Curious Cook: We don’t know enough about what is in the food we eat

We don’t know enough about what is in the food we eat, for instance, did you know that garlic contains more than 2,230 other chemical components, including allicin, the organo-sulphur compound responsible for the distinctly pungent aroma of raw garlic, especially when pressed or crushed? -

Dark matter, the fascinating structure of the universe is a possible analogy for our food.

Anyone with any interest in astronomy would be aware that the observable matter in our skies make up less than 5% of the material making up the universe. The rest is made up of exotic stuff such as dark energy (approximately 68%) and dark matter (roughly 27%), both of which are still inexplicable and unobservable to astronomers. This roughly reflects the true state of knowledge we have about what we are really eating.

The US Department of Agriculture (USDA) keeps a list of what they (currently) perceive to be the 150 key nutritional compounds or elements in food such as sugars, fats, proteins, vitamins, minerals, etc. These are compounds/elements which have been determined to affect health and/or cause common dietary diseases (usually due to deficiencies). Yet we are aware of over 26,500 different biochemicals which are also present in our food, and it is impossible to segregate them from USDA-listed compounds/elements during food preparation. Therefore, we eat a complex amalgamation of compounds/elements at every meal, and much of it may be considered as food “dark matter”.

Vast variance

The vast difference between the numbers of listed “core” nutritional components and what we are ingesting is a likely source of the confused advice we constantly receive from the media and sometimes from official sources. One plausible reason for the confusion is the huge amount of research into dietary issues, often sponsored or conducted without a common standard of scientific rigour. In many cases, such rigour may not even be possible due to the environments where research is conducted. This does not mean all research is invalid; but it may sometimes mean some results may not be wholly generically applicable to everyone.

For example, several papers years ago (notably one conducted in Bordeaux, France) claimed red wine has significant health benefits, especially related to dementia and other effects of ageing, possibly due to a compound called resveratrol. This was contradicted in 2016 by a global study of millions of people which found that alcohol contributed to almost 10% of all deaths of people between the ages of 15 to 49 and concluded starkly with: “Based on weighted relative risk curves for each health outcome associated with alcohol use, the level of consumption that minimises health loss due to alcohol use is ZERO”. Note that this wider study found no link between red wine and age-related benefits, just an association of ANY level of alcohol consumption with a broad range of negative health outcomes.

Resveratrol is not on the list of core nutrients noted by the USDA. However, potassium, vitamin B6 and phosphorus are catalogued, and these three nutrients are all found in garlic. I mention garlic because it is a good illustration of the complexity of common items of food.

Raw garlic figures heavily in the Mediterranean diet and contains 64 other USDA-classified nutritional compounds including lysine, leucine, tyrosine, glycine, serine, arginine, etc. That may sound complex enough already. But garlic contains more than 2,230 other chemical components, including allicin, the organo-sulphur compound responsible for the distinctly pungent aroma of raw garlic, especially when pressed or crushed. Fresh garlic also contains “luteolin”, one of a curious class of flavonoids known as “flavones”, natural plant compounds with various claimed health benefits.

Luteolin is interesting because of several research papers written in the 1990s, including the Zutphen Elderly Study done in the Netherlands which monitored the effects of ageing relative to diets. These papers found that the intake of flavonoids was inversely related to mortality and heart attack rates. Luteolin was singled out as one of the more beneficial compounds, though the studies thus far are more promising than conclusive.


Dietary research usually focuses on the effect of a food compound on some observable factor, such as heart health, longevity, organ function, etc. This kind of research can often be too narrow because in many cases, it is not necessarily a single compound which causes a direct effect.

Digesting food components through powerful stomach acids and enzymes transforms raw food compounds into other compounds known as metabolites. A classic example are nitrites and nitrates in processed meats. By themselves, nitrites and nitrates are relatively inert compounds, but the process of digesting them creates metabolites called nitrosamines, which are known carcinogens. The pervasive use of such compounds in processed meats caused the WHO to list processed meats as Group 1 carcinogens in 2015. Additionally, it seems digestion of meat proteins treated with nitrites and nitrates is also mildly impaired by the compounds.

It is difficult to ascertain the number of metabolites arising from digestive processes. One estimate is over 49,000 modified compounds can arise from food digestion. Not all these metabolites have negative health implications of course. Most of them result from the decomposition of natural food material in our digestive tracts as part of the process of extracting nutrition. However, there may be problems with eating food treated with artificial preservatives, flavourings or processing additives; the metabolites arising from such added chemicals are not researched enough, possibly because not enough people really want to know.


Most food is cooked before ingestion, and the process of cooking can introduce a range of other unexpected “dark matter” compounds into our food. Probably the most known compounds created during baking, broiling or dry-frying (usually at temperatures higher than 120C) are AGEs (Advanced Glycation End-products), which usually present themselves as brownish or dark substances on the surfaces of cooked ingredients.

AGEs are also known as glycotoxins and are complex compounds arising from the Maillard Reaction (the chemical interaction of sugars with amino acids in proteins which have been denatured by intense heat). Although often delicious (and an important aspect of making food look and taste good), many AGEs sadly also cause a process called glycation in the body, resulting in oxidative stress culminating with higher probabilities of inflammation, diabetes, poor eyesight, saggy skin, various organ diseases, etc.

Frying in oils can also introduce unhealthy compounds into foods, and the type of oil matters a lot. Over-used oils tend to have a lot of FFAs (free fatty acids) in them and combining FFAs with food compounds at high temperatures will create dangerous chemicals such as free radicals, peroxides, alkenals and aldehydes. All these compounds have been linked with inflammation, organ damage and/or various cancers.

Frying with polyunsaturated fats (PUFAs) is also problematic, even if the oil is fresh. That is because PUFAs turn into FFAs very rapidly at high temperatures and are simply unsuitable for cooking at high heat. (For more on this, please go HERE)

None of these compounds ever carry a warning sign on the food packaging, and most people are unaware of their deleterious effects on health.

Unlabelled Poisons

If you are fond of wholegrains or brown rice, then a suggestion would be to ensure the ingredients are obtained from organic sources. Otherwise, there is a risk of contamination with chemicals such as pesticides, herbicides, and fertilisers as many wholegrains are relatively unprocessed before sale.

Under current regulations, these crop-production chemicals do not need to be included on food labels, regardless of the amounts present. Neither is labelling mandatory for foods polluted with other compounds such as plastics, hormones, PFAS (perfluoroalkyl and polyfluoroalkyl substances), etc. The range of dark matter compounds which can pollute our food is extensive and may already be having a significant effect on human health.

In 2019, internal testing by some companies in the US found their own baby foods contained up to 91 times the permitted level for inorganic arsenic, up to 177 times the lead level, up to 69 times the cadmium level, and up to five times the mercury level allowed in bottled water.

Dark matter is routine

One serious problem is food pollution is now widespread and “routine” for several decades in most countries in the world. As such, it is hard to establish and quantify the exact health effects on humans due to such extensive and prolonged contamination.

For example, problems with Bisphenol-A (BPA, a plastic hardener) were detected over a prolonged period. One problem was unusual infertility issues in young women, and this was eventually linked to high levels of BPA in their urine. Subsequent testing in laboratory animals established that BPA is an endocrine (hormone) disruptor. This finally led to a ban on the use of the compound in many countries. Before the ban, BPA was detectable in 93% of the US population.

Another case is PFAS pollution. It is so widespread that currently 98% of US citizens have detectable levels of the compounds in their bodies. PFAS has been linked to liver damage, thyroid disease, decreased fertility, obesity, hormone disruption, cancer, etc, but these associations are usually based on obviously elevated exposures to PFAS. With such a high level of “background noise” regarding PFAS prevalence in the population as an example, it is hard to ascertain the impact of food “dark matter” on human health.

In short, how much of various kinds of “dark matter” can humans tolerate before it becomes a systemic, detectable problem? Currently, there are no concrete answers to such critical questions. And we have not even discussed the impact on such pollution on other species.

Can we avoid undesirable “dark matter” in food? Probably not, but in the absence of reliable data on health consequences, it would be sensible to try.

The views expressed here are entirely the writer’s own.

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