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??

Originally published July 28, 2010.

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.

Photo by Lord Jim

“What do you think of the Paleo diet which advocates zero grain consumption?”

The Paleolithic diet is one of the most rapidly growing diet trends of the past several years. Followers of the Paleo diet argue that humans have not evolved to eat agriculture-based foods and can only achieve optimal health by consuming a hunter-gatherer style diet. Thus the Paleo diet is completely devoid of grains and legumes, and also shuns dairy, salt, refined sugar and processed oils. The diet is composed primarily of meats, fish, vegetables, fruits, roots, nuts and seeds.

(The Wikipedia article on the Paleo diet is actually pretty good if you’d like to read up on the details. I particularly like the Opposing views section.)

Like most diets the Paleo diet has a little bit of good science behind it, but also a lot of logical leaps and baseless assumptions. The evolutionary argument that humans are somehow maladapted to agriculture-based diets is particularly unconvincing (resting on many unproven assumptions), yet is the fundamental premise on which the Paleo diet bases its recommendations.

The reasoning behind the Paleo diet is less interesting to me, however, than the impact of the diet itself. Will “eating like a caveman” really help you be healthier?

Possibly, but not necessarily.

The most obvious advantage of the Paleo diet is the lack of processed foods. There is ample evidence that societies on traditional diets boast far better health than those on modern, Western diets–and the hallmark of modern diets is food processing. Paleo diets therefore are low in sugar, refined carbohydrates, trans fats, excess salt and pretty much everything else that leads to “diseases of civilization.”

Paleo diets are also abundant in healthy, nutrient-rich foods such as vegetables, fruits, nuts, fish and meats. I have no doubt that anyone willing to stick to a Paleo eating plan will have a healthy weight and remain virtually free of heart disease, diabetes, hypertension and may even have lower rates of cancer.

But the question still remains, is it necessary to eat Paleo to be healthy?

This is where I take issue with the Paleo philosophy. While a diet completely free of processed foods is undeniably healthy, the Paleo diet goes beyond this and demands considerable sacrifice.

Paleo diets do not allow for any grains or legumes. This pretty much eliminates every traditional cuisine on earth including Japanese, Italian, Indian and Greek. Not only is this a culinary tragedy, it ignores the fact that these cuisines feed some of the world’s healthiest and longest-lived individuals.

Traditional, global diets that exclude highly processed foods but also include grains and legumes have been some of the most successful for health. Diseases of civilization are only problematic in Western cultures where processed foods make up a large proportion of the calories and few whole food are consumed.

Proponents of the Paleo diet argue that it is necessary to eliminate grains and legumes because they contain “antinutrients,” substances that can interfere with the body’s absorption of other important vitamins, minerals and proteins. However, well-nourished individuals who eat a varied diet of unprocessed foods (including grains and legumes) are not nutrient deficient and are generally healthy.

Given that it is possible to thrive on a diet that includes some grains, legumes and even small amounts of processed foods, one must question if giving up the culinary joys of travel and global cuisine are really worth the sacrifice.

In my experience, food substitutions and modified recipes designed to mimic traditional meals can sometimes be tasty but can never replace true authenticity.

Another contention I have with the Paleo diet is the assumption that the same eating patterns will work for everyone. People’s lives differ in countless ways. We each have different levels of daily activity, demands on our time and food preferences. We also have different genetic backgrounds, which can result in significant differences in metabolism and hormone levels. These individual variations make dietary needs different for each of us.

Because of our individual differences, there is undoubtedly a percentage of the population that thrives on the Paleo diet and finds it easy to stick to and achieve results. Hooray! However there may also be a segment of the population (myself included) that finds living without grains and legumes to be chronically unsatisfying and unsustainable.

Try telling a foodie they can never eat cheese or drink wine again and see how far you get pitching a Paleo diet.

If you currently eat a typical Western diet with little variety and many processed foods, tend to have better success following rigid diet plans, and have no qualms about giving up or modifying traditional meals to meet your dietary demands, then you might have luck following the Paleo diet. However there is no reason to believe it is the only path to good health.

The best diet is the one that works for you. Finding a healthstyle you can embrace and enjoy is essential if you want to build a lifetime of healthy habits.

Do you follow a Paleo diet? What do you think?

Originally published February 22, 2010.

Photo by Venex_jpb

If there is a single subject that befuddles the health-conscious eater, it is undoubtedly carbohydrates.

Most of us have seen the impressive results of at least temporarily restricting carbs, but studies examining the long-term effects of carbohydrate restriction are often ambiguous. Also, while some experts argue fervently for a low-carb lifestyle, some nutritionists still warn about the dangers of eating too much fat or protein.

So how do we know what to believe?

A full examination of the science behind carbohydrate metabolism is beyond the scope of a single blog post, and is in fact not entirely understood by the scientific community (for a thorough review of this topic read Gary Taubes’ book Good Calories, Bad Calories, which I have reviewed here).

However, there are a few things we do know about carbohydrates that are worth pointing out.

Lesson 1: Refined grains contribute to nearly every chronic disease in modern civilization.

It is universally agreed in the nutrition community that refined, processed carbohydrates are the worst things to eat on the entire planet.

And it is impossible to overstate how remarkable this is.

The nutrition community is one of the most disagreeable bunches in all of science. But across the board–from vegans like Colin Campbell to carnivores like Robert Atkins–not a single one of them considers processed carbs to be nutritionally neutral. They all consider them dangerous.

Without question, refined carbohydrates contribute to poor health.

Lesson 2: Vegetables protect against nearly every chronic disease in modern civilization.

Where things start to get more complicated is with unrefined carbohydrates, and the various iterations of this definition. There is ample evidence that the carbohydrates contained in vegetables are not harmful, and possibly beneficial.

To call these vegetable carbohydrates “fiber” is to oversimplify the science, but suffice to say that vegetables are good for you and contribute to your good health.

This is also generally agreed upon.

Lesson 3: Whole grains are different from intact grains.

Few people will argue against my first two points. But bring up whole grains and you will unleash a fury of controversy. Some people believe whole grains to be the cornerstone of any healthy diet, while others consider them superfluous and possibly detrimental to good health. You can find dozens of PhDs and MDs to back up your claims no matter what camp you align with.

So why is there so much disagreement? What does the science say?

The problem is that nutrition science conducted in free-living humans is virtually impossible to interpret. This is largely because the studies are so difficult to control and people’s behavior and self-reporting are so unreliable. Another problem is that the definition of “whole grains” has been watered down to a point where it is virtually meaningless.

One reason whole grains are hard to identify is because the US Food and Drug Administration (FDA) has created a definition that is friendly to food companies, but not to consumers.

The FDA requirements for a manufacturer to use the term “whole grain” on its label (along with the respective health claims) are as follows:

“Cereal grains that consist of the intact, ground, cracked or flaked caryopsis, whose principal anatomical components – the starchy endosperm, germ and bran – are present in the same relative proportions as they exist in the intact caryopsis - should be considered a whole grain food.” (emphasis added by me)

Get it? To be considered “whole,” grains do not actually have to be intact.

Thus food manufacturers create products using this loose definition to their advantage, demolishing grains as normal, then adding back the required ratios of grain parts (germ and bran) to meet the standard.

This is how products like Froot Loops get spiffy health labels claiming they lower heart disease when any unbiased nutrition scientist would agree that, with 41% sugar by weight, Froot Loops almost certainly contribute to heart disease.

On the other hand, there is compelling data that intact whole grains contribute to better health.

Lesson 4: Eating grains is a personal choice, not a nutritional imperative.

The good news is that it is really easy to tell the difference between fake “whole” grains and intact whole grains. If a food actually looks like a grain (i.e., it retains its original form and bran covering), then it is an intact grain. If it looks like a Cheerio, chip, loaf of bread or pasta with a “whole grain” label, then it is a fake whole grain.

People following a primal or paleo diet will argue that this difference is irrelevant and that all grains (and legumes?!) are unnecessary for good health. Personally I disagree, but remain fairly neutral on the personal choice of removing grains from the diet entirely.

Grains do not appear to be necessary for survival (Inuit tribes survive without them), but optimal nutrition may require slightly more effort than would be necessary following a traditional balanced diet.

This is generally how I feel about all healthy, restrictive regimens such as vegetarian, vegan and raw diets. You can make it work for yourself if you are willing to make sacrifices and put in the effort.

However you should be aware that for many people, myself included, cutting whole grains out of your diet completely is extremely difficult and, if you ask me, unnecessarily painful.

Conclusion

When making food choices about grains, the critical question is not whether or not a food is “whole” grain but whether the grain is intact. For this reason, it matters very little if you substitute “whole grain” products for regular refined products such as pasta.

Examples of intact grains are oats, barley, brown rice, whole wheat, quinoa (sort of) and faro. White rice is not a whole grain, and is closer to a refined grain than a whole grain.

For optimal health, processed and refined grains should be eaten very sparingly. Small amounts such as those eaten in traditional cultures can be part of any healthstyle, but including them is a personal choice that will depend on your own goals and preferences.

The irony is that if you are able to remove processed foods from your diet, the way you eat could probably be described as low-carb. But this label really undermines a healthstyle based on real food.

Though I eat relatively few grains compared to most Americans, I cringe when I see the shining example of low-carb living, The Atkins Diet website, with images of fake pancakes and pasta plastered all over it. If that is what low-carb is, I want nothing to do with it.

Processed food is still processed food, whether the carbohydrates have been synthetically removed or not. Stick to eating real food and you’ll never have to worry about carbs.

Do you count your carbohydrates?

Originally published November 25, 2009.

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.

Enough people have asked me if the kind of cholesterol in egg yolks is good or bad (hint: it’s neither) that I think it is time for a brief tutorial on this misunderstood molecule.

Rather than put you to sleep with a watered down version of a Wikipedia article I decided to explain the interaction of diet and cholesterol in a short video. Hopefully this will help clear up what cholesterol is and how you should eat to minimize your risk of heart disease.

As always, feel free to drop me questions in the comments.

If you like this story follow me on the new Digg!

Further reading:

• How To Raise Your HDL Cholesterol
• Intact Grains vs Whole Grains
• How To Make Eggs Taste As Good As Bacon
• Book Review: Good Calories, Bad Calories

Photo by Robyn's Nest

Artificial sweeteners and sugar substitutes can be very appealing to people looking to cut their calories or control blood sugar, and I get a lot of questions about them. Generally I don’t recommend processed or sweetened foods and encourage people to break free from regular sugar consumption, but I recently discovered coconut palm sugar and decided to look into it.

Coconut palm sugar has garnered attention as being a low-carb sugar substitute that is both more nutritious and sustainable than typical granulated sugar. Because of its complex flavor it is also gaining a reputation in foodie communities, with establishments like the popular Samovar Tea Lounge in San Francisco switching 100% of its sweeteners over to coconut palm sugar.

Pure coconut palm sugar is a natural product made from the nectar of the coconut palm tree. There are several different varieties of palm (Palmyra, date, etc.), and “coconut palm” specifically refers to the coco nucifera plant.

Most of the “palm sugar” commonly sold in Asian markets is not pure coconut palm sugar but is blended with other fillers such as white cane sugar. Pure certified organic coconut palm sugar is sold under the brand name Sweet Tree in the US, and can be found at some natural food stores. It is also available online at Samovar.

The information in this article applies only to 100% pure coconut palm sugar. Check your labels carefully.

Pure coconut palm sugar reportedly has a naturally low glycemic index (GI)–a measure of how food impacts blood sugar–which has led some people to claim that it is a valuable sugar substitute for people with diabetes or those looking to control blood sugar (the low-carb camp). Indeed, a lower GI may be a good indication that a food is safer for diabetics, though it is not a guarantee.

When I first saw that coconut palm sugar has a low GI I figured it would be composed largely of fructose, similar to the popular sweetener agave nectar (and high-fructose corn syrup). Fructose does not impact blood sugar because it is transported directly to the liver and converted to fat. For an explanation of this mechanism, check out Dr. Lustig’s video on the dangers of fructose.

I was surprised to find, however, that coconut palm sugar is reportedly very low in fructose, and its main sugar component is sucrose (aka table sugar). What confuses me is that the GI of coconut palm sugar is supposed to be 35, while the GI of sucrose is 64.

I feel obligated to qualify the numbers on coconut palm sugar, however, since I could only find a summary of how GI was measured and not the published study itself. Also, this information was only available on the website of a company that sells coconut palm sugar. This doesn’t mean the number is inaccurate, it just means I’d like to see the study repeated by another credible source or two before taking it as fact.

(UPDATE: It seems newer tests have indeed found discrepancies with the reported GI of Sweet Tree products)

The number of calories in coconut palm sugar is almost identical to the number in regular table sugar and its closer relative, brown sugar. But coconut palm sugar is notably higher in various micronutrients, probably because it is less processed than industrial sugars.

But does anyone really eat sugar for health benefits?

There are a number of good reasons to consider using coconut palm sugar as a substitute for white or brown sugar in your kitchen. For me the most obvious benefit is that it tastes amazing, similar to brown sugar but with a rich complexity I’ve never tasted in industrial sugars.

Coconut palm sugar is also supposed to be substantially better for the environment, having been called the most sustainable sweetener by the Food and Agriculture Organization (FAO) of the United Nations (couldn’t find the original FAO report though).

Overall coconut palm sugar is a tastier and possibly healthier and more sustainable substitute for granulated or brown sugar. I wouldn’t go so far as to call it a health food, or even low-carb just yet. However it is a nice pantry addition for foodies concerned with sustainable products.

Substitute coconut palm sugar for traditional sugar at a 1:1 ratio in normal cooking and baking.

Have you tried coconut palm sugar? What do you think?

Photo by markhillary

Last month The American Journal of Clinical Nutrition published a meta-analysis of 21 studies concluding that saturated fat is not linked to heart disease–a finding that flies in the face of 20th century nutrition dogma.

Despite the tremendous impact such information would have on the field of nutrition however, the research was largely ignored by mainstream media outlets.

The meta-analysis performed by scientists at the Children’s Hospital Oakland Research Institute was funded by the National Dairy Council and the Unilever corporation, two institutions with a vested interest in selling food products to consumers. The study was also funded by the National Institute of Health.

Technically funding source should not impact scientific outcomes, but analyses have repeatedly shown that industry sponsorship can strongly predict research conclusions that favor the source of funding.

I asked Marion Nestle, professor in the Department of Nutrition, Food Studies and Public Health at NYU, about the specific impact of industry funding on a meta-analysis of this nature.

“Meta-analyses are particularly subject to investigator bias (conscious or unconscious) because of the selection criteria for inclusion.”

So while this study may provide another clue about the relationship between saturated fat and heart disease, caution should be taken when interpreting the results.

Conflict of interest is a serious concern in science that is used to guide health policy and consumer behavior. In this case the influence of industry sponsorship would be especially unfortunate since an impartial evaluation of the link between saturated fat and heart disease is greatly needed.

Saturated fat is most commonly associated with animal products like beef and pork, and is known to raise cholesterol. Since high cholesterol is considered a biomarker of heart disease, it has long been assumed that saturated fat contributes directly to America’s number one killer.

But while this argument seems to make intuitive sense, a direct causal relationship between saturated fat and heart disease has never been established. Moreover, evidence is accumulating that cholesterol in general is not the best predictor of heart disease and that refined carbohydrates are a bigger problem.

Thus there is a real need for rigorous science regarding the role of saturated fat in heart health and other diseases.

“My take on this one is that it is one more piece of evidence that saturated fat may not be AS important a determinant of heart disease risk as is sometimes believed-at least in the kinds of studies included in the analysis.  These, of course, do not paint a complete picture of the situation.”

Saturated fat is unlikely to make or break any diet in terms of overall health, let alone heart disease in particular. General dietary patterns consistently prove to be better predictors of long-term health than any single food or nutrient, and anything we discover about saturated fat is unlikely to change this.

“In any case, this is another example of what happens when you look at single nutrients outside of their dietary context.”

While we’re waiting for science and industry to battle it out in the lab, focus on eating real, unprocessed foods most of the time and don’t get too hung up on the details.

What do you think of industry sponsorship in nutrition studies?

Update: After speaking with readers and colleagues I have made some revisions to this article to clear up my stand on this research. I do not intend to imply that the investigators of this study were influenced by their funding source, only that caution should be used when interpreting the results of any meta-analysis where there is a potential conflict of interest.

Organic Vegetables

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

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

A few fabulous articles are worth noting:

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

Key criticisms of the FSA report:

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

So what do you think?

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

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

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

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?