Meat and cheese may be as bad for you as smoking

“Crucially, the researchers found that plant-based proteins, such as those from beans, did not seem to have the same mortality effects as animal proteins. Rates of cancer and death also did not seem to be affected by controlling for carbohydrate or fat consumption, suggesting that animal protein is the main culprit.”



That chicken wing you’re eating could be as deadly as a cigarette. In a new study that tracked a large sample of adults for nearly two decades, researchers have found that eating a diet rich in animal proteins during middle age makes you four times more likely to die of cancer than someone with a low-protein diet — a mortality risk factor comparable to smoking.

“There’s a misconception that because we all eat, understanding nutrition is simple. But the question is not whether a certain diet allows you to do well for three days, but can it help you survive to be 100?” said corresponding author Valter Longo, the Edna M. Jones Professor of Biogerontology at the USC Davis School of Gerontology and director of the USC Longevity Institute.

Not only is excessive protein consumption linked to a dramatic rise in cancer mortality, but middle-aged people who eat lots of proteins from animal sources — including meat, milk and cheese — are also more susceptible to early death in general, reveals the study to be published March 4 in Cell Metabolism. Protein-lovers were 74 percent more likely to die of any cause within the study period than their more low-protein counterparts. They were also several times more likely to die of DIABETES.

But how much protein we should eat has long been a controversial topic — muddled by the popularity of protein-heavy DIETS such as Paleo and Atkins. Before this study, researchers had never shown a definitive correlation between high protein consumption and mortality risk.

Rather than look at adulthood as one monolithic phase of life, as other researchers have done, the latest study considers how biology changes as we age, and how decisions in middle life may play out across the human lifespan.

In other words, what’s good for you at one age may be damaging at another. Protein controls the growth hormone IGF-I, which helps our bodies grow but has been linked to cancer susceptibility. Levels of IGF-I drop off dramatically after age 65, leading to potential frailty and muscle loss. The study shows that while high protein intake during middle age is very harmful, it is protective for older adults: those over 65 who ate a moderate- or HIGH-PROTEIN diet were less susceptible to disease.

The latest paper draws from Longo’s past research on IGF-I, including on an Ecuadorian cohort that seemed to have little cancer or DIABETES susceptibility because of a genetic mutation that lowered levels of IGF-I; the members of the cohort were all less than five-feet tall.

“The research shows that a low-protein diet in middle age is useful for preventing cancer and overall mortality, through a process that involves regulating IGF-I and possibly insulin levels,” said co-author Eileen Crimmins, the AARP Chair in Gerontology at USC. “However, we also propose that at older ages, it may be important to avoid a low-protein diet to allow the maintenance of healthy weight and protection from frailty.”

Crucially, the researchers found that plant-based proteins, such as those from beans, did not seem to have the same mortality effects as animal proteins. Rates of cancer and death also did not seem to be affected by controlling for carbohydrate or fat consumption, suggesting that animal protein is the main culprit.

“The majority of Americans are eating about twice as much proteins as they should, and it seems that the best change would be to lower the daily intake of all proteins but especially animal-derived proteins,” Longo said. “But don’t get extreme in cutting out protein; you can go from protected to malnourished very quickly.”

Longo’s findings support recommendations from several leading health agencies to consume about 0.8 grams of protein per kilogram of body weight every day in middle age. For example, a 130-pound person should eat about 45-50 grams of protein a day, with preference for those derived from plants such as legumes, Longo explains.

The researchers define a “HIGH-PROTEIN” diet as deriving at least 20 percent of CALORIES from protein, including both plant-based and animal-based protein. A “moderate” protein diet includes 10-19 percent of calories from protein, and a “low-protein” diet includes less than 10 percent protein.

Even moderate amounts of protein had detrimental effects during middle age, the researchers found. Across all 6,318 adults over the age of 50 in the study, average protein intake was about 16 percent of total daily calories with about two-thirds from animal protein — corresponding to data about national protein consumption. The study sample was representative across ethnicity, education and health background.

People who ate a moderate amount of protein were still three times more likely to die of cancer than those who ate a low-protein DIET in middle age, the study shows. Overall, even the small change of decreasing protein intake from moderate levels to low levels reduced likelihood of early death by 21 percent.

For a randomly selected smaller portion of the sample – 2,253 people – levels of the growth hormone IGF-I were recorded directly. The results show that for every 10 ng/ml increase in IGF-I, those on a HIGH-PROTEIN diet were 9 percent more likely to die from cancer than those on a low-protein diet, in line with past research associating IGF-I levels to cancer risk.

The researchers also extended their findings about HIGH-PROTEIN diets and mortality risk, looking at causality in mice and cellular models. In a study of tumor rates and progression among mice, the researchers show lower cancer incidence and 45 percent smaller average tumor size among mice on a low-protein diet than those on a high-protein diet by the end of the two-month experiment.

“Almost everyone is going to have a cancer cell or pre-cancer cell in them at some point. The question is: Does it progress?” Longo said. “Turns out one of the major factors in determining if it does is is protein intake.”




Bauern verseuchen Menschen, Tiere, Fleisch, Milchprodukte, Flüsse und Seen mit Antibiotika

Forscher der Universitäten Bern und Zürich haben bei 48 von 571 getesteten Schlachtrindern antibiotika-resistente Bakterien gefunden.

Bei anderen Tierarten sei es noch schlimmer.

Jedes zwölfte Schlachtrind in der Schweiz trägt Darmbakterien mit gefährlichen Antibiotikaresistenzen. Zu diesem Schluss kommen Forscher der Vetsuisse-Fakultät der Universitäten Bern und Zürich in einer im Fachjournal «PLOS ONE» veröffentlichten Studie.

Das Team um Roger Stephan von der Uni Zürich hat 571 Schlachtrinder getestet und bei 48 davon sogenannte ESBL-produzierende Bakterien gefunden. Dies sind eigentlich gewöhnliche Darmbakterien, die aber ein Erbgutschnipsel namens «ESBL» besitzen. Es produziert ein Enzym, das Antibiotika wie Penizillin und Cephalosporine zerstört.

ESBL-produzierende Bakterien sind nicht nur selbst resistent gegen diese Medikamente, sondern können das Erbgutschnipsel auch an andere Bakterien übertragen. Sie stellten deshalb in der Human- und Tiermedizin ein gewaltiges Problem dar, sagte Stephan auf Anfrage der Nachrichtenagentur SDA. Etwa zwei Drittel der Humantherapien basierten auf dieser Klasse Antibiotika.

«Alarmierende Verbreitung»

Ursprünglich waren ESBL-produzierende Bakterien lediglich Spitalkeime, die zu zahlreichen Ausbrüchen führten. Inzwischen sind sie auch in gesunden Menschen und Nutztieren weit verbreitet; über 600 Varianten sind bekannt. Die Sorge wächst, dass ESBL-produzierende Kolibakterien im Nutzvieh herangezüchtet und über Milch und Fleisch auf den Menschen übertragen werden könnten.

Die aktuelle Studie deutet laut den Forschern darauf hin, dass es im Schweizer Rindvieh bereits ein solches Reservoir gibt. Ihre Proben stammen aus den fünf grössten Schlachthäusern der Schweiz und sind somit repräsentativ für die ganze Schweiz.

Bei anderen Tierarten schaut es noch schlimmer aus. In einer nicht repräsentativen Studie vom letzten Jahr fanden Stephan und Kollegen ESBL-produzierende Bakterien im Kot von 15 Prozent der Schweine, 13 Prozent der Rinder, 8 Prozent der Schafe – und sogar 63 Prozent der Hühner. Zudem fanden die Forscher solche Keime in 21 von 58 Schweizer Flüssen und Seen

«Die weite Verbreitung dieses Resistenzmechanismus in Tieren, in Menschen und in der Umwelt ist alarmierend», sagte Stephan. Immerhin waren Milch sowie Rinds- und Schweinshackfleisch frei von diesen Bakterien – laut den Forschern wohl dank der hohen Hygienestandards in Schweizer Schlachthöfen.

Übertragbare Resistenz

Für den Menschen ist die Gefahr der ESBL-produzierenden Bakterien indirekt. Zwar könnten sie über rohe tierische Lebensmittel zum Menschen gelangen, aber weil sie durch Erhitzen zerstört werden, seien direkte Krankheitsausbrüche unwahrscheinlich, sagte Stephan.

Es könne aber vorkommen, dass ein solches E.-coli-Bakterium eine Harnwegsinfektion auslöse, die dann mit Antibiotika schwierig zu therapieren sei. Die Hauptgefahr sei jedoch, dass die Keime die Fähigkeit, resistent zu sein, über das Erbgutschnipsel zum Beispiel im Darm an andere, gefährliche Erreger übertragen könnten.

Antibiotika in der Milchproduktion

In der jüngsten Studie haben die Forscher weiter untersucht, welche Faktoren das Vorkommen dieser Keime begünstigen. Es zeigte sich, dass vor allem sehr junge Rinder und solche, die aus Milchbetrieben stammten, diese trugen. Als Grund vermuten die Forscher den häufigen Einsatz der modernen Antibiotika in Milchbetrieben gegen Euterentzündungen.

Dazu komme die Schweizer Tradition, Kälber mit der Milch zu füttern, die wegen des Antibiotikaeinsatzes unverkäuflich ist. Die Autoren plädieren deshalb für einen vorsichtigen Umgang mit diesen Antibiotika, die auch für die Humanmedizin wichtig sind, in der Milchwirtschaft.