When we rip open a 100-calorie snack pack, few of us have an idea of how much energy that really is–or how much walking, biking, or schlepping groceries it will take to burn it off. But what if nutrition labels included descriptions of how much exercise you’d need to burn off that candy bar?

One recent study explored that possibility by testing the effects of signs describing in one of three different ways the energy contained in a sugary drink. Researchers found that a sign that said “Did you know that working off a bottle of soda or fruit juice takes about 50 minutes of running?” halved the number of drinks purchased from a drink cooler by African American teenagers, while signs that mentioned calorie count or percentage of total recommended calorie intake did not have a significant effect. Though the study was pretty small, and thus should be verified with larger studies, the effect seems plausible, given that exercise is a much more concrete measure of energy value than calories. Some health campaigns have in fact already taken up this tactic: if you’re a New Yorker, you may have noticed subway ads using exactly this strategy, linking the calories in a 20-oz soda with the three-mile walk between Yankee Stadium and Central Park. (more…)

Even when you’re trying to eat healthy foods, it can be hard to know what to buy: Few us have the time to decipher the nutrition facts on every item we’re considering at the grocery store, and the dizzying number of health claims plastered on labels make the task, if anything, more confusing. The Institute of Medicine offered a possible solution in a report released yesterday: put a simple, standardized rating—zero to three stars or checkmarks—on every food package.

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RNAs from rice can survive digestion and make their way into mammalian tissues, where they change the expression of genes.

What’s the News: It’s no secret that having lunch messes with your biochemistry. Once that sandwich hits your stomach, genes related to digestion have been activated and are causing the production of the many molecules that help break food down. But a new study suggests that the connection between your food’s biochemistry and your own may be more intimate than we thought. Tiny RNAs usually found in plants have been discovered circulating in blood, and animal studies indicate that they are directly manipulating the expression of genes.

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What’s the News: Fitting in is a perennial problem for almost everybody, especially immigrants and their children (for more, see The Joy Luck Club). And anxiety about food is definitely part of it: when your friends think your mom’s home cooking is weird, well, maybe you’ll just pretend you don’t like it either. In fact, maybe you’ll eat more French fries and pizza than is entirely healthy to fit in, something that might explain why newly arrived immigrants balloon to the rest of the U.S. population’s levels of obesity in just 15 years. In a study designed to see how being perceived as un-American changed peoples’ food choices, scientists behaved badly and then brought out the menus.

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What’s the News: Scientists found that periodic fasting may decrease the risk of coronary artery disease and diabetes, and also causes significant changes in heart-disease risk factors like cholesterol, blood-sugar, and triglyceride levels, which hadn’t been linked to fasting before. “We’ve shown it is not a chance finding. Fasting is not just an indicator for other healthy lifestyles,” says lead researcher Benjamin Horne of the Intermountain Medical Center Heart Institute. “It is actually the fasting that is working to reduce the risk of disease.”

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Most children shed their “baby fat.” But researchers say that in more and more cases, chubby babies (which are about 30 percent of all babies) are primed for obesity later in life.

“We are certainly not saying that overweight babies are doomed to be obese adults,” study researcher Brian Moss, PhD, of Detroit’s Wayne State University tells WebMD. “But we did find some evidence that being overweight at 9 months of age is a predictor of being overweight or obese later in childhood.” [Web MD]

The study followed a group of 7,500 babies born in 2001, classifying them by their position on the baby growth chart as “at risk” (those falling in the 85th to 95th percentile weight group) or “obese” (the 95th and above percentile). When the babies were nine months old and again at the age of two years, the parents filled out surveys about their child’s length and weight, their socioeconomic status, and race. The researchers found that 32 percent of the 9-month-olds were overweight, and 34 percent of the toddlers were. The study was published in the American Journal of Health Promotion.

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After two years of work developing new guidelines to tell us how much vitamin D and calcium is enough, the Institute of Medicine released its report this week with the basic message: Relax, you’re all doing pretty well.

Yet confusion still reigns in headlines about the report, as there are several different facets to the new standards (and the reaction to them). The new report also seem to contradict earlier, alarming studies that found vitamin D deficiencies in most Americans. So, what’s going on?

Most people are doing just fine

IOM looked at both Vitamin D and calcium intake for different age groups, and slogged through hundreds of studies of the levels of those nutrients versus health. The only group that was found deficient was adolescent girls, whom the researchers said should intake a little bit more calcium.

The panel said its findings challenged the notion that, when it comes to dietary nutrients, “more is better” — a belief that has inspired a multibillion-dollar market for dietary supplements in the United States. Americans spent $1.2 billion last year on calcium supplements and $430 million on pills containing vitamin D, according to the Nutrition Business Journal. [Los Angeles Times]

Ohio State oncologist Steven K. Clinton, a coauthor of the report, says most people have enough variety in their normal diet to get adequate amounts of both nutrients.

New findings? Not convincing enough

The reason that gigantic supplement market exists is that a number of studies have suggested vitamin D—found in some foods but mostly produced in your skin by the action of ultraviolet radiation—could help to prevent diseases like cancer, heart disease, diabetes, and more. But in its meta-review of vitamin D studies, IOM wasn’t convinced. Its report reinforced the traditional wisdom that vitamin D is crucial for skeletal health, but wouldn’t go further in determining healthy levels.

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Researchers have identified 30 genes that play a role in the onset of menstruation in girls. Some of these puberty genes have previously been linked to body weight and fat metabolism, strengthening the connection between the obesity epidemic and the early onset of puberty in industrialized nations.

For the study, published in Nature Genetics, researchers analyzed 32 genome-wide association studies that included more than 87,000 women from the United States, Europe and Australia, and then replicated the results in a further 14,000 women. Of the 30 genes that they found play a role in the timing of women’s first periods, four genes are linked to body mass index, three play a role in metabolism, and three are involved in hormone regulation.

Study co-author, Dr Enda Byrne of the Queensland Institute of Medical Research says the results from this study show that many of the genes that increase risk for weight gain and obesity in adulthood, also influence the onset of puberty. “This supports the idea that the body launches into puberty once it reaches a certain level of nutrient stores and therefore children who are overweight are more likely to undergo early puberty,” says Byrne. [Australian Broadcasting Corporation]

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Two recent studies are refuting the claims of omega-3 enthusiasts that the fatty acid, which is produced mainly by algae and is found in the animals that eat them (like fish), is the ultimate “brain food.”

Anecdotal reports had suggested that these fatty acids, called omega-3 because they have a kink in their structure three bonds from the end of the carbon chain, could improve brain function for everyone from the elderly to the unborn. Vitamin supplements of fish oil have therefore been flying off the shelves.

People who eat lots of fish are less likely to develop dementia or cognitive problems late in life. Observational studies have also found that taking omega-3s during pregnancy can reduce postpartum depression and improve neurodevelopment in children. What’s more, animals with an Alzheimer’s-like condition are helped by docosahexaenoic acid (DHA), one of several omega-3 fatty acids. And DHA disappears from the brains of people with Alzheimer’s. [ScienceNOW]

In an Alzheimer’s study published in The Journal of the American Medical Association, researcher Joseph Quinn gave about 400 patients suffering from mild to moderate Alzheimer’s 2 grams of either omega-3 DHA or a placebo each day. After 18 months, none of the patients showed improvement of their Alzheimer’s symptoms.

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About two-fifths of marathon runners “hit the wall” on the big day. That means they completely deplete their body’s stash of readily available energy, which makes them feel wiped out and severely limits their running pace; it sometimes forces people out of the run completely.

Marathoner and biomedical engineer Benjamin Rapoport has been physically and mentally struggling with this phenomenon for years, and had the bright idea to turn it into a research project. He published a mathematical theory in the journal PLoS Computational Biology describing how and why runners hit the wall–and how they can avoid it.

By taking into account the energy it takes to run a marathon, the body’s energy storage capacity and the runner’s power, the researchers were able to accurately calculate how many energy-rich carbohydrates a runner needed to eat before race day and how fast to run to complete all 26.2 miles (42 kilometers). [LiveScience]

Rapoport’s studies of marathoners were prompted by his desire to run in the Boston Marathon in 2005, and his teacher’s desire for him to be in class. In return for missing class, Rapoport was tasked with giving a class lecture on the physiology of the marathoner. That same year, Rapoport himself hit the wall while running the New York Marathon.

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It’s the most delicious genetic breakthrough yet. A consortium led by Mars Inc., the company behind such treats as M&Ms and Snickers, has announced the rough draft of the cacao tree’s genome, and researchers say the information could lead to improvements in the chocolate supply.

While the scientists are just beginning to analyze the genome, understanding the tree’s innermost workings could lead to breeding programs for drought- or disease-resistant varieties, or even for trees that produce tastier or healthier cocoa. The consortium has put the data online at the Cacao Genome Database for use by any and all.

The tree, known officially as Theobroma cacao (meaning “food of the gods”), contains about 420 million DNA units, represented by the letters A, C, G and T. That is fairly small for a plant. The human genome has about three billion units. [New York Times]

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“Hongerwinter,” or “hunger winter”—that’s what they called the end of 1944 in the Netherlands. As World War II lurched toward its end, Nazi Germany put up a blockade to prevent food from entering the Netherlands. According to a study by Dutch researchers, that famine is still felt all these years later in the brains of people who were born during those years.

Susanne de Rooij and colleagues looked at more than 700 people born during those years, 300 of whom experienced famine in utero, to see if that experience changed their brains.

In the study, 64 seniors who were exposed to famine in the early stages of gestation did worse on cognitive-function tests that required them to do tasks like name the color of the word “blue” when it was printed in yellow ink, than seniors who were exposed later or not at all to hunger in utero. The researchers also found that exposure to famine at any stage of the mother’s pregnancy resulted in a smaller head circumference at ages 56-59.”Head size is related to brain size and reduced size has been associated with decreased cognitive abilities in the elderly,” they wrote. [AFP]

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Your brain is hungry. That big gray calculating machine in your head is an energy hog that needs lots of calories—more than the diet of fruits and plants that our distant hominin ancestors probably ate could provide. It’s a mystery, then, just how human ancestors like Homo erectus—who were around when our craniums started to expand in a hurry—ate enough to start growing big brains. But buried in Kenya, a two-million-year-old hint has emerged: Those hominins started eating seafood way back then, archaeologists say.

Near a place called Lake Turkana, archaeologists David Braun found two intriguing groups of items: The bones of fish, turtles, and even crocodiles with the scars of stone tools still showing, and stone fragments that Braun says come from the simple tools these hominins used to carve up the marine animals. He and his colleagues report the find of our ancestors’ ancient feast in the Proceedings of the National Academy of Sciences.

Today, their leftovers—in the form of hundreds of bones and several thousand stone tools—are the earliest “definitive evidence” of hominins butchering and eating aquatic animals, which are rich in fatty acids essential for growing bigger brains [ScienceNOW].

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Scientists have long suspected that a link exists between mood and chocolate, as studies (done primarily with women) have suggested that eating a chocolate bar temporarily banished the blues. Now a study has brought new complexity to the issue with its finding that depressed people consume larger amounts of chocolate. But researchers are no closer to figuring out which factor is the cause and which is the effect: Do glum people reach for a Hershey bar to lift their spirits, or is the chocolate actually bringing them down?

For this study, researchers at the University of California studied 931 men and women who weren’t on antidepressants and quizzed them on their chocolate-chomping habits. Then, using a standard screening survey, they assessed the volunteers for symptoms of depression. The scientists found that those who were the most blue consumed the most chocolate.

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