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Antioxidant Supplements May Block Some Benefits of Exercise

by | May 13, 2009
Romanesco Broccoli In A Beaker

Romanesco Broccoli in a Beaker

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

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

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

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

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

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

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

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

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

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

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

Do you take vitamin supplements? Why? How much do you take?
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Fatty Foods Enhance Memory By Same Mechanism As Emotional Learning

by | May 4, 2009
Go Nuts!

Go Nuts!

Have you ever noticed that some of your strongest food memories are of rich, fat laden meals shared with family and friends? According to new research, this may not be a coincidence. A study published last week in the Proceedings of the National Academy of Sciences demonstrates that digesting fatty foods enhances memory consolidation using the same neural pathway as emotional learning.

This finding has far reaching implications for cognitive therapies to fight over-eating, but may also suggest new, easy to implement strategies for memory enhancement. Pistachios anyone?

In the study, rats being trained on memory tasks were administered a substance called oleoylethanolamide (OEA) that normally increases in the gut after the ingestion of dietary fat (not carbohydrate or protein). Several days later, the rats given OEA performed better on the tasks than rats that were not, demonstrating enhanced learning.

To determine the neural pathway involved in this effect, the researchers chemically blocked signaling in the region of the brain that receives neural inputs from the gut (solitary nucleus), which abolished the effect of OEA. Next they selectively blocked neural transmission between this region and another region of the brain that has been shown to be critical for emotional learning (amygdala). This also eliminated the memory enhancement effect of OEA, indicating that emotional memory and memory enhancement from fatty food ingestion share the same neural network.

These findings may partially explain the emotional component that is often associated with chronic over-eating, something that frequently involves learned habits triggered by emotional situations.

However, OEA does more than enhance memory. It is also critical in feelings of satiety after a meal (decreasing hunger) and has been implicated in controlling body weight. Is it possible this new information could be harnessed for the power of good?

Low-fat diets have proved to be a colossal failure for both health and weight loss, partially because they encourage over-consumption of starchy (usually refined) carbohydrates. Moreover, vegetable and fish oils are protective against many chronic diseases that plague Western culture. Regularly seeking healthy fats in your diet can help control hunger, promote weight loss and lower risk of disease. But it now seems that healthy fats could also be a useful tool in overcoming emotional eating, a problem more complex than the standard weight gain that comes from 21st century living.

Another interesting corollary of this study is that fat (specifically oleic acid, a healthy fat found predominantly in olive oil and nuts) may enhance learning and memory. Since the benefits of OEA were only evident when it was administered at the time of or immediately after training, the next time you study or prepare for a presentation you might want to have some nuts around to snack on. Almonds, cashews, hazelnuts, macadamia nuts, peanuts, pecans and pistachios are highest in oleic acid.

Are you interested in foods that could provide cognitive enhancement?

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Is Organic Food Really Better?

by | Mar 23, 2009

organic artichokesIt seems all the nation is abuzz with organic fever. The number of farmers markets has increased dramatically in the past several years, sales of organic products have more than doubled and even the new First Family has jumped on the organic bandwagon.

But in uncertain economic times, some people are asking if the higher cost of organic foods is worth the benefit. And when it comes down to it, what benefit are we really talking about anyway?

When discussing organic food, most people are referring to food that complies with and has been accepted as “Certified Organic” by the United States Department of Agriculture (USDA). USDA’s Organic Standards were set in 2002, twelve years after the Organic Foods Production Act of 1990.

In order for a food to become Certified Organic, the grower of the food must be inspected for compliance with the USDA’s “Organic Standards” by an accredited state or private agency. Generally this means the foods are free of chemical fertilizers, herbicides and pesticides, and have not been irradiated or genetically modified in any way.

There is extensive evidence that adults and children who eat exclusively organic foods have lower levels of pesticides in their bodies. How these pesticides can affect your long-term health is not clear, but they are unlikely to make you healthier and may in fact have lasting, negative consequences. If pesticides are a concern to you, organic is certainly a better option.

Beyond pesticides, the benefit of organic foods becomes a little murky. As recently pointed out by Mark Bittman in the New York Times, organic certification offers no guarantee that foods are either better for you or for the planet.

But that is not to say that how food is grown is not important. Soil quality is in fact one of the most significant determinants of the nutrient value of foods. Another important factor is the genetic make up (the strain and variety) of plants being grown. That is, ice burg lettuce will add little value to your diet whether it is organic or not.

But as Bittman points out, the reason Certified Organics “fall short of the lofty dreams of early organic farmers and consumers” is because Organic Standards make no mention of how far food may travel from soil to sale, nor do they promise anything about a food’s safety or nutrition. In other words, organic food is not local food.

It is generally accepted that the farther food travels to reach your plate, the less nutrients it has and the bigger its carbon footprint. Slapping a Certified Organic sticker on it does not change this fact. Better than buying Certified Organic is shopping at smaller, local farms that may or may not have the resources to comply with costly organic regulations.

But these subtle distinctions are largely irrelevant to most American’s who consume little, if any, fresh vegetables and fruits. At a certain point, arguing about the costs and benefits of organic produce is of little value. For most Americans, the first step in eating healthier is to focus on freshness.

That being said, there are many good reasons to avoid big agriculture whenever possible, organic or not. Whole Foods organic peanuts were not immune from the recent Salmonella outbreak. Large processing plants come with their own unique set of risks in food production.

Local produce is also better if money is your biggest concern. The fuel cost of shipping organic asparagus from Chile to San Francisco is substantial, as is the price of becoming a Certified Organic grower. For these reasons, locally grown but non-organic foods are less likely to carry the hefty price tag that most of us associate with Certified Organic.

Do you buy organic produce?

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Top 10 Food Facts Everyone Should Know

by | Feb 23, 2009

winter vegetablesIn honor of the food issue this week at Synapse, I compiled a list of ten essential diet and nutrition facts you might not know:

  1. “Vitamins” are not the same as whole foods. Instant ramen and a multivitamin is not a healthy meal. There is no substitute for a diet of whole foods rich in vegetables, beans, grains and fish.
  2. A healthy diet can prevent or even reverse four out of the six leading causes of death in the US. Evidence indicates that diet is more important than genetics in the vast majority of heart disease, stroke, cancer and type 2 diabetes cases.
  3. The thinnest, healthiest people in the world eat “high carb” diets. But they definitely do not eat the processed, refined carbohydrates that flood Western culture. If you want to lose weight and live longer without disease, eat more vegetables and whole grains.
  4. You get plenty of calcium. Americans consume more calcium than most countries on earth, yet still sport some of the highest rates of osteoporosis. This debilitating disease is more likely caused by insufficient vitamin D, not enough exercise and/or too much protein. Also, excess calcium is linked to prostate cancer and milk to ovarian cancer. Calcium does not support weight loss either.
  5. “Fiber” is not the same as vegetables and grains. Fiber supplements do not offer the same benefits as fiber-filled foods, and do not help with weight loss or protect against disease.
  6. The best sources of protein are plants and fish. It is relatively easy to get complete protein (i.e., all the essential amino acids) from a diverse diet. Protein from red meat offers more risk than reward. (Yes, pork is red meat.)
  7. Fruits and vegetables protect your vision. Both cataracts and macular degeneration are strongly tied to diet.
  8. Fats from factories are dangerous. Processed oils and trans fats (not total dietary fat) are associated with heart disease, type 2 diabetes, cancer and obesity. Replacing them with natural oils could save your life.
  9. Fats from plants and fish are essential. Mono- and polyunsaturated fats protect against heart disease, type 2 diabetes and memory loss. In moderation they can also aid in weight loss, since they increase the satiety you feel after a meal.
  10. You can lose weight on any short-term diet, but you will probably gain back more than you ultimately lose. This is often true even if you stay on the diet. Focusing on long-term health is the best strategy for sustained weight loss, but it requires patience.

What are other common myths about diet and nutrition?

UPDATE: For more information on the health value of oils from fish, please read my answer in the comments section.
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10 Steps To A Perfect Valentine’s Day Dinner

by | Feb 1, 2009

Call me old-fashioned, but I still think Valentine’s Day should be about romance. But that doesn’t mean you have to stick to the usual Valentine’s clichés to do it right.

For me, nothing is less romantic than aping exactly what everyone else is doing. Roses are beautiful, but there are 364 other days in the year to buy roses. (Hint boys: If you really want to woo your lady, bring her flowers when she isn’t expecting it).

Valentine’s Day dinner is your perfect opportunity to get creative.

When most people think of a romantic meal they envision a fancy French restaurant with candles, snooty waiters and expensive wine. I will not deny that I love restaurants like this, but you couldn’t pay me to go to one on Valentine’s Day.

The problem is that every year on February 14 restaurants are bombarded with customers, and to prepare they usually arrange a special prix fixe (i.e., price fixed, pronounce “pre-fee”) menu that costs way more than normal. Prix fixe menus are arranged into several courses where you pick from a short list of items for each course. These menus are almost always more limited than the restaurant’s traditional menu and lock you in to a preset number of items that you may or may not want.

Why not do something really romantic and make dinner yourself?

Cooking a romantic meal is not actually as hard as it sounds. The trick is investing time and money to be sure you get the best ingredients. The next step is picking through recipes until you find ones that are within your means.

I recommend aiming high. Preparing ambitious and exotic recipes is incredibly rewarding and will give you and your lover a fresh appreciation for the artistry of fine food and cooking.

Here are 10 steps for planning your perfect Valentine’s Day dinner:

  1. Plan in advance. The reason cooking at home is more romantic than going out is that you take the time and effort to do something thoughtful for your sweetheart. Do not skimp on the planning stage, that’s equivalent to buying a gift from Walmart. You will need the time for research and ingredient acquisition.
  2. Pick your ideal meal. At the beginning do not exclude recipes because you think you cannot cook them. You may be surprised by how easy it is to make a perfect filet mignon on an electric stove.
  3. Compile recipes. The internet is overflowing with fantastic gourmet recipes. Spend an hour or two searching for your favorite dishes and find the ones that sound the most delicious and seem within your means. At this stage you can start excluding recipes/dishes that are outside your technical prowess, but beware there is an easier way to do almost everything. You should also start noting the similarities between recipes for the same dish. This will help you when it comes time to put the meal together.
  4. Don’t forget dessert. Baking is more of an exact science than normal cooking. If this is out of your league (it is definitely out of mine), it may be a good idea to order something exquisite from your favorite bakery.
  5. Make the final cut. Choose dishes not only because you like them, but because the flavors go well together and you think you can get them all on a plate at about the same time. Consider presentation and appearance as well. Things that can be made a few hours or even days ahead are particularly nice. I usually end up mashing a few different recipes together to create the dish I want.
  6. Invite your date. Now that you have your menu it is time to invite your sweetie to your Valentine’s Day dinner. Tell him/her you have an amazing meal planned especially for them. Awwww, so sweet!
  7. Research your ingredients. Start early to make sure you can get the best of everything you want. If you don’t know what the best is, find out! If you want to have a special cut of meat or a certain spice or vegetable, spend some time on the internet to discover where and when you can get them in your city. Farmers markets are the best place to get most foods, but are usually only held 1-2 days per week. Luckily for you, this year Valentine’s Day falls on a Saturday. Do your planning now and go to the market early so you do not miss out.
  8. Prepare your kitchen. Check your kitchen to make sure you have everything you need for your perfect meal. If your recipe requires special equipment, go buy it right away. If you cannot find it, do some research on acceptable alternatives or see if you can borrow what you need from a friend.
  9. Arrange your props. Candles, music, champagne flutes and mushy cards add to the ambiance of your special evening. Do not forget to pay attention to these details.
  10. Make your meal and have a wonderful time. If you start with good ingredients, it is hard to mess up too bad, but do not let it ruin your evening if things don’t turn out as perfectly as you envisioned. Remember, you are doing something incredibly special for the one you love and that will earn you major bonus points. It is a scientific fact that a meal cooked from the heart tastes better than anything handed to you on a silver platter.

What are your favorite special occasion recipes?

UPDATE: This article is also available at Synapse.

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