We asked you recently what kind of food you think it's most important to limit your intake of. From the poll options, an overwhelming number of you chose Processed Foods as the food to eat less of, with Sugar coming in a distant second. Here are the complete results:

Of the following, which food do you think it's most important to limit your intake of?

There are many other foods and ingredients that people choose not to consume that weren't in the poll, from caffeine and artificial sweeteners to gluten or any kind of meat. The reasons why we choose to limit some foods are just as varied: flavor, health reasons, weight loss, personal ethics, political statements. For some, it's not a choice but a neccessity, either for financial reasons or as the result of a food intolerance or severe allergy.

Knowing that MOTHER EARTH NEWS readers are often health-conscience and choose to grow their own food, we're curious: Have you cut back or eliminated certain ingredients or foods from your diet? If so, why, and what affects have you noticed as a result?

Check out this compelling roundtable discussion of four expert climate change scientists: The State of the Climate — and of Climate Science.

It originally appeared in the June 2009 issue of DISCOVER Magazine. (I just "discovered" it ...) The introduction does a great job of describing the crossroads we're at today as science and public opinion meet:

"In the list of world challenges, global warming might be at once the most alarming and the most controversial. According to some predictions, climate change caused by human activity could cause mass extinction in the oceans, redraw the planet’s coastlines, and ravage world food supplies. At the same time, a significant portion of the American public questions whether global warming will really cause any major harm; many still doubt that human-driven warming is happening at all."

Here are a few highlights of the discussion:

"I spend a lot of time studying the ice sheets at the bottom of the planet—how they form and how they collapse. The poles are like the planet’s air conditioner. When things are working well, the poles keep the planet nice and cool and we don’t think about it. When things stop working, the poles can start to melt and there’s a puddle on the floor. Today both poles are getting warmer; in Greenland and Antarctica you can see the surface of the ice dropping, and you can see there’s less mass when you measure the ice from space. The process has been ongoing, but it looks like it’s happening faster than it was. We know the ice sheets have come and gone in the past. Why is this any different? One of the most compelling reasons is that in the past the ice sheets from the two poles didn’t move together—one would lead and the other would follow. This time, both the north and south are spewing ice into the global ocean, accelerating at the same time." 

— Robin E. Bell, a senior research scientist at Columbia University’s Lamont-Doherty Earth Observatory

[... the Earth got warm in the past, too] "but it got warm over millions of years, and ecosystems had a chance to adapt. What we’re seeing are rates of increase in greenhouse gases and warming that exceed natural rates by a factor of 100. So what we’re doing is really unusual when seen from a geologic perspective.

[Humans are doing in centuries what natural processes do over millions of years?] "Yes, and the other timescale mismatch is that what we do over the next decades will affect life on this planet for hundreds of thousands of years, if not millions of years. We are at a critical juncture in earth history. If we don’t do the right thing and there are geologists around 50 million years from now, they’ll be able to look at cores and see the remnants of a civilization that developed advanced technology but didn’t develop the wisdom to use it wisely."

"To me the most compelling evidence [that human behavior is actually warming the planet] is the fact that the stratosphere — the upper atmosphere — is cooling while the lower atmosphere and the land surface are warming. That’s a sign that greenhouse gases are trapping energy and keeping that energy close to the surface of the earth. I mentioned that in ocean acidification, you actually see animals that should make shells unable to make shells anymore. You could demonstrate the same kind of effect in a bell jar in the lab. There is a level of certainty about it."

— Ken Caldeira, a professor at Stanford and staff member in the department of global ecology at the Carnegie Institution of Washington

"One of the most remarkable achievements of the 20th century was the way we were able to increase the global food supply in pace with unprecedented population growth. We will have to raise the food supply another two times to feed all of the people that we think will be alive by the latter third of the 21st century. We have reason to be somewhat sanguine about doing it if climate stays more or less the same, but how will we do it with the climate change? Based on our simulations and on 25 years of research, what bothers us most is that in the tropics, where the majority of poor people live today, crops are currently raised at temperatures pretty close to their photosynthetic optimums."

— Bill Easterling, Dean of the College of Earth and Mineral Sciences at Pennsylvania State University

You can read the full discussion and learn more about the credentials of the panelists at The State of the Climate — and of Climate Science.

This week the Environmental Working Group released a report on the health of cell phones. Cell phones emit radiation, but scientists have not determined if the radiation is harmful or not. Some health concerns are that the radiation can increase risks of brain and mouth tumors.

The EWG provides a list of phones that release the least and most radiation. You can also look up your cell phone model to see how it rates on their list.

Rather than giving up your cell phone, the EWG has a guide with suggestions to reduce your risk of cell phone radiation exposure. Some suggestions are: buy a low-radiation cell phone, use a headset while talking on your cell phone, talk less on your cell phone, hold your cell phone away from your body and use speaker phone, text rather than talk on your cell phone and if your cell phone has a low signal, try not to use it because the cell phone emits more radiation while searching for a cell tower signal. 

You’ve probably caught wind of the recent British study that challenges the superiority of organic foods to their conventional counterparts. If you’re like me, your instant reaction was probably “hogwash,” and you’ve no doubt been patiently waiting for the real story. The Organic Center never disappoints — here’s the must-read response.  

State of Science: Nutritional Quality 

Authors:
Charles Benbrook, Ph.D.
Chief Scientist
The Organic Center

Donald R. Davis, PhD.
Retired Research Scientist
University of Texas at Austin

Preston K. Andrews
Department of Horticulture and Landscape Architechture
Washington State University 

An advance copy of a study appeared today that will be published in the September edition of the American Journal of Clinical Research. The published paper, "Nutritional Quality of Organic Foods: A Systematic Review," was written by a team led by Alan Dangour, at the London School of Hygiene and Tropical Medicine and funded by the United Kingdom's Food Standards Agency (FSA).

In their written report, the London team downplayed positive findings in favor of organic food. In several instances, their analysis showed that organic foods tend to be more nutrient dense than conventional foods. Plus, their study omitted measures of some important nutrients, including total antioxidant capacity. It also lacked quality controls contained in a competing study released in 2008 by The Organic Center (TOC). Last, the FSA-funded team also used data from very old studies assessing nutrient levels in plant varieties that are no longer on the market.

The London team reported finding statistically significant differences between organically and conventionally grown crops in three of thirteen categories of nutrients. Significant differences cited by the team included nitrogen, which was higher in conventional crops, and phosphorus and tritratable acids, both of which were higher in the organic crops. Elevated levels of nitrogen in food are regarded by most scientists as a public health hazard because of the potential for cancer-causing nitrosamine compounds to form in the human GI tract. Hence, this finding of higher nitrogen in conventional food favors organic crops, as do the other two differences.

Despite the fact that these three categories of nutrients favored organic foods, and none favored conventionally grown foods, the London-based team concluded that there are no nutritional differences between organically and conventionally grown crops.

A team of scientists convened by The Organic Center (TOC) carried out a similar, but more rigorous, review of the same literature. The TOC team analyzed published research just on plant-based foods. Results differ significantly from the more narrow FSA review and are reported in the study "New Evidence Confirms the Nutritional Superiority of Plant-Based Organic Foods." 

The TOC findings are similar for some of the nutrients analyzed by the FSA team, but differ significantly for two critical classes of nutrients of great importance in promoting human health – total polyphenols, and total antioxidant content. The FSA team did not include total antioxidant capacity among the nutrients studied, and it found no differences in the phenolic content in 80 comparisons across 13 studies.

Unlike the London study, The Organic Center review focused on nutrient differences in "matched pairs" of crops grown on nearby farms, on the same type of soil, with the same irrigation systems and harvest timing, and grown from the same plant variety. It also rigorously screened studies for the quality of the analytical methods used to measure nutrient levels, and eliminated from further consideration a much greater percentage of the published literature than the FSA team.

While the FSA team found 80 comparisons of phenolic compounds, the TOC team focused on the more precise measure of total phenolic acids, or total polyphenols, and found just 25 scientifically valid "matched pairs." By mixing together in their statistical analysis the results of several specific phenolic acids, the FSA team likely lost statistical precision.

Instead, the TOC team focused on studies reporting values for total phenolic acids, and also applied more rigorous selection criteria to exclude poorer quality studies.

The TOC team found:

• Twenty-five matched pairs of organic and conventional crops for which total phenolic acid data was reported. The levels were higher in the organic crops in 18 of these 25 cases, conventional crops were higher in six. In five of the matched pairs, phenolic acid levels were higher in organic crops by 20 percent or more. On average across the 25 matched pairs, total phenolics were 10 percent higher in the organic samples, compared to conventional crops.
• In seven of eight matched pairs reporting total antioxidant capacity data, the levels were higher in the organically grown crop. Of 15 matched pairs for the key antioxidant quercetin, 13 reported higher values in the organic food. In the case of kaempferol, another important antioxidant, the organic samples were higher in six cases, while five were higher in the conventional crops.

In the TOC study, there were an ample number of matched pairs to compare the levels of 11 nutrients, including five of the nutrients in the FSA review. For the five nutrients covered in each review, the TOC team was in general agreement with the FSA findings for two (nitrogen and phosphorous).

The London team did not assess differences in key individual antioxidants, nor in total antioxidant activity, important nutrients that have been measured in several more recent studies.

Across all the valid matched pairs and the 11 nutrients included in the TOC study, nutrient levels in organic food averaged 25 percent higher than in conventional food. Given that some of the most significant differences favoring organic foods were for key antioxidant nutrients that most Americans do not get enough of on most days, the team concluded that the consumption of organic fruits and vegetables, in particular, offered significant health benefits, roughly equivalent to an additional serving of a moderately nutrient dense fruit or vegetable on an average day.

Why the Different Results?

A review of the London-based team's methodology and study design points clearly to why the FSA and Organic Center studies reached some different conclusions.

Inclusion of Older Studies

The FSA review included studies over a 50-year period: January 1958 through February 2008. The TOC team included studies published since 1980. Most studies published before 1980 were found flawed for purposes of comparing the nutrient content of today's conventional and organic crops.

Most of the older studies used plant varieties no longer in use, and did not measure or report total phenolics or antioxidant capacity (since these nutrients were just being discovered). The older studies used analytical methods that are now considered inferior, compared to modern methods.

Further, since the 1950s, plant breeders and growers have consistently increased the yields of food crops, leading, in some cases, to a dilution of nutrients. In 2004, one of us (Donald R. Davis) reported evidence for a general decline in some nutrient levels in 43 garden crops between 1950 and 1999 (Davis et al., "Changes in USDA Food Composition Data for 43 Garden Crops, 1950 to 1999," Journal of the American College of Nutrition, Vol. 23(6): 669-682; a summary of the Davis paper is posted).

Similarly, an Organic Center report by Brian Halweil describes in detail the evidence linking higher yields and nutrient decline ("Still No Free Lunch: Nutrient levels in the U.S. food supply eroded by pursuit of high yields").
Thus, results in the FSA study are likely confounded by the team's decision to include data from over three decades ago.

New Studies Support Greater Nutrient Density in Organic Foods

Since February 2008, the cut-off date of the London study, some 15 new studies have been published, most of which use superior design and analytical methods based on criticisms of older studies. The Organic Center is updating its earlier analysis with these additional studies. These new studies generally reinforce the findings reported in the March 2008 TOC report, particularly in the case of nitrogen (higher in conventional crops, a disadvantage), and Vitamin C, total phenolics, and total antioxidant capacity, which are typically higher in organically grown foods.

The Center's study finds that protein content and beta-carotene, a precursor of Vitamin A, are typically higher in conventionally grown foods, but since both are present at ample or excessive levels in the diets of most Americans, these differences do not confer a nutritional advantage nearly as important as heightened levels of phenolics and antioxidants in organic foods.

Exclusion of Studies Analyzing Results on "Integrated" Farms

The FSA team excluded studies comparing organic foods to "integrated" and biodynamic production systems, stating that "integrated" systems are not conventional. Most conventional U.S. fruit and vegetable producers are now using advanced levels of Integrated Pest Management. Thus, "integrated" systems are now a more accurate description of "conventional" agriculture in the U.S., than a definition grounded in monoculture, the calendar spraying of pesticides, and excessive applications of chemical fertilizers. The London team did not report in the published paper which "integrated" studies were dropped, but we suspect some important U.S.-based studies may have been eliminated.

TOC Study Applied Much Stricter Screens for Scientific Validity

The two teams agree that many published studies are methodologically flawed, and hence should not be included in comparative studies. But the FSA and TOC teams used very different rules to screen studies for scientific quality and to select matched pairs for analyses.

The FSA team cites five criteria: definition of the organic system; specification of the plant variety (i.e., crop genetics); statement of nutrients analyzed; description of laboratory method used; and, a statement regarding statistical methods for assessing differences. The London team states that they simply required some discussion of these issues in published papers, but did not set or apply any qualitative thresholds in judging scientific validity.

The Organic Center team focused on the same factors (plus several others) and used stated, objective criteria for assessing them. The TOC team reviewed the statistical power and reliability of the analytical methods, a process that eliminated dozens of results. Finally, the TOC team insisted upon a close match of soils, plant genetics (variety), harvest method and timing, and irrigation systems, all factors that can bias the results of a comparison study.

Inclusion of Market-Basket Studies

The FSA team included some market basket studies, for which there is no way to know the specific circumstances of the farm locations, the plant genetics, the soil type, or harvest method and timing. In the Organic Center study, market basket results were judged as "invalid" based on several quality-control screening criteria.

This review is also available as a pdf document below.

Review of FSA Sponsored Study on Nutrient Content 

Looking for a simple (and delicious) way to keep your mind sharp? Offer your diet the olive branch! In addition to olives’ distinct flavors, these petite fruits offer impressive health perks.

The May/June 2009 issue of Psychology Today reports that the antioxidant hydroxytyrosol, abundant in olives, slows cell death in the brain and can thus reduce the incidence of neurodegenerative diseases such as Alzheimer’s disease. 

More olive insight from Psychology Today:

• Olives’ skin is rich in maslinic acid, a natural compound that destroys colon cancer cells in humans.

• Choose extra virgin olive oil rather than virgin or “pure” varieties. Only extra virgin olive oil fully retains the olives’ healthful qualities. A rule of thumb: The greener the oil, the richer it is in polyphenols — antioxidants (including hydroxytyrosol) that research has shown to have a host of beneficial qualities, namely preventing degenerative diseases and cancer. (Read Tested, Tasted and Terrific Olive Oils for our top olive oil picks.)

Pastas, pizzas and plenty of other Mediterranean pleasures often come packed with olives, but there are numerous other, easier ways to get more olives on your plate. Here’s a variety of recipes from Epicurious that are packed with olive goodness:

• Chunky Tomato and Black Olive Salad

• Green Olive and Coriander Relish

• Green Olive Pesto

• Olive Focaccia Dough

For more on keeping your brain in top form, read Aging and Brain Health: What Have You Been Learning Lately?.

Photo by kin lush/Flickr

Learning a new instrument or language may help  keep your mind sharp.

According to Can Memory Loss be Prevented?, from the New York Times, recent cognitive study suggests that learning a challenging new skill, such as a new language or musical instrument, “may be even more effective than mental games [think Sudoku] at keeping the brain sharp.” While crossword puzzles alone can aid in very specific types of mental agility, such as word recall, you may get more significant results with “mental cross-training” — specifically, trying a variety of activities, especially those that will challenge your brain in “entirely different ways, preferably for years.”

“One problem with aging is that you develop expertise in a few things and do them over and over,” said Dr. Carstensen [director of the Center on Longevity at Stanford University]. “Proficiency is good, but it’s probably not growing new synapses.”

The benefits of taking up a new activity aren't limited to good brain health (though that's certainly worthy on it's own). As part of one recent study, participant Bob Branham, 78, was randomly assigned to take up quilting — and discovered he loved it. In addition to staying sharp as a tack, Branham found a new passion, is making new friends and developing new skills, and might even start a new business. Not a bad list of side effects.

Have you taken up a challenging new hobby or activity recently?

Photo by iStockphoto

ISTOCKPHOTO

Will consumers make healthier beverage choices if the cost of soda increases?

A new federal tax on soda and other sugary beverages has been suggested recently as a way to pay for part of the major overhaul of the U.S. health-care system proposed by the Obama administration.

According to the Wall Street Journal, "The Center for Science in the Public Interest, a Washington-based watchdog group that pressures food companies to make healthier products, plans to propose a federal excise tax on soda, certain fruit drinks, energy drinks, sports drinks and ready-to-drink teas. It would not include most diet beverages."

Supporters argue that the tax would have multiple benefits. In addition to partially funding health-care reform, supporters argue that a tax on sugary beverages would likely discourage their consumption, potentially relieving some of the burden on taxpayers covering the medical costs incurred because of overweight and obesity.

Addressing these issues, a recent article from the New England Journal of Medicine reports, "For each extra can or glass of sugared beverage consumed per day, the likelihood of a child’s becoming obese increases by 60 percent," and that "a review conducted by Yale University’s Rudd Center for Food Policy and Obesity suggested that for every 10 percent increase in price, consumption decreases by 7.8 percent."

Finally, the article states that "The contribution of unhealthful diets to health care costs is already high and is increasing — an estimated $79 billion is spent annually for overweight and obesity alone — and approximately half of these costs are paid by Medicare and Medicaid, at taxpayers’ expense. Diet-related diseases also cost society in terms of decreased work productivity, increased absenteeism, poorer school performance, and reduced fitness on the part of military recruits, among other negative effects."

The same Wall Street Journal article notes that "The main beverage lobby that represents Coca-Cola Co., PepsiCo Inc., Kraft Foods Inc. and other companies said such a tax would unfairly hit lower-income Americans and wouldn't deter consumption.

'Taxes are not going to teach our children how to have a healthy lifestyle,' said Susan Neely, president of the American Beverage Association. Instead, the association says it's backing programs that limit sugary beverage consumption in schools."

What do you think of a tax on sugary beverages? Would you support it?