging.

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