Spinach: Its Acne-Clearing Properties Revealed

Spinach is a surprisingly popular vegetable these days, with the average American eating roughly 2.5 pounds per year.

That’s 4 times higher than 40 years ago, and women over 40 are said to be top of the spinach-eating pile. It’s all down to spinach’s longstanding reputation as the Incredible Hulk in bottle. This dates back to the 1930s, when German scientist Emil von Wolff accidentally misplaced a decimal point and recorded an iron content in spinach ten times higher than the reality.

Cartoonists were soon inspired to create Popeye the sailor, whose bulging forearms came solely from his spinach obsession. Thanks to Popeye, US spinach farmers enjoyed a 33% increase in sales during the 1930s, and the prominent spinach-growing town of Crystal City, Texas even erected a full-sized statue of Popeye to display their gratitude.

Thanks to this origin story, spinach has the shining reputation of an immensely nutritious leafy green vegetable, standing shoulder to shoulder with the superfood kale. But is it really, and can acne patients like you use this supposed nutrition?

 

Why spinach is a deceptive vegetable

Firstly, understand that spinach has two fantastic rare acne powers which barely anybody away from the internet knows about. However, we’ll get the downsides out of the way first.

On the face of it, spinach looks like an excellent source of acne nutrients, with 20% of the recommended daily intake of magnesium per 100 grams, the top mineral for sleep quality and boosting glutathione production. There’s also 467% of the RDI for vitamin C, a vital ingredient of collagen production, and a massive 188% for vitamin A, which lowers the production of pore clogging sebum (oil) and keratin.

Unfortunately, however, spinach has one unavoidable roadblock. It’s the cruciferous vegetable highest in oxalic acid, a potent and highly annoying mineral-binder that stops the absorption of calcium, zinc, magnesium and iron dead in its tracks.

Traces of oxalic acid are perfectly normal in plant foods, as strawberries have 34mg per half cup, and spinach’s fellow vegetable celery has 35mg per half cup. Normally, oxalates are so insignificant that their impact is barely felt, but spinach looms over the competition, with 750mg per half cup. Only rhubarb, puriane and beet greens contain more, with 860mg, 910mg, and 916mg per half cup respectively.

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The problem then? On paper, spinach’s magnesium content looks fantastic, because strong sources of magnesium which are simultaneously acne-friendly are very rare. However, only a fraction will be absorbed into the bloodstream via the gastrointestinal tract, because human beings lack the necessary gut bacteria for breaking down oxalates.

This 2004 study confirmed the problem, feeding 9 healthy people either white bread with 300 grams of spinach, or white bread with 300 grams of curly kale. Kale is also packed with magnesium, but contains only 15% of spinach’s oxalates, with 110mg per 100 grams.

The absorption prophecy was fulfilled, as the magnesium in spinach was 27% less bioavailable than that of kale: 26.7% absorption versus 36.5%. The conclusion said it all: “the difference in Mg absorption… is attributed to the difference in oxalic acid content between the two vegetables”.

The kale wasn’t amazing itself, as 110mg of oxalates dwarfs broccoli (1.8mg) or Brussel sprouts (37mg). However, with spinach, you only absorb 5% of the RDI for magnesium, when a serving actually contains 20%. If your gut function is compromised, as is true for many acne patients, then the bloodstream absorption will likely be poorer.

 

Why the vitamin C is also deceptive

One happy fact is that oxalic acid only binds to minerals, not vitamins. However, the health dangers of this toxin also mean that spinach needs to be cooked more intensely than the average cruciferous vegetable, with the most notorious danger being kidney stone formation.

In the bloodstream, oxalic acid is strongly attracted to dietary calcium, binding together in the kidneys to form rock hard stones that snowball into monsters. Low oxalate diets are commonly prescribed to kidney stone patients, and spinach is normally outlawed completely.

Secondly, there’s strong evidence that bloodstream oxalates can send your inflammation soaring as well, as suggested by the following symptoms: painful joints, aching muscles and a clouded mind.

It’s never good for calcium crystals to be floating around your bloodstream, and there’s also evidence that oxalates deplete glutathione levels, allowing free radicals to run wild.

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For healthy people, the risks are minimal, as only 5% of dietary oxalates are absorbed, compared to 50% when gut function is compromised. The problem is that acne patients are notorious for gut problems, particularly increased intestinal permeability (leaky gut syndrome), where the gut cannot control the absorption of unhealthy toxins.

Because of oxalates, I advise all acne patients to cook their spinach thoroughly…

…and that’s where the problem kicks in, because all cruciferous vegetables are vulnerable to nutritional depletion when cooking. This 2000 study found that boiling spinach decreased the vitamin C content by 46.5%, outdoing peas (25.2%) and green beans (18.2%).

A 2013 study found a 10% loss of vitamin C when boiled for 5 minutes (a normal duration for deactivating oxalates), while studies elsewhere suggest a 75% reduction in healthy phytonutrients after boiling spinach for 10 minutes.

Therefore, rather than 47%, spinach provides more like 35-40% of the RDI for vitamin C. Spinach is a lot less nutritious for acne than supermarket labels suggest. 

 

But spinach is still highly nutritious!

That said, 40% is undoubtedly still respectable for acne. Better, there’s no evidence that the colossal vitamin A count (great for oily skin) is affected severely.

One study found that you only need 5 minutes of boiling to reduce spinach’s oxalates by 30-87%, while steaming led to a 5-53% decline.

Make no mistake that spinach is still slightly fraudulent, but the study showing a decline in vitamin C of 47.5% cooked the spinach for 30 minutes. Another study found a 60% decline after 30 minutes, and those cooking times are completely unnecessary: 30 minutes would leave you with green slime.

Additionally, seeing as magnesium isn’t warped or depleted by cooking, the deactivation of oxalates will push its absorption higher again, to the equivalent of approximately 10% of the RDI.

This study found that after boiling spinach, the oxalate content fell so far that magnesium was barely affected anymore. It called spinach “one of the most promising sources“.

 

Spinach – a top 10 sun protection food

Then there’s spinach’s army of rare phytonutrients. This is the first of the two secret acne powers we mentioned, as spinach is the second best confirmed source of the carotenoid antioxidants lutein/zeaxanthin, with potent abilities to reduce bloodstream lipid peroxides.

This study concluded that feeding 10mg or 20mg of lutein to non-smokers dramatically lowered their malondialdehyde levels, a bodily marker of lipid peroxidation. That’s excellent news because lipid peroxides are among the worst free radicals for acne, melting your vitamin E stocks. Lutein/zeaxanthin (which are grouped together due to being nearly identical) succeed by being fat-soluble rather than water soluble antioxidants.

This study also found that dietary lutein/zeaxanthin protected rats against sunlight-induced lipid peroxide damage to the skin. The two carotenoids even migrate to the cornea of your eye and protect against age-related macular degeneration there.

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As for spinach, 100 grams contains 15.691mg of lutein/zeaxanthin, which is only beaten by kale (19.686mg), and far beyond the realms of broccoli (1.080mg) and Brussel sprouts (1.541mg). For mysterious reasons, the lutein content of spinach increases after cooking, while in kale, it decreases.

When cooking is complete, spinach is slightly inferior to kale for vitamin A (188% vs 200%), vitamin C, magnesium, and lutein/zeaxanthin.

However, the one area where spinach really shines is antioxidants. According to this 2003 analysis, spinach defeated every other vegetable in two out of three common antioxidant tests. Raw spinach has an official ORAC score of 1513, which stands proudly next to kale (1770) and broccoli (1510).

The studies on spinach and blood antioxidants are equally promising:

ONE: firstly, there’s this 1998 study where eight elderly women were fed either 240 grams of strawberries, 294 grams of spinach, 300ml of red wine, or 1250mg of vitamin C. Using the ORAC test, bloodstream antioxidants increased by 7-24% roughly 4 hours after eating the foods. Urinary levels of antioxidants increased by 27.5% after eating spinach, compared to 9.6% for strawberries.

Vitamin C levels also increased significantly, but the scientists remarked that this couldn’t fully account for spinach’s antioxidant magic. Clearly, spinach contains other acne-friendly antioxidants.

They concluded that “strawberries, spinach or red wine, which are rich in antioxidant phenolic compounds, can increase the serum antioxidant capacity in humans”.

TWO: next, we have this 2011 study where 8 participants were given 225 grams of spinach for 16 days. Antioxidant protection of DNA increased both 6 hours after consumption and after 11 days of continuous spinach consumption (any volunteers?).

Spinach also decreased the blood content of homocysteine, a notorious amino acid for heart disease which also correlates tightly with oxidative stress. It seems that spinach hoovers up free radicals through many mechanisms.

THREE: this 2014 study fed spinach extract to some rats for 6 weeks, and the result was a big reduction in thiobarbituric acid reactive substances (TBARs), another highly accurate marker of free radicals.

The number of different antioxidants identified in spinach is truly enormous. Lutein/zeaxanthin are carotenoid antioxidants that specifically hunt down lipid peroxides, and other carotenoids in spinach include neoxanthin, fucoxanthin, violaxanthin, and beta carotene.

Spinach’s flavonoid antioxidant catalogue includes jaceidin and patuletin, and even two unique flavonoids called spinacetin and spinatoside. In fact, scientists have only recently identified this pair, so who knows what unique powers they possess?

The basic acne nutrition is useful (if deceptive), particularly the towering vitamin A levels, but the smaller phytonutrients are where the fascination really lies.

 

Spinach boosts your friendly bacteria

Meanwhile, eating spinach is particularly smart if you’re convinced that your acne is due to poor gut health somehow.

Two fantastic studies have caught my eye recently, the first testing thylakoids, hidden compounds wrapped up in spinach’s leafy chloroplasts. These thylakoids have strong appetite-suppressing properties and are even sold as a deep green-coloured weight loss powder.

In a study where healthy rats were fed thylakoid-enriched diet, their gut flora was much richer than the placebo rats after 10 days, and particularly in one friendly strain – lactobacillus reuteri.

The advantage for acne is that l. reuteri heals many digestive woes related to skin problems. For example, it suppresses the inflammatory bacteria strain helicobacter pylori, which plagues third world countries causing peptic ulcers, but also prevents nutrient absorption.

L reuteri was shown here to control intestinal permeability (AKA leaky gut syndrome), which means less inflammatory molecules flooding into the bloodstream. L. reuteri may have direct anti-inflammatory activity on human epithelial cells (which regulate the absorption of nutrients from food), upregulate an unusual anti-inflammatory molecule called NGF, and inhibit the pro-inflammatory messenger NF-KappaB.

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L. reuteri is a trusted ally of us acne-clearing fanatics, and the rare compounds in spinach can apparently increase it. Elsewhere, another batch of spinach compounds called glycoglycerolipids have been shown to protect the gut lining.

 

Yet another gut-protecting compound

The story doesn’t end there. Recently, I scoured the dark catacombs of the internet and discovered that spinach is packed with quercetin, a water-soluble antioxidant.

In our sweet potato article, we discussed how quercetin suppresses the mast cells in the small intestine which fire out pro-inflammatory chemicals, and is better at doing so than the pharmaceutical drug cromolyn.

It turns out that we’ve only scratched the surface:

ONE: a secretive player in digestive health is the tight junctions, proteins which directly control the opening of the semi-permeable membrane to allow nutrients to pass through and to keep inflammatory molecules out. Quercetin can improve both the quantity and performance of tight junction proteins, and thus improve overall intestinal barrier function (2011 study).

TWO: once again, quercetin induced a “strong increase” in tight junction proteins, particularly claudin 4 (2008 study). Claudins are the main family of proteins in the gut’s semipermeable membrane, with 24 members in total. Their individual properties are still under investigation, but quercetin somehow affected claudin 4 at the genetic level. Quercetin had “an important protective effect” against “barrier disturbance in intestinal inflammation”.

THREE: a nearly identical result: “this study demonstrates that quercetin enhances the intestinal barrier function”. Quercetin was compared to a blueberry flavonoid called myricetin and proved to be significantly better for a leaky gut. Claudin 4 was affected once again, giving us consistency (2009 study).

Spinach contains 4.86mg of quercetin per 100 grams, whereas raw broccoli contains 3.21mg and kale is even better with 7.71mg. Quercetin can also combat food allergies.

Combine quercetin with thylakoids and glycoglycerolipids, and spinach may be the ultimate vegetable for acne outbreaks with digestive connections.

 

DOWNSIDE – organic spinach is necessary

The only real problem with spinach, outside of the goitrogens which people blame for thyroid problems (but are mostly safe), is its heavy pesticide contamination.

When investigating 43 different fruits and vegetables, the Environmental Working Group discovered that sweet bell peppers, lettuce, celery, potatoes and spinach were top of the pile for agrochemical residues. Whatsonmyfood.com lists a grand total of 54 different pesticides, including 21 suspected hormone disruptors, 11 neurotoxins, 7 developmental or reproductive toxins, and 20 honeybee toxins. Back in 2015, spinach ranked 7th on the yearly “dirty dozen” list of the 12 worst foods for pesticides (with apples being highest).

The physical explanation is simple. Spinach, kale and lettuce are leafy vegetables, which creates a far greater surface area for insects to sink their teeth into. Therefore, more pesticides have to be sprayed, and more can be sprayed. Consider the square inches exposed to the outside world on spinach leaves versus a whole potato.

Worse, it’s impossible for farmers to wash the pesticides off properly, because the leaves would shred up and fall to bits. Potatoes, meanwhile, are easy to drench and scrub clean without damaging the potato.

Consequently, more than 60% of non-organic spinach tested by the FDA contains detectable pesticide residue.

The most ubiquitous is the insecticide permethrin, a neurotoxin found on 51.9% of samples. The US Environmental Protection Agency (EPA) claims that permethrin is carcinogenic and causes lung and liver tumours in mice. It’s also linked to tremors, loss of coordination and behavioural problems, but most pertinently for acne, glutathione is closely involved in permethrin’s detoxification (study), meaning that constantly ingesting permethrin may deplete your all-important antioxidant supplies (with glutathione being a vital one).

Another common pesticide is DDT, which was banned by the USA in 1972 after cancer and birth defects emerged, but is still shipped out en masse to developing countries in South America where the insects are extra aggressive. Hence, imported spinach still contains DDT, and what’s more, DDT lingers in the soil for decades. Spinach grown in non-organic US fields still comes up positive for DDT occasionally.

 

Why other vegetables are much safer

Compare this carnage to the trusted broccoli or asparagus. Broccoli is sprayed with chemicals sometimes, but pesticides don’t work as well on the plant, so farmers often don’t bother. Broccoli has dramatically less surface area too. Asparagus, meanwhile, enjoys complete immunity because insects find its taste weird, like the insect world version of marmite.

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Spinach is more nutritious than either vegetable, but it comes dead last for chemical contamination. Given that the authorities detect the presence of agrochemicals but rarely state the dosage, the contamination might well be too insignificant to destroy your skin. The sheer force of nutrition in spinach could make even the conventional version a net bonus.

Nevertheless, if you’re determined to avoid all chemical contaminants, then spinach has one unarguable flaw.

If, for example, your goal is to flood your skin with vitamin A, then you’d be better off feasting on sweet potatoes, with their happily miniscule pesticide counts. If you’re hunting for vitamin C, you can dine on pineapple (protected by its thick shell).

If you’re healing gut problems, then onions, with the highest natural count of quercetin, will do the trick. Onions have their own natural pests controls, as the same strong sulphurous compounds that revolt many humans scare insects far, far away.

Alternatively, if you’re a walking cashpoint, then you can buy organic spinach. Compared to organic kale, it’s not a complete and utter rip-off, although it is more expensive than organic broccoli or celery. 

 

Conclusion – the verdict on spinach

The final judgement is that spinach is excellent for acne if you 1) need plant-based vitamin A, 2) are afflicted with digestive woes, or 3) need antioxidants.

In its natural state (so ignoring pesticides), spinach is probably the second greatest green vegetable overall, standing just behind kale. Kale wins for gut health as its quercetin count is even higher. It also wins for vitamin A and definitively vitamin C, with 199% of the RDI vs 46%. However, spinach is the master of cruciferous vegetables for antioxidants.

Broccoli beats spinach for vitamin C, with 148% of the RDI, but spinach crushes it for vitamin A; broccoli contains just 12% per 100 grams. Spinach is moderately higher in antioxidants and quercetin, and 17 times higher in lutein/zeaxanthin, but broccoli is superior if you’re on a budget and organic spinach is tantalisingly out of reach.

Remember though, that these comparisons are totally relative. If you’re a newbie whose sole vegetable is currently potatoes, any green vegetable will blast your skin with gamechanging acne nutrition.

Boiling your spinach for 5 minutes is optimal, to shatter the oxalates, and always remember that the darker the spinach leaves, the more vitamin C and phytonutrients they contain.

That rules applies to strawberries and pomegranates alike, as in nature, it’s antioxidants and phytonutrients that provide colour. 

NEXT: discover the root causes of acne and banish your pimples forever

 

 

Thanks for reading!