August 25, 2012

Lactose tolerance favors obesity

While the lactose tolerance allele may have some positive health effects, notably because milk is one of the few good dietary sources of calcium, it seems to correlate also with some negative effects, namely obesity.

Ricardo Almon et al., Association of the European Lactase Persistence Variant (LCT-13910 C>T Polymorphism) with Obesity in the Canary Islands. PLoS ONE 2012. Open access ··> LINK [doi:10.1371/journal.pone.0043978]

Canary Islands, in spite of its subtropical geography, is one of the regions of the European Union where milk is most consumed, at levels comparable to Scandinavia. 

Although there is a strong correlation between being lactose tolerant and milk consumption it is not fully clear yet if it is excess milk consumption what makes people obese or an unknown collateral effect of the European lactase persistence allele.

Interestingly the correlation, very strong, is only found for obesity and not for being overweight:

Fig. 1 - BMI classification by LCT genotypes (LP: n = 330; LNP: n = 221)

2 comments:

  1. Nonsense. It's the calories.

    The highest rate of diabetes in the US is among the Pima Indians of the US (in contrast to the low rate among the Pima Indians of Mexico). Both groups are lactose intolerant, but have a different diet, thanks to American government food subsidies.

    So one wonders if many in the Canary Islands who are lactose intolerant can afford other sources of protein or high calorie foods... Are the lactose intolerant descendants of the Arab/Berber immigrants poorer than the Spanish/European descended population? Do they eat a high fish/fiber/bean diet of their ancestral home rather than European type foods?

    Was the study only among the native Canarians, whose genetics are different?

    and how much of the milk is eaten as yogurt, which can be tolerated by many with lactose intolerance?

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    Replies
    1. Sorry, Boinky, but Blogger Spam Filter sent your comment to the spam folder again. Nothing I can do but to approve it ex-post-facto, as I did.

      Notice that this paper does not deal with diabetes but obesity, related maybe but different illnesses (actually I recently learned that diabetics lose weight initially in fact). It should also be caused by things totally unrelated to milk consumption, for example fructose syrup consumption in sodas and bakery.

      Also to have the known "European" lactose tolerance allele is not synonym of being lactose tolerant, much less vice versa. For example Central Italians only have the genotype at the frequency of 21% but they have the phenotype at the level of 82%, instead among Tajiks the genotype is as high as 51% but actual lactose tolerants are only 18% - see here.

      Said that, I'd agree that the percentages of people without the genotype seem rather high for Spain's levels and that may be caused by Guanche blood (North Africans have lower levels of the allele than Spaniards).

      "Was the study only among the native Canarians, whose genetics are different?"

      Nobody knows anymore who are "Native Canarians", as you say. The blend was completed long ago and now there are just Canarians. You can read the details in the link anyhow, because it is an open access paper, no particulars are reported anyhow.

      "and how much of the milk is eaten as yogurt, which can be tolerated by many with lactose intolerance?"

      The paper only mentions high consumption of "milk", no mention of dairies in general. Milk usually means unprocessed milk. What is less clear is how much of it is low fat and how much is full. The paper only mentions this high consumption in a few lines comparing it with Norway and close to Sweden. You can research the source yourself, if you are so interested.

      Milk is used, mixed with beer, among the Dinka of South Sudan for "fattening contests" which usually end up killing the "winner". It's therefore no surprise for me to find that milk can be a cause of obesity, after all full milk has more than 30% of fat (dry residue), and that's a lot of fat (WHO recommends not eating more than 20% of fat but the healthy levels should probably be set quite lower, specially for high calorie diets).

      Delete

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