Tuesday, December 3, 2013

Fructose-Nation: No Change in Fructose Availability in the US Since the Early 1970s. So Why Are We Fat, Then?

From fat to Fructose - just another scapegoat for a fundamental problem?
Over the past 5 years or so, the idea that that fructose is to blame for the ever-increasing rates of diabesity has become so popular that hypotheses such as "the fructose consumption has exploded over the past decade" are usually accepted as scientifically verified facts.

A recent paper from the Department of Nutrition and Health Sciences at the University of Nebraska did now remind me that not all things that appear logical and consistent with our believes are necessarily true.

Do we even consume that much fructose?

As Trevor J Carden and Timothy P Carr point out, "the consumption pattern of fructose and other key nutrients" in the past 4 decades, "remains a topic of debate" (Carden. 2013). To determine whether fructose consumption in the US has increased sufficiently to be a casual factor in the rise in obesity prevalence Carden and Carr analyzed the USDA Loss-Adjusted Food Availability Database.
The researchers found that the food availability of glucose and fat, but not fructose, increased in the US between 1970 and 2009.
To calculate the percent change in energy from food groups and individual nutrients, Carden and Carr started initially compiled the available data on the per capita loss-adjusted food availability for 132 individual items were. In a second step they analyzed the corresponding nutrient profiles and used their findings to determine the availability of energy as well as macronutrients and monosaccharides during the years 1970-2009. By comparing the values for a given year to the baselinen in 1970, they did eventually determine the percent change in energy from food groups and individual nutrients.
Figure 1: Change in food energy availability per capita, 1970-2009 (Carden. 2013)
If you take a glance at the data in Figure 1 it's easy to see that their findings indicate that during this 40 year period the total energy availability increased by +10.7%. In that, the main "offenders" were grains and oils, the net change in total fructose availability, on the other hand was 0% - in other words, the added sweeteners (1%) were not even fructose based. Furthermore, Carden and Carr observed that the ...
"[e]nergy available from total glucose (from all digestible food sources) increased 13.0% [and ended up being] more than 3-times greater than fructose." (Carden. 2013)
With 14.6%, the amount of fat increased to a very similar extend as that of glucose. That's a 3x higher increase than for protein (+4.7) and am 1.6x higher increase in energy availability than for carbohydrates ,in general (+9.8).

So, it's the fat and sugar that's to blame? Not the fructose?

Despite the fact that I am not particular fond of the "fructose theory of everything evil", I believe that we got to be cautious about the significance of Trevor J Garden's and Timothy P Carr's conclusion, that their data would "suggest" that fructose is "unlikely to have been a unique causal factor in the increased obesity prevalence". If you take a look at the supplemental data they provided you will find, that their list of 132 foods used to calculate USDA food availability, i.e.
  • Head Lettuce
  • Kale
  • Lima Beans
  • Whole flavored milk
  • Buttermilk
  • Lowfat flavored milk
  • Plain 1-percent milk
  • Plain 2-percent milk
  • Skim milk
  • Eggnog and Half and Half (dairy and fat share of)
  • Sour cream
  • Yogurt
  • Cheeses
  • Lowfat cottage cheese
  • Reg. cottage cheese
  • Frozen yogurt and other misc
  • Ice cream
  • Lowfat ice cream
  • Condensed bulk and canned skim milk
  • Condensed bulk whole milk
  • Condensed canned whole milk
  • Dry buttermilk
  • Dry whole milk
  • Nonfat dry milk
  • Barley products
  • Corn flour and meal
  • Corn hominy and grits
  • Corn starch
  • Durum flour
  • Oat products
  • Rice
  • Rye flour
  • White and whole wheat flour
  • Beef
  • Lamb
  • Pork
  • Veal
  • Chicken
  • Turkey
  • Fish and Shellfish
  • Eggs
  • Great N. Beans
  • Butter
  • Edible beef tallow
  • Lard
  • Margarine
  • Other edible fats and oils
  • Salad and cooking oils
  • Shortening
  • Beer
  • Wine
  • Distilled Spirits
  • Garlic
  • Frozen Veggies
  • Mushrooms
  • Mustard Greens
  • Navy Beans
  • Okra
  • Onions
  • Canned Veggies
  • Other Dry Beans
  • Peas and Lentils
  • Pinto Beans
  • Potatoes
  • Pumpkin
  • Radishes
  • Red Kidney Beans
  • Lettuce
  • Snap Beans
  • Spinach
  • Squash
  • Sweet Corn
  • Sweet Potatoes
  • Tomatoes
  • Turnip Greens
  • Peanuts
  • Tree Nuts
  • Coconuts
  • Refined sugar
  • Dextrose
  • Glucose
  • HFCS
  • Edible syrups
  • Honey
  • Plain whole milk
  • Green Peas
  • Collard Greens
  • Avacado
  • Bananas
  • Blackberries
  • Blueberries
  • Canteloup
  • Cherries
  • Cranberries
  • Dates
  • Figs
  • Grapefruit
  • Grapes
  • Honeydew
  • Kiwifruit
  • Lemons
  • Limes
  • Mangos
  • Olives
  • Oranges
  • Frozen Berries
  • Papayas
  • Peaches
  • Pears
  • Pineapple
  • Plums and Prunes
  • Raisins
  • Raspberries
  • Stawberries
  • Tangerines
  • Watermelon
  • Artichokes
  • Asparagus
  • Bell Peppers
  • Black Beans
  • Broccoli
  • Brussel Sprouts
  • Cabbage
  • Carrots
  • Cauliflower
  • Celery
  • Cucumbers
  • Eggplant
  • Apples
  • Apricots
  • Chili Peppers
  • Escarole & Endive
... is representative of the variety of foods US citizens eat, but it does not tell you which of these foods, they will eventually select. Let's take apples, coconuts, and white and whole wheat flour as an example triplet. I guess if you had to rank them according to their contribution to the total energy intake of the average US citizen, none of you would hesitate to give me an answer like this: "White and whole wheat flour > apples > coconuts". Without the corresponding "weights" that would tell the scientists that white and whole wheat flour has a 10x higher impact on the average macronutrient composition of the average American diet, we be talking about the nutrient and fructose availability, not the actual intakes.

Better treat the data with the appropriate caution

Unfortunately, the scientists provide only rudimentary information about the impact of food choices, i.e. how much of the items listed above, the average US citizen actually consumes, namely:
  • The food categories that increased the most during this time were grains and fats/oils, having increased 24.2% and 25.3%, respectively. 
  • Caloric sweeteners (including both sucrose and HFCS) increased a modest 1.3%. 
With respect to the sweeteners Carden and Carr emphasize that the "sugar" availability, or as they put it the "monosaccharides available for metabolic absorption" is more than 3x higher than that of fructose.
In other words: Despite the fact that fructose appears to have become ubiquitous, overeating on plain sugar is still 3x easier. That this does not imply that you cannot do so, is the main and in my humble opinion crucial problem Carden and Carr fail to address. The result of their study do after all not exclude that a significant parts of the US population increased their fructose intake, in spit of the fact that its availability remained essentially the same.
The availability of a given nutrient on the shelves of US supermarket may provide a realistic image of the diets of a society of identical clones, who wheel their carts back and forth through the whole supermarket and buy foods from all each and every shelf. The "real" American, however, is no clone. On the contrary! He has his preferences and for a large part of the society these preferences can be found in the "highly processed, high sugar, high fat"-shelves of the super market. He does not care about the coconuts, apples, kale, mushrooms, olives and all the other foods in the "whole foods" section of the supermarket. They are available, but not what he is looking for.
Figure 2: The increase in total energy intake is one of the most fundamental contributers to the obesity epidemic (adapted from Carden. 2013)
Bottom Line: Despte the disconnect between availability and consumption you will be hard pressed to debate the scientists' conclusion that "increased total energy intake, due to increased availability of foods providing glucose (primarily as starch in grains) and fat" are the major contributors to the increased obesity in the US.

What is annoying, though, is the fact that a vast majority of the researchers fails to realize that their studies already account for the obesogenic effects of nutrient density. The average "high fat diets are bad for ..." is after all based on experiments, where animals or humans are fed diets that are high in both fat and carbohydrates.

Despite the fact that these studies provide a realistic portrayal of the average Western diet, the messages people infer, when they read about these results in the mainstream media is flawed.

It's not about eating less, fat, fructose, sugar or whatever scapegoat the author of the corresponding article believes was to blame for our misery. It's about nothing else than turning our whole way of eating upside down. It's about the right foods, not the right macros and it's about moderation and mindfulness.
References:
  • Carden, T. J., & Carr, T. P. (2013). Food availability of glucose and fat, but not fructose, increased in the US between 1970 and 2009: analysis of the USDA food availability data system. Nutrition journal, 12(1), 130.