Tuesday, May 14, 2013

Why Your Growing Child Needs to Eat More Fat

The low-fat craze of the 90's just won't die.  I thought we were past low-fat at this point, yet every time I go to the grocery store I'm still bombarded with the fat-free message.  It's worse at Whole Foods, my place of employment. We even have a whole line of "healthy" fat-free salad dressings at our salad bar. And in my current school lunch rotation (part of the joyful road to becoming an RD), fat is being pulled from the menu like never before in favor of whole grains, vegetables, and skim milk.  New York City schools have gone as far to ban butter (!?!?). For the average consumer, the message is loud and clear: fat is bad, mmmkay? We've gotta eat more vegetables! Eat your broccoli, eat your salad! Throw out the butter and oil! Fat's killing the kids!

But there's a problem with that. A big one. Of course vegetables are full of nutrients, but eating them without fat renders their fat-soluble vitamins (mainly vitamin A) useless. And you do NOT want that, especially if you're a little cherub in the 1st grade. Read on now, ya hear?

Eating fat allows you to absorb more nutrients out of your fruits and veggies.
I found this study via Chris Masterjohn; he mentioned it in passing in this article, but I feel that it deserves more attention.  It's an extremely well-done study, and it proves conclusively that absorption of fat-soluble nutrients is dependent on the amount of fat in the meal. 

The study, done in 2004, tested carotenoid absorption from a salad with varying levels of fat added (1).  For the non-scientifically minded, carotenoids are vitamin A precursors; alpha-carotene, beta-carotene and lycopene were tested here.  The researchers recruited 7 subjects, who each consumed 3 salads consisting of equivalent amounts of spinach, romaine lettuce, cherry tomatoes, and carrots with salad dressings containing 0, 6, or 28 g canola oil. The salads were consumed in random order separated by washout periods of at least 2 weeks, and the participants were instructed to avoid carotenoid-containing foods for 4 days preceding each test.  Blood samples were collected hourly from 0 to 12 h post-meal. 

Triangles = no fat, Open circles = 6 g fat, Closed circles = 28 g fat

To quote the abstract of the study... "Essentially no absorption of carotenoids was observed when salads with fat-free salad dressing were consumed. A substantially greater absorption of carotenoids was observed when salads were consumed with full-fat than with reduced-fat salad dressing." Translation: no fat = no absorption. A little fat = a little absorption. A lot of fat = a lot of absorption. Doesn't get any simpler than that. We need fat for carotenoid absorption, no two ways about it.

The type of fat matters too. Another study examined the difference in carotenoid absorption in the presence of olive oil (monounsaturated fat) versus corn oil (polyunsaturated fat) (2). Absorption was shown to be much higher with olive oil in all cases, and this is likely to apply to other monounsaturated fats as well, like canola oil.

Why this matters: It's all about the kids.
But, you may say, these studies only apply to vitamin A precursors like beta-carotene... we get plenty of vitamin A in the diet so we don't need to worry about it. Not so fast. We consume enough vitamin A, yes. And nearly all of us absorb enough of it to prevent a deficiency. But does that mean we have enough to be optimal? Absolutely not. Especially for growing children, who need vitamin A for bone growth and facial development.  Some evidence, like the work of Weston A. Price, shows that intake of vitamin A beyond just the minimum is needed for optimal skeletal development (3).

According to the authors of that first study, "Carotenoids are most commonly consumed in fruit and vegetables, and most populations depend on provitamin A carotenoids in these foods to meet vitamin A requirements." Since we know that the absorption of these vitamin A precursors is entirely dependent on the fat content of the meal, we can say that the presence or absence of fat in a child's diet may be the determining factor in their vitamin A status. In other words, your child's bone and facial development could be stunted due to a lack of fat in the diet. Every parent wants to do the best they can for their children right? Well, part of this would be liberalizing their fat intake.

The benefits of vitamin A.
The benefits of optimal bone development and facial structure are many-fold, but here are a few of them...
  • Straight Teeth - Proper facial development will allow enough room for teeth to grow in and minimize the need for braces
  • Injury Prevention - Giving your child a strong set of bones will lessen their chances of breaking one in the future
  • Physical Attractiveness - Let's be real, people with fully developed faces and straight teeth are usually more attractive... and we all know there are perks to that (4

Eating fat sounds like a no-brainer doesn't it? But this is a problem in today's fat-phobic society, with fat-free dressings and butterless school lunches. Parents want to do the right thing, but restricting fat is NOT the way to do it. We need a balanced diet with natural fats... natural fats like extra virgin olive oil, butter, coconut oil, and even some animal fat. A little fat does a body good. Let go of your fat phobia, please. Do it for the children.

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