If you’ve ever attempted to shed so much as two pounds, then you’ll have heard that micronutrient deficiencies increase your appetite.
It’s among the most commonly referenced, yet mysterious subjects in the food craving universe: that your subconscious mind is secretly controlling you with a joystick from a bridge just behind your eyes, directing you to the foods that will replenish its stocks.
The internet, no the world, no the galaxy is split down the middle. On social media, it’s common sense that a zinc or magnesium deficiency will put you on the prowl. However, news outlets like the BBC or giant health organisations dismiss the theory completely.
Clearly, there are no revitalising minerals in methamphetamine or sugar cane crystals. If it’s true, then red wine deficiency is surely an epidemic.
However, other cravings being much more powerful doesn’t mean that vitamins and minerals have no role. There’s surprisingly little evidence in either direction, but I’m cautiously optimistic.
Some claims are suspicious
Firstly, these micronutrient cravings clearly aren’t an infallible homing beacon, which makes you sleepwalk through the nutritional world grabbing everything necessary to be the perfect human being. Otherwise, obesity would not exist. We wouldn’t be controlled by Ronald McDonald and his fast food friends.
If you want a laugh, then read this infographic. It gives you the foods corresponding to sulphur deficiency (sweets), manganese deficiency (tofu), and finally, the foods for “prosperous” deficiency. The real solution is clearly posing for the camera with a fistful of dollars. Countless flow charts like this are circulating Facebook; another recommends cuddling your pet when you crave bulky or fluffy foods (does anyone crave fluffy foods?), while looking at old photo albums will supposedly erase soft or smooth food cravings.
If there’s one theory which has entered the public conscious, it has to be that magnesium deficiency manifests as chocolate cravings.
Paleo websites believe this, and alongside its cocaine-related stimulant phenylethlamine and the bliss compound anandamide, it may explain chocoholism. If true, though, then why wouldn’t we crave the much better sources of magnesium?
How often do people crave nuts or beans? Another classic is that cheese addiction, a grave epidemic sweeping our lands, is caused by calcium deficiency. As hyperconcentrated milk, it’s packed with this bone concentrating mineral, but nobody has cravings for the equally concentrated kale.
Some other theorised examples include…
Candy – your body needs sulphur and it needs it now.
Pasta – craving it indicates a nitrogen deficiency.
Energy drinks – your body is crying out for potassium.
All these are similarly flawed. If you really needed sulphur, you would just eat Brussels spouts, and nobody does that except for Christmas day.
Still a strong chance
However, my gut feeling is that there is something to this theory. They won’t match the satiety hormone leptin, but vitamin and mineral deficiencies will probably exert a subtle pull.
One classic argument is that macronutrient deficiencies are far more important. For example, articles might list very real studies where pregnant women report cravings, but only for foods rich in carbohydrates and fat. It’s undeniable that energy bombshells stimulate satiety hormones like leptin and ghrelin the most – how many people are addicted to broccoli?
However, this doesn’t disprove a secondary role for micronutrients whatsoever. It’s purely logical, that our body would compel us to eat. It’s a survival mechanism – we have as many communicating nerve cells in our gut as a cat does in its brain.
The real problem is not negative studies, but non-existent studies. One dismissal I’ve seen is that low carb and low fat diets actually reduce the cravings for those nutrients. There’s two flaws here, the first being that fat and carbs are macronutrients, and not comparable to vitamins and minerals. Secondly, the carbohydrate result is well understood. Carbohydrates stimulate leptin, and withdrawal gradually resensitises the leptin receptors in the brain to smaller amounts.
People often talk about sociological and cultural factors as well. For example, how eating chocolate brings all the memories of Christmas rushing back. Supposedly, only 2 thirds of languages have a word for craving (true), Japanese women crave their staples of rice and sushi instead, and only 1% and 6% of Egyptian men and women ever crave chocolate.
All of this is true – the psychological side is real – but it doesn’t discount vitamins and minerals whatsoever.
Signs are everywhere
In nature, there’s many examples of crazy food cravings springing up from nowhere, for better and worse.
For example, the scurvy epidemic of the 1700s gave sailors bleeding gums and bruising skin worldwide. These boats did bring vitamin C sources with them, but there are no stories of sailors wildly staggering towards apples.
Over in the savannahs of Namibia, though, giraffes have been observed munching on bones. When lacking in vital minerals, they pick up skeletons of dead buffalo in their mouths and chew them relentlessly. Why do they do this? How do they know? It’s pure giraffe instinct. Bones don’t contain any dense, fattening nutrition, just micronutrients. The still photos look horrific and would break a giraffe lover’s heart, but don’t worry – they’re only looking for calcium and phosphorous. This activity is called “osteophagy”, and African antelopes also know the secret.
In 2006, the TV series “I Shouldn’t Be Alive” had an episode about Steven Callahan, lost at sea for 73 days in 1981.
He was lucky that a huge school of fish drifted slowly westwards with him through the Atlantic ocean, but as the damp, salty weeks wore on, a strange calling hit him. He wanted to eat the fish’s eyes, and when he did, he called them as delicious as skittles. An unknown micronutrient deficiency was manipulating his taste buds into finding a disgusting animal part tasty (maybe).
Likewise, anaemics routinely crave red meat, the great source of iron. It’s similar with people taking blood thinners, who need iron to regenerate red blood cells.
People have eaten whole cans of spinach too (and his name wasn’t Mr P. Eye either), and women commonly crave raw meat at that time of the month. Failed vegans have even reported dreaming about red meat.
Iron seems to be the most consistently craved nutrient. Other ones are probably less powerful, less compulsive, but can still add up to a significant force.
Even vegans are susceptible to cravings for nutritional yeast, a popular vegan source of protein. There are reports all over forums and social media.
A subtle yet compulsive force?
We barely understand even the best understood satiety neurotransmitters. Leptin was first discovered in 1994, while ghrelin showed up in 1999. This prompted a rush in pharmaceutical companies trying to cash in, which totally failed. Likewise, peptide YY, glucogan-like peptide 1, oxyntomodulin, and neuropeptide Y are still wrapped in cloaks of mystery. Dismissing micronutrients in food cravings is not the logical path when we know so little – my money is on a role for them.
The micronutrient gravitational pull might be a parallel to your taste buds. Supposedly, the human tongue has receptors for 5 tastes – unami, sweet, sour, bitter, and salt.
However, why does a strawberry then taste so much different to a blueberry? In reality, we have thousands of subtle receptors for phenolic antioxidants, anthoycyinins, bitter tannins, poisonous compounds, sulphur – the list stretches on.
Our craving programming might be similar, with 4 or 5 gigantic central planets which cause most of the grief (carbs, fat, salt…), but countless subtle players orbiting around them, whose effects are masked, harder to spot, and commonly blend together. Micronutrients are probably an example, and certain bodily states like chronic inflammation could also spur cravings, maybe for omega 3s or zinc. It could even burrow down to individual inflammatory chemicals like TNF-a being elevated.
What do the studies say?
The common claim by skeptical articles is that “no research has investigated this topic”. There are studies, buried deep within the archives of the internet – but yes, it’s crazy how few. Wouldn’t it be a miracle for magnesium supplement companies? If I ran one, I would be funding my own studies, obviously smoothed by a hefty laundry bag full of bank notes.
The perfect study would be gathering a high and a low bloodstream zinc (or magnesium) group, and comparing their body weight and food cravings. However, we do have this fascinating multivitamin study from 2006.
The first part used questionnaire data from the decades-long population-based Québec Family Study (used in many studies). The multivitamin men had a significantly lower body weight and body fat percentage, with women benefiting too, but by smaller amounts. However, the women did have much lower hunger and disinhibition (lack of restraint) scores.
In the second experiment, 45 obese women, who didn’t previously take supplements, were given a placebo or a multivitamin. Weight failed to fall, as did body fat. However, their hunger did plummet, including fasting appetite and post-prandial (post meal) appetite.
Better, the study had a happy design flaw that worked in our favour: all the women were ordered to lose weight anyway. If their food intake was uncontrolled, then the multivitamin’s craving powers would have been far clearer. The scientists mentioned this flaw themselves.
In a similar vein, some 15,656 citizens of western Washington state filled in a questionnaire (study), starting with men and women aged 45. Alongside exotic herbs like gingko biloba, ginseng, and St John’s wort, the part we care about was taking chromium, vitamin B6, vitamin B12, and a multivitamin.
After 8-12 years, all 4 micronutrient supplements reduced weight gain. For example, the no chromium men gained 11.7 pounds on average, while the 150mcg chromium men shed 3.1 pounds, after ten years. This doesn’t prove our micronutrient hunting theory – maybe the nutrients had fat-burning effects, like chromium stoking the flames of the metabolism – but it is highly suggestive.
A more negative study divided pregnant women into higher cravings and lower cravings. Their vitamin C, vitamin D, calcium, and iron levels were statistically equal. However, because pregnancy transforms the body so dramatically, the results are only slightly applicable to normal people.
The studies, part 2
These studies are excellent, but none are smoking guns. For example, in the Quebec Family Study, the multivitamin men could have been inherently more health-oriented. The same applies to the western Washington patients.
Now though, we have my favourite study. It was aptly titled “Magnesium appetite in the rat” and dated back to the fogs of 2002. In part 1, male rats were either deprived of magnesium, or kept replete in magnesium. All rats were offered a calcium liquid or magnesium liquid, at varying concentrations of up to 100mM.
The magnesium deficient rats drank far more of every mineral liquid, even at just 3.2mM. However, a sweet saccharin liquid went totally ignored.
Could this be a laboratory parallel to the chocolate-magnesium axis people believe in? The second section said yes, as the rats were offered a magnesium water, a placebo water, or a calcium-infused water.
Guess what – the purposefully calcium-deficient rats drank 3.9ml of the calcium liquid and 1.8ml of the magnesium. Meanwhile, the purposefully magnesium-deficient rats drank 1.1ml and 3.1ml respectively.
Make no mistake that rats couldn’t read the label on the bottle. It was pure instinct, the instinct that supposedly guides us.
Obviously, we’re not rats (presumably), and perhaps our taste buds aren’t sharp enough to sniff out these minerals. However, cravings are one area where our ancient animal instincts remain just as sharp, just as automatic as a bird flying south for the winter. That’s the whole root of compulsive eating, after all.
Another study was completely and utterly unreliable. Its methodology was as flimsy as a castle made from plywood.
The 768 participants were gathered on a physician-run website of 4000 subscribers, which guided people towards a high nutrient diet. This was a perfect pool to source from, then, but the website specifically boasted of decreased appetite. The placebo effect would be in full swing, with the responders enthusiastically searching for any sign.
The scientists didn’t test bloodstream nutrients either. They only questioned participants about their cravings during their previous life and the new diet.
Nevertheless, the scientists confessed to these flaws themselves, so all is well…
…and the results were fantastic. 80% reported reduced hunger and 51% a completely transformation of their hunger experience. Interestingly, the location also shifted. On their old diet, 69.9% felt hunger predominantly in their “upper abdomen/mid stomach”, and 6.4% in their throat, but after the flood of micronutrients this changed from 39.4% to 29.9%.
The longer patients adhered to the diet, the more the negative physical and emotional discomforts of hunger fell. Frequency of hunger lacked this correlation (maybe it improved instantly, but not further), but discomfort after skipping a meal and hunger pains in the stomach also improved over time.
Most importantly, the diet only increased micronutrients, the vitamins and minerals, and not macros like carbs and fat.
We probably shouldn’t have included this study at all, but I couldn’t resist it.
The verdict
This is a classic question where you can’t ignore common sense. The evidence is shaky, but I’m confident that vitamin and mineral deficiencies have at least a moderate role in food cravings.
In fact, there’s a big advantage here. Satiety neurotransmitters like peptide YY and glucogan-like peptide may be far more important, but we haven’t got a clue how to control them. By contrast, you only have to pop a multivitamin, or dine on red meat and broccoli to reap the rewards here.
Our remaining questions include which nutrients are important, whether they control different aspects of hunger, their interactions with other hunger hormones, and whether healing deficiencies or sprinkling a little extra on top is most effective. New appetite suppressing discoveries are surely on the way, discoveries which will make acne villains like high fructose corn syrup perfectly resistible.
It also means that an acne-friendly diet might reduce your cravings automatically. This was already true anyway for increasing your leptin receptor sensitivity, via lowering carbs – micronutrients are the cherry on top.
If food cravings are a vast unexplored universe, then the role of micronutrients is the most distant galaxy our telescopes can see.
Thanks for reading!