Fats are all the rage lately, as people who become interested in nutrition start to realize that the field's methods are far from perfect and leave the science pretty soft. I find the conversation to be a bit nauseating at times, as we try to isolate one nutrient while ignoring the whole food complex, and the food's place in the context of the diet**.Lately, the conversation seems to be about butter - is butter back? Bittman proudly declared it so. Time Magazine had a cover with the headline "Eat Butter". Harvard School of Public Health responded with an article, "Is Butter Really Back?". What's the deal - is the nutritional sciences community really that split on whether you should be using butter or oil?
My take on the issue is much more simplistic than opinions on fatty acid profiles that can't be backed up by the current data (unless someone can find me some data where humans replaced only palmitic acid with only linoleic acid and saw benefits for CVD outcomes..).
For starters, butter was never gone, so it didn't need to come back; anyone who actually read the Dietary Guidelines, even back from 1980, would know that. Recommendations are rarely to never consume a food or nutrient (trans fats being a rarer exception here) - proper nutrition always has, still is, and always will be about balance and variety.
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| http://www.health.gov/dietaryguidelines/1980thin.pdf |
A major goal of the guidelines is to get individuals to consume a nutrient dense diet. This was a concern in 1980 and it is still a concern today. All of the field's nutrition surveillance data suggests that individuals consume sub-optimal levels of many nutrients and rarely achieve the guideline recommendations; Colby Vorland had a nice post on that here - virtually no one hits the dietary recommendations. If you look at "What We Eat In America" 2011-2012 - see here - you can see that we have sub-optimal intake of many nutrients. This was graphically well represented by Dwyer et al (1):
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| Compares Naturally Occurring + Fortified Foods |
Many Americans fall below the Estimate Average Requirement (intake necessary to meet the needs of 50% of the population) on a number of nutrients. Given this, public health guidance should probably be pushing Americans towards a more nutrient dense diet. This is where I think it's pertinent to take a look at the sobering nutrient profiles of both butter and added oils (2,3,*):
In the table I made below, the columns are the individual nutrients, the recommended amounts to consume in the DRIs set by the Institute of Medicine, followed by the amounts of those nutrients in Butter, Soybean and Olive Oil, and I threw in almonds there too for comparison.
You can quite clearly see that butter and oils are not adding a significant proportion of any particular micronutrient to the diet - there's some notable ones like vitamin E, but focusing on just one nutrient is a bit narrow-sighted IMO. While public health authorities would prefer you replace butter with vegetable oils based off of their fatty acid profile, in my opinion, when you add nutrient density to the equation (including fiber!), you might consider minimizing your use of both butters and added oils****. Of course, a nutritious diet isn't made or broken by any one food item, and you can certainly manipulate the other components of your diet and have room for added fats/oils, I find it very relevant to keep in mind the whole profile of a food. The war between butter and vegetable oils seem a bit silly when you compare their nutrient profiles to almonds. And even better than the overly-sensationalized war between PUFAs and SFAs, there is a plethora of data, with varying levels of quality, to support the health benefits of almonds/nuts and seeds, on everything from body weight to CVD (4-8). This issue of lower micronutrient intakes with oils isn't totally devoid from the literature either - in the PREDIMED trial, where individuals were consuming a good bit of olive oil, those with the lowest probability of failing to hit the EAR for either 6 or 8 nutrients were those with the lowest fat quality scores. (12)
Diet's take planning (check out SuperTracker!), and when planning your diet while maintaining/losing weight, it's a good idea to get the most bang for your buck (nutrients per kilocalorie). Oils and butter can be a great incentive for sautéing some vegetables, but let's not fool ourselves into thinking that your chocolate chip cookie recipe*** sees any significant nutritional improvement by swapping out butter for oil or vice versa.
*For any interested in grass-fed butters, note that the USDA does not have an official nutrient analysis of them. The nutrient changes vary greatly depending on the amount/duration of grass fed to the cow (9). There a few clinical trials to support the health effects of consuming grass-fed butter - the only studies i know of are rather short (10). Many of the fatty acid changes that are noted even between no grass and 100% grassfed are unimpressive - Total saturated fats drop from 72 to 65g per 100g of milk fat and polyunsaturated fatty acids increase 1.7g per 100g of milk fat due to increases mostly in trans fatty acids and ALA.
**I don't mean to overly trivialize the importance of fatty acids. The literature in this area is rather weak, in my opinion, due to the inability to isolate the effects of individual fatty acids and the synergy between them. Dietary replacement trials are very hard to conduct, and are often confounded by accompanied changes in the diet. As we move into a time when we can genetically modify oils to optimize their fatty acid profiles, I concede that individual fatty acids will matter a lot, and the answer may not always be as simple as prioritize "nuts, seeds and avocados" as your sources of fats.
***As John Coupland, professor of Food Science at Penn State, recently tweeted about, recommendations regarding PUFAs often don't take into account toxic products (11) that are formed during heating/frying, and is something public health professionals need to keep in mind when making broad recommendations.
****Yes, even coconut oil! These oil profiles are virtually identical to the ever-so-magical coconut oil as well. See here.
1. http://advances.nutrition.org/content/3/4/536.full.pdf+html
2. http://www.nal.usda.gov/fnic/DRI/DRI_Tables/RDA_AI_vitamins_elements.pdf
3. http://ndb.nal.usda.gov/ndb/foods
4. http://www.ncbi.nlm.nih.gov/pubmed/24898229
5. http://ajcn.nutrition.org/content/59/5/995
6. http://ajcn.nutrition.org/content/89/5/1649S.full
7. http://informahealthcare.com/doi/abs/10.3109/10715762.2014.896458
8. http://www.ncbi.nlm.nih.gov/pubmed/12221048
9. http://www.sciencedirect.com/science/article/pii/S0022030206722639
10. http://www.ncbi.nlm.nih.gov/pubmed/23842081
11. http://www.aocs.org/Membership/informArticleDetail.cfm?itemnumber=40690
12. http://www.ncbi.nlm.nih.gov/pubmed/25616935
I’ve been reading a number of articles lately that suggest that a nutrient-based approach is a poor way to do nutrition and that it would be better to look at the effects foods and dietary patterns, that maybe we can’t reduce health outcomes of diet to a list of nutrients. For some reason it just really struck me that looking at nutrient list in almonds kind of goes against that approach. If I have your position right, the problem comes about more from getting too fixated on a single nutrient rather than considering the nutrient requirements collectively?
ReplyDeleteI think the critiques you're talking of are the single nutrient approach, and the alternatives are food-based approaches (e.g. single nutrient approaches overcomplicate the issue of whether butter is healthy - whether saturated fats are particularly metabolically damaging doesn't change the fact that butter shouldn't make up a large portion of your kcals). I'd argue my almond example is still food-based. I think this example of oils versus almonds is a perfect example of why we need both food and nutrient based approaches - both are foods but nutrients help us decide. To note, the food based approach is more of a public health perspective - i highly doubt you will see nutritional scientists abandoning nutrient-based approaches.
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