For The Love of Food

Welcome to Friday’s For The Love of Food, Summer Tomato’s weekly link roundup.

This week’s top 10 require careful reading and a little extra thinking, but it’s worth it. Learn why daily activity is more important than formal exercise, how habits can affect your food intake, some encouraging news from the USDA and more.

Want to see all my favorite links? Be sure to follow me on on Digg. I also share links on Twitter (@summertomato) and the Summer Tomato Facebook fan page. I’m very active on all these sites and would love to connect with you.

Links of the week

• Routine Chores Might Help Keep Dementia at Bay <<This title is misleading, because the most interesting part of this story is that daily activity is more effective than formal exercise for burning calories. Also, this preserves your mind. (Medline)
• People eat out of habit, a study finds, even when food is stale <<This is exactly why I’m always encouraging you to eat mindfully. Interestingly, in this study even eating with your non-dominant hand seemed to help. (Los Angeles Times)
• Nutrition: A Low-Calorie Meal Is Shown to Pay Off <<BS of the week. I’m all for eating less and I think you can be successful at it, but this is a poorly designed study using junk food as a meal and it only lasted 2 weeks. How that can be considered “effective” is beyond me. (New York Times)
• USDA seeks method to compensate farmers for GM contamination <<Remember in the movie Food Inc. when Monsanto sues an organic farmer because their seeds contaminated his crop? Hopefully this works out and puts and end to ridiculous things like that. (Food Politics)
• Why I never eat breakfast cereal. <<Breakfast cereal isn’t really food, and my friend Yoni who works with obesity patients for a living thinks it may also prevent weight loss. Worth considering. (Weighty Matters)
• Eating purple potato may lower blood pressure for the overweight <<This really isn’t necessarily restricted to purple potatoes. What it shows is that at least some potatoes aren’t as bad for you as bread. (Los Angeles Times)
• Helpful Gut Microbes May Differ Based on Diet <<I find this new area of research absolutely fascinating. This study shows heavy meat eaters have different microbial gut patterns than herbivores. At this point there’s no reason to prefer one to the other, but down the line it may help explain why dietary patterns are more important to your health than short-term changes. (Medline)
• Vitamin D levels tied to colon cancer risk <<Yet another reason to be sure your vitamin D levels are in a healthy range. Mine weren’t until I started taking supplements. (Medline)
• Hyperinsulinemia: Cause or Effect of Obesity? <<For geeks’ eyes only. Understanding this article requires a fairly sophisticated understanding of human metabolism and biochemistry, but if you have those things and are interested in exploring some of the fallacies of Gary Taubes’ carb argument, you’ll love this one. (Whole Health Source)
• roasted tomato and thyme soup <<A beautiful looking recipe, though I would personally leave out the sugar since tomatoes are so sweet right now. (the sophisticated gourmet)

What inspired you this week?

Photo by E.Baron

Cutting processed foods and refined sugars out of your diet is arguably the most important dietary change you can make to improve health and lose weight. But will one slice of birthday cake inevitably tighten your pants and cut your life short?

Not necessarily.

Quality of life is hard to measure, but it certainly involves some balance between good health and hedonistic enjoyment of things that might not be perfectly healthy. The question is how we find this balance for ourselves, and how do we make sure our behavior helps us keep that balance?

The answer, of course, will be different for everyone. Competitive athletes have higher physical demands for maintaining ideal health than, say, a scientist. And I’m not a fan of watering down my favorite foods—especially desserts—with “healthier” ingredients. But there are a few general guidelines that can help the majority of us live a little without constantly fighting the battle of the bulge.

9 Tips For Dealing With Dessert

1. Eat dessert once per week or less

As a general rule I try to keep my dessert consumption to once per week or less (it is often less). A larger person may be able to get away with a bit more, but setting a weekly maximum can help you keep tabs on your sugar consumption. If you are actively trying to lose weight, aiming for once every two weeks or less is ideal.

Sugar is problematic for several reasons. Most of you probably realize by now that excess sugar causes rapid blood sugar and insulin spikes that force extra calories to be stored as fat. Over time these spikes will alter your sensitivity to insulin, negatively impacting your metabolism and risk of type 2 diabetes. Extra insulin signaling is also associated with heart disease, high blood pressure and accelerated aging.

The less refined sugar you eat the better, but assuming most of us aren’t willing to give it up completely it is helpful to have a weekly maximum to keep consumption in a reasonable range.

2. Pick your occasions

Once you decide to budget your sugar consumption, it is time to start choosing your priorities.

Is your weekly group meeting at the office (the one where there’s always doughnuts) really a special occasion? In other words, is that stale chocolate doughnut you wolf down while half asleep really worth the extra workout or skipping dessert with your kids this weekend? Probably not.

If you think about it, there’s a good chance you don’t even enjoy that doughnut as much as you assume you do. And we both know you’ll feel horrible after eating it anyway. So why do you believe that you want it?

When you stop and really think about your food choices, you’ll often find that many of them come from conditioning rather than true preference. But just because 12-year old you liked low-quality sweets doesn’t mean the adult you has to continue eating them.

Save desserts for the times that are really worth it, and realize you aren’t missing much by skipping the Costco brownie bites.

3. Don’t eat dessert alone

Special occasions are moments of celebration you share with people you care about. One of the wonderful things about life is these moments happen all the time. Our weeks and months are perpetually marked by birthdays, weddings, promotions, vacations and a million other reasons to celebrate. Use these special times as cues for when to indulge.

On the other hand, there is nothing particularly special about sitting alone on your couch watching TV. Try to get out of the habit of eating dessert alone, especially if this is something you rely on for comfort. If you just want something sweet, try having a piece of fruit or some herbal tea instead.

I recommend not keeping any pre-made desserts in the house at all. Why torture yourself?

4. Know dessert when you see it

If you’re eating dessert several times a day but only think you are eating it once or twice per week, none of these rules are going to help you maintain your health and physique.

Last week I wrote about the hidden sugars in common foods such as sandwiches, salads and fruit yogurts. There are clearly benefits to eating a salad, but syrupy dressings contribute to your sugar intake whether there is lettuce around or not. Overly sweet non-dessert foods make it more difficult for you to enjoy real indulgences without consequences.

Be aware of the sugar content in the foods you eat and actively try to minimize it in the bulk of your diet (i.e. choose sandwiches without teriyaki or BBQ sauce, salads with savory (not sweet) dressing, cocktails without juice or syrup, and plain yogurt).

If you’re eating healthy and minimizing sugar 90+% of the time, your waist will hardly notice the occasional birthday cupcake.

5. Little indulgences count

Just as you cannot ignore the 27 grams of sugar in Yoplait yogurt, you can’t grab 2 or 3 pieces of candy every afternoon from the bowl in the office without it adding up.

Be aware of the little cheats you make throughout the week and don’t kid yourself about their impact. If you decide that the work day is just too hard to get through without these, that’s fine. But you aren’t doing yourself any favors by pretending they don’t exist. Remember to count them in your mental dessert tally and keep it in mind when you’re looking lustfully at your grandma’s homemade apple pie and wishing you hadn’t had so much sugar this week.

6. Choose quality over quantity

If your goal is to limit your sweets but you don’t want to feel like you’re missing out, make sure your choices emphasize quality over quantity.

A few bites of good quality dark chocolate is infinitely more satisfying than a handful of Hershey’s kisses. Desserts can rack up 25-100 calories per bite. Get the most bang for your buck by picking foods with actual flavor and not just extra sugar and salt.

Hint: This tip should also help you stick to tips #2 and #5.

7. Go splitsies

Half a dessert is 100% better for you than a whole dessert.

If you really really want to try one of those cookies your co-worker has been bragging about for months but have already had your ice cream this week, try taking only half of one. Better yet, find someone to split it with you so you aren’t tempted to finish it. If it’s that good, a few bites should be plenty satisfying.

8. Resist peer pressure

Some people take a special pleasure in encouraging others to do things they know are bad for them. These people also tend to be good at recruiting others to join in their banter.

Be prepared to get nagged occasionally for not wanting to eat foods that aren’t worth it. But if you have decided in advance to stick to desserts you know taste better than what your friends are pushing, it really isn’t that hard to ignore them.

Who’s really missing out here?

9. Use the gym

Despite our best efforts, we all eat too much dessert every now and then. This isn’t good, but it isn’t the end of the world either.

When this happens to me I use it as an opportunity to amp up my workout routine. By far my best runs are on days when we have birthday cake in lab–I feel like I can run for days with all my extra energy.

Your muscles use sugar as fuel, so use it up while you can and give your metabolism a little boost (having a little extra blood sugar and insulin around when you’re exercising can actually improve your metabolism) and prevent those spare calories from being stored as fat.

You’ll probably feel better after working it off too.

How do you deal with dessert in your healthstyle?

Originally published March 31, 2010

For those of you who haven’t been following along with the Tomato Slice newsletter, I recently launched a segment called Office Hours where I make myself available to take any questions subscribers may have.

This week I held a special Office Hours to discuss 2 articles from last week’s For The Love Of Food post:

1. Is Sugar Toxic? by Gary Taubes
2. The latest scientific consensus on saturated fat and heart disease

Since I had so many questions on these papers, I recorded the session and posted it above.

If you’d like to know more about the sugar article, I also recommend Dr. Lustig’s YouTube video mentioned in the article, as well as his interview this week on KQED which I’ve included below.

Feel free to leave your thoughts or ask questions in the comments.

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.

My biggest problem with Taubes’ first book is that it was very difficult to read, and that of course means most people won’t finish it. In Why We Get Fat Taubes repackages the data in a way that is much more logical and easy to digest. The book is substantially shorter, and is mostly free of the rants and tirades that peppered Good Calories, Bad Calories.

Instead, Why We Get Fat takes the reader through a clear and concise explanation of why all calories are not created equal, and that carbohydrates are the reason for the vast majority of the health and weight problems plaguing modern civilization. He also does a fantastic job demolishing the currently prevailing hypothesis that dietary fat and blood cholesterol are the causes of heart disease. They aren’t.

That so few people understand these points is why I recommend everyone read this book. It breaks my heart every time someone writes to me for nutrition advice and proudly points to their butter-less popcorn or baked chips as proof of their already “healthy” diet. Until it becomes common knowledge that fat is good for you and processed carbohydrates are the worst thing you can eat, I think this book is the best resource we have to explain it.

Still I do not agree 100% with Taubes’ conclusions. Though I do think the evidence is overwhelming that all calories are not created equal, I disagree that calories therefore do not matter and cannot be manipulated to help with weight loss. Taubes argues that how much we eat is dependent on our hormone levels (specifically insulin levels) that regulate energy balance, and that depending on this balance we naturally regulate our feeding and energy expenditure (exercise) so that we maintain our weight.

Taubes makes a compelling case that severe calorie restriction is counterproductive in weight management, and I agree. However there is some evidence that a small calorie deficit, on the order of 100-200 calories per day, is within the range of our natural homeostatic mechanisms and can be effective at controlling body weight.

In his book, Why We Eat More Than We Think (another must-read), Brian Wansink explores study after study where environmental cues are manipulated to get people to eat either significantly more, or significantly less than they believed. Importantly, the participants never reported any difference in satiation no matter how much they ate. Wansink argues that people can make small dietary changes resulting in a moderate 100-200 calorie per day deficit that does not affect hunger levels and can be used to effectively control weight.

Similarly, in The End of Overeating (here’s my review) Dr. David Kessler discusses how eating can become uncoupled from hunger when it is associated with external cues, making a strong case that some of us really do eat more than we need to. I think many of Kessler’s points about overeating are valid, particularly for emotional eaters. His argument is further strengthened by individual case studies of people who learn to eat less without experiencing sensations of starvation that are predicted by Taubes. One such example is Frank Bruni’s book Born Round (my review), in which he overcomes his weight struggles by moving to Italy and changing his relationship with food. Bruni is able to maintain his weight even after accepting the job of food critic at the New York Times.

These accounts conflict with Taubes’ argument that people overeat to satisfy a caloric deficit caused by a carbohydrate-induced faulty metabolism. Though there is good reason to believe Taubes’ metabolic hypothesis accounts for a large part of the health issues in today’s society, I think it is premature to conclude that this is the only force at work in why we get fat. Indeed, some research suggests learned feeding cues can directly impact insulin and metabolic pathways even in the absence of food. This data does not refute Taubes’ hypothesis, but rather makes it more complicated than he implies.

Even if we assume Taubes’ metabolic theory accounts for the majority of our health problems, insulin response (the ultimate cause of fat accumulation) should also be affected by eating rate and exercise, and vary among individuals. However Taubes handedly dismisses the possibility that any behavioral modification other than carbohydrate restriction can impact metabolic function because, he argues, we will modify our physical activity to adjust for any nutritional changes. His case is compelling, but not air tight, and my interpretation is that while carbohydrate consumption is clearly very important, there are likely other factors that may also be helpful in controlling metabolism and body weight.

In his book The 4-Hour Body (my review), Tim Ferriss describes how WordPress founder Matt Mullenweg lost 18 pounds by simply chewing each bite of food 20 times. Extra chewing or “masticating” was made popular as a weight loss technique in the late 1800s by Horace Fletcher and is explored in Gina Kolata’s book Rethinking Thin (not a particularly good read). Extended chewing and eating slowly are both effective at inducing weight loss, likely because they slow the glycemic response and almost always result in decreased meal size.

One of the most interesting points made in The 4-Hour Body was Ferriss’ personal glycemic response to a low-carbohydrate diet of just meat and vegetables. He claims that even with this meal he could easily spike his glucose to over 150 mg/dL (this is very high) by simply eating quickly, and that this effect could be controlled by slowing down and taking a full 30 minutes to finish a meal. Unfortunately I could not find a similar experiment in the scientific literature, but Ferriss’ observation suggests that behavioral modification can have a powerful impact on metabolic response independent of diet composition.

My final complaint about Why We Get Fat is that Taubes never considers that individual variation may preclude his theory from applying to everyone. He suggests that while some people are genetically blessed with a higher tolerance for carbohydrates, others will only thrive on an almost zero carbohydrate diet. Unfortunately this is the one part of the book he does not provide data to back up his assertions.

Though Taubes frequently argues the importance of paying attention to outliers, he never explores the possibility that some individuals may actually do better (rather than less bad) on a diet with slightly more carbohydrates. (Let’s assume for now that I mean slowly digesting, natural carbohydrates and not highly processed sugars and grains.) In a healthy person there is no reason to assume that such a diet would induce insulin resistance, and there may be some additional advantage outside of metabolic health for including such foods. I don’t think this is a possibility we should dismiss without solid evidence.

To summarize, Taubes does an excellent job describing the importance of carbohydrates in both weight management and health but oversimplifies the science, particularly neglecting the importance of behavioral factors on metabolism. However, the analysis presented in Why We Get Fat is still the most clear explanation of the relationship between metabolism and health that I’ve found and is an invaluable resource for the general public.

What did you think of Taubes’ latest book?

Mango Vendor in Bangkok

Several readers have asked lately about the impact of fruit–specifically the sugar in fruit–and it’s capacity to cause weight gain and accelerate aging through insulin signaling:

“Do people usually gain weight because of eating fruit and does the sugar in fruit age us?  I just hate to think that I am doing my body harm by eating fruit.”

If this question sounds insane to you, it shouldn’t. It is actually a very reasonable query that was sparked by two Summer Tomato articles, one about saving money while eating healthy and another on calorie restriction, aging and quality of life. In the first article I recommend thinking of fruit as dessert, a treat to be enjoyed once or twice per day. The second article is about the impact of sugar and calories on aging.

Body Weight

The fact is that fruit contains a lot more sugar than other natural foods and in large enough quantities it can contribute to weight gain. But fruit is certainly not bad for you, nor is it worse for your health than anything else in life.

The sugar in fruit contributes calories to your diet, but since you need calories to survive fruit is still a very good choice. The reason is that in addition to sugar (fructose, to be specific) fruit also has vitamins, minerals, antioxidants, fiber and many other things that contribute to health and possibly slow aging.

On the rare occasions when I do make an effort to lose a little weight, however, remembering that fruit should be dessert is something I keep in the back of my mind. I eat fruit every day, but when trying to lose weight I keep it under two servings and always choose whole fruit–avoiding anything blended or juiced. (Drinking calories is usually a bad idea.)

But this healthstyle tactic is not for everyone.

Why?

Unlike most people trying to lose weight, I already have a very healthy diet and fruit is one of the easiest places I can trim calories without feeling deprived. Cutting out things like fat and protein make dieting very difficult because you are always hungry. In my experience reducing unnecessary carbohydrates–especially sugars–is the easiest and healthiest way to lose weight.

But it is essential to remember most people are not overweight because they eat too much fruit and the vast majority of people would benefit from eating more of it.

Aging

The question about whether sugar causes aging is a fascinating one that I am very interested in.

Yes, in most organisms eating sugar has been shown to promote aging, but this has not been proven in humans. Sugar induces aging via the insulin signaling pathway, so therefore any food that increases insulin signaling could theoretically accelerate aging. The problem is that you need insulin to survive–those who cannot produce insulin have a disease called type 1 diabetes.

The good news is that eating a diet that minimizes insulin signaling is also the best way to lose weight and stay healthy, so if you are living a healthy lifestyle (one that includes fruit) you do not need to worry about anything else.

Although fruits have sugar, it is extremely unlikely that they accelerate aging. In fact, most evidence suggests that fruit slows aging because of its high levels of vitamins, minerals and antioxidants.

If anti-aging is your goal, fruit is your friend not your enemy.

For more on insulin signaling, check out my post at MizFit Online, When is a calorie not a calorie.

Conclusion

While fruits contain sugar, they do not pose a special threat to your health goals. Eat and enjoy fruits as a wonderful and delicious part of life.

How much fruit do you eat?

Originally published August 31, 2009.

For The Love of Food

Welcome to Friday’s For The Love of Food, Summer Tomato’s weekly link roundup.

The interwebs gave us lots of great healthy food tips this week, from an unexpected benefit of eating (and smelling) real, quality food to peeling a mango like a zen master. There is also a great article on DIY packed lunch tips and some good news about beer.

I read many more wonderful articles than I post here each week. If you’d like to see more or just don’t want to wait until Friday, be sure to follow me on Twitter (@summertomato) or the Summer Tomato Facebook fan page. For complete reading lists join me on the social bookmarking sites StumbleUpon and Delicious. I’m very active on all these sites and would love to connect with you there. (Note: If you want a follow back on Twitter introduce yourself with an @ message).

Links of the week

• Confused about nutrition? Eat food! <<Marion Nestle elaborates on her position regarding single nutrient science and why we’re better off just eating food. (Food Politics)
• Complex smells make food more filling <<One of the reasons I emphasize real, high-quality foods on this blog is because they are so much more satisfying and contribute profoundly to a better quality of life. A new study suggests that their wonderful smells may be partially responsible. (New Scientist)
• Another perspective on the sodium wars <<I always love to read Monica Reinagel’s perspective on nutrition trends. Here she elaborates on sodium and high blood pressure. (Nutrition Data)
• Beer for the Bones? <<That’s right. The silicon present in some beers may contribute to bone health. I wouldn’t start drinking more to prevent osteoporosis, but it’s nice to fantasize right? (HealthDay)
• The Zen of Peeling a Mango <<It’s mango season, Mangoes are good and healthy, Easy to peel. (Who doesn’t want to start the weekend with a mango haiku?) (ReadyMade)
• A Butcher’s Tips for Avoiding Cuts in the Kitchen <<Safety first. Playing in the kitchen is fun, but it is easy to hurt yourself. Learn to handle a knife safely from the pros. (Lifehacker)
• 8 Foods That Will Hide Your Bad Breath <<I haven’t written much about Valentine’s Day this year, but a little good breath could never hurt anyone. (Dumb Little Man)
• How to cultivate the packed lunch habit & save <<I’m a big fan of lunch, habits and DIY foods. Saving money doesn’t suck either. This article is full of great tips. (Stone Soup)
• You Know About Insulin. And Now, the REST of the Story . . . <<People LOVE to over-simplify health and nutrition. Insulin gets blamed for a lot, and rightly so, but keep in mind there is a lot more going on than just carbs and insulin spikes. (Diabetic Mediterranean Diet Blog)
• Farro & Winter Vegetables Recipe <<I love Amy. I love seasonal vegetables. And for some reason I’ve never cooked with farro. Something is wrong with this story and I think this recipe solves it. (Cooking With Amy)

What inspired you to eat well this week?

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?

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?