Let’s start with some definitions.
Organic foods are produced without:
- Human made pesticides, herbicides and fertilisers. Organic farmers may use natural pesticides that have been approved for organic food production.
- Antibiotics or growth hormones
- There is also no use of radiation, which could be used to preserve food or get rid of disease or pests.
Differences in Nutrients
- I wanted to start by talking about a study that is one of the more “pro” organic in a way that is easier to identify.
- Before we talk about pesticides and other stuff, we will talk about differences in nutrients.
- A 2014 systematic review and meta-analysis of 343 studies found that organic produce had 19-69% higher levels of antioxidants than non-organic produce
- The title of the study was – “Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops”
- They also identified some other differences in vitamins and minerals, but nothing particular stood out.
- Another review of 67 study found that organic meat has slightly lower levels of saturated fat and higher levels of polyunsaturated fats, including omega 3’s
Analysing Aspects/Criticisms of Those Two Studies
- Firstly addressing the organic red meat aspect. They found that the omega 3 content was 47% higher. But is that actually relevant? The omega 3 content of meat is so low unless we are talking about oily fish like salmon
- However, it was apparent that the organic meats were slightly lower in saturated fat than their non-organic counterparts
- The other study requires a bit more analysis.
- Starting with a bit of pro-organic thinking. That is a significant increase of antioxidants. And over 343 studies, it’s not like the sample size is small.
- From the other perspective though, I’ll quickly list some key things people have been commonly mentioned as well.
- The study was funded by an organic farming charity (this in isolation isn’t a big deal)
- But The authors arguably overhyped the results when speaking to media etc
- Even though non-organic produce had 4x higher cadmium levels. But it was still way less than the amount that is considered to be unsafe.
- Of course the pesticide residue is lower in organic foods. That’s the point. The larger argument is whether that is relevant, considering that non-organic produce is also limited to supposedly safe levels.
- Although it is a lot of research, some people questioned whether that antioxidant difference was within natural variations, and whether it was even that nutritionally relevant.
- Using an example to double down on that point, technically this review also found that organic cereals have significantly less protein than non-organic. But I personally would just brush that off and not think too deeply about that. But obviously that isn’t an aspect that would be heavily reported on.
Pesticides Part 1
- By definition, the amount of pesticides in organic produce should be significantly lower
- In Australia, we have quite strong food safety standards. All non-organic produce still needs to meet strict criteria.
- There are limits that are set on each pesticide that is used to ideally reduce exposure to very safe levels.
- If wanting to do everything you can to avoid even trace amounts of pesticides, I can see why somebody would want to choose organic.
- One argument I see is that these safe levels of pesticides are set based on using each pesticide ingredient. What happens if we have exposure to heaps of them in combination?
“The Dirty Dozen and Clean 15”
- Since finances are often a constraint when it comes to purchasing organic vs non-organic, it makes sense that people want to know “what are the most important fruits and veg to buy organic”
- The Dirty Dozen and Clean 15 are lists of fruits and vegetables put out by the Environmental Working Group (EWG) which is designed to help with this.
- Theoretically, the dirty dozen has the highest pesticide levels, and you should only buy organic versions of those foods. Meanwhile the clean 15 is the opposite, and non-organic versions should be fine.
- This list gets updated each year as practices change over time
- It sounds good in theory but there are some flaws
Flaws in The Dirty Dozen
- The first thing to be aware of is that all the foods on the list still fall into the category of having what is considered to be a safe level of pesticides
- Another flaw is that the weighting system of the dirty dozen is effected by the number of different pesticides pretty heavily. So even if barely detectable levels are found, it skews the results.
- It also isn’t weighted in comparison to risk or anything, or even the impact of “better” or “worse” pesticides. It is more just measuring the amount of different pesticides and the total amount.
“Safe levels” of Pesticides
- One obvious thing to address is “what is a safe level” of pesticides
- I see comments on Instagram saying “no amount of pesticides is safe.” But as with most things, the dose makes the poison.
- The way that pesticide safety thresholds have been chosen is by finding the level in animal studies where chronic exposure causes adverse effects. They find the spot where no adverse effects are found, and then they divide it by a safety number, usually by 100.
- So usually the tolerance threshold that is proposed is 100x lower than a level that has been demonstrated to cause no adverse effects with chronic exposure.
- The point about the “what happens if we have heaps of different pesticides” is still relevant. But the 100x lower number should be factored into that too.
- Using a specific example:
Strawberries have topped the dirty dozen list previously. It would take the average person consuming 453 strawberries per day, at the highest level of average pesticides recorded on strawberries, to reach that dose threshold. And theoretically it would take 100x that amount to reach a dose where adverse effects have been observed with chronic intakes.
Overall Health, Cancer & Mortality
- The most pro-organic systematic review I’ve seen on health outcomes was in 2020 and they found “Significant positive outcomes in longitudinal studies where increased organic intake was associated with reduced incidence of infertility, birth defects, allergic sensitisation, otitis media, pre-eclampsia, metabolic syndrome, high BMI, and non-Hodgkin lymphoma.”
- One aspect to consider is how much of a role things like healthy user bias and socioeconomic status effected this too though – particularly in the observational studies
- In this study they noted – Organic consumers tend to be more health conscious, are more likely to be vegetarian or vegan and are more likely to be physically active
- Most other reviews (some are linked in the show notes) have found no noticeable differences in health outcomes when all other factors are equal.
Overall Health Benefits of Just Consuming ANY Produce
- Another angle we could look at it is the opposite perspective. What happens if you eat non-organic produce?
- Most of the research identifying benefits of fruit and vegetable intake has actually been done involving non-organic produce.
- Research looking at fruit and vegetable intake on mortality in general found reductions in mortality up to about 800g of fruit and veg per day. Reductions in cancer risk specifically topped out at around 600g.
- A study from this year covering >40,000 people found no difference in cancer rates over a 15 year period with organic vs non-organic intakes
- We know that <6% of Australians eat the recommended intake of fruits and vegetables. Eating more of those in general would be a good thing.
- Organic vs non-organic is a complex topic.
- This is a broad overview. Although it might seem like it is downplaying any benefits of organic, this is also a huge topic. There are situations where it likely matters more than others. This is also why lists like The Dirty Dozen have some level of appeal.
- On the one hand, if you have the access and financial situation to buy organic, it can make sense to do that. On the other hand, we consistently see benefits from eating more fruits and veg in general.
- Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops
- Composition differences between organic and conventional meat: a systematic literature review and meta-analysis
- A Systematic Review of Organic Versus Conventional Food Consumption: Is There a Measurable Benefit on Human Health?
- Are organic foods safer or healthier than conventional alternatives?: a systematic review
- Organic food: buying more safety or just peace of mind? A critical review of the literature
- Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality-a systematic review and dose-response meta-analysis of prospective studies
- Organic food consumption and the incidence of cancer in the Danish diet, cancer and health cohort