Thursday, June 7, 2012

Quantifying the Healthiness of a Diet

To be clear - when I use the word diet here, I mean what you eat on a regular basis- not some strategy you engage in to lose weight.

The purpose of dietary guidelines from governments, health organizations and public health authorities (e.g. DHHS/USDA, the AHA or HSPH) is to reduce the risk of disease.  This would include the prevention of fatness. 

Remember, it is not weighing more that leads to disease - simply being taller can make you weigh more - it is being fatter - having too much fat - that leads to disease risks.

When researchers evaluate the effects of guidelines, they choose an outcome to measure such as, BMI, saturated fat intake, heart disease etc. Some scientists use a diet index which will contain 10 or more items that are scored.  This often leads to totals between 0 and 110 such that a perfect diet would be 110.  When a researcher conducts a study, he or she might break the scores into categories, for instance, 0-30 is poor, 31-60 is needs improvement,  61-80 is good, and 81+ is great.  Or it might be a two way measure, above and below 50 say.  Most Americans do NOT score above 70, in case you are wondering.

Today I want to tell you about a particular index because it should give you the information you need to rethink the choices you make. I think that this info can help to make the DGAs more real for you. The index is the AHEI-2010 or the Alternative Healthy Eating Index.  Alternative to what you might ask, I hope you did ask.... It is an alternative to the one that was created to align with the Dietary Guidelines for Americans (from the DHHS/USDA).  The 2010 HEI is not yet complete but it is good.  I just feel, after reading about the criteria for the alternative, that it is a little better.  And YES, it has everything to do with it coming from the Harvard School of Public Health and that I learned about it when Walter Willett responded personally to my email.  I wrote to him because he had written an article that said the DGAs did not go far enough.  I wanted to know if he had a better measure of a healthy diet - a diet that HE thought was healthy... of course he did! He sent me the article.  (to be fair, the HEI 2010 may be just as good, I just haven't seen it yet)

The AHEI 2010 was only recently completed and there is one journal article that describes and applies it to an older set of data.  I have read this article and the foot notes about the index are incredibly enlightening.  I am going to see if it is possible to get them in the blog, but for today I encourage you to once again visit HSPH and the Healthy Eating Plate.  I know I shared this with you before - but the AHEI is based on this plate and recommendations you'll find on that page.

I will tell you more about how the AHEI is scored tomorrow but I will leave you with the categories today - there are 11.  A person can score 0 to 10 on each one.  Remember high score is better.  You can spend the day wondering what qualifies a person for a ten and I will do my best to tell you tomorrow.  (OF note, fruit juice is in the same category as sugar sweetened beverages, potatoes are NOT counted as a vegetable [the reason is given in the foot notes] and instead of saturated fat as a category, they have red and processed meats).  Here are the 11 items.  Oops, one more thing - two of the categories have separate criteria numbers for men and women (*).  

*Whole Grains
Sugar Sweetened Beverages/Fruit Juice
Nuts and Legumes
Red/Processed Meats
trans Fat (as a % of total intake)
Long chain fats (as a %) - think fish - Omega 3s (EPA+DHA)
PUFA (as a %) -polyunsaturated fats (oils, liquid at room temp)

Here is the link to the study where I learned about the AHEI 2010 and which has the table with all the awesome notes.  Only the abstract is available without logging on to a library site which has access to the journal, sorry.

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