Photo by Werwin15

The science of aging is among the most dynamic and provocative in modern biology. Over the past two decades we have seen a virtual explosion in research investigating the molecular and behavioral systems that control the aging process. But the more researchers uncover about the science of aging, the more questions emerge.

Dietary restriction has long been considered the most potent regulator of aging. Restricting food intake by any means induces a series of metabolic changes in organisms from yeast to primates that serve to extend life. Studies are currently underway to investigate the ability of dietary restriction to extend life in humans.

Several biological changes are known to occur upon the onset of dietary restriction including a decline in reproductive ability, increased stress resistance and a slowdown of some metabolic processes.

Insulin signaling was among the first molecular pathways to be identified in the regulation of aging, and offered a direct tie between diet and the aging process.  In 1998 UCSF scientist Cynthia Kenyon showed that removing an insulin receptor gene (daf-2) in worms could double their lifespan. Her lab later showed that removing another insulin signaling gene (daf-16) could extend life even longer. I spoke to Kenyon about the relationship between diet and aging for this article.

Blocking insulin signaling in these worms did not just prevent the worms from dying and allow them to age longer. Instead the aging process actually slows so that older worms continue to behave like young worms. Also, as these experiments were repeated in different animals, it was shown that lowering insulin signaling also helps protect animals from stress and diseases such as cancer and heart disease.

Insulin is released as a direct response to glucose in the blood. This means that any time you eat a meal with carbohydrates, you are increasing your insulin signaling and likely accelerating aging. But this does not mean that you will live forever if you stop eating carbohydrates.

Interestingly, protein metabolism also contributes to accelerated aging, but through a different mechanism. Even more intriguing is that restricting protein increases lifespan to a greater extent than restricting sugar.

So is it simply calories that promote aging?

Probably not. For one thing, the effect of a calorie from protein is greater than a calorie from carbohydrate, making it unlikely that a calorie is the basic unit of impact. Second, there is evidence that calories are not required to accelerate aging.

Recent studies have shown that the mere act of smelling food can reduce lifespan. The mechanism for this effect is still unknown, but seems to be tied to respiration.

According to Kenyon it is clear that “sensory perception influences lifespan,” at least in worms and flies.

Thus it is likely that aging is controlled by the interaction of several pathways, including metabolism, respiration and stress. Importantly, however, lifespan seems to be dependent on a handful of specific pathways rather than global changes in cellular function or breakdown. The idea that aging is an inevitable function of time must be put aside given the evidence that it is controlled at a genetic and environmental level.

This makes sense when you think about it. Different organisms exhibit vastly different lifespans and rates of aging that are too great to be explained by some kind of universal cellular breakdown. A more parsimonious hypothesis is that organisms differ in specific genetic factors that, combined with environmental influences, regulate lifespan.

So how should we mortal humans react to these findings?

The genes linking diet and aging are highly conserved through evolution, indicating that there is a great chance human aging is sensitive to diet. Indeed, insulin-related genes have been found to be important in long-lived human populations. This suggests that the pathways discovered in worms and other organisms have similar functions in humans.

What is not clear is how much influence diet has on lifespan and to what extent we are able to manipulate it. It is already known that abnormal insulin activity in humans is linked to higher disease rates, especially “diseases of civilization” such as heart disease, hypertension, type 2 diabetes and cancer. And these diseases are clearly associated with diets rich in processed foods, especially refined carbohydrates.

The effect of protein consumption on lifespan in humans has yet to be investigated. Envisioning an experiment that would test the influence of smelling food on human aging is difficult to even imagine.

Although direct evidence is not available, there is good reason to suspect that a diet with low glycemic load may extend human lifespan. In November 2009, Kenyon’s lab reported that adding glucose to a worm’s normal diet shortens lifespan, but has no effect on the long-lived worms that lack insulin signaling genes daf-2 and daf-16. This discovery prompted Kenyon herself to adopt a low-carbohydrate diet.

Despite this there is still not sufficient evidence to recommend a calorie restricted diet for humans to extend life, largely because optimal nutrition levels for a given individual are unknown. However, most people would benefit vastly by eliminating processed foods and refined carbohydrates from their diets as much as possible.

Focusing on fresh, whole foods, enjoying an occasional glass of wine, avoiding smoking and getting regular exercise can add 14 years to the life of an average person. Maintain a healthy weight as well and your outlook gets even better.

Would you change your diet to be healthier and live longer?

Originally published February 3, 2010.

With the launch of the iPad I was excited to review and recommend a few of the early release health apps for Summer Tomato readers. But after spending a few days browsing apps from the “health,” “diet,” and “food” categories it became clear such a post would be impossible.

At this point there is still nothing worthy to recommend.

So far there are only a handful of healthy eating apps, and by far the majority of them are calorie counters and rudimentary or overly complicated food journals. Some of them seem okay for what they are, but I couldn’t picture myself using them or recommending them to anyone looking to get healthy.

But my time searching wasn’t entirely wasted. In my quest it appears I may have stumbled upon the worst (aka funniest) iPad app in existence.

HealthCalc XL is supposed to be a Body Mass Index (BMI) calculator and health assessment app. I’m not sure why you would need this on your iPad, but since it is free I was willing to give them the benefit of the doubt.

So far, so good.

To calculate BMI the interface is pretty close to what you might expect. Since BMI is a ratio of height to weight, you can enter those fields. Unfortunately, however, the default measurement units are centimeters and kilograms, which isn’t particularly useful for most of us here in the U.S. You can switch over to feet and “lbf” (presumably that means pounds) if you wish, but this requires an extra step.

In addition to height and weight, HealthCalc XL asks for your age, gender and physical activity level. No standardization of what is considered “low,” “middle,” or “high” activity levels is provided.

Once you’ve entered this information you hit the “calc” button for a read-out of your “BMI,” “Ideal weight,” “recommended calory” (no, I did not mistype that), and an assessment of your health in the form of: “You are”

This is where the fun starts.

HealthCalc XL does not sugar coat your health assessment for you. And chances are it thinks you are carrying a few too many pounds.

Anything at the higher end of the normal BMI range (typically measured as between 18.5-24.9) HealthCalc XL considers “a little fat” (see top image). If your BMI creeps above 27, HealthCalc XL is sure to tell you “You are fat.”

And if your BMI is higher?

Whether you agree with HealthCalc XL’s assessment or not might be a point of debate if the BMI was calculated correctly. Unfortunately, it is not.

According to HealthCalc XL, a highly active 5’5″ woman weighing 100 “lbf” has a BMI of 19.4.

In reality this height and weight pair calculates to a BMI of 16.6 and is considered significantly underweight.

But HealthCalc XL considers her “standard.” This is more than wrong, it is dangerous. Young girls are the most prone to body images and incorrect BMI calculations can fuel eating disorders and other health problems.

At the end of the day, HealthCalc XL is both mean and incompetent. I hope it never applies for a service job in San Francisco.

Have you found any decent health apps yet for iPad?

Dr. Andrew Weil is the father of integrative medicine and has one of the most sane and straightforward healthy eating programs available. Here he sat down with Kevin Rose and answered an extensive range of geek health questions asked by Twitter users.

The question I was most curious about is the role of dairy in health. I have done countless hours of research on potential links between dairy and prostate cancer, type 1 diabetes, osteoporosis, asthma and other problems, and was happy to see Dr. Weil’s interpretation of the data is very similar to mine (very little is conclusive). He also adds an interesting aside on the importance of Mongolian cows that you shouldn’t miss.

Other topics covered include the potential dangers of soda and energy drinks, the risks and benefits of soy, which supplements are worthwhile, the best sources of antioxidants, how much vitamin D is necessary, the importance of fish oil, the deal with cellphone radiation, screen time and eye problems, tea, chocolate, low-carb diets, depression and those “fancy detox kits.”

It’s an incredibly informative video and definitely worth a half hour of your time.

And don’t forget to follow @drweil and @kevinrose on Twitter.

Enjoy!

Photo by TheBittenWord.com

Chances are that if you do much cooking, especially during the winter, you rely on canned tomatoes as the base for many dishes. Canned tomatoes are one of the staples of my kitchen and I’ve recommended them many times as a good alternative to fresh winter tomatoes (yuck).

But recent reports indicate that the lining of most cans (including tomatoes, beans and soda) contain a resin that leaches a toxic chemical, bisphenol-A (BPA), into food.

BPA has been shown to be a neuroendocrine disruptor and causes several biological problems, especially during development. Outrage over BPA back in April 2008 led to massive changes in consumer demands about the safety of food containers, especially baby bottles and the then-popular Nalgene bottles.

Since publication of the The 7 Foods Experts Won’t Eat article in Shine, I’ve been bombarded with questions asking if it is still okay to eat canned tomatoes.

Here are my thoughts on canned tomatoes & BPA:

1. Canned tomatoes aren’t great, but soda is worse. In the article, Fredrick vom Saal, PhD, says that tomatoes are a particular problem in cans lined with resin because they are acidic, which increases the rate at which BPA enters food. He goes on to argue that this amount exceeds recommended doses and can “impact people.”

Since Dr. vom Saal studies BPA and I do not, I concede his point. But I think it is also important to consider the context of this argument. It is true that tomatoes are acidic, but tomatoes also have many health benefits and can be a valuable part of your diet.

I don’t drink soda (which is substantially more acidic than tomatoes) or eat canned beans, so tomatoes are the only canned food I eat. I also don’t eat canned tomatoes every day. I therefore question if the tiny, sporadic amount of BPA that I am exposed to through canned tomatoes has a real effect on my disease risk, given my healthstyle.

My guess is the risk is very small. If you do drink a lot of soda, however, you may have more to worry about.

2. Glass jars are a fantastic alternative. Home canning was all the rage this summer, and I’m sure those of you who produced gallons of home stewed tomatoes are feeling pretty awesome right now with your BPA-free stockpiles.

There is no way on earth I would have time for a massive canning project of my own, but fortunately there are some wonderful independent companies willing to do it for me and sell them to me as I need.

I have yet to try tomatoes from a glass jar, but my guess is they lack the metallic aftertaste of those in cans. As an experiment, I’ll make my next preserved tomato purchase from one of my favorite companies, Happy Girl Kitchen, to see if I can tell the difference. They are more expensive than the cans I normally get, but it might be worth it for the better flavor. You can also find their products at Foodzie.

Keep up with my foodie experiments on Twitter @summertomato.

3. I’m not a kid, but if you are you should be more careful. One of the biggest problems with BPA is its effect on children. Kids are small, so the amount of BPA they are exposed to pound-for-pound is relatively higher than it is for the rest of us. Children also metabolize (eliminate) BPA more slowly, so the toxins stay in their bodies longer. Lastly, during development certain organs are more susceptible to the effects of BPA, which may result in serious problems later in life.

In other words, BPA is substantially more dangerous for children than it is for adults.

So while BPA may be a mild concern for grownups with a basically healthy lifestyle, it may be worth keeping it out of your diet for the sake of the younger members of your family.

Conclusion

BPA in canned tomatoes is a legitimate concern. However unless you are a regular consumer or are under the age of 6, the long-term impact of BPA on your life is probably mild.

If you would rather be safe than sorry, glass jars are a fantastic BPA-free alternative that will probably improve the taste of your winter tomato dishes.

As for the other items on the list, I mostly agree with their conclusions. However the selection of these particular 7 things (as opposed to dozens of other problematic foods) seems rather random and arbitrary. In my opinion you will get much more out of shopping at the farmers market than you will from fretting over blacklisted foods.

What do you think about canned tomatoes and BPA? Did I answer your questions?

Organic Vegetables

There has been a lot of back and forth trash talking between fans of organic and fans of conventional produce ever since a new review study by the Food Standards Agency (FSA) reported no nutritional superiority for organics. Let’s take a look at some of the opposing arguments and have a vote.

Since the publication of the review last week I have been collecting the opinions of various experts around the internet.

A few fabulous articles are worth noting:

• Organic Versus Conventional Food: UK Report Flawed by Paula Crossfield at Civil Eats. This is the best analysis I have found. If you only have time to read one article of criticism, make it this one.
• Organic Center Response to the FSA Study is particularly interesting because it points out that the FSA actually did find a nutritional benefit of organic foods, but simply decided the differences were not important.
• Soil Association response to the Food Standards Agency’s Organic Review presents some additional scientifically valid criticisms/omissions of the report.
• Today’s huge flap about organics. NYU professor of nutrition, Marion Nestle, offers her usual dose of common sense: doesn’t taste matter to anyone?

Key criticisms of the FSA report:

1. The nutrient analysis is questionable and incomplete.
2. Findings contradict conclusions of other scientists.
3. Report does not account for the presence of toxins and contaminants.
4. Conflicts of interest may exist among the investigators of the report and agribusiness.

So what do you think?

Do you believe the review? Think it’s a flawed piece of industry propaganda? Still undecided? How will this study affect your buying habits?

Do you even think about these things before making food purchases?

Vote in the poll and leave additional thoughts in the comments.

[poll id=”4″]

Jeff Miller/University of Wisconsin Madison

Last week The New York Times published a story on the life prolonging effects of a low calorie diet in primates. The study in question found that like other organisms (from yeast to worms to mice), rhesus monkeys that eat 30% fewer calories age more slowly and develop fewer diseases than animals on a traditional diet. Those of us who follow the scientific literature on nutrition and aging are not surprised by this at all.

A few days after the story was published The Times published an op-ed questioning the value of the research. Roger Cohen argues that Canto, the healthier monkey, has suffered tremendously as a result of his restricted diet. He contends that it is far better to be fat and happy (and dead?) than thin and miserable.

To me it seems questionable why Cohen believes Canto is unhappy. If he is making his judgment solely on the image above, I must respectfully disagree with his assessment. To me both monkeys appear relatively miserable.

However, Cohen brings up a crucial question about diet and health. How far are we willing to go–how much are we willing to change our diets–in order to extend our lives?

Quality of life is a very important question.

To me one of the most interesting things about calorie restriction is that life extension is only one of many health benefits. Calorie restriction literally slows down the aging process. As a result the animals subject to a limited diet are able to maintain a high level of physical activity into old age. They are also relatively free of age-related diseases including cancer, heart disease, diabetes and neurodegenerative diseases.

Extended life would arguably not be as desirable if these diseases maintained the same progression as they do in those with normal diets. But freedom from these diseases and preserved physical and mental capacities may indeed be worth some dietary alteration.

The next question is how must the diet be changed?

In the monkey experiment, the calorie-restricted group received 30% fewer calories than the control monkeys, who were allowed to eat what they wanted. It is still unknown if a 30% reduction in calories will extend human life in a similar manner, but short-term experiments have indicated that at least some benefits are immediately apparent when calories are limited, such as lower triglycerides, body fat and blood pressure.

Interestingly, however, there may be alternatives to a strict low calorie diet. Cynthia Kenyon, a scientist at UCSF, was the first to show that the key to the life extending properties of calorie restriction is the insulin signaling pathway. A decrease in insulin signaling slows the aging process and extends life.

In the laboratory, organisms like worms, mice and monkeys always receive a uniform diet that has a consistent effect on insulin signaling. But humans do not eat lab food (at least not usually).

Extensive research over the past several decades has made it clear that different foods impact insulin signaling differently in humans. For example, refined carbohydrates have a large, rapid impact on blood sugar, insulin secretion and insulin signaling. By contrast, fat, protein and fiber have next to zero impact on blood sugar and subsequent insulin signaling.

The implication of the diverse human diet is that we are able to alter insulin levels and signaling in our bodies without undergoing severe calorie restriction. Whether or not a diet that promotes less insulin signaling can slow aging in humans is still unknown, but there are many other benefits associated with a diet that lacks refined carbohydrates.

Insulin signaling is not only tied to the aging process, it is also the primary cause of metabolic syndrome–high triglycerides, insulin resistance, hyperinsulinemia, abdominal obesity, low HDL cholesterol and high blood pressure–as well as type 2 diabetes and heart disease.

A diet that improves these symptoms may or may not slow the aging process directly, but it can certainly promotes a higher quality of life by lowering the risk of many debilitating and life threatening diseases.

Going to farmers markets and eating delicious meals isn’t so bad either.

What are your thoughts on health, diet and quality of life?

Collards, Carrots and Lentils

There is much debate among nutrition scientists over whether meat eating is healthy. On one side there are the hardcore low-fat vegetarian advocates like Dr. Colin Campbell, author of The China Study, who believe all animal fat and protein is dangerous. On the other side are those who point to refined carbohydrates as the biggest threat to public health, citing studies that suggest meat alone is harmless or even helpful (for more information read Good Calories, Bad Calories, by Gary Taubes).

I tend to agree somewhat with both.

For heart disease, the evidence certainly seems to indicate that refined carbohydrates are the worst culprit. Though health advocates once pointed to saturated fat as the cause, this suggestion has not stood up to rigorous scientific testing. In fact, dietary fat (particularly from plants) seems to be protective against heart disease.

Refined carbohydrates are also the cause of type 2 diabetes and metabolic syndrome (a combination of insulin resistance, high blood pressure, heart disease and obesity), which is arguably the biggest health threat of our time.

For these reasons and many others, I avoid refined sugar and flour as much as possible in my daily life.

Heart disease and metabolic syndrome are not the only diseases that concern me, however. Cancer is another modern ailment that has been linked to diets high in both carbohydrates and meat. Though the studies are not perfectly consistent in showing harm or no harm regarding meat consumption and cancer, rarely does anything suggest meat eating is actually beneficial (though studies are almost always confounded because meat eaters also tend to eat the most sugar and refined grains).

Fish is another story entirely. Although fish is technically a meat, its properties are very different from land animals. For one thing, fish eating has consistently proven beneficial in scientific studies of heart disease and metabolic syndrome. It also seems to play a role in protecting the brain against degenerative diseases.

I am an avid fish eater and try to include seafood in my diet several times per week.

Until now, however, I have not read much about the role of fish in cancer. A new meta-analysis published in the British Journal of Cancer (part of the Nature publishing group) suggests that vegetarians have significantly less cancer than meat eaters, and that cancer rates are even lower in fish eaters.

The researchers analyzed data from two British studies of vegetarians from the early 80s and early 90s that includes over 60,000 individuals, mostly women but some men. The participants were followed until the end of 2006.

Incidence of malignant tumors was compiled for all the subjects and the relative risks were calculated. Vegetarians and fish eaters had significantly lower risk for stomach cancer, ovarian cancer, lymphatic and bone marrow cancers, and bladder cancer. Vegetarians had a higher risk of cervical cancer than meat eaters. Fish eaters had a lower risk of prostate cancer than meat eaters.

Overall vegetarians had 8% fewer cancers than meat eaters and fish eaters had 20% fewer.

Interestingly, no difference was found in breast cancer or colorectal cancer incidence, which have both been tied to meat consumption. The authors speculate that this study could be lacking in statistical power to observe a difference. However, the current data is inconsistent and no conclusions can be drawn.

While the results of this study are very compelling, there are several caveats that must be addressed. First, the number of cancers at individual sites were relatively few, meaning that findings may be exaggerated or due to chance. For me the most convincing numbers are of the overall cancer rates (the largest numbers and strongest statistics), but this leaves many questions about the causes of the different cancers.

Another issue is that vegetarians and fish eaters in the study tended to be younger and get more exercise than the meat eaters, so there may be important confounding factors that could influence the results. Likewise, studies that rely on self-reported dietary patterns have well-documented flaws (basically everyone believes they eat healthier than they really do).

It is not clear what is causing the differences in cancer incidence among vegetarians, fish eaters and meat eaters. Vegetables and fruits have been suspected of actively protecting against cancers, but so far the mechanisms are only speculative and not concrete. Recent studies have suggested vitamin D can be protective against certain cancers. Since some fish can be very high in vitamin D, this may explain some of the benefit seen in fish eaters.

The higher incidence of cervical cancer among vegetarians is also compelling and warrants further research.

Despite the flaws in this study it is mostly consistent with other research suggesting that an optimal diet is primarily fresh, unprocessed plants, some fish and little meat.

Moderation is usually the best policy.

What is your take on this study? How do you feel about health vs the ethics of fish consumption?

1 lb Fat

Last week the New York Times and many other reputable news sources reported on a Canadian study that claims people with a normal body mass index (BMI) had a slightly increased risk of dying over a 12-year period than those with a BMI in the overweight range (25-29).

The use of the phrase “overweight was protective” landed this article just a hair’s width from being labeled Summer Tomato’s B.S. of the week on Friday. An observational study cannot determine cause and effect, as implied by the word “protective.” This study does not prove that extra body weight protects against all cause mortality, and saying so is irresponsible.

Studies (and reporting) like this have instigated wide-spread confusion about health and body weight. First people are told they are too heavy and should lose weight for health, then in the same breath they are told a little extra weight might not be so bad.

What is the average person supposed to believe? How should we act?

If you want to understand the facts it important to know exactly what the data does and does not say. Indeed, some studies (including one on Japanese men reported in the same issue of Obesity) have reported lower or equal risk of mortality for people with an overweight BMI compared to people of normal BMI (18.5-24). However, this is not the whole story.

First, the alleged benefit of being overweight has only been found in older individuals and does not apply to healthy, young people. Second, although it appears in some cases that overall mortality may be reduced, disease incidence is notably higher in overweight individuals compared to people of normal weight.

To point, a study in the most recent issue of Obesity (same journal, 2 weeks later) examines the relationship of BMI with many measures of cardiovascular disease in healthy, athletic men. In this study, those on the lowest end of BMI in the normal range (18.5-22.5) had a much lower risk of dying from or developing cardiovascular disease than normal weight men with a slightly higher BMI (22.5-25).

Men with the lowest healthy BMIs also had lower risk of hypertension, lower cholesterol and half the risk of diabetes. While the length of this study was only 7.7 years (compared to the 12 years reported in the Times story), there were more than double the number of participants (28,776 vs. 11,834).

(Why did this story not make the news? My guess is that it makes for a less compelling storyline and people would rather not hear it.)

Mortality is certainly an important measure in any study, but it is arguably not the most relevant endpoint. Disease and excess body weight can severely impact quality of life, particularly for older individuals (as illustrated by another study in the latest issue of Obesity). While I cannot speak for everyone, it seems probable that quality of life is equally if not more important than longevity alone. Thus it is questionable how much stock to put into studies that ignore these other factors.

It is also critical to remember that BMI is a measure that was designed to describe people at a population level, not as individuals. While large cohort studies can tell us useful things about relative risk, they are not directly applicable to individual people.

The inconsistency of the data related to BMI and mortality may in fact be an indication of its inadequacy as a general measurement. Remember that BMI represents a ratio between height and weight, making it possible to compare people of various body sizes. Normalizing for height may, however, be deceptive.

Decades of data on caloric restriction consistently show that smaller body size (irrespective of body fat levels and, possibly, BMI) is associated with longer life and decreased risk of nearly all diseases. This is true in all animals from yeast, to worms and flies, to mice and monkeys. While humans are certainly different from all these model organisms, there is tremendous evolutionary precedent indicating smaller body size as the best for health.

The principle of parsimony tells us the simplest hypothesis–that smaller body size is beneficial–is probably correct. Substantial evidence must be accumulated before this hypothesis can be rejected, and I have yet to see that data.

Furthermore, while the research on the risk of overweight may be slightly ambiguous, the data on obesity is not. It is painfully clear that the dangers of obesity are profound and on par with those of smoking cigarettes. Overweight is a necessary step to becoming obese, and according to the National Population Health Survey nearly a quarter of Canadians who were overweight in 1994/1995 were obese by 2002/2003. Since overweight is still a substantial risk factor for becoming obese, misleading public health messages about the benefits of body fat are especially dangerous.

As a consumer of information, the most important thing you can do is be skeptical of what you read. Just because something is printed in the New York Times does not make it true. In fact, many of our most trusted sources of health information do not base their recommendations on rigorous scientific thinking, which is probably the reason for the health disaster we are currently facing.

Thanks to Jan from Quest for Health for sparking this discussion.

What does your gut tell you about the relationship between health and body fat?

Collards, Carrots and Lentils

A new study published yesterday in the Archives of Internal Medicine suggests that both weight loss and risk factors for heart disease can be improved following a vegan version of the low-carb, high-protein Atkins diet.

The “Eco-Atkins” diet focuses primarily on soy, nuts and wheat proteins (gluten) to increase the amount of vegetarian protein in the diet. Carbohydrates were restricted to 130 g/day, which is on the higher end of most low-carb diets. All starchy foods such as bread, baked goods, potatoes and rice were eliminated. Carbohydrates were provided in the form of whole, intact grains (barley and oats) and low-starch vegetables.

In a small (47 participants), short-term randomized controlled trial, this diet lowered bad LDL cholesterol by 20%, without negatively impacting good HDL cholesterol (statin drugs improve cholesterol levels by 30%). The diet also substantially lowered blood pressure and other markers of cardiovascular disease, such as triglycerides and apolipoprotein B.

The original meat-based Atkins diet has been shown to be effective for temporary weight loss (after 1 year the effects of the Atkins diet are diminished), but cardiovascular risk factors such as LDL cholesterol and blood pressure are not substantially improved under the traditional Atkins regimen.

Interestingly, a traditional Atkins-style diet based on animal protein was not used as a control in this study, so a true comparison of the diets cannot be made using the present data. Instead the researchers chose a control diet representative of a typical high-carb, low-fat vegetarian diet that included eggs and dairy products. Both diets tested in this study represented a 60% decrease in total calories.

Because of the study design, we cannot conclude that this diet is more effective than the Atkins diet for health, though you would predict it would be if future studies made this comparison. On the other hand, it does seem that a plant-based high-protein diet is more effective at improving health than a high-carbohydrate lacto-ovo vegetarian diet, at least in the short-term in a highly controlled environment.

This study took place over the course of 4 weeks, and all the food was provided for the particpants by the researchers. Thus, compliance in the program was very high. It is not clear if the participants would have had the same level of success if they were instructed to provide their own food to comply with the dietary programs.

Despite this, satiety levels were notably improved in the high-protein group and it would be expected that the increase in satiety would encourage greater compliance in a free living situation.

A small four week study, however, tells us very little about the effectiveness of this diet. While it is possible to improve risk factors such as cholesterol and blood pressure in such a short period of time, disease outcome is the true measure of a successful diet. Also, this study did not test the feasibility of the Eco-Atkins diet in the long-term, and it is likely many dieters would object to a strictly vegan regimen.

Interesting points raised by this preliminary study include:

• Plant-based, high-protein diets may be more effective at improving cholesterol and other cardiovascular measures than traditional lacto-ovo vegetarian diets.
• Short-term weight loss is primarily determined by the number of calories consumed, not macronutrient content.
• Low-carb diets that include intact whole grains and plant-based protein can be effective at improving both weight and cardiovascular risk factors in the short-term.
• Plant-based high-protein diets can increase satiety compared to high-carb vegetarian diets.

However, many questions must be addressed before this diet can be recommended to individuals trying to improve cardiovascular measures and lose weight.

New questions:

• Can the Eco-Atkins diet be maintained in the long-term by normal individuals?
• Does the Eco-Atkins diet continue to improve cardiovascular risk factors including weight loss after 4 weeks?
• What would result from this study if beans and lentils were used instead of soy and gluten?
• Does the Eco-Atkins diet improve disease outcome?
• Does the Eco-Atkins diet extend life?
• Does the Eco-Atkins diet affect quality of life?
• Can these effects be attained through other diets that include some animal protein, more whole grains or more fat?
• Is the effectiveness of the Eco-Atkins diet affected by an individual’s level of insulin resistance?
• Can adding fish further improve the results of the Eco-Atkins diet?
• Can a further reduction in carbohydrates improve the results?
• Will you get these same results if the study is NOT funded by the soy industry?

In summary, the results of this study are interesting and encouraging, especially for those of us who think both carbohydrates and meat should be limited in a healthy diet. I very much look forward to future studies exploring this idea.

What concerns me most is the lack of marine omega-3 fatty acids (fish) in the Eco-Atkins diet, which could potentially improve cardiovascular measures even further. Fish is also important for cognitive health and may lower cancer risk.

I am also worried that a strictly vegan diet would not be feasible in the long-term for many Americans. Moreover, it is not necessarily the healthiest option available. Vitamin B12 deficiency is a particular concern, but could be addressed with supplements. Generally, however, I do not recommend relying on supplements for optimal nutrition.

Finally, this study was funded by a company that makes soy and gluten products. Personally I would have prefered to see these protein sources used in combination with other things such as beans and lentils. Many people question how much soy can be safely consumed and gluten intolerance is more common than ever, so wouldn’t it be interesting to know if there were safer alternatives? It really annoys me to see science being influenced by industry funding.

What do you think of the Eco-Atkins diet?

Romanesco Broccoli in a Beaker

One of the most consistent themes of nutrition science is that vitamin supplements (pills, powders, liquids, etc.) are almost never able to mimic the beneficial effects of foods that contain the same vitamins. Now new evidence suggests that high doses of these antioxidant supplements–but not whole foods containing them–may actually block the beneficial effects of exercise on insulin sensitivity and metabolism.

Exercise has countless benefits for people of all levels of fitness. One of the most important of these is its ability to improve insulin sensitivity and increase metabolism. For this reason, exercise is considered among the most effective ways to protect against type 2 diabetes.

One of the byproducts of exercise, however, is the production of free radicals that results from the breakdown of oxygen in the muscles. These reactive oxygen molecules can damage cells and DNA, and are implicated in many chronic diseases. Since antioxidants can easily neutralize these reactive oxygen molecules, it has been assumed that antioxidants such as vitamins C and E could only benefit the body.

A new study published in the Proceedings of the National Academy of Sciences suggests that rather than help protect against oxidative damage from exercise, high doses of antioxidant supplements may actually hinder the body’s natural protection against oxidative damage and block exercise-induced metabolic benefits.

In the study, human subjects were given either placebo or 500 mg vitamin C twice per day and 400 IU vitamin E. They were then trained in both cardio and strength training workouts at the gym for 5 consecutive weekdays, 4 weeks in a row. This trial was performed on both previously trained and untrained individuals.

Metabolic rates were tested by blood sample both before the trial and after 1 and 4 weeks of training. Muscle biopsies were taken both before and after the trial for all participants. Several measures of metabolism and insulin sensitivity were measured including plasma glucose concentrations, plasma insulin concentrations, maximal oxygen uptake (VO₂ max), as well as several molecular markers in muscle that are linked to insulin sensitivity and are known to promote the body’s natural defense against oxidative damage.

The researchers found that exercise improved measures of insulin sensitivity in all individuals except those given antioxidant supplements. Also, molecules that protect against oxidative damage are upregulated in response to training, but not when antioxidants are administered.

Previous studies suggest that the body’s natural defenses against oxidative damage require activation by a small amount of reactive oxygen chemicals in the body. These same chemicals have been shown to mediate insulin sensitivity in muscles, and in this study both were shown to be blocked by high antioxidant administration.

The researchers suggest that small doses of reactive oxygen molecules such as the amounts produced by exercise are necessary to induce the body’s natural defense against oxidative damage, and that this process is essential for mediating exercise-induced insulin sensitivity. If this is true it could mean that some (but not all) of the metabolic benefits of exercise could be limited by taking high doses of vitamin supplements. This may be particularly important to individuals at high risk for type 2 diabetes.

Interestingly, foods that contain high levels of these antioxidants have previously been shown to be protective against type 2 diabetes. Although the reason for this is still unknown, the authors suggest the benefit is unlikely due to the antioxidant content of the foods and may depend on other factors.

Even if we do not understand the reason vegetables and fruits are the best source of nutrition, we can still enjoy all their benefits. If you choose to continue taking vitamin supplements, it is advisable to stick to a basic multivitamin that does not contain megadoses of one particular nutrient.

Do you take vitamin supplements? Why? How much do you take?
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