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Coconut milk and fruit can be a great snack for Paleo folks, and coconut milk smoothies make a great Paleo breakfast choice - especially in the summer.
So what could be wrong with coconut milk? Here are three things to consider.
Bisphenol-A
Bisphenol-A (BPA) is a chemical that has been used in consumer goods since the 50s. It's found in reusable drink containers, DVDs, cell phones, eyeglass lenses, automobile parts and sports equipment. One of the highest sources of BPA is cash register receipts.
We've known for decades that BPA has estrogenic activity. In vivo animal studies and in vitro cell-culture research has linked low-level estrogenic activity associated with BPA exposure to all kinds of fun stuff, like diabetes, ADHD, heart disease, infertility and cancer.
Is BPA exposure common? You bet. This CDC report found BPA in the urine of 93% of adults. Perhaps most troubling is that companies like Nestle, Similac, Enfamil and PBM all use BPA in the linings of metal cans holding baby formula. This is scary in light of a recent study which found an association between neurobehavioral problems in infants and high levels of BPA in their mothers.
So why is BPA even legal, you ask? Its safety status is still somewhat controversial. Although I'm not sure how "real" the controversy is.
On the one side you have consumer advocates and independent researchers and scientists who claim that there's sufficient evidence against BPA, including plausible mechanisms for how it causes harm, to ban it completely. They argue that continued use of BPA in industrial and commercial materials is akin to performing a large, uncontrolled experiment on us all. I tend to agree.
On the other side, you've got industry scientists claiming that there's no significant evidence that low levels of BPA causes harm in humans. If I was a cynic, I might point out that these chemical industry groups are out to protect a multi-billion dollar market from government regulation. Global BPA demand is up to 12 billion pounds and growing at 5% per year.
Okay, back to coconut milk. BPA is used in the lining of certain canned foods. BPA especially leaches into canned foods that are acidic, salty or fatty, such as coconut milk, tomatoes, soup, and vegetables.
So what's the solution here? In short, if you want to be on the safe side and reduce your exposure to BPA, you have to reduce your consumption of canned foods (including coconut milk) as much as possible. I made this recommendation in 9 Steps for Perfect Health-#3: Eat Real Food.
A study published in Environmental Health Perspectives found that families who ate fresh food for three days with no canned food, and using only glass storage containers, experienced a 60% reduction of BPA in their urine. The reductions were even higher (75%) for those with the highest BPA levels at the beginning of the study.
The good news, however, is that there are at least two brands of coconut milk that don't have BPA in them. One is Native Forest, which you can purchase on Amazon if it's not available at your local store. The other is Arroy-D, which is a brand imported from Thailand. You can get it here (but you have to scroll down and order the version that comes in cartons, not the cans at the top). I'm a little suspicious of Arroy-D, though, because one Thai reader mentioned that it does contain other ingredients aside from coconut milk. I don't read Thai, so I can't confirm this. If anyone out there can, please leave a comment below.
Coconut milk can also be made quite easily at home, with coconut flakes, a blender and cheesecloth. Here's a video to show you how (get a load of the soundtrack). I find that blanching the coconut flakes prior to blending improves the results.
Guar gum
The other potential problem with canned coconut milk is guar gum. Guar gum is a galactomannan, which is a polysaccharide consisting of a mannose backbone with a galactose side group. It's primarily the endosperm of guar beans.
Beans and legumes have a variety of compounds in them that make them difficult to digest, especially for people with digestive problems (1 in 3 Americans, from the latest statistics).
In my clinical experience, many patients with gut issues improve when they remove guar gum from their diet - including canned coconut milk.
Unlike BPA, there's no evidence that guar gum may cause serious harm. So, if you're able to tolerate guar gum, I don't see a problem with buying coconut milk from Native Forest or Arroy-D or making it at home.
Fructose malabsorption
Fructose malabsorption (FM) is a digestive disorder characterized by impaired transport of fructose across the small intestine. This results in increased levels of undigested fructose in the gut, which in turn causes overgrowth of bacteria in the small intestine. Undigested fructose also reduces the absorption of water into the intestine.
The clinical effects of FM include: intestinal dysbiosis, changes in motility, promotion of mucosal biofilm, and decreased levels of tryptophan, folates and zinc in the blood. Symptoms produced include bloating, gas, pain, constipation or diarrhea, vomiting and fatigue (to name a few). Recent research has also tied fructose malabsorption to depression.
Lest you think this isn't a common problem, studies have shown that up to 40% of people in Western countries suffer from fructose malabsorption.
Even in healthy people without fructose malabsorption, however, only about 20-25g of fructose can be properly absorbed at one sitting. Glucose assists in transport of fructose across the intestine, so in general foods with equal amounts of glucose and fructose will be better absorbed than foods with excess amounts of fructose (in relation to glucose).
While fructose malabsorption can cause symptoms in anyone, those with Irritable Bowel Syndrome (IBS) or Inflammatory Bowel Disease (IBD) are particularly affected. While the prevalence of FM is the same in healthy populations and those with IBS & IBD, the experience of FM appears to be more intense in the latter group. This is probably due to the increased visceral sensitivity common in IBS and IBD patients.
In fact, one of the most promising clinical approaches to treating IBS & IBD right now is something called the FODMAP diet. FODMAP stands for Fermentable Oligo-, Di- and Mono-saccharides And Polyols. These include:
- fructose (fruits, honey, HFCS)
- fructans (wheat, onions)
- lactose (milk sugar)
- polyols (sugar alcohols like sorbitol, xylitol & mannitol, along with fruits like apples, pears and plums)
- galactooligosaccharides (legumes & beans, brussel sprouts, onions)
- other sweeteners like polydextrose and isomalt
What does this have to do with coconut milk, you ask? According to Drs. Gibson & Barrett, experts in fructose malabsorption, coconut milk is is a FODMAP and should be avoided by people with digestive conditions like IBS & IBD.
According to NutritionData.com, coconut milk has very little sugar of any kind - including fructose. Nevertheless, I do have patients that cannot even tolerate homemade coconut milk (which has no guar gum in it), even though they are fine with coconut oil. I assume that they are reacting to the fructose in the coconut milk - but I can't be sure.
Recommendations
Let's bring this together into recommendations for three different groups of people:
- Women who are trying to get pregnant, pregnant or breastfeeding, children and other vulnerable populations (chronically ill): should avoid canned coconut milk products except for those that are BPA-free, like Native Forest and Arroy-D
- People with digestive problems (IBS, IBD, GERD, etc.): may want to avoid coconut products entirely, except for coconut oil
- Healthy people: may be fine with canned coconut milk, provided they don't react to the guar gum, and provided they're willing to take the side of industry scientists that claim BPA doesn't cause harm in humans
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