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ephion comments on Lifestyle interventions to increase longevity - Less Wrong

122 Post author: RomeoStevens 28 February 2014 06:28AM

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Comment author: ephion 28 February 2014 03:27:44PM *  7 points [-]

I've downvoted your post due to use of a misleading graphic (EDIT: Downvote retracted after your reply). The graphic is comparing low fat milk, not whole milk, while whole milk has much more nutrition than low fat milk. Additionally, nutrient density can refer to both nutrients/calorie, nutrients/volume, and nutrients/price. All are important measures. Spinach wins on nutrients/calorie, but the other two, not so much.

Whole milk, for example, has 124IU of Vitamin D while the chart only lists 2.4 IU, which approximates the 1% fat figure from Google's nutrition information.

This is what 200 calories of whole milk looks like. This is 200 calories of eggs. This is 100 calories of spinach.

Spinach has little protein (0.9g/serving), while eggs and milk both contain 8g and 7g per serving. This extremely important number is missing from the chart. A cup (30g) of spinach (standard serving size) contains 7 calories, so you'd need to multiply your numbers in the charts by 0.07 to get the expected nutrition per serving of spinach. A serving of whole milk (8oz/244g) is around 148 calories, so we'd need to multipy by 1.48 for a serving:serving comparison. Doing this, the differences in nutrient content are much smaller for most nutrients, and milk 'winning' several of them.

A gallon of whole milk (16 servings) costs ~$3 in my town, and a 10oz bag of spinach (roughly 9 servings) costs ~$2. The price per calorie, per gram protein, and for most micronutrients is smaller for milk than spinach.

Spinach is, of course, great to eat and very healthy. But so are milk and eggs. That they compare so favorably to your chosen food when using more realistic comparisons supports "milk and eggs are nutrient dense."

Comment author: Pablo_Stafforini 28 February 2014 04:30:09PM *  4 points [-]
  • I originally used whole milk in my graph, but later removed it because the data was for fortified milk. (Clearly, in assessing the nutrient density of a food, one should exclude whatever nutrients are added in supplement form by manufacturers.) I have now found data for unfortified whole milk, and have updated my original comment with a graph displaying nutrition data for that type of milk.

  • Whole milk does not contain significantly more vitamin D than low fat milk does. The figure you quote corresponds to fortified whole milk, which for the reasons mentioned in the preceding bullet point should not be used in this context. And even if we used both fortified whole milk and fortified low fat milk, it would also be false to say that former contains significantly more vitamin D than the latter does.

  • Nor is the nutrient content of whole milk higher than that of low fat milk; if anything, the opposite is the case. Here's an isocaloric (100 Cal.) comparison of the nutrient content of whole milk and low fat milk:

  • According to Wikipedia, "Most commonly, nutrient density is defined as a ratio of nutrient content to the total energy content." That source also provides other definitions, while noting that they are less commonly used. But none of those definitions include the two alternative definitions you provide yourself. Nor have I seen those definitions used in journals or respectable discussion groups, like the Calorie Restriction Society mailing list. I think it's unfair to claim that my graph is misleading--and downvote me accordingly--for relying on the most commonly accepted definition of that expression, instead of using definitions which are rarely if ever used by knowledgeable authorities.

  • Everything else you write might support your argument if price or volume were relevant metrics for assessing the nutritional density of foods. It doesn't support your argument under adequate definitions, and sometimes provides extra support for my own position (for instance, 100 Calories of spinach contain (much) more, not less, protein than 100 Calories of whole milk).

Comment author: fubarobfusco 28 February 2014 05:12:27PM 2 points [-]

Clearly, in assessing the nutrient density of a food, one should exclude whatever nutrients are added in supplement form by manufacturers.

Most of the milk I see for sale is fortified with vitamins A and D. I would want studies regarding milk's health effects to report on the same sort of milk that I can buy in a store.

Comment author: Pablo_Stafforini 28 February 2014 05:17:41PM *  0 points [-]

I think that for the purposes of assessing the claim in question ("Eggs and whole milk are very nutrient dense"), unfortified versions of those foods should be considered. Otherwise, we should also regard cereals and many other foods as "very nutrient dense", simply because manufacturers decide to fortify them in all sorts of ways. (And I note that it's generally not a good idea to obtain your nutrients from supplements when you can obtain them from real food instead.)

In any case, even if we used data for fortified milk, it would still be false, in my opinion, that "whole milk is very nutrient dense." Vitamin D levels make a minor contribution to overall nutritional density.

Comment author: shokwave 02 March 2014 12:26:31AM *  0 points [-]

I suspect the real issue is using the "nutrients per calorie" meaning of nutrient dense, rather than interpreting it as "nutrients per some measure of food amount that makes intuitive sense to humans, like what serving size is supposed to be but isn't".

Ideally we would have some way of, for each person, saying "drink some milk" and seeing how much they drank, and "eat some spinach" and seeing how much they ate, then compare the total amount of nutrients in each amount on a person by person basis.

I know this is not the correct meaning of nutrient dense, but I think it's more useful.

Comment author: Pablo_Stafforini 02 March 2014 02:14:14AM *  0 points [-]

I think the best we can hope in this context is to have a number of distinct and precise metrics--like nutrients per calorie, nutrients per dollar and nutrients per bulk--, feed these to intuition, and decide accordingly. In other words, when it comes to food, I think we should make decisions according to a "rational" rather than a "quantified" model, given the difficulties of coming up with adequate definitions of a "serving size". Your approach wouldn't work, I believe, because how much people eat of a given food often depends on the presence or absence of other complement and substitute foods.

Comment author: Jiro 02 March 2014 07:38:45AM -1 points [-]

Googling quickly brings up http://www.cnpp.usda.gov/Publications/NutritionInsights/insight11.pdf

Serving size is defined as follows:

  1. Amount of foods from a food group typically reported in surveys as consumed on one eating occasion;
  2. Amount of foods that provide a comparable amount of key nutrients from that food group, for example, the amount of cheese that provides the same amount of calcium as 1 cup fluid milk;
  3. Amount of foods recognized by most consumers (e.g., household measures) or that can be easily multiplied or divided to describe a quantity of food actually consumed (portion);
  4. Amount traditionally used in previous food guides to describe servings.

While the amount of food people would eat is not the only factor used, it's a major one.

Comment author: [deleted] 28 February 2014 09:55:40PM 0 points [-]

Why should I care what someone's semi-arbitrary idea of what a serving is is?

Comment author: Jiro 28 February 2014 11:40:48PM *  0 points [-]

Because people eat by servings, not by fixed numbers of calories. Comparing by semi-arbitrary servings isn't perfect, but it's better than not comparing by servings at all, and you haven't offered any serving sizes that you believe are better, so semi-arbitrary is the best we have.

Comment author: Nornagest 01 March 2014 12:31:11AM *  2 points [-]

Servings are fine for candy bars, but they're almost totally meaningless if we're talking about fungible ingredients like spinach; those are going to be used in all sorts of ways, almost all of them different from whatever the relevant regulatory body had in mind. (Milk and eggs are a bit less so since they're often consumed in quanta of one egg or a glass of milk, but neither one's exactly an uncommon ingredient.)

I'm not sure there's a perfect way of comparing nutrient density under these circumstances, but volume is probably what I'd go for; you can only fit so much on a plate, so ingredients generally displace each other on a volume basis. For leafy greens in particular I might use cooked volume, since they usually cook way down.

Comment author: [deleted] 01 March 2014 03:29:29PM 1 point [-]

Because people eat by servings, not by fixed numbers of calories.

Who eats 30 grams of spinach and then stops?

Comment author: Jiro 01 March 2014 07:46:58PM -1 points [-]

That doesn't mean that people don't eat by servings, it means that 30 grams isn't a good serving size.

Furthermore, since we're comparing different foods, the fact that 30 grams may be too small is compensated for by the fact that the serving size for milk is a cup, which is also too small.