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.”



Never mind the meat — worry about eating enough plants

Most people erroneously think proper nutrition is mainly about vitamins and minerals, but there is a whole other world within the plant kingdom: phytonutrients. Photo: MJM and large, the most environmentally friendly dietary decision one can make is to eat less animal protein (see deforestation, water pollution, andgreenhouse-gas emissions, etc). But for many, the notion of eschewing — or significantly cutting back on — meat, eggs, and dairy brings up nutritional concerns. As I see it, not only are those concerns usually unfounded, they should pale in comparison to the question of getting enough plant-based foods.

Let’s begin with protein. Here’s something most people don’t know: Barring oils and some fruits, there is protein in almost every food. Yes, that includes broccoli, spinach, and potatoes. Most people are surprised to learn that a cup of cooked oatmeal offers as much protein as an egg, and an almond butter sandwich on whole grain bread provides 15 grams of protein (around a quarter of a day’s recommendation for a 160-pound male).  To determine your protein requirement, divide your weight in pounds by 2.2, and then multiply that number by 0.8. You can, of course, surpass that figure.

You’ll hear lots of talk about “complete” versus “incomplete” proteins, but I consider that concept irrelevant and outdated. It goes something like this: Complete proteins contain all essential amino acids (“essential” meaning our bodies don’t produce them, so we need to get them from food); incomplete ones have very low amounts of — or lack — an essential amino acid. Meat, poultry, and fish are complete proteins. While there are some plant-based complete proteins like amaranth, buckwheat, quinoa, and soy, the vast majority is “incomplete.”

Incomplete proteins are only a concern if someone eats exclusively from one food group (i.e. nothing but potatoes, or nothing but bread) for extended periods of time. Luckily, eating from more than one food group is not only possible, it’s what most of us crave. You would be hard pressed to find someone who won’t naturally, throughout the course of the day, consume food from more than one food group. Even if you subsist on nothing but peanut butter sandwiches for a week you are getting all the essential amino acids (legumes and grains are two different food groups, and it just so happens that the essential amino acids that are low in bread are high in legumes, and vice versa).

Frances Moore Lappé, who popularized the idea of “protein combining” in the first edition of her book Diet For A Small Planet(1971), retracted that theory in the book’s 1981 edition:

In 1971 I stressed protein complementarity because I assumed that the only way to get enough protein … was to create a protein as usable by the body as animal protein. In combating the myth that meat is the only way to get high-quality protein, I reinforced another myth. I gave the impression that in order to get enough protein without meat, considerable care was needed in choosing foods. Actually, it is much easier than I thought.

With three important exceptions, there is little danger of protein deficiency in a plant food diet. The exceptions are diets very heavily dependent on [1] fruit or on [2] some tubers, such as sweet potatoes or cassava, or on [3] junk food (refined flours, sugars, and fat). Fortunately, relatively few people in the world try to survive on diets in which these foods are virtually the sole source of calories. In all other diets, if people are getting enough calories, they are virtually certain of getting enough protein. [Emphasis mine.]

Even the National Institutes of Health (a conservative group when it comes to nutrition issues) supports Lappé’s point. On their website, they say that “protein foods are no longer described as being ‘complete proteins’ or ‘incomplete proteins.’” So, please, let’s put this issue to rest.

The other group of plant protein critics are those who believe its quality to be low. They usually reference the “Protein Digestibility Corrected Amino Acid Score,” which is a tool for measuring protein digestibility in humans. A quick glance at the list and you may conclude that plant-based protein sources are indeed inferior to milk, eggs, and beef. After all, the only plant-based food with a “perfect” score of 1.0 is soy protein, while chickpeas get a 0.78 and vegetables get a 0.73. However, as with the “complete vs. incomplete protein” argument, as long as you eat different types of plant-based foods throughout the course of the day, they will complement each other and form a “perfect” protein score.

As a nutrition professional, I get very frustrated by the protein-centric framework that inevitably comes up when plant-based eating is discussed, particularly because the average American consumes sufficient protein, but nowhere near the daily recommended amounts of fiber and several important minerals, like magnesium. Low intakes of both are associated with higher risks of chronic disease. And, here’s an indisputable fact: No matter how humane, local, pastured, or organic your steak or chicken is, it does not offer fiber or significant levels of magnesium. Vegetarian sources of protein, meanwhile (nuts, seeds, beans, whole grains, pseudograins, and vegetables) are good — and in some cases, excellent — sources of both.

Never heard of “pseudograins” before? Though cooked and consumed like grains, amaranth, buckwheat, millet, quinoa, and wild rice are seeds.

Most people erroneously think proper nutrition is mainly about vitamins and minerals, but there is a whole other world within the plant kingdom: phytonutrients. These chemical compounds, which we are learning more about with each passing year, are not present in animal products. But, they occur naturally in plant-based foods. These compounds give fruits, vegetables, beans, and grains their particular colors and aromas. Added bonus: They also confer their own sets of health benefits.

Quercetin —  a phytonutrient found in apple peels, onions, and tea — is believed to improve blood cholesterol levels and help lower the risk of some cancers. Research on isothiocyanates, abundant in dark leafy greens, has also demonstrated their capacity to help protect against chronic disease. Other popular phytonutrients include lignans (in flax and sesame seeds) and phenolic acids (peanuts, walnuts). Mind you,there are over 170 phytochemicals in a single orange.

Phytonutrients are sensitive to processing, which is why they are most abundant in whole, plant-based foods (think a diced apple in a salad rather than a glass of commercial apple juice). Most importantly, phytonutrients are relatively new to the field of nutrition, so there are many still yet to be discovered and studied.

As you can see, plant-based foods are more than just meat and protein substitutes. We must stop treating meat as the nutritional golden standard, especially since so-called “alternatives” offer an array of health-promoting compounds. The United States is in the grips of a nutritional deficit disorder that would be drastically minimized if we all started eating less meat and more plants.