Thursday, April 5, 2012

POTATO RE-HASH



DISCLAIMER-NO RECIPE! SORRY!
As you know I am pretty enamored with potatoes. Hell, that's putting it pretty mildly! I love them! I have eaten white potatoes 4-5 times a week every week for the last year and have completely reversed diabetes in the process. For those of you with some interest in potatoes and the ability to read more than a paragraph in one sitting (ummm sometimes I can't so don't feel bad, guess its all the video games over the years) I would like to share a wonderfully in depth article by registered dietitian and funny man Jeff Novick on potatoes and their correlation with Type 2 Diabetes. 

Enjoy and to your health!

-benjamin


Potatoes & Diabetes:
Dietary Trends & Truths About Taters
Jeff Novick, MS, RD

Are potatoes dangerous?  Do potatoes cause diabetes?

You might think so if you followed the headlines, as in 2006, the media was full of reports making these claims, some of which are still being made today.   All of this attention was based on the results of a study published in the American Journal of Clinical Nutrition.(1)

The study was a prospective study of 84,555 women in the Nurses’ Health Study.  At the start, the women, aged 34–59 years, had no history of chronic disease, and completed a validated food frequency questionnaire.  These women were then followed for 20 years with repeated assessments of their diet.  The studies conclusion, as stated in the abstract was, "Our findings suggest a modest positive association between the consumption of potatoes and the risk of type 2 diabetes in women. This association was more pronounced when potatoes were substituted for whole grains.”

So, lets take a closer look at the study and see how accurate these claims are, and where the "truth about taters" really lies.   Specifically, we will look at 6 important key points.

1) Are all potatoes equal? Or “when is a potato not a potato?”

In the study, participants were asked how often, on average, in the previous year, they had consumed potatoes. The options they were given to choose from  were either

a) - 1 baked or 1 cup mashed potato
b) - 4 oz of French fried potatoes

These were the only 2 choices the subjects could pick from.  So, while these may represent how potatoes are often consumed here in American, they do not account for any differences in how the potatoes were prepared and served.  And, mashed potatoes were counted in with baked potatoes, which are two completely different forms of potatoes. So, lets take a closer look at these important issues.

In American, whether it is at home or in restaurants, most all mashed potatoes are made with milk and butter and/or margarine.  In addition, most all baked potatoes are served with butter, sour cream and/or cheese. 

The following analysis represents these important differences.  They are of a serving of mashed potatoes, a loaded baked potato and a plain baked potato as served in a popular national restaurant chain.  They are typical for how mashed potatoes and baked potatoes are often served and consumed in American.  In addition, I have included the analysis of a plain medium baked potato for comparison.

Mashed Potatoes (Restaurant)
367 calories
24 grams of fat
59% calories from fat
11.4 grams of sat fat
28% calories from sat fat
9 mgs of cholesterol

Loaded Baked Potato (Restaurant)
505 calories
22 grams of fat
39% calories from fat
10 grams of fat
18% calories from sat fat
30 mgs cholesterol

Regular Baked Potato (Restaurant)
329 calories
4.5 grams of fat
12% calories from fat
.4 grams of Sat fat
1% calories from sat fat
22 mgs cholesterol

Baked Potato (Home)
A typical medium potato
160 calories
.2 grams of fat
1% calories from fat
.1 grams of fat
.05% calories from sat fat
0 mgs cholesterol

So, compared to an at-home, plain baked potato;

The mashed potato gets 207 calories (56%), 23.8 grams of fat (99%), 11.3 grams of sat fat (99%), and 9 mgs of cholesterol (100%) from the other "non potato" ingredients,

The loaded potato get 345 calories (68%), 21.8 grams of fat (99%), 9.9 grams of sat fat (99%), and 30 mgs of cholesterol (100%) from the other "non potato" ingredients,

Even the regular baked potato from the restaurant gets 169 calories (51%), 4.3 grams of fat (96%), .3 grams of sat fat (75%), and 22 mgs of cholesterol (100%) from the other "non potato" ingredients (most likely oil and/or butter used on the outside and/or as a regular topping)

As we can see, the potato is contributing only a small percentage to what is most likely being counted as “potatoes” in this study.   This is very important to take this into consideration when applying the conclusion of the study to "potatoes" because the association applied to potatoes in this study may be more accurately applied to how potatoes are prepared and consumed and the toppings they are served with here in America, more so then just the potato itself. The study admitted that "cooking methods" were not assessed so it is safe to assume that these were typical Americans consuming potatoes the way there are typically served.

In addition, other studies on the Nurses database show the majority of their diets are not low fat, low saturated fat, low cholesterol or high fiber which confirms that they are not choosing or consuming the healthier versions.

So, when is a potato not a potato?  When nurses in American consume them.

2) The Potato: The Finger or the Moon?

In Buddhism there is a famous saying, "the finger pointing to the moon is not the moon."

In other words, language and words are merely symbols with which to express the truth. Words points at the truth, but the truth is not in words. Language and words are merely symbols with which to express the truth.    In science, we call these "markers."  A marker is something that may not be responsible for the observed effect, but points to what is responsible for the observed effect.  

So, in this study, was the potato the problem itself, or was the potato acting as a marker and pointing to something else that was associated with potato consumption.

Quoting the researchers.

"White potatoes and French fries are large components of a “Western pattern” diet. This dietary pattern is characterized by a high consumption of red meat, refined grains, processed meat, high-fat dairy products, desserts, high-sugar drinks, and eggs, as well as French fries and potatoes. A Western pattern diet previously predicted a risk of type 2 diabetes. Thus, we cannot completely separate the effects of potatoes and French fries from the effects of the overall Western dietary pattern.”

This "previous" study the authors refer to is a study of dietary patterns and risk for type 2 diabetes in men, which was reported in the Annals of Internal Medicine back in 2002 (2). In that paper, which followed 42,504 male health professionals for a period of 12 years, the “Western dietary pattern” was associated with a modest increase in type 2 diabetes.

This “Western dietary pattern” discussed in this previous study was characterized by a “high consumption of red meat, processed meat, refined grains, French fries, high-fat dairy products, sweets and desserts, high-sugar drinks and eggs.” "However, the correlation of potatoes with the Western pattern of eating was low and the association with type 2 diabetes wasnonexistent."   The only individual foods that had a significant positive association with type 2 diabetes were red meat and refined grains. 

We see similar patterns here in the current study under discussion; the subjects who ate more potatoes also ate more red meat, more refined grains and consumed more total calories, over 500 more calories per day. In addition, potato intake was also associated with a slightly higher intake of sat fat and trans fat and less physical activity.

Lastly, the significance of the association between potatoes and type 2 diabetes, which was modest to begin with, disappears completely in the subjects who were not obese.

So, was the potato the problem, or was the potato a marker for a dietary pattern and lifestyle that was responsible for the results.   In this study, the potato was the finger pointing to the moon and not the moon itself.

3) Trends and Truth in Taters

If a food really is a causative factor in a disease, then as we consume more of the food (as an individual or as a nation) we should see the disease rates go up accordingly.  In addition, when we remove or lessen the consumption of the food, we should see disease rates (as an individual or as a nation) go down.

However, this is not the case for potatoes and diabetes.

Total Potato Consumption
1970: 122 lbs/person/yr
1996: 145 lbs/person/yr
2008: 117 lbs/person/yr

Potato consumption rose from 1970 to its peak in 1996 at which time it began to fall and by 2008 was lower than its 1970 level, a drop of 18% since its peak.

Fresh Potatoes
1970: 61 lbs
1996: 50 lbs
2008: 36 lbs

As we can see, fresh potatoes (the ones most likely to be prepared and served in a healthy manner) have fallen steadily from 1970, dropping over 41%

Frozen Potatoes
1970: 28 lbs
1996: 60 lbs
2008: 52 lbs

Frozen potatoes, (the ones most likely to be prepared and served as French fries) doubled from 1970 to 1996 and then fell slightly but are still up significantly from 1970, up around 86%

Prevalence of Diabetes
1970: 2%
1996: 2.89%
2008: 6.29

During this same period, diabetes rose 45% from 1970 to 1996 and then rose another 117% from 1996 to 2008.  From 1970 to 2008, there is a 215% increase in diabetes

So, from 1996 to 2008, potato consumption fell 19% but diabetes rose over 200%.

When we look closer at the types of potato, the only clear relationship we see is an "inverse" relationship between fresh potatoes and diabetes and a trend towards correlation between frozen potatoes and total potatoes but only until 1996-1998 where we see an inverse relationship develop.  So consumption of all types of potatoes is now trending down yet prevalence of diabetes is rising faster than ever.

Most importantly, the prevalence of diabetes really began to increase in 1996-1998, which is the same time that potato consumption of all types, began to fall sharply.

Potato consumption is not related to the prevalence of diabetes and shows an inverse relationship with the consumption of fresh potatoes.

This link is to a picture of a graph that highlights this information.  

http://www.facebook.com/pages/Jeff-Novick-MS-RD/177550385124?v=photos&ref=ts#!/photo.php?pid=14970538&id=177550385124&ref=fbx_album

I use a factor of 10 on the prevalence of diabetes so it would scale better with potato consumption.  Therefore, instead of 2 in 1970 I uses 20 and instead of 6.29 I used 62.9.   Diabetes prevalence from CDC, Potato consumption figures from USDA ERS. 

4) Associations

Studies like the Nurses Study cannot prove cause and effect but only show associations.  These associations can be of various "strengths" depending on other variables.

Quoting.

"Although we assessed and adjusted for a variety of potential confounding variables, we cannot rule out the possibility of residual confounding, especially because the observed association between potatoes and the risk of type 2 diabetes was modest in the present study."

In this study, the association was "modest" at best.

5) Replication

In science, the results of any one study are always interesting but never prove anything unless they can replicated and/or reproduced.  Reproduction and replication are what increase the validity of any claim.

In a 4-year prospective study of 36,787 adults which was done one year later, researchers,  working independently from any food industry sponsors, investigated the association between a variety of dietary patterns and type 2 diabetes (3)  The study results, which were published in the American Journal of Epidemiology, looked at potatoes and diabetes and also looked at cooking method and only found an association with potatoes when they were cooked with oil.  They concluded that consuming a variety of cooked vegetables, including potatoes, cooked in ways other than frying, was associated with a reduced risk of developing Type 2 diabetes.

From the study.

"Fish, chicken, and potatoes, when cooked in ways other than frying, loaded on factors that were not associated with increased risk of diabetes."

"The results indicated that a dietary pattern characterized by meats and fatty foods was associated with increased diabetes risk while a dietary pattern characterized by a variety of salad and cooked vegetables, including potatoes cooked in ways other than frying, was associated with a decreased risk."

Also, as I mentioned before in point 2, there was an earlier study of dietary patterns and risk for type 2 diabetes in men, which was reported in the Annals of Internal Medicine back in 2002 (2). In that paper, which followed 42,504 male health professionals for a period of 12 years, the “Western dietary pattern” was associated with a modest increase in type 2 diabetes.   "However, the correlation of potatoes with the Western pattern of eating was low and the association with type 2 diabetes wasnonexistent."

Therefore, other studies have not found the same results. In fact, one found no association at all and one, which accounted for cooking methods, only found an association for potatoes when they were cooked with oil/fat and otherwise, found a decreased risk..

6) The Moon

What really causes diabetes and do potatoes play a role. 

Being overweight or obese, and physical inactivity are two key factors in developing diabetes and have an over 90% correlation.   In addition, high blood pressure and elevated cholesterol and triglycerides also play a role.

During the 20 years that the subjects in the Nurses study were followed, we saw a dramatic shift in the dietary and lifestyle pattern of Americans. Not only in potato consumption and the type of potato which changed dramatically, but in many other areas as well.  During that same time, other components of the “Western dietary pattern” sharply increased including; refined sugars/sweeteners, refined grains/carbohydrates, added oils/fats, hydrogenated fats/trans fat, cheese, calories etc.  In addition we saw a large increase in the calorie density of foods and the American diet and in the  percentage of Americans who are overweight and/or obese while at the same time, the percentage of Americans who were active fell dramatically.

This is what is responsible for the dramatic increase in the incidence of diabetes.

Mashed potatoes, loaded baked potatoes and French fries, as prepared and consumed as part of a “Western Dietary Pattern” are extremely calorie dense, high in fat, saturated fat, cholesterol, sugar, and salt and increase your risk for disease.    Even the typical baked potato, as served in a restaurant today, can be much higher in calories, fat, and saturated fat than a plain baked potato made with nothing added. 

Therefore, avoid all these Western forms of potatoes.

However, there is no real credible evidence at all that potatoes, when consumed close to their natural state and cooked conservatively by baking, boiling, and/or steaming, etc,  without added fat, salt, sugar, oil as part of a healthy diet of fruits, veggies, starchy veggies, intact whole grains and legumes, will cause diabetes or are associated with an increased risk.  

In Health,
Jeff

(1) Potato and French fry consumption and risk of type 2 diabetes in women– Am J Clin Nutr 2006;83:284 –90.

(2) “Dietary Patterns and Risk for Type 2 Diabetes Mellitus in U.S. Men. Ann Intern Med. 2002;136:201-209.

(3) Dietary Patterns and Diabetes Incidence in the Melbourne Collaborative Cohort Study Am J Epidemiol 2007;165:603–610

1 comment:

  1. Thansk, Jeff. I have always loved potatoes, but everyone I know tells me that they are bad for anyone trying to lose weight. I tired of hearing this and forgoing one of my favorite foods, so I began eating them anyway.

    Your information is so very welcome. It provides me with facts to back up my belief that potatoes and natural starches like my homemade wheat and oat bread are good for you and will not kill a weight-loss diet.

    I have lost over 30 pounds so far, eating a plant-based diet that includes the above. I do eat meat, but not as often as previously. And, I try to exclude all non-healthy foods, as much as my will power will enable me.

    Thanks for your blog. It is very refreshing, informational, and supportive.

    ReplyDelete

Printfriendly