Nutritional Harmony: Keeping PUFA and Vitamin E in Balance
As I sat down to eat lunch today with my colleagues, they had a question for me: what is healthier to eat for breakfast, a fried egg or a bowl of cereal? Humans love dichotomies almost as much as talking about why their own dietary choices are the best, and my first reaction was to tell them that what I eat for breakfast, a bowl of natural muesli, is the superior choice. But with a second’s deliberation, perhaps partly due to reading a case report this morning on an infant on a strict elimination diet who developed protein malnutrition and probably would have been better off being given a fried egg, my answer was that it depends. Good nutrition is not about what single food we eat at one moment in the day. Nutrient status is based on nutrient intakes and metabolism over the prior months, or even years. The aim of nutrition recommendations such as MyPlate is to encourage individuals to eat a wide variety of different foods in order to get a balanced amount of different nutrients.
Getting the balance right is the subject of a recent research article by Raederstorff and colleagues. A little know nutrient interaction is between polyunsaturated fatty acids (PUFA) and vitamin E. The unsaturated bonds in PUFA are a double-edged sword. On the one hand, the unsaturated double bonds cause a “kink” in the molecule that provides some of the functionality of fatty acids. On the other hand, the double bonds are more prone to oxidation in the body. Vitamin E is a fat-soluble antioxidant and its role in protecting PUFA from oxidative damage is recognized by national nutrition bodies such as the Institute of Medicine (IOM) in the US, the Organisations for Nutrition in Germany, Austria and Switzerland (D-A-CH) and the National Health and Medical Research Council (NHMRC) in Australia. There appears to be an ideal ratio of PUFA to vitamin E that provides PUFA with adequate protection from oxidative damage, which is estimated to be around 0.4 - 0.6 mg alpha-tocopherol per gram of PUFA.
One would expect, perhaps, that vitamin E recommendations would therefore be based on PUFA intakes. This is not the case: IOM base the US/Canadian recommendations on the level of vitamin E needed to prevent the breakdown of red blood cells, and the Australian recommendations are based on median population intakes in a population assumed to be vitamin E replete. Only the D-A-CH recommendations take the requirement for PUFA into account. Setting recommendations based on the amount of vitamin E needed to protect PUFA from oxidative damage results in a slightly increased requirement for vitamin E when typical PUFA intakes are assumed. However, it may be better to consider vitamin E requirements based on a certain basal requirement to prevent red blood cell lysis, plus an extra amount based on the degree of saturation of fatty acids in the diet, both mono- and polyunsaturated fatty acids are protected from oxidation by vitamin E. Requirements for vitamin E range from 0.075 mg vitamin E per g of mono-unsaturated fatty acids (MUFA) to 1.5 mg vitamin E per g of docosahexaenoic acid (DHA), which has six double bonds. As global MUFA&PUFA intakes range between 33 to 54 mg per day for adults, 12.5 to 20 mg vitamin E is required using the formula given by Raederstorff et al. to compensate for fatty acid saturation. Given that the majority of people living in high income countries do not meet the current lower vitamin E requirements, it seems that vitamin E intakes are also not high enough to protect PUFA in the body.
What does this mean in terms of nutritional balance? Many foods contain both vitamin E and unsaturated fatty acids. However, as vitamin E intakes are relatively low, people should focus on increasing their vitamin E intakes to make sure that they are in balance with PUFA intakes.
The table below lists a number of foods, their vitamin E content and the amount of vitamin E needed to balance the PUFA&MUFA in the food, sorted by the amount of vitamin E relative to the amount of PUFA. When the vitamin E content is higher than the vitamin E "requirement", then the food will improve vitamin E intakes relative to its unsaturated fatty acid content.
|Description||Vitamin E content (mg/100g)||Vitamin E requirement (mg/100g
RTE,KELLOGG,KELLOGG'S ALL-BRAN COMPLETE WHEAT FLAKES
RTE,GENERAL MILLS,WHL GRAIN TOTAL
FORMULA. MEAD JOHNSON, PREGESTIMIL, W/IRON, PDR,NO RECON
SPRD,SMART BALANCE LT BUTTERY SPRD
USA NASOYA,LITE SILKEN TOFU
RTE,QUAKER,MOTHER'S TSTD OAT BRAN CRL
SOL,WO/ SKN & BONES
W/ ENR FLR,UNSALTED
14" PEPPERONI PIZZA,CLASSIC HAND-TOSSED CRUST
GAME HENS,MEAT ONLY,RAW
Daniel Raederstorff, Adrian Wyss, Philip C. Calder, Peter Weber, Manfred Eggersdorfer. Vitamin E function and requirements in relation to PUFA. British Journal of Nutrition Published online: 21 August 2015 http://dx.doi.org/10.1017/S000711451500272X
Ma DW, Seo J, Switzer KC, Fan YY, McMurray DN, Lupton JR, Chapkin RS. n-3 PUFA and membrane microdomains: a new frontier in bioactive lipid research. J Nutr Biochem. 2004 Nov;15(11):700-6. http://www.ncbi.nlm.nih.gov/pubmed/15590275
Mori F, Serranti D, Barni S, Pucci N, Rossi ME, de Martino M, Novembre E. A kwashiorkor case due to the use of an exclusive rice milk diet to treat atopic dermatitis. Nutr J. 2015 Aug 21;14(1):83. doi: 10.1186/s12937-015-0071-7.
Barbara Troesch, Birgit Hoeft, Michael McBurney, Manfred Eggersdorfer and Peter Weber. Dietary surveys indicate vitamin intakes below recommendations are common in representative Western countries. Volume 108 / Issue 04 / August 2012, pp 692-698. http://dx.doi.org/10.1017/S0007114512001808
Food nutrient content data from the USDA Food Database SR27. http://www.ars.usda.gov/Services/docs.htm?docid=24912