It’s been more than 70 years since scientists discovered that reducing the number of calories fed to a rat could nearly double the rat’s lifespan. In the 1980s, research intensified on the possible life-prolonging properties of reduced caloric intake, and the correlation has held in virtually every corner of the animal kingdom studied—from single-celled yeast to worms, insects to mice—that eating less translates to a longer life.
This research has inspired many people to actively reduce their caloric intake. Most prominent among these under eaters is the Calorie Restriction Society—motto: “Fewer Calories. More Life.” The CR Society was established in 1994 to provide support and information to those interested in pursuing the “CR Lifestyle,” as they call it. The website www.calorierestriction.org, contains a lot of published research data supporting the benefits of CR Lifestyle, and press clippings of CR in the media. But the results of one recent study are absent. This omission is especially conspicuous given that CR Society members were a focus of the study.
The report, titled “Long-term effects of calorie or protein restriction on serum IGF-1 and IGFBP-3 concentration in humans,” was written by Luigi Fontana, among others, and published in the journal Aging Cell. The study investigates the relationship between dietary calories and protein on the body’s IGF-1 levels. IGF-1, which stands for “insulin-like growth factor 1,” is a protein-based hormone. IGF-1 has been shown to promote tumor development, and it’s widely believed in biomedical research circles that IGF-1 regulation is a key factor in determining the lifespan of many organisms.
Reduced caloric intake in rodents has been shown to cause a dramatic reduction in IGF-1 levels, and this is presumed to play a role in the extension of the rodent’s lifespan. But when Fontana and company measured the IGF-1 levels of members of the CR Society, after an average of six years of caloric restriction, they found, to their surprise, IGF-1 levels nearly comparable to those eating a typical Western diet. This suggests that eating less might not give humans the same life-prolonging benefits it gives mice.
Another dietary group in this study were vegans. As they eat no animal products, vegans tend to eat less protein, while consuming more calories and weighing more, on average, than the calorie restrictors. And while calorie restrictors don’t have dramatically lower levels of IGF-1, vegans do.
The researchers then tweaked the diets of calorie restrictors, holding calorie intake low and reducing their protein intake. After three weeks, these people showed a dramatic reduction in IGF-1 levels, leading the researchers to conclude that in humans, caloric restriction alone isn’t enough to lower IGF-1 levels—it must also be coupled with protein restriction.
But for some reason these results have not made it onto calorierestriction.org, which continues to promote high levels of protein consumption in the CR diet.
This research shoots a big hole in many of the trendy low-carb, high fat and high protein diets, such as Atkins, The Zone and South Beach. While not disputing these diets may indeed help you lose weight, this research suggests they aren’t good for you.
Kudos to Michael Pollan, whose 2008 book In Defense of Food argues that the healthiest diet consists of smaller portions of high-quality plant-based foods.
The book’s central creed reads: “Eat food. Not too much. Mostly plants.” And while his “Eater’s Manifesto” is supported by the IGF-1 study, Pollan maintains a level of skepticism toward using reductionist science to study diet—a practice he calls nutritionism:
“…The widely shared but unexamined assumption [of nutritionism] is that the key to understanding food is indeed the nutrient. Put another way: Foods are essentially the sum of their nutrient parts.”
While Pollan is by no mean’s anti-science, he argues that nutritionism has sent dietary guidelines on a roller coaster ride in recent decades. In other words, foods like margarine come in and out of favor, while a deluge of low-fat foods helped increase obesity rates. He argues that there is an ecology to food that makes it greater than the sum of its parts.
In the IGF-1 study, there is little mention of where the protein comes from, aside from the obvious fact that the vegans got all of their protein from plants. But the processes by which different proteins are created have different health implications on the eater.
Protein from 100 percent grass-fed beef, for example, may be similar to protein from factory-farmed beef, but the factory-farmed beef was fed a diet of grain, which will create, literally, a different animal. Since cows didn’t evolve to eat grain, grain-fed cattle tend to get sick more often, and are thus injected with more antibiotics. While I can’t say how these differences might affect IGF-1 levels in the blood of the cow eater, a relationship isn’t inconceivable.
The fact that the IGF-1 study made no attempt to standardize the sources of the proteins in question is a big deal, I believe. Plant protein vs. animal protein; wild meat vs. domestic; free-range vs. confinement—these all have major bearing on the ecology of a meal. As would the presence or absence of a nice glass of wine along with it.
So while I read with interest the results of studies like this one, I’ll continue to take them with a grain of salt—plus a dollop of full-fat mayo, just to be safe.
Ask Ari: Finding Rose Finn Fingerlings
Q: I enjoyed very much your article on gardening, and thanks for all the tips. I tried last fall to get some seed potatoes, but found nothing local or in the more popular catalogues.
Could you please take a second and e-mail me where I can find some of your Rose Finn Apple potatoes? They sound too good to pass up. Many thanks.
A: Dear Spuds,
Those Rose Finn Fingerlings I wrote about so approvingly were a gift from Lorie Rustvold, the intrepid Front Desk Czar at the Independent. She got them from Wood Prairie Farms in Bridgewater, Maine.
For small-time gardeners, however, it really isn’t necessary to purchase seed potatoes. The difference between seed potatoes and the potatoes you buy in the store is that the seed potatoes are processed to ensure that they can be certified as disease-free. This is important if you are growing a big commercial crop, and worth paying extra for. But gardeners can usually get away with finding potatoes you like at the store and stashing them in a dark place, which will cause them to sprout. And it just so happens that the Good Food Store carries fingerling potatoes from Lifeline Farms that closely resemble the Rose Finn Fingerlings I was gushing about, at a fraction of the price. They’re in a bushel basket labeled Montana Homegrown Fingerling Potatoes.
If you do end up using store-bought spuds for seed, they should be organic, as conventional spuds are often chemically treated to prevent sprouting.
Send your food and garden queries to firstname.lastname@example.org.