Thursday, July 1, 2010

Organic Food versus Conventional Food

After people have low-carbed for a while, they start to look better and feel better. As their health improves, one of the natural questions to ask is, "If I feel this good by dropping the carbs, wouldn't I feel even better if I ate organic food?" When this question is asked in the form of scientific studies, the short answer is, "Probably not."

To be sure, the alternative medicine community makes many claims for organic food. In Alternative Medicine Review, Walter J. Crinnion, a Nutritional Doctor, states that organic foods contain higher levels of certain nutrients, lower levels of pesticides, and may provide health benefits for the consumer. Please click the link for an extensive list of references.

On the other hand, in 2010 in the American Journal of Clinical Nutrition, Dangour et al. interviewed experts, searched bibliographies, and checked peer-reviewed articles with English abstracts. They found a total of 12 studies that evaluated health effects following the use of organic compared with conventionally produced foods. The authors reported that the largest study showed a 36% reduction in risk for allergic eczema when children under two consumed organic dairy products. Other than that, the majority of the studies showed no differences resulting from organic foods versus conventionally produced foods in nutrition-related health outcomes.

In one sense, this is not surprising. A 2009 literature review by the same group showed that there were very few differences in nutrients between organic and conventionally produced foods. In crops, eleven nutrient categories were analyzed. Conventionally produced crops had a significantly higher content of nitrogen, while organically produced crops had a significantly higher phosphorus and more acidity. The other eight categories were not different between the two groups. An analysis of the database on livestock products found no differences in nutrients between organic and conventionally produced products.

This finding is supported by the UK Food Standards Agency which found that nutrient levels vary as a result of freshness, storage conditions, crop variety, soil conditions, weather conditions and how animals are fed, rather than as a function of whether the food is produced in an organic or a conventional manner. They caution that while single papers may show differences in the nutritional content of a particular food, it is important to evaluate the weight of evidence across a range of published papers.

An important consideration favoring organic food is that organically grown foods have about one third the pesticide residues as do conventionally grown foods. A study in elementary age children found that their urinary organophosphorus pesticide metabolites were significantly lower when a conventional diet was replaced by one with organic food items. However, chemical pesticides are not the only ones available. It is important to note that while organic farming does not allow the use of synthetic pesticides, it does permit the use of plant-derived pesticides including Bt, pyrethrins and rotenone, and all of these exhibit varying degrees of toxicity in humans.

Another concern is ecological rather than health-related. Organic farming requires more land per unit of food produced. Repeated use of soil for growing crops makes it necessary to use fertilizer. In place of chemical nitrates and ammonia, organic farmers must obtain and apply manure and use crop rotation with leguminous plants to return nitrogen to the soil. When soils are phosphate-depleted, conventional farmers can use highly soluble chemically-made superphosphate while organic farmers must use poorly soluble rock phosphate. These practices, along with the poorer efficiency of organic pesticides and the need to till the land frequently to prevent weeds, means that the production of food is up to 50% less efficient when it is done organically. (See Reference 15 here.)

Even if a country has plenty of land to devote to food production, there are a couple of other items that should be considered. The use of manure rather than chemicals as fertilizer introduces the presence of bacteria, especially in fruits and vegetables that are eaten fresh. Because organic food production does not use antibacterial techniques such as food irradiation or chemical washes, it is very important to wash organic foods before they are consumed. Finally, organic foods tend to spoil more quickly than their conventionally produced counterparts, which makes it necessary to buy them when they are fresh and to use them up quickly. This is especially important with grains, seeds and nuts which are liable to produce mold and its associated toxins.

As is frequently the case, I can't come down on one side or the other in the case of organic versus conventional food. Sometimes people have worries about the possible effects of agricultural chemicals. Sometimes they prefer the taste and smell of organically produced food. Sometimes they simply want to get back to a more natural way of living. If that's the case, and if they are aware that eating natural foods is not completely risk-free, then they should go ahead and buy organic food. But speaking from a scientific perspective, and looking at groups of people rather than at individuals, it's probably fine to buy and eat food that is produced in conventional ways.


Trevor said...

Thanks so much for the great article, Stargazey!

I was finding that the studies were back and forth as well in terms of the nutritional density of the foods. Sometimes the organic would be more nutrient dense, and sometimes pesticides actually made the foods more nutritious. It seems to me that if people are getting enough calories in their diet while eating the low-carb foods you recommend, that the tiny difference between the foods would not really matter. I know when I have kept track of my food intake on I have found the the natural foods I eat put me way over the top for the rda for all of the micronutrients they track.

The interesting question to me would be how the extra little bit of pesticides interacts with the body on a biochemical level. Are they flushed out or do they accumulate? The test with the children showed that some at least are flushed out. To me it is not a cause for alarm if pesticides are seen observed leaving the body. But if they are not, and twenty years later they have accumulated enough to have a negative impact on one's health, then that would obviously be cause for alarm.

Thanks again for your diligent research, Stargazey!

Stargazey said...

You're welcome, Trevor! It was a very interesting project.

As for your question on accumulation of pesticides, I have some work to do in the real world, so give me a few days and I'll see what I can come up with.

Stargazey said...

Trevor, you asked, "The interesting question to me would be how the extra little bit of pesticides interacts with the body on a biochemical level."

Of course that's different for each pesticide, and probably it's somewhat different for each individual person.

To answer your question in a broader sense, we can look at the Agricultural Health Study, a longitudinal study of the effects of pesticides on farmers, their families, and on people who apply pesticides. (Because these people are exposed to the pesticides as they are applied, presumably any effect of pesticides would be greater for them.) Under Cancer Incidence in the Agricultural Health Study it says, "The overall cancer occurrence among farmers and their spouses in the Agricultural Health Study (AHS) is significantly less than that expected compared to other men and women of the same age living in Iowa and North Carolina. Farmers have only 88% of the cancer expected and their spouses have only 84% of the cancer expected. Commercial pesticide applicators, on the other hand, were observed to have the same cancer frequency as that of other men in Iowa and North Carolina." That would imply that for consumers, there isn’t much cause for worry from pesticides currently being applied in the U.S.

Another way of looking at the problem is the fact that many of the chemicals found in our food are natural pesticides that plants synthesize on their own to protect themselves. Bruce Ames (the developer of the Ames Test) published an extensive article in the Proceedings of the National Academy of Science. He states, "We calculate that 99.99% (by weight) of the pesticides in the American diet are chemicals that plants produce to defend themselves. Only 52 natural pesticides have been tested in high-dose animal cancer tests, and about half (27) are rodent carcinogens; these 27 are shown to be present in many common foods." That is, the vast majority of the pesticides we eat are produced by the plants themselves, and of the ones that have been tested, half of those are carcinogenic in rats.

Read the article and you will never think of tomatoes, potatoes, celery and coffee in the same way you used to.

Trevor said...

Wow, that study by Bruce Ames definitely opened my eyes to a much greater degree about natural pesticides! I knew they existed but not to that extent. I run into a number of people who think that if the food is natural it is healthy. But that is too simplistic of a view. As the study shows, many of the thousands of defense mechanisms that plants have are mutagenic and pose a greater risk to our health than synthetic pesticides. I'm not worried about either though, unless the concentrations are great enough, like in hemlock. The point of the study was not to make people afraid of eating altogether, but to cast doubt on the potential harm of synthetic pesticides when they are measured in the parts per billion, while the naturally occurring ones are measured in parts per thousand or million.

I was very surprised by the other study which showed fewer incidences of cancer among farmers exposed to pesticides than those in neighboring areas. I thought the rates would either be the same or a little higher.

Once again I thank you for sharing your time and expertise, Stargazey.

Trevor said...

Hi Stargazey,
As I’ve been learning more about biochemistry from a number of books and sites, including your own, I’ve noticed that most of the emphasis is on weight-loss or weight-gain prevention. What I have gleaned, among other things, is that carbs not immediately used for energy are stored as fat. I’ve read this at least 50 times. This makes sense for those who have had or are having weight problems. It doesn’t ring true for me though because I have been slim/athletic my whole life, and until the last 6 months I was eating a very high carb and high calorie diet where I avoided eating fat like the plague because I was under the impression that it was bad for me. Whether or not I would exercise I would not gain fat. If I worked out hard consistently I could put on some muscle weight, but never fat. I was not skinny-fat either. My body fat % hovers around 6-7% and I have always been quite strong.


What happens to the consumed carbs for people like me since they don’t get turned into fat and don’t need to be used right away in exercise?

I’ve heard mention that different body types can handle different amount of carbs. I can definitely eat carbs and not gain weight, but does the carb consumption still have the negative impact internally (AGEs, etc.) that it does for those who are more weight-sensitive to carbs? Are carbs destructive in the long term whether or not someone gains weight from them? I don’t just want to be a healthy weight, I want my cells to be healthy as well.

Thank you!

Stargazey said...

Good question, Trevor. What you're missing is the concept of insulin resistance.

It is not practical for us to eat continuously. So we eat discrete meals, use some of that energy immediately, and (in response to a signal from insulin) store the rest for use later. Several hours after a meal is consumed, our insulin levels will normally fall, and this will permit nutrients to come back out of storage until it is time for our next meal.

As people get older, the insulin response system may begin to break down. When that happens, the pancreas has to secrete more and more insulin in order to store nutrients following a meal. The elevated insulin takes longer and longer to return to its normal baseline levels, until it stays somewhat elevated all the time. This is called insulin resistance.

When blood insulin remains high over time, it becomes progressively harder for stored nutrients to be released between meals. In other words, energy (mostly in the form of fat) is being stored at mealtime, but the energy in the fat can no longer be released efficiently between meals. The result? If a person has excess fat stores but also has persistently high insulin levels, he will be less and less able to access the energy he has stored.

Not everybody develops insulin resistance, but eating high carb meals requires high insulin secretion for post-meal storage. After several decades of intense use, our insulin signaling system may no longer work as efficiently as it did when we were young. Sometimes (but not always) the clue that this is happening is weight gain.

Bottom line: do some reading about insulin resistance and all of this should start to make sense.

And yes, until the carbs you have eaten can be cleared from your blood, protein glycosylation can happen.