For The Love of Food

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

This week how your nose fools your brain, why olive oil is better than canola, and the secret to perfectly cooked veggies.

Want to see all my favorite links? (There’s lots more). Be sure to follow me on on Delicious. I also share links on Twitter @summertomato,  Google+ and the Summer Tomato Facebook page. I’m very active on all these sites and would love to connect with you. (And yes, I took that pepper heart pic myself).

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For The Love of Food

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

This week the emphasis seems to be on the value of whole foods over single nutrients or supplements. Check out my article on the danger of vitamin E supplements over at KQED, the cool new study about why whole broccoli is better than its single nutrients as well as a cool trick for preventing avocados from browning.

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

Links of the week

• Vitamin E Supplements Increase Prostate Cancer Risk <<Scary stuff. But read all the way to the bottom, dosage is important. (KQED Quest)
• Health Benefits of Broccoli Require the Whole Food, Not Supplements <<A small clue as to why vegetables are still more healthy than supplements. I imagine there are many more. (ScienceDaily)
• Is “Natural” A Food Marketing Scheme? <<Big thanks to Food Republic for calling BS of the week for me on the food industry’s gratuitous use of the word “natural.”
• Radical thinking on antioxidants <<I love a nice, healthy dose of reality. Antioxidants aren’t a magic bullet, not by a long shot. (Chicago Tribune)
• Cheating Father Time: 50-Year-Old Can Be Every Bit as Fit as Someone 30 Years Younger, but Exercise Is Key <<Though I still think diet is the most important factor in body weight, don’t forget that exercise is just as important in health. It also makes you look better at any size. (ScienceDaily)
• Eating Green Veggies Improves Immune Defenses <<The difference was much larger than researchers expected. (ScienceDaily)
• Proper Protein Intake Crucial for Moderating Energy Intake, Keeping Obesity at Bay <<Interestingly, raising protein intake from 10% to 15% made a significant difference in reducing overall energy intake, but raising from 15% to 25% did not. (ScienceDaily)
• First Physical Evidence Bilingualism Delays Onset of Alzheimer’s Symptoms <<I think this is really cool. Use that brain, travel, it’s good for you. (ScienceDaily)
• ‘Gardener’ Gives ‘Heirloom Life’ To Forgotten Flora <<Looks like a great resource for gardeners looking to expand their crop. (NPR)
• How To Stop An Avocado From Browning <<Really cool trick from Chow (via Treehugger) on preventing avocado browning with an onion. Also sounds like the start of a great guacamole.

http://www.cbs.com/e/7gcqHsHaWrENebawgpv5c5B_kWM4_xVm/chow/1/

What inspired you this week?

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?
http://forms.aweber.com/form/30/split_210533730.htm

This week, the Journal of the American Medical Association (JAMA) reports that long-term supplementation with either vitamins C (500 mg) or E (400 IU) is ineffective at reducing major cardiovascular events, including heart attack and stroke.

The study was a ten year randomized, double-blind, placebo-controlled trial in low risk, healthy men over 50-years old.

Unfortunately, results do not get any more conclusive than this. Sorry boys, you are going to have to stick with diet and exercise for now.

It was thought that antioxidants such as vitamins C and E may reduce risk of cardiovascular disease by decreasing oxidative damage and reducing inflammation. But it appears that consuming these vitamins in supplement form is ineffective.

It is still a good idea to get enough of these antioxidants from dietary sources, however. Fruit is a good source of vitamin C. Almonds are good for vitamin E. A bonus is that a diet rich in fruits and nuts actually is associated with a lower risk of heart disease.

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Also in JAMA, low-dose aspirin was shown to be ineffective at reducing the risk of cardiac events in patients with type 2 diabetes. This finding is somewhat surprising because aspirin is effective at reducing cardiac events in non-diabetic individuals, and patients with diabetes are considered to be at particularly high risk for heart disease. It was thus reasoned that aspirin should be recommended for people with diabetes. However, in this group of diabetic patients in Japan, aspirin did not the reduce risk of a cardiovascular event.

One thing to note is that this study was relatively small, only 2,539 participants. So it may have lacked statistical power to find a real benefit. If you have type 2 diabetes and are currently taking daily aspirin, I wouldn’t stop just yet.

The good news for everyone is that basic dietary and lifestyle factors are by far the largest contributors to heart disease, diabetes and cancer. You can avoid most of these problems by eating a varied diet of whole foods, maintaining a healthy weight and staying moderately active. I’d choose that over aspirin any day!

Do you take many dietary supplements?

UPDATE: The problems with vitamin C and E supplements were expanded on this week by Tara Parker-Pope at the New York Times Well Blog. It is a great read if you are interested in this topic.