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.”



Social Situations

Once you decide to live vegan you’ll find new favorite foods.  You’ll find out what you like and don’t like to eat.  You’ll find great new food options on menus and in your grocery store.  The food part gets easier and easier.  And you’ll find that navigating health concerns wasn’t such a big deal after all.  That’s easy too. 

But then there may be the sideways glances, rolling eyes, and the questions-questions-questions asked by family, friends, and coworkers.  Some people ask with excitement, wonder, or genuine concern.  Others ask to challenge your commitment to compassion and justice.  It’s not always easy. 

Let’s make it easier.  Social Settings offers some interesting insights we’ve discovered along the way, a few easy tips for your social tool belt, and a helpful reminder to stay true to yourself and kind to others. 

If you’re the only one in your family or group of friends who is vegan, you may feel social pressures to conform (see Social Pressures). 

These pressures are especially strong in small groups like family and friends where the group, consciously or unconsciously, attempts to protect the intimate social fabric of the group.  New ideas and new behaviors can feel threatening to a small group because there is a fear that the group will dismantle.  The unspoken fear is that the culture of the group will change or end, traditions may change or end, belief systems will be challenged, and even social structures might change.  None of these things need interrupt happy families or end friendships.



If you’re out on the town discovering vegan food on your own or with your vegan friends, there’s no need to over-prepare.  But if you’re going out with friends or family who are not vegan or you’re having a planned business lunch, it makes sense to explore your vegan options before you go out to eat.  There are several websites offering reviews of thousands of restaurants — even fast-food chains. Explore Helpful Resources for more links or get started at and National Chain Vegan Guide.

Here are some tips to make dining out enjoyable for everyone involved:


Talk about pressure to conform! School can be one long social challenge. From kindergarten to graduate studies, school is fraught with demands to perform in certain ways at certain times with certain people. As much as school is a place for learning, it’s also a place for socialization – that is, school plays a large role in teaching us how to be part of society.

Living vegan is not (yet) the norm. It is counter-culture. That is, it runs counter to current agreed-upon norms of society — specifically that using and eating animals and animal products is socially acceptable. Going against current norms can be seen as a rebellious act. And rebellion is frowned upon in most schools where conformity is not only easier, it is taught.

It’s interesting that some people see living vegan as a rebellious act — as if being vegan is against society. The truth is that living vegan goes against convention, but it serves to better our world community. It works FOR society, not against it. Vegan living invites society to explore a more just, compassionate, and sustainable way of being. It creates a world where everyone cares about animals, about other people, and about the planet we all share.

Staying emotionally strong in school can sometimes take courage and dedication to one’s principles. Read more in this section for insights into social pressures, transforming anger, and more.


If you’re vegan, you know how tempting it can be to fill people in on the joys of living vegan whenever you get the chance.  Having your little brother refuse to talk to you for a month because you told him what actually goes into a hotdog is painful, but he’ll get over it.  Having the same discomfort at work, in close-quartered cubicles can make work start to feel even more long and oppressive than it already is. 

So what’s a consistent and dedicated vegan to do?  We highly suggest living by example.  If someone asks you a question, by all means share your answer.  But when in doubt, offer up vegan cupcakes instead of opinions.  Coworkers might get annoyed being offered the latest graphic YouTube video documenting the truth about animal agribusiness — but nobody gets perturbed by being offered a yummy vegan treat. 

If somebody is stinking up the joint warming up a fish fillet in the microwave, you could have a word, but chances are you’ll get further by warming up your delicious lunch, fanning it down the hallways, and waiting for the inquiries.  For many of your coworkers, your vegan food might be their only regular exposure to the vegan message.  Overcoming the question “what do vegans eat?” is a major success.  If a picture is worth a thousand words, great vegan food is worth ten thousand.

Of course, this is a kind of “outreach” and you’ll have to be comfortable sharing recipes or answering questions like “where’d you get that?” and, “can I read the ingredients label?”  If you get stuck on bigger questions, send them on over to and we’d be happy to take it from there!

If you’re looking to just keep your head down and survive work, remember to pack a great lunch and some tasty vegan snacks.  For those expected and unexpected work lunches or after work parties, check out Dining Out for specific ideas.

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