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Let me introduce myself. My name is Mark Sisson. I’m 63 years young. I live and work in Malibu, California. In a past life I was a professional marathoner and triathlete. Now my life goal is to help 100 million people get healthy. I started this blog in 2006 to empower people to take full responsibility for their own health and enjoyment of life by investigating, discussing, and critically rethinking everything we’ve assumed to be true about health and wellness...

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October 04, 2008

Challenging Assumptions

By Worker Bee

Here at Mark’s Daily Apple, we talk about food a lot. The Primal Blueprint is basically founded on the notion that following the approximated diet and lifestyle of our Primal ancestors is the key to lasting health. A large portion of our posts center on examining long-held conventional wisdom about food – ridiculous stuff like “fat is bad,” “carbo-loading is necessary for any athlete,” “avoid egg yolks,” and “vegetarianism represents the pinnacle of dietary health.” Time and time again, we’ve shown that blindly subscribing to popular notions about food is not only misinformed, but also potentially damaging. It is only through examination that we progress and learn; taking “food experts” and Big Pharma at their word has been shown to be a grave misstep. And so, with this in mind, we move to examine two new scientific developments that question some fairly entrenched dietary conventional wisdom.

Fish Will Poison Your Baby

Old wives’ tale? A word of caution from the family pediatrician? Or just something you heard from the gals at the office? Whatever the source, the idea that feeding your baby fish will somehow cause irreparable harm is fairly deep-seated in our society. It’s one of those “facts” that people just “know,” but are unable to cite actual reason for believing. Of course, like most pieces of common knowledge, this fish business has some basis in reality. As we all know, seafood – especially the farmed variety – can be pretty susceptible to mercury absorption. Mercury is absorbed through the gills and by eating contaminated fish, so the larger predatory species, like shark, swordfish, and the larger varieties of tuna sold as steaks or sashimi, generally have higher mercury levels. Canned tuna, salmon, shrimp, cod, and crab, some of the more popular varieties of fish, have the lowest mercury levels. In addition, shellfish are one of the more common allergens, making uninhibited feeding to your children potentially dangerous. Just be careful. So if you have the hankering for some seafood, go wild (literally – avoid farmed fish!) and don’t make the more mercury-laden varieties a dinner staple.

Now we have some more ammo for the pro-fish contingent (read: us). A new study out of Sweden followed 5,000 6-month old infants for six months. Infant eczema had become an increasingly prevalent issue there, and researchers suspected diet was playing a role. At six months, 13% of the babies suffered from eczema, and the parents were quizzed on diet and environment. After twelve months, 1 in 5 children had the condition. Genes had an effect; kids with a sibling or parent with eczema were nearly twice as likely to also develop it. Furry pets (sounds like a weird variable to test for, we know) had no impact. What did seem to have an effect was the introduction of fish into the child’s diet. If fish was introduced by the nine-month mark, the chance of developing eczema was slashed by 25%. Pretty solid evidence in support of feeding your kids fish, we’d say. Oh, and furry pets didn’t do much for kids, but you know what did? Having a pet bird. So, parents – reconsider roasting a chicken for dinner tonight and maybe set him up in a sweet hen house out back and broil some salmon fillets instead.

Is This Still Good?

We doubt spoiled foods are much of an issue for our insect munching, dirt bath taking readers, but this piece of news might still be interesting. A British group has discovered what we’ve known for years – that most people waste incredible amounts of perfectly good food. It turns out that most “Use By” dates are generated based on the “better safe than sorry” mindset. Food distributors, looking to avoid lawsuits, assume the worst about a particular batch of food and date everything accordingly. While it may prevent the odd case of food poisoning, this dating methodology arguably causes more damage because of the waste of consumers throwing out anything that reaches the date. Thankfully, though, new devices are being developed that can accurately determine the correct date a food item will expire by monitoring food throughout the production process. “Most food is perfectly ok to eat after its displayed best before date,” say UIC director Bruce Grieve (the group developing the sensors), but the new food sensors might make it official for everyday people quick to throw food out.

Since the Primal Blueprint so heavily relies on fresh, whole foods, new sensors that effectively prolong their shelf lives are probably something to look out for.

Further Reading:

More Worker Bees’ Weekly Bites

Vegetable Victory: How to Best Preserve Produce

When Do Foods Really Go Bad?

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7 Comments on "Challenging Assumptions"


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8 years 10 months ago

Hi Mark,

Just wondering if you had ever heard of the book “Nutrition and Physical Degeneration” by Westin A. Price. It was written in 1939 and this man and his wife traveled the world for 10 years studying the nutrition habits of natives on traditional diets and those who had begun eating what he calls the “white man’s diet”. It is FASCINATING. There are 140 or so pictures comparing dental health, changes in physique, and it is absolutely mind blowing. If you haven’t read it I highly recommend you do – the text and pictures can be found online at:

Son of Grok
Son of Grok
8 years 10 months ago

I never ate fish as a kid. I thought I hated it, but I think I hardly ever really tried it. Could be one of the reasons that I was so sickly as a child.

Tom Parker
8 years 10 months ago

The waste section really doesn’t surprise me. Living in student accomodation for a number of years it’s quite horrifying how much perfectly good food I saw thrown out based on the sell by date.

8 years 10 months ago

I go to a local store that panics and marks things down about 80% when they get within a month of the expiration date. I’ve gotten some killer deals on things like frozen organic fruit and chicken breasts.

Most people turn their noses up at fruit or veggies with some tiny blemish; I’ve bought cartons of organic blueberries for 50-cents because a couple of berries in the corner got mashed.

Yep, people sure are spoiled.

8 years 10 months ago

You can also look into the Metabolic Typing Diet by William Wolcott and Trish Fahey. It is based on Weston Price’s research. It is the diet I used as a guideline before going Paleo. I was lucky because according to the book I am a protein type and the guidelines were very similar to the Paleo diet.

7 years 5 months ago

You’re wrong about canned tuna having low Mercury levels. It is actually quite high.

7 years 2 months ago

While tuna does have a high content of mercury, it also has very high levels of selenium (80% of the RDA in one serving). Selenium binds
to a number of toxic metals, and is protective against cadmium, arsenic, mercury, and lead.

Here is an article about it.