Coincidence. My daughter Mimi’s school was debating whether chocolate milk, skim or otherwise, is really a good thing — whole milk of course is not a choice. At the same time, her first grade class was studying states of matter, specifically solids and liquids. According to Mimi, they learned that solids do not change shape and liquids flow. These two topics come together in the bizarre world of the USDA Dietary Guidelines. Whole milk, it seems, is not a choice because it may be a solid.
Stepping back, the logic of the USDA recommendations is that
1) we now know that total dietary fat poses no risk for cardiovascular disease (CVD), but
2) saturated fat is a risk for CVD and therefore Americans must
3) reduce total dietary fat intake and drink skim-milk or fat-reduced milk. If you are confused about this syllogism, not to worry. The Guidelines have made it simple. The Advisory Committee has always had a concern for the ability of the public to think. Dr. Xavier Pi-Sunyer (pr. Pea-soon-yay), a member of the committee wrote an editorial about a scientific report that showed no difference in the effect of different diets (never mind that, in practice, what people ate was about the same, regardless of the “diet” to which they were assigned.) He suggested that it “seems unwise at this point to burden type 2 diabetes patients with trying to pick and choose among different high- and low-GI foods.” Also, in unveiling the new Guidelines, secretary of Agriculture Tom Vilsack said that he had not read the previous versions. So, any simplification is welcome. The Dietary Guidelines has, as one of its latest innovations, the introduction of the term SoFAS, which stands for Solid Fats and Added Sugar and was in line for a SAY! Award (Stupidest Acronym of the Year). So, we simply have to understand what they mean by solid.
If there is anything in science that is well understood and should not be open to conjecture, it is the states of matter. Outside of the extreme conditions that produce plasmas and other exotica, the idea of solids, liquids and gasses seems pretty much, well, solid. It turns out, though, that since the term saturated fat is, after all, a chemical term, it is necessary to make things simple for the consumer who is now advised to look for something “solid” instead. To do this, the DGAC explains: “To determine whether foods contain oils or solid fats, consumers can read the ingredients list to make sure that fats in the foods are oils containing primarily unsaturated fatty acids and that solid fats are not one of the first few ingredients…. Examples of solid fats that may be used in the ingredients list are provided in Table A4-1.” But, of course, labels don’t list “solid fats.” Got it? To find out if foods contain solid fats, see if it says solid fats on the ingredient list, but since labels don’t list “solid fats” you only have to use Table A4-1 which is shown below. The table, however, has some surprising entries. The presence of cream and vegetable oils certainly seems a little strange. Not to worry. It is easy to understand if you remember that those oils “are high in saturated fat…therefore, for nutritional purposes, these oils are considered solid fats.” In other words: when is a solid not a solid? When the USDA says so. Not to milk this idea too much, we have to figure out how the consumer is to deal with the fact that “fat in fluid milk also is considered to be solid fat; milk fat (butter) is solid at room temperature but is suspended in fluid milk by the process of homogenization (p. 27).” Apparently, the simple process of distilling the fluid from milk is all that is required for the consumer to find out whether the fat is solid.
For Mimi, this is not a problem because, the fat has been reduced or removed from the milk that she is offered at school and if there is some added sugar (8 oz. Nesquik® has 29 g.) at least we know that removal of the fat will make the milk more nutrient dense (p. 5). In a future post, I will explain how removing nutrients can make food more nutrient dense. For the moment, I think understanding that sometimes a liquid is a solid is enough new information. Now, for the evidence.
“That which is not”
In one of the countries visited in Gulliver’s Travels, the inhabitants referred to “That which is not” because their language did not have a word for lying. Now the Guidelines prides itself on transparency and evidence-based conclusions so, at the meeting on saturated fat in Detroit, I asked the representative from the USDA where the evidence was on solid fat. The literature is large but as far as I knew, there were no studies at all that specifically looked at solid fat. He said he would get back to me on that. That was a while ago.
So in the first grade, we learned that solids hold their shape. My question: are the USDA Dietary Guidelines solid science?
Nutrition & Metabolism Society