Garlic

People often say that garlic has medicinal properties. Some claim it lowers blood pressure, others swear it helps cholesterol and reduces clotting, and some even think it protects against cancer. I’ve also heard that garlic is “healthier” 10-15 minutes after it has been crushed or minced. Is any of this true?

The Science of Single Foods

As someone who regularly reads the scientific literature on the health benefits of food I can assure you that this is not an easy question to answer. The problem is that the effect of any single food on human health is likely to be small at best, and small effects are very difficult to detect with reliability. Studies must be incredibly well-designed to contribute anything of value to our understanding of how a food works in the human body. Also, many studies must be taken together in context for the data to be evaluated properly.

I have been researching this garlic question on and off for months and feel only slightly more confident today than I did when I started. To summarize, there are a good number of studies addressing the health value of garlic, but very very few of them are well-designed and published in reputable journals. The problem with having a large number of poor-quality studies is that results are often conflicting and difficult to interpret. Thus, when another scientist comes in to do a meta-analysis (pooling data from many studies and re-analyzing it for stronger statistics) the findings are usually inconclusive.

However, inconclusive findings do not enable me (or anyone) to say there is no benefit. What I can say is that more research is needed and if there is a benefit it is likely to be small. (How unsatisfying is that?!). But personally I would still recommend eating garlic for health. Why?

Small Benefits Are Important

Although we cannot say exactly why garlic is good for you, it is almost certainly not bad for you. Moreover, although it is difficult to attribute a particular health benefit to a single food, we do know that people who eat the most vegetables tend to be healthier than people who fewer.

Many nutrition scientists are beginning to suspect that the benefit of foods like garlic are primarily relevant in the context of a whole diet and cannot be evaluated independently. This means that it is less important that the individual studies I mentioned earlier are inconclusive, because they are likely not sensitive enough to evaluate the complex interactions of whole foods and food combinations on human physiology.

The Best Reason To Eat Garlic

The most important thing you can do for your health is eat a diverse diet of natural, unprocessed foods. Garlic is an amazing ingredient that imparts a unique and wonderful taste to the food it is cooked with. If you like garlic and it encourages you to eat your vegetables, then it’s good for you.

If it makes you feel slightly better knowing that it may help your heart or reduce inflammation, that’s awesome but less important.

What About The Crush?

If you do hope garlic can add to your health, is there any benefit in crushing it early? Probably.

Scientists have long suspected that the active ingredient in garlic is a substance called allicin. A recent study from Queen’s University showed that it is actually a decomposition product of allicin that has the most potent antioxidant activity.

Interestingly, allicin is created from an enzyme called alliinase that is not released from plant cells until they are damaged. Alliinase is what gives garlic (and onions) their strong odor and is thought to be a self-defense mechanism for these plants. When garlic is crushed, alliinase becomes active and begins creating allicin. As allicin is created and breaks down, the antioxidant potential of garlic is dramatically increased. Optimal antioxidant levels are created about 10 minutes after garlic is crushed.

It has not yet been shown that this increased antioxidant activity is a benefit to humans, but the principle is compelling enough to try to remember to crush your garlic a little early. If you are anything like me though, this feat is almost impossible. Apparently garlic hasn’t done that much for my memory.

What are your favorite reasons to eat garlic?

Originally published March 27, 2009.

Tags: allicin, alliinase, crushed garlic, garlic, minced garlic

Photo by Mr. T in DC

“I’ve always wondered what the scientific perspective of alcohol consumption is. I have been doing some research but the actual effects of it on the body range from beneficial to cancerous.”

The clinical science on alcohol consumption is vast and diverse. It’s easy to find studies that demonstrate the benefits of alcohol, but it is equally common to find research showing its dangers. Sorting through the data is not trivial, and getting the right answer from news reports is virtually impossible.

Let’s start with the facts:

1. Alcohol is addictive

Alcohol addiction is one of the most well-understood and dangerous risks of drinking. A propensity for addiction can run in families, but can affect anyone who drinks in excess. None of the health benefits of alcohol can negate the destruction caused by addiction, and anyone who drinks should be careful to avoid this terrible condition.

2. Alcohol damages the liver

Alcohol metabolism occurs in the liver and can cause severe damage when consumed in large quantities. Liver damage can usually be reversed if alcohol consumption stops.

3. Alcohol is associated with breast cancer (sort of)

Drinking is weakly associated with an increased risk of breast cancer. This is likely because alcohol increases aromatase activity in the human body, which increases estrogen production. Estrogen imbalance is a known cause of breast cancer. However, the association between drinking and breast cancer is negated by sufficient folate intake. Folate or folic acid is a B vitamin found in leafy green vegetables, fruits and legumes (and fortified foods). In other words, a healthy diet protects against alcohol induced breast cancer risk.

4. Alcohol protects against mortality from heart disease

Drinking alcohol reduces your risk of dying from a heart attack by preventing blood clotting. This effect is not limited to red wine, all spirits elicit substantial protection. The association appears to be dose-dependent, meaning that the more you drink the more protection you get. HOWEVER, you start raising your risk for the above mentioned problems with every additional drink per day. For men the ideal dosage is 2 drinks per day, for women it is 1 drink per day.

5. Alcohol raises good HDL cholesterol

Moderate drinking also reduces your risk of getting heart disease in the first place by raising beneficial HDL cholesterol without raising LDL cholesterol. Low HDL is a serious problem in America, and alcohol could be a significant benefit for some people. Here are other ways to raise your HDL cholesterol.

6. Red wine may slow aging

Aging research has been revolutionized by the discovery of a compound in red wine called resveratrol. Resveratrol has been shown to slow aging substantially in several model organisms. Though the effect in humans is still unknown, red wine is associated with many benefits that seem to go above and beyond the benefits of alcohol in general.

7. Red wine may protect against Alzheimer’s disease

Several studies have shown that red wine is associated with a decreased risk for Alzheimer’s Dementia, a devastating neurodegenerative disease that affects 1 in 4 people over the age of 90. The mechanism of action is unclear, but the benefits may be linked to the effect of red wine on fatty acids in the blood (raising the good stuff), or by slowing the aging process itself.

8. Alcohol causes accidents and behavioral problems

Even relatively safe levels of drinking can be deadly when combined with poor decision making. If you do choose to drink alcohol, always be sure that you’re in a safe environment and can get help if you need it. Being safe sometimes, or even usually, is simply not good enough.

There are plenty of good reasons to avoid alcohol if you choose, and many of the benefits can be garnered by simply increasing the amount or intensity of your daily physical activity.

However, the evidence is pretty clear that moderate alcohol consumption (1-2 drinks per day) can improve health and may be an important component of a healthy lifestyle. This is even true for those who pick up the habit later in life.

And last but certainly not least, some of the best times of my life have been over a drink with friends. And I guarantee you most of us aren’t thinking about our heart health while enjoying a great bottle of wine. As long as you consider safety first, never forget that smiling is one of the healthiest things you will ever do.

Here’s a fun question: what’s your favorite drink??

Tags: alcohol, breast cancer, cholesterol, HDL, heart disease, 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?

Originally published August 31, 2009.

Tags: calories, fruit, insulin

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