What Everyone Needs to Know About Aluminum Cookware

Wondering about Aluminum Cookware?  Here’s an interesting fact…

According to the Cookware Manufacturers Association, aluminum cookware sales accounted for almost 60% of all cookware sold in the USA in 2015.So basically, more than half of us are using aluminum cookware.  Yet we don’t seem to know enough about it.  Not a day goes by when I don’t get a query about aluminum cookware or a request to do an in-depth review.   Questions like:

– What is anodized aluminum?
– What is hard anodized aluminum?
– Difference between hard anodized aluminum and non-stick cookware?
And the overriding question: Is aluminum cookware safe?

My goal is to have answers to all those questions by the end of this article.  And more.  

So let’s get started.  

Why use aluminum?

Aluminum is a great conductor of heat which makes it an ideal choice for cookware.  Here’s a table so you can see how Aluminum compares to other metals.  The thermal conductivity of metals is measured in w/m.k or watts per meter-kelvin.   Aluminum has a thermal conductivity that is 16 times that of stainless steel.   

What that means for you is that Aluminum will heat up quickly, evenly and 16 times faster than a stainless steel pot!   

Copper 401 W/m.K
Aluminum 237 W/m.K
Nickel 91 W/m.K
Cast Iron: 80 W/m.K
Tin: 67 W/m.K
Stainless Steel: 14.2 W/m.K

Source:  http://www.tibtech.com/conductivity.php

Aluminum is also the third most abundant element in nature.  Read ‘cheaply available’.  Which means aluminum cookware is generally affordable.  Plus it’s light weight.  It’s no wonder we favor Aluminum cookware over all others.  

 

The problem with Aluminum is…

Aluminum reacts with acidic food which causes the metal to leach into the food.  Because of that, you will find that most of the aluminum cookware that is available is either coated with a non-stick layer or is anodized.  

 

What is anodized aluminum?  

Ok, time for some chemistry 101.  If you leave aluminum exposed to the air, it will naturally form a thin layer of aluminum oxide on the surface.  While this layer is very thin, it is strong and hard.  It prevents the metal from further oxidation by forming a barrier between the aluminum and the air.  Scientist call this process ‘passivation’… meaning it makes the metal passive vs reactive.

As a matter of interest, both sapphires and rubies are gems made of aluminum oxide (different colors).  Because of its hardness, aluminum oxide is also used as a commercial abrasive.

Now in order to make the layer of aluminum oxide thicker, the metal is subjected to an electrochemical process called anodization.  This forms a much thicker layer of the non-reactive aluminum oxide, creating what is known as anodized or hard-anodized aluminum.    

 

Is anodized aluminum the same as hard anodized aluminum?

While both imply a layer of aluminum oxide on the surface of the metal, there is a difference.  Hard anodized is, in simple terms, an even thicker layer of aluminum oxide than regular anodized.  The resulting metal has twice the strength of stainless steel and is durable, non-reactive and resistant to corrosion and abrasion.  

 

Can hard anodized aluminum peel off?

The layer of aluminum oxide in anodized aluminum is not like paint or a coating but is completely fused into the base metal.  Meaning it’s a part of it.   This means that it cannot peel away or chip off. 

By some accounts, it’s also almost as hard as diamond.   Which means it does a great job of preventing scratches and exposing the aluminum core inside.  

 

Is hard anodized aluminum non-stick?

By its nature, hard anodized aluminum is low stick, not totally non-stick.  Most hard anodized aluminum pans today are coated with a non-stick coating.  

 

What’s the difference between hard anodized and non-stick?

Hard anodized cookware is made of aluminum that has been anodized to form a hard, durable layer.  It may or may not have a non-stick coating on it.

Anodized aluminum was initially developed by Calphalon in 1968 for professional chefs. It was developed in response to the demanding requirements of chefs in professional kitchens.   Calphalon Commercial Hard Anodized line was later made available to the public in 1976  so that home cooks could also enjoy this type of cookware.  However this product is no longer available and has been replaced with traditional non-stick coated cookware.  

Non-stick aluminum cookware is aluminum cookware with a non-stick coating.  The non-stick coating can be PTFE based (i.e like Teflon) or Ceramic based. It may or may not be hard anodized aluminum.  

For more on Teflon see our guide here

For more on ceramic coatings, see our guide here

 

Is a non-stick coated pan with hard anodized aluminum better than one with non-anodized aluminum?

A quick look on Amazon shows that a non-stick pan with hard anodized aluminum generally costs more than a non-stick pan with plain aluminum.  And yet, despite the extra cost, I would always recommend choose a non-stick pan or set that is hard anodized vs. plain aluminum.  Here’s why:

Firstly, hard-anodized aluminum goes through an extra process that makes it much harder, stronger and scratch resistant than plain aluminum.    This means you get a much more durable pan due to the outstanding toughness of the hard anodized surface.  

Secondly, a non-stick coating applied to a hard anodized aluminum pan lasts much longer than a plain aluminum pan.  In fact, according to Circuloncanada.ca,  when an abrasion test was performed on a hard anodized aluminum surface and a plain aluminum surface with the same quality of non-stick coating, the hard anodized material proved 3 times more durable!

Lastly, in the case of hard anodized,  even if the non-stick coating wears off or scratches, the food will not be exposed to plain aluminum.  Aluminum, as we know by now, reacts with some foods, particularly acidic foods, leaching the metal into the cooking.  Hard anodized, on the other hand, is quite non-reactive.

So in conclusion, shell out the extra bucks for a hard anodized non-stick.  From my personal experience, you’ll get a much longer lasting non-stick pan.  

 

And now the raging debate : Is aluminum cookware safe?

Disclaimer: since this is a sensitive subject for many people I want to make it clear that I have no intention of trying to change anyone’s opinion.  My sole purpose is to share what I have researched and to lay it out.  If it makes sense to you, great.  If not, that’s OK too.  Get a stainless steel or copper set.  

There are actually two parts to this question: 1. Does aluminum leach into food from cookware?  2. Is aluminum safe?

Let’s tackle them one at a time.

Does aluminum leach into food from cookware?

The concise answer: not much!

It’s important to keep in mind that most aluminum cookware is either coated with non-stick, is hard anodized or even stainless steel clad (e.g. Cuisinart MCP).  In all these cases, food is not directly in contact with plain aluminum, so chances of leaching are very low.

Now we come to plain aluminum pans, which most of us are not using anyway.  According to NCBI (National Center for Biotechnology Information), cooking in aluminum containers results in small but unimportant increases in the aluminum content of foods.    

Livestrong.com references a study that was published in the “Journal of Food Protection” which estimates that cooking in aluminum pans or foil can add about 3.5 mg aluminum to the daily intake.  Given that most people consume an average of 1-10mg of aluminum daily from natural sources, this amount would not be enough to constitute a health hazard.  

Further, in an independent lab test done by Cook’s Illustrated (America’s Test Kitchen) in 2012, it was found that tomato sauce (an acidic food) that was cooked in an aluminum pan for 2 hours and then stored in the same pan overnight contained only 0.0024 mg of aluminum per cup.  

As a point of comparison, some common over-the-counter antacids have more than 100 mg of aluminum in a single dose.  

Conclusion:

  1. Aluminum does not leach into food from coated or anodized aluminum cookware.  
  2. The amount that leaches from untreated aluminum cookware is not enough to cause a health hazard.

 

Which brings me to the second part of the question:

Is aluminum safe?

Let’s see, we’ve established that most aluminum cookware is either coated, anodized or clad.   This means food is not in direct contact with the metal.

If you are among the minority using plain aluminum cookware, the amount of metal leaching seems to be negligible.   This would also apply to non-stick aluminum pans that have a worn or scratched Teflon or ceramic coating.  

So that makes it pretty safe, in my opinion.

And while 60% of us are using some form of aluminum cookware, the myth that aluminum cookware causes Alzheimer’s lives on.

Let’s go back to the birth of that myth.  Some decades ago, in the study of a deceased Alzheimer’s patient, it was discovered that his brain had an unusually high concentration of aluminum.  Since then, aluminum was linked to Alzheimer’s and aluminum pots and pans were vilified as possible culprits.  

The connection between Alzheimer’s and aluminum has been debunked many times since then.   In fact, according to the Alzheimer’s society :

“there is no convincing evidence that aluminum increases a person’s risk of developing Alzheimer’s disease.”


FDA reports that aluminum does not cause Alzheimer’s disease and the use of aluminum products does not harm health.   

Lastly, according to Dr. David Perlmutter, renowned neurologist and bestselling author of Grain Brain, brain disorders, including Alzheimer’s disease, are caused by excess consumption of carbohydrates and grains.

Not aluminum cookware.  

With that, I rest my case.  To me, aluminum cookware is safe.   

If you’re still troubled by the idea of using aluminum cookware, do yourself a favor.  Choose stainless steel.


12 Responses to What Everyone Needs to Know About Aluminum Cookware

  1. Pingback: Bake King aluminum loaf pan – onekarelar

  2. Jeremy says:

    Great article.

  3. George says:

    Hi everybody!

    Please be so kind to enlighten me about the differences between cast aluminum and hard anodized aluminum.

    Thank you so much and kind regards,

    G

    • Cookware Advisor says:

      hi George, cast aluminum is when molten aluminum is poured into a cast to form a pot (vs a pot made from a sheet of aluminum). Hard anodized aluminum, which as the article explains, is aluminum that has been treated to form a thick layer of oxide on top.
      Hope that helps!

    • Chris says:

      As the Cookware Advisor explained, Cast Aluminum means that molten Aluminum is poured into a cast to form the shape. Hard Anodized (HA) cookware has the shape formed by deep drawing (pressing) an Aluminum sheet into the shape of a pot. The resulting shape is then dipped into a bath containing electrolytes, and the pot forms the “Anode” in an electrical circuit. The very thin Aluminum Oxide layer that grows on the surface is much harder than the Aluminum itself. Hence the term “Hard Anodization”. The benefit of HA is that the pots and pans still have great thermal conductivity (and heat-spreading capability) and they are lighter in comparison with their Cast counterparts, which tend to be made of thicker Aluminum. HA has that characteristic Grey exterior whereas Cast Aluminum tends to have a range of brighter colored coatings on the outside. However, one thing to note, unless the HA pot has a dishwasher-safe coating on the exterior, it will rapidly discolor, and the HA surface will gradually dissolve in the dishwasher. At the end of the day, it comes down to personal preference and budget.

  4. Chris says:

    I agree with most of what is said in the article by Dr. McDougall. Again, please follow the link that I mentioned previously (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3056430/), which is full of data that are referenced to highly credible scientific sources.

    “Aluminum is a widely recognized neurotoxin that inhibits more than 200 biologically important functions and causes various adverse effects in plants, animals, and humans.”

    “Recent studies using mass spectrometry of 26Al have demonstrated that small, but a considerable amount of Al crosses the blood brain barrier, enters into the brain, and accumulates in a semipermanent manner. Therefore, Al can cause severe health problems in particular populations, including infants, elderly people, and patients with impaired renal functions, and unnecessary exposure to Al should be avoided for such patients.”

    In plain language, it would be prudent to try to minimize exposure to significant sources of Aluminum and its compounds.

    Having said that, with Aluminum and Hard Anodized cookware, the interior surfaces are coated. The function of the coating is not only to provide a non-stick surface, it also serves as a protective barrier against leaching (migration) of the metal beneath, even when cooking with acidic foods. In fact, the basis of all international food contact regulations is that nothing shall come out of the food contact surface that would change the taste or odor of the food or render it harmful to humans. This is often called the “Zero Migration Principle”. Of course, as mentioned before, if in doubt, replace worn, scratched or otherwise damaged cookware. Alternatively, go for stainless steel albeit generally heavier, less thermally responsive and harder to wash (if uncoated).

    Accordingly, coated cookware is very likely to be the least of our worries. The general population is exposed to higher amounts of Aluminum through a variety of other sources including drinking water (Aluminum salts are commonly used flocculants in water purification plants), diet, inoculations, dialysis solutions, etc.

    Rather than throw away perfectly good coated Aluminum pots and pans, it would be a better idea, for example, to buy an RO (Reverse Osmosis) water filter that will help reduce the concentration of toxic metals including Aluminum from our drinking water. Drinking water, BTW, is reported to account on average for approximately 5% of our daily intake of Aluminum, which is much more significant than what we would receive from undamaged coated cookware.

    Aluminum exposure is but one of several factors that might potentially contribute to Alzheimer’s. You can do your brain the biggest favor of all by: (i) eliminating unnecessary simple carbohydrates such as those in sugary drinks (e.g. sodas); (ii) avoiding like the plague anything that contains High Fructose Corn Syrup (HFCS) such as bought fruit juices; and (iii) upping the amount of healthy Omega 3 oils (e.g. from fish oil or Krill oil or walnuts) in the diet.

  5. Ann Marie Clark says:

    I think everyone should read Dr. McDougall’s June newsletter. It’s full of well-researched facts and experience with aluminum as a poison and main cause of Alzheimer’s. https://www.drmcdougall.com/misc/2017nl/jun/alzheimers.htm

  6. Chris says:

    Excellent, very well informed article.

    Regarding the properties of common cookware materials, here are two further links that are useful from a technical perspective (Section 2.2 for the 2nd link):

    http://www.cookingforengineers.com/article/120/Common-Materials-of-Cookware

    http://emerald.tufts.edu/as/tampl/en43/lecture_notes/ch2.html

    (Thermal conductivity BTW has units of W/m.K).

    In addition to good conductivity, Aluminum (Al) has a high ratio of ability to spread the heat vs its heat holding capacity. This is called Thermal Diffusivity. It means that Al is less likely to develop hotspots, and it will give a more even cooking result in comparison with Stainless Steel or Cast Iron.

    3-ply material is a great choice where Al is sandwiched between layers of Stainless Steel. However, watch out for the cheaper version called 2-ply (bi-ply) as the difference in thermal expansion of just these two metal layers (SS/Al) will cause the cookware base to distort and wobble, which also means less effective heating up on electric stoves.

    Finally, sorry to wade into the discussion on safety of Al. Actually, the debate on Al contributing to Alzheimer’s swings backwards and forwards.: debunked for a time, then new evidence comes to light. One argument goes that our bodies and therefore brains deal with the background level of Al that we are generally exposed to over a lifetime until a certain threshold is reached. Above this, Al can accumulate and undergo complex interactions. Then, it is the additional Al that has the potential to start the downwards spiral. However, until we have concrete proof, then the jury is still out and all we know for sure is that we need to know more.

    Whilst I totally agree that the amount of Al leaching from scratched non-stick pans is relatively low when you consider that we get it from multiple other sources (e.g. tap water, diet, antacid tablets, inoculations, etc). Nevertheless, Al is definitely amongst other things an established neurotoxin:

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3056430/

    The article is quite long and technical, but the 2nd sentence in the Abstract (or the 1st paragraph of the Conclusions) sums things up.

    It means, in my book anyway, that it would be wiser not to add further amounts to our systems. It would therefore be advisable to replace badly scratched non-stick Aluminum cookware – i.e. on a better safe than sorry basis.

    • Cookware Advisor says:

      Hi Chris, thanks for yet another well informed comment, great points about the Thermal Diffusivity of Aluminum.
      [Thanks also for pointing out the correct units for measuring Thermal conductivity, I’ve made the edits in the article.]
      And I agree, it is always a good idea to replace scratched and worn cookware.
      Cheers!

      • Chris says:

        PS: forgot to mention, I’m totally with you on the “Grain Brain” link. In addition to the bad effects of simple carbs on our metabolism, some people can suffer a subclinical intolerance to Gluten from grains without even knowing it. Metabolic disease and, in particular high blood sugar, has links to impaired cognitive function and problems such as Alzheimer’s. I trust that Grain Brain should advise how to eliminate the grains whilst still getting sufficient fiber in the diet.

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