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?

Tags: aging, calorie restriction, carbs, Cynthia Kenyon, diseases of civilization, glycemic load, insulin, low-carb, protein, refined carbohydrates

Today is my 30th birthday and a perfect time to reflect on life, the universe and everything.

Despite being female and thus held to tough and often unrealistic physical standards, hitting my third decade doesn’t cause me anxiety about either my appearance or place in the world.

In my experience, age is not an amount of time but a state of mind. As a child I always wanted to be a grown up, so I acted like one. It freaked my parents out sometimes, but that’s just how I was. In my mind, I still feel pretty much the same in that regard. I love to work hard and I thrive in positions of responsibility. Since both these traits get more important with age, I have actually enjoyed stepping into the adult role I’ve always felt I belonged in.

But that’s only one part of me.

In many other ways I’m as juvenile as ever. If you spend much time with me on Twitter (@summertomato) you’ve probably noticed I have the sense of humor of a 12-year-old boy. I blame my dad for that one. I’m also still shocked every time I hear that friends my age are getting married and having children. In my brain we’re not nearly old enough for that yet! But in reality, it is my friends who are normal and I’m the outlier.

Oh, and did I mention I’m still in school? Up until a couple years ago I carried a backpack with me everywhere, for better or for worse.

All these things give me a sense of agelessness, so it is hard to think of this birthday as anything but another day to do things I love. But part of my peace of mind certainly comes from the fact that I’m in pretty good shape physically–probably the best of my life. And at 30 this is definitely something to be proud of.

Summer Tomato readers know I attribute my good health almost entirely to my eating habits. I also spend a good amount of time in the gym, though I don’t workout nearly as much as I used to. But healthstyle extends to more than just diet and exercise.

Here I’ve compiled my favorite 30 habits to slow aging and keep you young in more than just your heart.

30 Healthstyle Tips To Keep You Young

1. Be happy The physical damage caused to your body by stress has only recently become appreciated by the scientific community. Fill your life with things you love and get rid of almost everything else. Practice stress relieving activities like meditation and exercise, and learn to appreciate joy when you find it. Happiness does a body good.
2. Eat vegetables There is good evidence that oxidative damage caused by toxins and metabolism contributes to the aging process at a cellular level. Foods (but not supplements) high in antioxidants seem to protect us from oxidative stress.
3. Avoid sugar Sugar is a direct cause of aging and significantly reduces lifespan in organisms from yeast to primates. Not by a small amount either.
4. Moisturize The appearance of your skin is largely dependent upon moisture. Help it out by using moisturizers to keep your skin soft and hydrated. Work with a professional to determine what type is best for you.
5. Don’t raise your eyebrows Credit my mother for teaching me this one, it has been a lifesaver. As a kid she used to warn me about raising my eyebrows, saying it would give me wrinkles and I’d regret it. I thought she was crazy, but still learned to express myself without much forehead crinkling. As a result I have far fewer forehead lines than some people years younger than me.
6. Sleep For me the most important determinant of how I look (and feel) on a given day is how much sleep I get. Seven hours is my ideal, but everyone is different.
7. Eat fish Some evidence suggests that the omega-3 fatty acids found in fish are particularly beneficial to the skin.
8. Wear sunscreen I love the sun and spend as much time in it as possible, but I never walk out the door without sunscreen on my face. UV radiation from the sun damages your skin and promotes aging.
9. Don’t smoke Smoking is one of the easiest ways to look older than you really are and shorten your life at the same time. Avoid both primary and secondary smoke like the plague.
10. Step out of your comfort zone Mental exercise seems to be one of the key elements of quality aging, but this doesn’t mean you should sit around all day doing crossword puzzles. Neuroscientist and cognitive aging specialist Dr. Adam Gazzaley suggests going out of your way to challenge yourself mentally, doing things like traveling and learning new languages even over the age of 60.
11. Take vitamin D Some research suggests that vitamin D may be particularly important in slowing the aging process. The jury is still out on the value of vitamin D supplements for aging, but they seem to have enough other benefits that it’s worth the investment.
12. Eat fruit Like vegetables, fruits have an enormous amount of antioxidants and help with hydration. Vitamin C in particular is thought to benefit skin.
13. No foundation or powder makeup Generally I avoid putting any makeup directly onto my skin. I realize I have a very flexible work environment and this is not possible for every woman, but skipping the makeup does help maintain your skin’s hydration and elasticity. I do wear makeup occasionally, maybe once or twice per week. But in general I find that mascara and lip gloss are enough for most situations.
14. Hydrate Your skin is very sensitive to water levels. Stay hydrated by sipping water and eating fruits and vegetables throughout the day.
15. Whiten teeth I know this isn’t something you can find at the farmers market, but when you drink as much coffee and red wine as I do, minor (and admittedly superficial) fixes like teeth whitening can go a long way. If you don’t believe me, try and remember the last time you saw a 20-year-old with yellow teeth….
16. Wear sunglasses If you’re a happy person (and I know you are), your wrinkles will most likely be caused by smiling and show up predominantly around your eyes. Block out extra sun (and look super cool) by always wearing sunglasses when you go outside.
17. Eat beans and lentils Legumes are a fabulous source of minerals that can help keep your skin hydrated and looking young.
18. Tea Afternoon tea time is one of the greatest discoveries I’ve ever made. Not only is tea full of antioxidants and other cancer-fighting compounds, a midday break can be just what the doctor ordered to sip away stress.
19. Cardio I’m not the biggest believer in cardio exercise for weight loss, but it is still important for vascular health. Not to mention how awesome you feel after a good session. Cardio doesn’t need to kill you, but you should do it regularly.
20. Strength training Building strong, toned muscles is one of the most effective ways to look younger than your years. Ask anyone who looks fabulous and they’ll swear by strength training. A little goes a long way.
21. Eat intact whole grains Intact grains (not fake “whole” grains that are ground into flour) are an excellent source of vitamins, minerals and soluble fiber. They are also perfect fuel for those killer workouts.
22. Olive oil It is hard to think of something more versatile, healthy and delicious than olive oil. It breaks my heart that dietary fat got such a bad rap the past few decades, since the benefits of healthy fats like olive oil are innumerable. Fat isn’t just “not bad” for you, it’s essential.
23. Kill your television We all have things we enjoy watching (I’m partial to NBA championship teams), but if it takes up a significant amount of your time each week (>5 hrs) it may be time to reevaluate. How many years of your life do you really want to spend on your couch?
24. Don’t stuff yourself Cutting back on calories is the single most effective way to slow aging and extend life. I don’t advise starving yourself, but it’s a good idea to avoid overeating in any situation.
25. Eat nuts Nuts are the perfect snack food and are filled with anti-aging fats, vitamins and minerals. They are also great for suppressing appetite–just don’t eat more than a handful.
26. Avoid dairy Studies of aging skin have shown that milk and milk products are associated with more aging and wrinkles.
27. Avoid processed meats Processed meats contain high amounts of nitrates and nitrites, which are associated with many different health problems in humans. No need to get too hung up on this, but you may not want to eat deli meat every single day if you want to stay young.
28. No processed carbohydrates Just like sugar, processed carbohydrates are a direct cause of aging and disease. I eat these things occasionally, but don’t let it happen too often.
29. Coconut oil Fats come in all different shapes and sizes, and I try to incorporate a good mix of all of them. Medium-chain fatty acids like those found in coconut oil are starting to be recognized as important by researchers, but the evidence is limited. Coconut oil is also a healthy source of saturated fat for vegetarians. I always use coconut oil when cooking Southeast Asian food.
30. Red wine Red wine has a powerful anti-aging compound in it known as resveratrol. Though it is unlikely that the dosage of resveratrol in red wine is high enough to impact lifespan, drinking alcohol in moderation is also associated with decreased risk of heart disease and other vascular problems. Cheers!

Do you have any anti-aging secrets?

Tags: aging, alcohol, beans, calories, carbs, cardio, coconut oil, dairy, Exercise, fat, fish, lentils, mood, nuts, olive oil, refined carbs, resveratrol, sleep, smoking, strength training, sugar, sunscreen, tea, teeth, television, Twitter, vitamin D, water, wine

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?

Tags: calories, fruit, insulin

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?

Tags: BMI, body fat, body mass index, caloric restriction, mortality

Tapeworm Diet Pills

Throughout history there has never been a shortage of (bad) diet, health and weight loss advice. Everything under the sun has been called a weight loss cure at some time or another. And now that we are blessed with the amazingness which is the internet, snake oil is more abundant than ever.

So who should you listen to?

Most people I speak to are so cynical about health advice they ignore all of it completely and simply hope they are one of the few blessed with the genetics to withstand decades of smoking, poor diet and/or no exercise. They always point to a great aunt who smoked like a chimney and lived to 95. At least she enjoyed her life, right?

The problem with this approach is that the vast, vast majority of us are not blessed with these genetics (sorry, being related to someone with those genes has very little effect on your own personal chances). Also, even if you have the most resilient body in the world the only way to test it is to do an experiment on yourself: Eat whatever you want and maybe you’ll make it to 60 without a heart attack. Maybe you’ll make it to 80 without colon cancer. Or maybe not.

It is also important to consider that no matter how long you live you can improve the quality of that life by making better decisions about how you treat your body now. And contrary to popular belief, these choices need not sacrifice fun and enjoyment. I for one consider my healthstyle habits–fresh delicious food and regular workouts–the best part of my daily grind. By far. The trick is finding a personal healthstyle that makes your life better, not worse.

But if bad advice is so abundant who should you listen to? Who do I listen to?

As hard as I tried, I could not come up with a way to describe someone who can be trusted for diet advice. I wanted to say “scientists,” but I could think of too many examples (usually involving money) where this simply isn’t true. Instead it is easier to think about who cannot be trusted and why.

10 People You Can’t Trust For Diet Advice

1. USDA Sadly, the government agency that has been given the responsibility of establishing the dietary guidelines for the United States is the Department of Agriculture. As you can tell from its name, the responsibility of this organization is to protect the interests of American agriculture industries. It has a far lesser interest in public health. Dairy and sugar lobbyists are the reason we are told up to 55% of our total calories can come from these sources. Obviously the USDA recommendations were not based on the data that clearly describes these substances as dangerous. Stay away from the bizarre food “pyramid” on their website.
2. Food companies When KFC tells you their grilled chicken is healthier for you than their fried chicken, do you believe them? How about Yoplait’s yogurt? Companies trying to sell you something are notorious for twisting scientific facts to make you believe their products are healthy. Think twice before you believe them, history tells us it is more likely the opposite is true (remember margarine and fat-free cookies?).
3. Your mom Although your mother has more interest in your personal health than lobbyists and food companies, she has been subjected to the same deceptive nutrition advertisements as you. A tragic fact of the past 60 years is that our parents grew up learning in school what the USDA wanted them to learn: calcium does a body good, fat = bad health, protein = good health. But these things are not true, no matter how strongly your parents believe them.
4. Celebrities It is difficult to look at a beautiful person and not believe they are doing something right or know some secret to perfect health. But just like your great aunt, celebrities have many advantages you probably don’t have that make their looks deceptive: genetics, time and money. These people make a living off looking beautiful and have all the resources in the world to achieve it. If they claim to have some secret to health or weight loss, chances are it is not something that will be effective in the long-term for a normal person. Even more likely is that they are being paid to sell you something.
5. Athletes If you are not a professional athlete or Olympian, chances are you do not have the same metabolism or dietary needs as someone who is. As much as I loved watching Michael Phelps win 8 gold medals, I am not going to start eating like him.
6. Cardiologists (or any M.D. with no research experience) Cardiologists are highly trained doctors that specialize in disorders of the heart and blood vessels. But while heart disease is strongly tied to diet, cardiologists are not necessarily trained in science or nutrition. I do not wish to take anything away from what these individuals do–most are incredibly talented, skilled professionals. However medical school and residency training focus more on treatment than prevention. Moreover, science (Ph.D.) and medicine (M.D.) are different, and few doctors have the time or training to keep up with and evaluate nutrition science. But some certainly do, and it is worth it to find out who. Another thing to consider is that heart disease is only one chronic disease related to diet. If you are worried at all about cancer, stroke, diabetes or Alzheimer’s disease would you ask a cardiologist?
7. Main stream media We all love a good story and journalists are trained to sell them to us. But very few journalists–even science writers–have more than a bachelors degree in biology or other hard science. This, of course, is less than the doctors I mentioned above. Though journalists are often very intelligent and can do a great job of analyzing the available scientific evidence (Michael Pollan comes to mind), even my beloved New York Times can drop the ball on nutrition science on occasion. When push comes to shove, they are more trained in story telling than scientific analysis.
8. Personal testimony We are all impressed by the person who lost 200 lbs on the Biggest Loser, and I salute anyone who has ever achieved substantial weight loss. But all diet advice from these people should be taken with a grain of salt. Personal testimony is the ultimate in non-scientific fluff (check out any website selling diet pills). In science a personal testimony is called N=1 and is proof of absolutely nothing. These people may be a great source of moral support, but real evidence and facts have numbers and statistics tied to them.
9. Natural health “gurus” Cynicism about health, medicine and science frequently cause people to turn to “alternative” solutions that often involve “natural” remedies. I would never suggest that natural solutions might not be the best path to health, but something being “natural” is not a guarantee of any particular benefit. In my experience, advice from natural health “gurus” is often based on poorly designed, poorly controlled studies that do not stand up to rigorous scientific testing. That does not mean these methods will never be proven effective, but keep in mind that most of them never will.
10. Personal trainers The gym is one of my favorite places in the world, and if I need help with a certain exercise I ask a personal trainer. Most trainers have (hopefully) gone through a (fairly easy) certification program where they learn the basics of body mechanics. They are not scientists and are not trained in nutrition.

I am not suggesting that these people contribute nothing to our conversation about diet. However you should always be skeptical of who you take your advice from, particularly when it comes to your health.

Is there anyone you would trust for diet advice?

Read my answer….

Tags: agriculture, athletes, celebrities, facts, gurus, industry, journalism, medicine, trainers, USDA