Meatas a Potential Source of Vitamin DForsome time now, the human diet has been a topic of interest to our growingpopulation. In more recent years, that interest has fuelled extensivescientific research. This has led to studies regarding the uses and effects of differentfood sources on our bodies. With the vast range of information around us, itcan be difficult to deliver the facts. In this review entitled “Meat as aPotential Source of Vitamin D”, it is my intention to deliver clear andcomprehensive facts under this heading. VitaminD- It’s Sources and Benefits VitaminD is a nutrient essential for maintaining a satisfactory calcium homeostasiswithin the body, aiding bone development (Holick, 2004).
Pure vitamin D3 underapplication is a white or almost white crystalline powder, almost odourless(EFSA, 2013). We are all familiar with the benefits of including Vitamin D inour diet – it aids the absorption of calcium in our bones, strengthening bonedensity. As it is a fat-soluble vitamin, it can be obtained from naturallyfat-containing foods (for example egg yolk, milk, butter). It is also known as’the sunshine vitamin’. This is because Vitamin D can also be obtained from naturalsunlight through the metabolism of 7-dehydrocholesterol to pre-vitamin D in theskin by UV-B radiation. During the summer months, this exposure to directsunlight is the primary source of Vitamin D. Throughout the winter or reducedperiods of sunlight, one would rely on oral intake of Vitamin D (Holick, 2004)perhaps in the form of supplements. The inclusion of Vitamin D in the diet hasbeen proven to decrease the incidence of osteoporosis which can be particularlyuseful for the elderly as their bones become more porous and also formenstruating females.
Vitamin D occurs naturally in animal foods as cholecalciferol(D3) while ergocalciferol (vitamin D2)is manufactured in the body (Deharveng, 1999). Role of Red Meat in International Dietary GuidelinesTherole of red meat in dietary guidelines can vary slightly from country tocountry as generally, a country will have their own dietary preferences andneeds. The public often receive mixed messages in relation to the nutritionalvalue of meat. In recent years, the emergence of popular vegetarian and vegandiets have led the population to believe that meat is ‘unhealthy’ and shouldhave no place in our diets. Meat is a valuable source of high biological valueprotein, iron, vitamin B12 in the diet as well as other B complex vitamins.
Accordingto the World Health Organisation, irondeficiency is the most common and widespread nutritional disorder in the worldaffecting both developing and developed nations (McNeill & Elswyk, 2012). Fatcontent, a continuous area of concern when referring to meat consumption, dependson animal type, feed type and quantity as well as the meat cut used. Pork meatcan have the highest fat content. Information like this can portray red meat ina negative light. In developedcountries, pork accounts for 50% of total red meat consumed, making it the mostwidely consumed red meat (in those developed countries) (McNeill & VanElswyk, 2012).Table1.
International dietary guidelines for healthy eating in relation to meatconsumption. Country (Reference document) Year published Protein group no. of serving/day Meat-serving size (g) Other meat-related comments US (Dietary guidelines for americans 2015–2020, 8th edition) 2015 ~ 155 g/day from protein foods – as part of a healthy US style eating pattern (2000 cal level). No specific reference to meat serving size Recommend a variety of protein foods.
Lower intakes of meats, including processed meats; have often been identified as characteristics of healthy eating patterns. Specific recommendation to include ~ 225 g of seafood/week. Canada (Eating well with Canada’s food guide) 2011 Females: 2 servings/day; Males: 3 servings/day 75 g of cooked beef, pork or game-meat.
Meat and alternatives group provides important nutrients such as iron, zinc, magnesium, B vitamins, protein and fat. Ireland (Healthy food for life – healthy eating guidelines and food pyramid) 2016 2 servings/day 50–75 g cooked – lean beef, lamb, pork, mince. Lean red meat is good source of iron. Limit processed salty meats such as sausages, bacon and ham – not every day.
UK (Eatwell guide) 2016 No protein food group serving recommendation 70 g/day red and processed meat – average daily consumption in the UK If you eat > 90 g of red or processed meat per day, try to cut down to ? 70 g/day. (Tablefrom Cashman & Hayes, 2017).Itis also worth noting that there is a difference in dietary quality of processedand unprocessed red meat – processed meat was declared carcinogenic in 2015 byIARC (Cashman et Hayes,2017).
In the table above we see the term ‘lean’ meat.Lean meat is generally defined as meat containing 5%-10% fat (Williamson et al,2005) i.e 5-10g total fat per 100g meat. As stated by Cashman & Hayes (2017)- “Interms of optimal quantity of meat within a healthy diet, the Canadian and Irishdietary guidelines suggest 50–75 g of cooked meat as a protein food groupserving” – leaving us with a guideline to follow, where lean meat would be thepreferred meat type. International bodies addressed in the table above have notoutlined a limit for daily lean meat consumption. However, there is agreementamongst all bodies that a variety of protein sources in the diet is best,placing particular emphasis on the inclusion of fish. (Cashman & Hayes,2017). Pushing fish as a replacement protein source instead of red meat is anattempt to lower fat intake.
Meat and meat products are divided into subgroupswithin the UK food composition tables including meat, poultry, game, offal, andmeat products (Cashman & Hayes, 2017). NNR’s (Nordic NutritionRecommendations) RDA equivalents for vitamin D was set at 10 ?g/d for allindividuals aged 2-70 years. This RDA value was below the IOM’s15 ?g/d for the same age range (Cashman, 2015).
The Irish dietaryguidelines propose that processed meat should not be eaten every day while theUK ‘Eatwell Guide’ specifically recommends that consumersconsume only 70 g/day of meat in the diet and urge those who consume over90 g/day to reduce their intake (Cashman, 2015). Dietary requirementestimates which form the DRI (Dietary Reference Intakes) values are based from theEAR (10 ?g/d for persons aged 1 and over) and RDA (15 ?g/d ages 1 to70, and 20 ?g/d for those over 70 yrs of age) (IOMInstitute of Medicine, 2011). Howto Increase Vitamin D Concentration in Meat VitaminD supplementation has been suggested as a means of bridging the gap betweencurrent vitamin D intakes and new recommendations, but their usage appears tobe quite low.
The fortification of food with vitamin D has been suggested as astrategy for increasing intake (Cashman, 2015). These suggestions are anattempt to reduce vitamin D deficiencies such as osteoporosis, a disease of thebones, among the population. Increasing the vitamin D concentration in food,and in this case red meat, can be done via a process known as biofortification- the addition of vitamin D to animal feed to enhance vitamin D concentrationin the meat ahead of slaughter. Regarding biofortification with vitamin D, theanimal could have increased vitamin D and/or 25-hydroxyvitamin D contents by theiraddition to the livestock feeds.
Meat type, quantities fed and period offeeding time will all have an impact on residual levels of Vitamin D in themeat. Meat samples can be analysed for their Vitamin D content by undergoingsolid phase extraction followed with analysis by normal phase liquidchromatography, after initial saponification. This method allows for the rapidand sensitive analysis of vitamin D and 25OH-Vit D in meat (Strobel et Al, 2013),giving us accurate measurements of residual vitamin D levels in meat. Feedingof Animals and Residual Effect on MeatVitaminD content of meat may be boosted through biofortification. This is a process inwhich additional vitamin D is added to animal feed. Various trials have beencarried out involving vitamin D fortified feed being given to different animaltypes (e.g beef cattle, lamb). One such trial was conducted to investigate theinfluence of feeding vitamin D3 and aging on the tenderness of four lambmuscles.
In Trial 1, different levels (0, 250,000, 500,000 or 750,000 IU) ofvitamin D3 were fed to rams (n=26) for 4 days to determine themost effective dose to increase calcium concentrations in the blood. In Trial 2,feedlot lambs (n=40) were fed different levels (0 or 750,000 IU) ofvitamin D3 for 14 days to determine if vitamin D3 couldimprove the tenderness of lamb muscles. Lambs were slaughtered and the M.longissimus lumborum, M. biceps femoris, M.semitendinosus, and M. semimembranosus were removed afterchilling, cut into chops, and assigned to an aging period (5, 10 or 15 days). Resultsof Trial 1 showed weight gain was lower for rams supplemented with 500,000 IUof vitamin D3.
Trial 2 results showed that “Control chops fromthe M. longissimus lumborum had lower (P<0.05)WBS values than chops from vitamin D3 fed lambs, but no othermuscles were affected by vitamin D3 feeding". VitaminD3 supplementation was not an effective means of improving thetenderness characteristics of lamb muscles (Boleman et al, 2004). The rams usedin Trial 1 weighed approximately 40kg. The doses of vitamin D3 wereadministered via bolus or feed supplementation to the rams.
Vitamin D3 wasmixed with corn meal for feed supplementation at a ratio of 1:2 During thetrial, vitamin D doses were administered days 1 through 4. For Trial 2, lambsused were approximately 40kg and 8 months old. A control pen was created containingtwenty lambs while the remaining 20 lambs (n=40), divided into 4 pens (5 lambsper pen) were administered a treatment of 750,000 IU vitamin D3.
Pensassigned to receive vitamin D3 supplementation were fed amixture of the commercial feed ration and Rovimax D3 500. Oneweek before commencing the trial, lambs were given free access to hay to allowthem to adjust to the new environment. After adjustment phase, each penreceived 4.54 kg of feed each day for a total of 14 days.
Each day beforenew feed was given, refused feed was cleaned from feeders and weighed tocalculate percent intake (Boleman et al, 2004). No significant differences werenoted in blood calcium level between all treatment levels and controls.However, rams administered 750,000 IU vitamin D3 tended (P=0.0916)to have higher blood calcium levels at day 5 than control rams.
Overall,results showed that feeding high levels ofvitamin D3 to lambs did not improve the tenderness or agingcharacteristics of lamb muscles (Boleman et al, 2004).Another study involving 142 steers of 3 biological types wasconducted; Bos taurus-English Bos taurus-Continental(predominantly Charolais and Limousin), and Bos indicus. Thesteers were housed for 14 days, fed a 60% concentrate diet to start and then separatedinto the three respective breed types. For each breed type, steers were groupedby starting weight and grouped to one of the four dietary vitamin D3 treatments.Their diet was enhanced to a 90% concentrate diet over a period of 14 days. Day1 of the study was marked by weighing and sorting each steer to a new pen afterthe 14 day period. The feeding system used to dispense the 90% concentrate dietwas The Burnett Center feed milling system which is computer-controlled. Oncethe total diet was mixed, the feed was delivered via a belt-feeding system.
Thequantity of feed remaining in each bunk was recorded every day. Study outlined that feed troughswere cleaned, and unconsumed feed was weighed. Steers in all pens were weighedafter 99 days on feed and allocated into final study pens based on their weights.The dietary treatments consisted of 0, 0.5, 1.0, or 5.0 × 106IU/(steer•(d)of VITD during the last 8 d of feeding (study d 116 to 123). Four pens of eachbiological type received one of the four VITD treatments for the last 8 d offeeding (d 116 through 123 of the study).
Every day the VITD amount per pen wasnoted and diluted in 100 g of ground cornmeal. For the final 8 d of treatment,bunks were cleaned and leftover feed was collected and weighed. At study day123, each steer was again individually weighed before being transferred toanother facility for slaughter and carcass analysis on day 124. Feedlotperformance data, carcass traits, and plasma Ca and P concentrations wereanalyzed using a 4 (VITD treatment) × 3 (biological type) factorial arrangementof treatments. Treating steers with VITD resulted in a quadratic increase (P =0.007) in blood plasma Ca concentrations at slaughter.
Supplemental VITD at5 million IU/(steer•d) had the greatest effect on increasing plasma Ca2+ andP compared with the other VITD treatments. Results from research show that cattle can be supplementedwith 0.5 million IU of VITD/(steer•d) to improve beef tenderness withoutadversely affecting feedlot performance and carcass traits but cannot raiseresidual level of vitamin D in the meat for it to be classified as a ‘source ofvitamin D’.
(Montgomery et al, 2004). Astudy outlined by Duffy et al, 2017, documenting the effect on vitamin Dconcentration of cholecalciferol supplementation in heifer diets has provedinvaluable to this review. Thirty continental heifers(Charolais × Limousin crosses) were grouped according to weight andage and then randomly allocated to one of three dietary treatments: (Treatment1) basal + 0 IU of vitamin D?/kg diet; (Treatment 2)basal + 2000 IU of vitamin D?/kg diet and (Treatment 3)basal + 4000 IU of vitamin D?/kg diet. These dietary treatmentswere carried out for the 30 day period before slaughter of the animal. Thebasal diet consisted of a standard ad-libitum finishing regime ofconcentrates and forage (straw) at a ratio of 90:10. The 4000 IU ofvitamin D?/kg/feed is the maximum inclusion rate in bovine diets. Taking thisinclusion rate into consideration, it was ensured that the treatments compliedwith EU regulations (Duffy et al, 2017).
Diets were created to meet nutrientrequirements of finishing beef heifers. Typically, 2000 (half the maximuminclusion rate) IU of vitamin D? is the upper inclusion rate used in most commerciallymade feeds. Generally, farmers would choose a feedwith maize as the main constituent, yielding a high-energy mix. Ingredientssuch as rapeseed and maize distillers may be used as a protein source, soyahulls as a fibre source, and then the inclusion of the required vitaminconcentrate would then be added. The concentrate:forage ratio for the study wasoffered at 90:10.
Composition of the concentrate was as follows: Item (g/kg) Dietary treatments1 T1 T2 T3 Concentrate Dry matter 830.2 828.0 826.
8 Ash 57.5 54.4 52.
8 Crude protein (N × 6.25) 107.4 103.9 101.
9 Ether extract 16.7 16.8 16.9 Neutral detergent fibre 192.1 200.8 198.0 Cholecalciferol (IU/kg)2 376.
0 1680.0 4320.0 (Tabletaken from Duffy et al, 2017).
Asystem was in place to monitor feed management and weight gain of the heiferswhile being housed in a slatted shed. A total of 5 pens, with 6 heifers per penwas set up. The Calan Broadbent controlled feeding system was used to feed eachheifer individually. A unique key hanging from a neck cord was fitted to eachanimal. The animal’s sensor key unlocks the feed door as it recognises theelectronic circuit board on each feeder. This controlled feeding system also meantfeed was weighed in and uneaten (refused) food was weighed out on a daily basis.For the duration of the experiment heifers were weighed weekly using a ‘WeighCrate’ (Duffy et al, 2017). Once animalsreached slaughter weight, they were then stunned.
After slaughter, the carcasswas drained of blood and eviscerated and post-slaughter carcass weight (hotcarcass weight x 0.98) was noted. The whole carcass aged for a total of 14 daysat 4°C before the longissimus thoracis (LT) muscle was cut into 2.5 cmthick steaks for vitamin D analysis. The ‘total vitamin D activity’ of the14-day aged steaks and vitamin D3 and 25-OH-D3 contentof experimental diets were analysed using modifications of a sensitive liquidchromatography-tandem mass spectrometry (total vitamin D activity oflongissimus thoracis muscle was defined as vitamin D3 + (25-OH-D3 × 5).In this study, supplementing heifer diets with vitamin D? “linearly increased (P < 0.
001)serum 25-OH-D3 concentrations, the index of vitamin D status”(Duffy et al,2017). Results showed thatas dietary vitamin D? levels increased in the heifer’s diet, vitamin D activityin the LT including, LT total vitamin D (R2 = 0.78),LT vitamin D? (R2 = 0.84) and LT 25-OH-D? (R2 = 0.
75)content also linearly increased (P < 0.001). Heifers whowere fed the highest EU acceptable diet of 4000 IU of vitamin D?/kg diet(Treatment 3) had a 42% increase in LT total vitamin D activity over heifers partakingin Treatment 2, the 2000 IU of vitamin D?/kg diet, and a 145% increaseover those on the 0 IU vitamin D?/kg diet (Treatment 1). Results of the datafrom this study would indicate that eating beef derived from cattle fed avitamin D? enriched diet (not above the EU limit of 4000 IU of vitamin D?)before slaughter has the potential to contribute up to 9% (per 100 g beefintake) of an individual's recommended daily intake of vitamin D (between 15and 20 ?g/day as recommended by the IOM) and 13.5% of the EAR of400 IU/day (Duffy et al, 2017). Inturn, with the use of vitamin D fortified feed to finish beef heifers, red meatcan qualify as a potential source of vitamin D in the diet.ConclusionItis clear that for most populations there are a majority of individuals failingto meet the EAR for vitamin D (Cashman, 2015). Consumers should now be moreaware of the gap between recommended intake of vitamin D and the currentdietary intake.
According to the EFSA, regarding vitamin D3 supplementationof feed concludes that the use of vitamin D in animal nutrition at thecurrently authorised maximum dietary content has not and will not cause thetolerable upper intake level to be exceeded (EFSA, 2013). It must be acknowledged that there is a needfor a solution to bridge this gap. This review shows us that biofortifictationof food, and in this instance the biofortification of meat byaddition of vitamin D to feedstuffs, is an area that has attracted seriousattention as a likely food fortification strategy. References: Boleman, C.
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