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http://npic.orst.edu/health/foodprac.html

 

I am wondering about Dean's elaborate washing methods. According to this objective, science based site above that is not necessary.

 

Plain running water for 20 seconds while rubbing with your hands and drying it afterwards for tender things like strawberries, plums, tomatoes and for leafy stuff disposing outer leaves and then rinsing and for thick skinned foods scrubbing/peeling/rinsing. No mention of peroxide, vinegar etc.

So what's up with that Dean?

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Mike,

 

Thanks for the link to the National Pesticide Information Center (NPIC), which from their About Us page describes themselves as follows:

 

NPIC provides objective, science-based information about pesticides and pesticide-related topics to enable people to make informed decisions about pesticides and their use. NPIC is a cooperative agreement between Oregon State University and the U.S. Environmental Protection Agency.

 

NPIC provides some really helpful insights and advice. I'll quote a couple passages, and then address your question about my own elaborate washing methods.

 

Mitigating Alex's concerns to a certain degree:

 

By the time food reaches your grocery store, pesticide residues are generally far below the legal limits. However, low levels of pesticide residues may still remain on some foods, even organic foods.

 

Here is the first strategy they recommend for minimizing the possibility of harmful pesticide exposure, with which I wholeheartedly agree (their emphasis):

  • First, eat a variety of fruits and vegetables to minimize the potential of increased exposure to a single pesticide.

Here are their other advice bullet items:

  • Thoroughly wash all produce, even that which is labeled organic and that which you plan to peel.
  • Wash your produce under running water rather than soaking or dunking it.
  • Dry produce with a clean cloth towel or paper towel when possible.
  • Scrub firm fruits and vegetables, like melons and root vegetables.
  • Discard the outer layer of leafy vegetables, such as lettuce or cabbage.
  • Peel fruits and vegetables when possible.
  • Trim fat and skin from meat, poultry, and fish to minimize pesticide residue that may accumulate in the fat.

I must say I eat the skin of some fruit (like oranges) which I buy organic. But I don't peel many of my produce items, even those I buy conventional (e.g. apples, potatoes, peaches, cucumbers). Many of these I get from my CSA during spring/summer/fall, which I know uses minimal spraying and not near harvest time, having discussed it with the farmer who runs it. For the vegetables I grow myself for much of the year (leafy greens & tomatoes), I know they haven't been sprayed, so I'm not worried. In fact, I hesitate to say it, but for my own homegrown produce, I often don't even wash it...

 

But there are definitely both fruits and vegetables that I buy conventional from the grocery store and don't peel. The fruit that falls into this category (e.g. strawberries, blueberries, apples), I do as you suggest, just running them under water and scrubbing the tree fruits with my hand.

 

The only stuff I triple wash, using 10-min baths in diluted hydrogen peroxide, diluted white vinegar, and water, with thorough rinsing between each round (described above here), for my 'chunky' veggies, and leafy greens in the winter when I buy them from the grocery store (mostly Aldi's). The motivation for that strategy is twofold. First, I eat so many and so much vegetables, scrubbing each one seems too much of a pain. Plus I loathe wasting good produce, so I don't like to peel off and discard the outer leaves of anything. Plus, given the convoluted surfaces of many vegetables (e.g. broccoli) scrubbing seems like it would be ineffective and removing much anyway - unable to reach into all the little nooks and crannies.

 

So in lieu of scrubbing, I give all my vegetables several rigorous and agitated dunks in the three liquids, making sure the peroxide solution is first so that by the time the produce has gotten through the other two stages, the peroxide is neutralized and washed away.

 

The other reason is based on advice from Dr. Greger, who actually these days (in this video) recommends washing with either vinegar or salt solutions to eliminate pesticide residue, based on this study [1], showing both vinegar (acetic acid) and salt solutions were much more effective than soaking in water for removing pesticides:

 

Washing with acetic acid solutions (at 10% concentration for 20 min) caused 79.8%, 65.8%, 74.0% and 75.0% loss of the above pesticides, respectively. Washing with NaCl solutions (at 10% concentration for 20 min) produced 67.2%, 65.0%, 73.3% and 74.1% loss, respectively, and washing by tap water (for 20 min) were 17.6%, 17.1%, 19.1% and 15.2% loss, respectively. 

 

But the effective salt amount was a 10% solution. That's a lot of salt, especially since I use 5 gallon buckets to wash my veggies once per week. I put about 3 gallons of water in each bucket, which weight ~25 lbs, meaning I'd have to use ~3 lbs of salt per week to reach the recommended concentration to eliminate pesticides. That's a lot of salt, and I'm not sure how well it would wash off (or soak in instead!). Of course I don't use the full strength vinegar shown to eliminate pesticides in the study he references either, so...

 

The hydrogen peroxide isn't meant to remove pesticides, but to reduce or eliminate bacteria that might be living on the surface of the produce. Thanks so much Mike for prompting me to look into this. I've been doing this for years, spending about $0.50 per week on a half bottle (8oz) of hydrogen peroxide solution, which I dump into my first bucket of rinse water. Given it's a 3% solution to start with, which I'm dumping into 3gal of water, I've known it's not much, but I figured it might be doing something...

 

But this 2015 study [2] shows I've been wasting my time and money:

 

There was no significant difference between the [bacterial count] on fresh-cut leafy vegetables washed with H2O2 and those washed with water.

 

I'm definitely discontinuing my hydrogen peroxide rinse practice. I may dump some salt into the first bucket, but definitely not 3 lbs...

 

Thanks again for prompting me to review of my practice in this area!

 

I'm curious what other people do to wash their fruits and veggies.

 

--Dean

 

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[1] Food Control Volume 18, Issue 12, December 2007, Pages 1484–1487

 

Zhi-Yong Zhanga, b, Xian-Jin Liub, , , Xiao-Yue Honga,

 

Abstract
Experiment was carried out to evaluate the pesticides (chlorpyrifos, p,p-DDT, cypermethrin, chlorothalonil) residue levels in cabbage in the process of home preparation by washing with different concentrations of acetic acid and sodium chlorine, and tap water, preserving in refrigerator, and stir-frying for different time. Results showed that washing by tap water and/or detergent solution for cooking are necessary to decrease the concentration of pesticide residues in cabbage. Washing with acetic acid solutions (at 10% concentration for 20 min) caused 79.8%, 65.8%, 74.0% and 75.0% loss of the above pesticides, respectively. Washing with NaCl solutions (at 10% concentration for 20 min) produced 67.2%, 65.0%, 73.3% and 74.1% loss, respectively, and washing by tap water (for 20 min) were 17.6%, 17.1%, 19.1% and 15.2% loss, respectively. The reductions due to the refrigeration (for 48 h) were 3.4%, 2.6%, 3.1% and 3.6%, respectively, and those due to the stir-frying (for 5 min) were 86.6%, 67.5%, 84.7% and 84.8%, respectively. The data indicated that washing by detergent solutions and stir-frying of cabbage are the most effective home preparations for the elimination of pesticide residues.
 
Keywords

Pesticide residues; Home preparation; Cabbage

 

DOI: http://dx.doi.org/10.1016/j.foodcont.2006.11.002

 

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[2] Food Control Volume 50, April 2015, Pages 173–183

 

Wash water disinfection of a full-scale leafy vegetables washing process with hydrogen peroxide and the use of a commercial metal ion mixture to improve disinfection efficiency
 
S. Van Haute, b, I. Tryland, A. Veys, I. Sampers
 
Abstract
Hydrogen peroxide (H2O2) was used to maintain the microbial wash water quality of a full-scale leafy vegetables (radicchio, sugar loaf, curled endive, lollo, lollo rosso) wash water process. Despite addition of 300 L/h of 1.8% H2O2 to a 450 L washing bath (333 ± 50 kg/h fresh-cut produce introduction speed), the H2O2 quickly decreased and a lower wash water contamination of aerobic psychrotrophic plate count (APC) and enterococci than without addition of H2O2 could not be maintained. There was no significant difference between the APC on fresh-cut leafy vegetables washed with H2O2 and those washed with water.
 
In a second part, lab-scale experiments were performed to assess the impact of a commercial metal ion formulation (Bacsan®, containing a. o. Cu2+, Zn2+, Ag+) on the stability of H2O2 in artificial wash water, made from iceberg lettuce and tap water. Bacsan improved the stability of H2O2 in artificial lettuce wash water and fresh-cut leafy vegetables wash water from a processing company and synergistically increased the disinfection efficiency of APC and Escherichia coli (E. coli) compared to H2O2 or Bacsan. Increasing chemical oxygen demand (COD) had detrimental effect on the H2O2 stability and disinfection efficiency. Addition of Ag+ to Bacsan further synergistically enhanced the H2O2 stability.
 
H2O2 is not suited as an in situ wash water disinfectant to avoid cross-contamination in fresh-cut leafy vegetables washing processes due to the slow water disinfection kinetics and the rapid H2O2 consumption. However, H2O2/Bacsan shows potential for use in off-line processes.
 

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Alex asked above about my perspective on pesticides, and the Environmental Working Group's (EWG's) "Dirty Dozen". I pointed to a few posts (herehere and especially here) where I documented the reasons for my skepticism about risks of conventional produce.

 

When asked about evidence of toxicity, Alex said:

I haven't found any non-developmental studies [i.e. studies that show detrimental effects of dietary pesticide residue beyond fetal/infant development], but this is a scenario where erring on the safe side may be preferable just in case... (though this usually means that I'll eat less rose-family fruits/strawberries/grapes, as I'm not super-rich).

 

Ironically, the next day Alex reported potentially having sickened (I hesitate to say poisoned) himself from too much iodine from seaweed, or eating too much chia and/or cabbage. 

 

Which brings me to this new interview (embedded below) by Andrew Perlot on his Renaissance Human podcast of a toxicologist who worries that the public has been frightened into not eating enough total or enough variety of fruits and vegetables due to the fact that they can't afford organic produce and the mistaken belief that conventionally-grown produce is toxic due to pesticide residue.

 

At 15:20 (direct link), he specifically talks about how bogus the EWG's "dirty dozen" methodology is for assessing risk.

 

Very eye-opening interview. See the show notes under the video below.

 

--Dean

 

 

Show Notes:
 
2:39 – Why Dr. Winter got interested in toxicology and food safety.
3:43 – Is toxicology a field where a scientist’s work can lead to real-world health improvements?
 
5:22 – The disproportionate amount of fear surrounding conventionally-sprayed produce vs other high priority food threats.
 
9:45 – Do most toxicologists have great concerns over the presence of pesticide residue on fruits and veggies.
 
10:56 – The upsides and downsides of conventional and organic produce
 
15:20 – The validity of the dirty dozen list
 
19:08 – We hear bad things about conventional produce and the pesticides on them on a regular basis. What criteria should we use to determine if we should really be concerned about our risk?
 
23:18 – Is it probable or possible that the necessary science hasn’t been done to detect the harm that pesticides and conventionally-sprayed produce is doing to us?
 
25:37 – Has our food supply become more dangerous or safer over the last generation or two?
 
27:36 – Is the amount of pesticide residue consumers are exposed to declining over time?
 
28:46 – Do organophosphates or any other pesticides need to be further investigated?
 
32:19 – Food safety standards in the European Union vs The United States
 
34:51 – Home exposure to toxins that may be worse than what you get from food.
 
37:50 – The surprisingly high toxicity of organic-approved pesticides.
 
41:20 – What to make of higher disease risks among farm workers in high spray areas.
 
44:58 – Where Dr. Winter would put his research dollars to improve health regarding pesticides?

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Very interesting example of nearly 100% raw, vegan diet. The health benefits of such a diet most probably would include enhanced lifespan.

 

One issue which apparently is vital to the good outcome of a raw vegan diet is the large volume of food ingested. It also requires that the digestive system accepts and accomodates the food. The single attempt I made to such a diet failed miserably since my hunger went rock bottom and I only could eat 2 apples, 100 grams of almonds and a bunch of lettuce per day.

 

There is the example on Youtube of the girl named FullyRaw Kristina, whom you guys probably know, who eats raw vegan without even nuts but when you see what she eats you would almost think that's the meal of an elephant. Sheer quantities, obviously coupled to some variety,  would seem to do the trick here. On another vid she is in Dr Garth Davis clinic to have her blood sampled, and she turns out with perfect labs. the 'elephant meal' I saw maybe in another vid but it was impressing. Congratulations to her digestive system.

 

 

 

Edited by mccoy

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On 8/26/2016 at 2:06 PM, Dean Pomerleau said:

 [Some] stuff I triple wash, using 10-min baths in diluted hydrogen peroxide, diluted white vinegar, and water, with thorough rinsing between each round (described above here), ... I give all my vegetables several rigorous and agitated dunks in the three liquids, making sure the peroxide solution is first so that by the time the produce has gotten through the other two stages, the peroxide is neutralized and washed away.

The other reason is [that] ... vinegar or salt solutions [may] eliminate pesticide residue, based on this study [1] ... But the effective salt amount was a 10% solution. That's a lot of salt ... Of course I don't use the full strength vinegar shown to eliminate pesticides in the study he references either, so...

The hydrogen peroxide isn't meant to remove pesticides, but to reduce or eliminate bacteria that might be living on the surface of the produce. ... But this 2015 study [2] shows I've been wasting my time and money:

There was no significant difference between the [bacterial count] on fresh-cut leafy vegetables washed with H2O2 and those washed with water.

I'm definitely discontinuing my hydrogen peroxide rinse practice. I may dump some salt into the first bucket, but definitely not 3 lbs...

[2] Food Control Volume 50, April 2015, Pages 173–183

Wash water disinfection of a full-scale leafy vegetables washing process with hydrogen peroxide and the use of a commercial metal ion mixture to improve disinfection efficiency
S. Van Haute, b, I. Tryland, A. Veys, I. Sampers

DOI: http://dx.doi.org/10.1016/j.foodcont.2014.08.028

I don't think anyone ever suggested that dilute vinegar or peroxide was any good for either microbes or pesticides: I use these less than I used to, but I use them at full off-the-shelf potency, with a misting spray bottle or (rarely) by swishing during immersion. (I don't do this with things like berries, however, as it's hard to get the taste out and they sometimes exacerbate damage to the fruit).

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Hey Dean, I just watched Dr. Greger's latest video today and I'm wondering what you make of it. I know you precut a weeks worth of veggies (or at least you used to). Wondering if this will make you reconsider that approach or what you make of it. Maybe it's too minor of an issue to really spend any thought/energy on. I can't tell myself.

 

 

 

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Interesting. This is why I'm obsessed with "protocol and dosing" - clearly necessary with diet components too. You can't just say "eat onions", but "freshly chopped" etc.

OT - can I just say, that I always found Dr. Greger's mannered delivery very distracting, but now that he actually appears physically in the video this effect is hugely exaggerated - his bobbing and weaving and gesturing distracts from the studies he highlights and it takes up screen real estate. I think he should go back to just reading his commentary without the visual horror show... but who knows, it might be just me - YMMV.

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Hi Thomas!

I saw Dr. Greger's video earlier today. He basically points to evidence that inflammation-causing bacteria can build up in pre-chopped veggies over time. I looked at the full text of the studies he cites. Here was the most relevant section:

Stimulants of [inflammatory] TLR2 or TLR4 were not detectable in freshly chopped onion or carrot on the day of preparation, but tended to increase with time from 4 days onwards when stored exposed to air at 5 degC.

What it appeared they did was buy pre-chopped onions and carrots at a supermarket where they'd been sitting at who knows what temperature for a couple days, and them stored them for a further 4-12 days at 5 degC (41degF). No wonder the freshness suffered and bacterial load increased!

As I've discussed before, the key to keeping chopped veggies very fresh for up to a week is to store them very close to freezing. I've got my fridge dialed in so that cycles between 30 and 34degF. I see very little change in freshness of chopped veggies after 7 days at this temperature.

But having said that, I feel compelled to report a recent shift in my eating pattern given the title of this thread. Two months ago, I underwent a medical procedure that prevented me from eating or exercising as much as I normally do. So I shifted from eating one very big meal per day to spreading my eating over a 5 hour period, and chopping veggies "to order" depending on how active I was that day and how much I thought I could eat.

I'm now back to eating and exercising my normal amount but have retained the more distributed eating pattern (19:5), and daily (rather than weekly) veggie chopping. Why? Habit mostly, but also because I realized I'm not so busy anymore that the increased efficiency of weekly chopping or eating only once per day is very important. This evidence of the advantage of freshly chopped produce adds a tiny bit of motivation to continue with this new regime.

P.S. I agree with you Tom that Dr. Greger appearing "in the flesh" in his own videos adds nothing and is a bit distracting.

--Dean

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I buy various leafy veggies - arugula, baby kale, baby spinach etc. for our daily salads - and they all come in plastic bags at the market (usually TJ's). Now I wonder if this "bacteria buildup" applies to this as well? If the bacterial growth is a function of surface area, then freshly chopped onions have a very large area on which the bacteria can grow, wheras the leafs of baby kale or arugula or spinach mostly expose the stem - of course some, as in the arugula, the leaves themselves may be somewhat torn, but the torn edges should not be very large in area. 

[...]I realized I'm not so busy anymore that the increased efficiency of weekly chopping or eating only once per day is very important.

That's intriguing - because I've been moving in the opposite direction. I have found that through the years I've accumulated a number of health/wellness practices/behaviors which in aggregate are taking up a not insignificant chunk out of my day. Each behavior in isolation may seem just a few minutes, but when put together are very costly time-wise. Combine that with doubts about the ultimate effectiveness of some of these and I'm increasingly thinking about either eliminating or transforming them.

For example, it takes me a few minutes daily to do my Power Breathing (I started a thread about this practice), but I'm really wondering if I should continue - I had a brief conversation with a physician about this, and he pointed out something that I've been already thinking - the studies which show benefits of PB were done in elderly people who may have not started out in good shape. This may mean that PB makes a big difference to them, but very small or none for someone like me - and I don't feel subjectively, nor have I measured any benefits. 

The same incidentally is true - at least to some degree - with Whole Body Vibration. Many studies actually explicitly say that there are benefits for "untrained" but not "trained" or benefits for "elderly" but not young (f.ex. wrt. balance benefits) and so forth. Since the recent study about glucose control and WBV, I've gone back to using the machine, but I've somewhat changed my protocol. I do it for 5 days a week, and 2 days break. Each day's treatment is composed of ten one minute vibration sessions separated by 30 seconds (following one of the studies showing big benefits for cyclists) - so about 15 minutes daily for those 5 days. That's a big chunk of time. The reason I initially stopped doing it years ago, is that I felt demoralized by the thought that it might not be doing me any good and there's no easy way of checking benefits - meanwhile I'm sacrificing 15 mintes of my life 5 days a week. So my modification is that while I'm standing on the machine, I'm doing slow squats throughout - this way getting at least some exercise which probably has tangible benefits; I don't think the squats take away from the benefits of WBV, because what is really happening is that throughout the movement of the squat the vibration exposure changes - and if the vibration is what mimics some aspect of movement for the body (f.ex. running), then a more varied profile of vibration through movement more closely mimics what happens to the body naturally vs standing still.

In any case this is an example of modifying a behavior to at least make sure you are getting something hopefully more tangible out of a speculative health intervention - similar to how I've been standing on a slightly bent leg while brushing teeth as discussed years ago; that way it doesn't feel like wasted time just brushing teeth.  And make no mistake - a ton of our dietary, supplement and other behaviors are frankly very speculative, often with dubious justifications (especially in the case of supplements). So that provides a huge incentive to at least try for something concrete while doing the speculative.

In this light, in distinction to Dean, I feel greater time pressure - I am spending a ton of time daily (counting exercise) on health maintenance and often despair of the sense of all of this - if I'm doing it to enhance QOL or longevity, what is the point of that "extra" earned time is spent on the "earning" - the net gain might not exist, and be a net loss, especially if I don't particularly enjoy the activity like WBV or PB etc. (f.ex. in contrast to many, I personally don't enjoy exercise).

Therefore while Dean deprecates the gains of increased efficiency, I in contrast keep looking for greater and greater increases in efficiency to offset the cost (in time lost) of my health/wellness related activities. YMMV.

 

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I hear you Tom. I consider myself very fortunate in that I find enjoyment in virtually everything I do these days including some activities that others might be considered onerous time sinks like exercise, WBV, food prep, walking the dog in the cold, etc.

--Dean

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I buy a lot of bags of chopped leafys like kale and collards, mainly because it makes it so much more convenient to eat without having to wash them. I think I've got to keep doing that just because I'm already spending so much time/energy on food prep. But it seems this is not ideal.

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Good point, Ron. There are many food preparation effects that have disparate impact - which sometimes goes against the "raw unprocessed" cult. Obvious ones are increased lycopene availability in tomato paste, and research shows that when you crush garlic, you increase some of the active ingredients vs just eating a clove, cooking can result in a loss of nutrients, but it can also increase availability of other nutrients. As always, it's complicated. 

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