Fatty acid ratio in food
{{Short description|Proportion of omega-3 to omega-6 fatty acids in a diet}}
Only two essential fatty acids are known to be essential for humans: alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid).{{cite book |author1=Whitney Ellie |author2=Rolfes SR | title = Understanding Nutrition | edition = 11th | location = California | publisher = Thomson Wadsworth | year = 2008 | pages = 154}} Closely related, these fatty acids act as competing substrates for the same enzymes. The biological effects of the ω-3 and ω-6 fatty acids are largely mediated by essential fatty acid interactions. The proportion of omega-3 to omega-6 fatty acids in a diet may have metabolic consequences.{{Cite journal|last1 = Bibus|first1 = Doug|last2 = Lands|first2 = Bill|title = Balancing proportions of competing omega-3 and omega-6 highly unsaturated fatty acids (HUFA) in tissue lipids|doi = 10.1016/j.plefa.2015.04.005|date = April 18, 2015|pmid = 26002802|volume=99|journal=Prostaglandins Leukot. Essent. Fatty Acids|pages=19–23|doi-access = free}} Unlike omega-3 fatty acids and omega-6 fatty acids, omega-9 fatty acids are not classed as essential fatty acids because they can be created by the human body from monounsaturated and saturated fatty acids, and are therefore not essential in the diet.
Ratio of omega-6 to omega-3 fats in the diets of hunter-gatherers
It has been claimed that among hunter-gatherer populations, omega-6 fats and omega-3 fats are typically consumed in roughly a 1:1 ratio.Andrew Stoll, The Omega-3 Connection. New York: Simon and Schuster, 2001, p. 43. "Populations maintaining historic omega-6 to omega-3 ratios (approximately 1 to 1) are protected from many of the scourges of the modern age."{{Cite journal |last=Simopoulos |first=Artemis P. |date=2010-09-01 |title=The omega-6/omega-3 fatty acid ratio: health implications |url=https://www.ocl-journal.org/articles/ocl/abs/2010/05/ocl2010175p267/ocl2010175p267.html |journal=Oléagineux, Corps gras, Lipides |language=en |volume=17 |issue=5 |pages=267–275 |doi=10.1051/ocl.2010.0325 |issn=1258-8210|doi-access=free }}{{Better source needed|date=December 2020}} At one extreme of the spectrum of hunter-gatherer diets, the Greenland Inuit, before the late 20th century, consumed a diet with twice as much omega-3 as omega-6, thanks to a diet rich in cold-water fish (a rich source of omega-3s) and completely devoid of omega-6-rich seed oils.William Lands, Fish, Omega-3 and Human Health. Urbana, Illinois: APCS Press, 2005, p. 10.
Optimal ratio of omega-6 to omega-3 fats
To date, "no one knows what the optimal ratio in the diet is for these two families of fats."Susan Allport, The Queen of Fats: Why Omega-3 Fats Were Removed From the Western Diet and What We Can Do to Replace Them. Berkeley: University of California Press, 2007, p. 115. Science writer Susan Allport writes that the current ratio in Japan is associated with a very low incidence of heart and other diseases. A dietary ratio of 4:1 produces almost a 1:1 ratio of highly unsaturated fatty acids (HUFAs) in cell membranes."{{Clarify | date = February 2019 | reason = Although this is a direct quote from the book, it's unclear that the ratio of omega-6 to omega-3 at 4:1 produces the ratio of 1:1 of what specific 'highly unsaturated fatty acids in the membrane, making the sentence rather unhelpful. }}
In a study with rats, a dietary ratio of 4:1 showed significant favorable effects on learning performance and pain tolerance compared to 6:1.{{cite journal | title=Modulation of learning, pain thresholds, and thermoregulation in the rat by preparations of free purified alpha-linolenic and linoleic acids: determination of the optimal omega 3-to-omega 6 ratio. | date=1993-11-01 | pmc=47771 | last1=Yehuda | first1=S. | last2=Carasso | first2=R. L. | journal=Proceedings of the National Academy of Sciences of the United States of America | volume=90 | issue=21 | pages=10345–10349 | doi=10.1073/pnas.90.21.10345 | pmid=7901853 | bibcode=1993PNAS...9010345Y | doi-access=free }}
Andrew Stoll, M.D., Director of the Psycho-pharmacology Research Laboratory at Harvard's McLean Hospital, who advocates the consumption of the two fats in a 1:1 ratio, states, "Once in the body, omega-3 and omega-6 fatty acids follow parallel pathways, continually competing with each other for chemical conversion to various structures and molecules inside and outside the cells. Given this mechanism, it makes sense that the two fats might be required in approximately equal amounts."Andrew Stoll, The Omega-3 Connection. New York: Simon and Schuster, 2001, p. 40.
Both Stoll and Allport assert that present-day diets in the developed world have departed dramatically from this ratio. It has been estimated that in developed countries, the ratio of omega-6s to omega-3s is closer to 15:1{{cite journal | pmid = 12442909 | year = 2002 | last1 = Simopoulos | first1 = AP | title = The importance of the ratio of omega-6/omega-3 essential fatty acids | volume = 56 | issue = 8 | pages = 365–79 | journal = Biomedicine & Pharmacotherapy | doi=10.1016/S0753-3322(02)00253-6}} Another estimate is that "[t]he diet consumed by the typical American tends to contain 14–25 times more omega-6 fatty acids than omega-3 fatty acids."http://umm.edu/health/medical/altmed/supplement/omega6-fatty-acids {{Dead link| date = February 2019 | fix-attempted=yes}}
According to a 2009 review by the American Heart Association, instead of avoiding ω-6 fats, the ω-6:ω-3 ratio should be decreased by consuming more ω-3 fats. The conversion rate of linoleic acid (LA) into arachidonic acid is very low with a diet high in linolenic acid.{{cite journal |last1=Harris |first1=WS |last2=Mozaffarian |first2=D |last3=Rimm |first3=E |last4=Kris-Etherton |first4=P |last5=Rudel |first5=LL |last6=Appel |first6=LJ |last7=Engler |first7=MM |last8=Engler |first8=MB |last9=Sacks |first9=F |title=Omega-6 fatty acids and risk for cardiovascular disease: a science advisory from the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. |journal=Circulation |date=17 February 2009 |volume=119 |issue=6 |pages=902–7 |doi=10.1161/CIRCULATIONAHA.108.191627 |pmid=19171857|doi-access=free }}
The maximum ω-6:ω-3 ratio allowed in dog food by the AAFCO is 30:1.{{cite web|date=2013|title=AAFCO methods for substantiating nutritional adequacy of dog and cat foods (proposed for 2014 publication)|url=https://www.aafco.org/Portals/0/SiteContent/Regulatory/Committees/Pet-Food/Reports/Pet_Food_Report_2013_Midyear-Proposed_Revisions_to_AAFCO_Nutrient_Profiles.pdf|publisher=AAFCO|access-date=2020-12-01|archive-date=2020-10-22|archive-url=https://web.archive.org/web/20201022110300/https://www.aafco.org/Portals/0/SiteContent/Regulatory/Committees/Pet-Food/Reports/Pet_Food_Report_2013_Midyear-Proposed_Revisions_to_AAFCO_Nutrient_Profiles.pdf|url-status=dead}}
Fish
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Nuts and seeds
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! Food !! Citation !! Serving |
| Almonds, dry roasted
|100 |12065 |6 |2010 |
| Cashews
|100 |7782 |62 |125 |
| Chia seeds
|100 |5785 |17552 |0.33 |
| Coconut, raw
|100 |366 | - | - |
| Flax seeds
|100 |5911 |22813 |0.26 |
| Hazelnuts, filberts
|100 |7832 |87 |90 |
| Hemp seeds
|{{cite journal | title = The cardiac and haemostatic effects of dietary hempseed | date = 2010 | publisher = PubMed Central | pmc = 2868018 | last1 = Rodriguez-Leyva | first1 = D. | last2 = Pierce | first2 = G. N. | journal = Nutrition & Metabolism | volume = 7 | page = 32 | doi = 10.1186/1743-7075-7-32 | pmid = 20409317 | doi-access = free }} |100 |56000 |22000 |2.5 |
| Macadamia nuts, dry roasted
|100 |1720 |259 |6.6 |
| Pecans
|100 |20630 |986 |21 |
| Pistachios, raw
|100 |13200 |254 |52 |
| Poppy seed
|100 |28291 |273 |104 |
| Pumpkin seeds, whole, roasted
|100 |8759 |77 |114 |
| Sesame seeds, whole, dried
|100 |21372 |376 |57 |
| Sunflower seeds, kernels, dried
|100 |23048 |74 |311 |
| Walnuts
|100 |38092 |9079 |4.2 |
| Lentils, mature seeds, cooked, boiled, without salt
|100 |137 |37 |3.7 |
See also
- Monounsaturated fat
- For listings of particular classes of polyunsaturated fatty acids, see:
- Polyunsaturated fat
- Omega-3 fatty acid
- Omega-6 fatty acid
- Omega-9 fatty acid
- Conjugated linoleic acid
- Essential fatty acid – for biochemistry of most polyunsaturated fats
- Essential fatty acid interactions – for the interactions between ω-6 and ω-3 fatty acids
- Unsaturated fat
- Israeli paradox