Friday, December 19, 2014

Vitamin D: arming our immune system


D-eficiency D-efence
 
Cold, dark, winter months usually mean dashing outside when necessary and enjoying the rest of time in the warm indoors. But with the lack of sun and sunlight during this period, people in the UK are faced with the possibility of having a low vitamin D status.

Vitamin D is important in helping maintaining good health. In fact vitamin D trains and arms T-cells — the foot soldiers of our immune system which seek out and destroy threats, such as bacteria and viruses[1].

There is also a growing body of evidence indicating that vitamin D has an important role in maintaining bone health, ameliorating cell ageing and preventing cardiovascular disease, diabetes, immune dysfunction and certain cancers[2].  Recently, there has been increasing interest in vitamin D deficiency and disrupted sleeping patterns.  More work needs to be undertaken but it is thought that bone diseases and nonspecific pain bought about by vitamin D shortfalls could disrupt sleep[3]. 

Lack of sunlight - what can we do?
Well, we should still enjoy the outdoors, and exercising outside regularly is a way to assists with endogenous production of vitamin D. We should also look at our diet. The latest data from the NDNS found that ‘meat and meat products’ were the main contributor to vitamin D intakes across all age groups[4], so incorporating lean red meat into your diet is one of the key ways to improve your vitamin D levels. We should also regularly include other foods such as fortified margarines, milks and cereals.

 
It’s worth noting that the Meat Advisory Panel recently conducted some research about people’s understanding of vitamins and a lot of respondents believed that green leafy vegetables contain vitamin D, when in fact they contain none.

Red meat: the ‘wow’ factors
Besides being one of the few foods that provide useful quantities of vitamin D lean red meat also contains protein, zinc, iron and B12 - which contributes to energy production, helping to prevent tiredness and fatigue. 

 

MAP FACT: Adding lean red meat to soups and stews during the winter months is a tasty way to help boost vitamin D status!

 

Dr Emma Derbyshire



[2] Ruxton C and Derbyshire E (2009) Health impacts of vitamin D: are we getting enough? Nutrition Bulletin 34: 185-97.
[3] McCarty DE (2014) The link between vitamin D metabolism and sleep medicine. Sleep Med Rev 18(4):311-9.
[4] Public Health England (2014) National Diet and Nutrition Survey Results from Years 1, 2, 3 and 4 (combined) of the Rolling Programme (2008/2009 – 2011/2012). A survey carried out on behalf of Public Health England and the Food Standards Agency. PHE/FSA: London.

Tuesday, November 4, 2014

Cholesterol confusion?


Dr Emma Derbyshire

It was recently National Cholesterol Month and while health campaigns are effective at raising awareness and educating people about particular conditions, cholesterol is one area that can lead people feeling a little confused – especially with differing views on what has an impact on cholesterol levels.

Quite often this advice paints red meat as a villain and more often than not includes guidance on reducing red meat intake.

Firstly, cholesterol is a lipid and a sterol, so is used to make steroid hormones, along with the all-important vitamin D and bile salts that aid the digestion of fat. While there may be concerns over the amount of cholesterol that we ‘eat’, we also actually make cholesterol in the body itself with the liver producing about 1,000mg per day.

There are a multitude of life factors that impact on blood cholesterol levels, such as smoking, which increases levels, while active lifestyles reduce blood cholesterol levels[1]. Also, genetic conditions such as hypercholesterolemia can lead to cholesterol being present in naturally high amounts in the bloodstream.

Foods themselves can be a source of cholesterol with kidneys, eggs and prawns often being named as forerunners. 

In terms of red meat, many studies quoted in advice and the media have include meat pastries within their analysis rather than looking at lean cuts of meat, so it is the saturated fat content of the pastries that could be influencing blood cholesterol levels rather than the meat itself.

Meat and meat products make a significant contribution to intakes of iron, zinc, selenium, vitamin D and B vitamins.  So, cutting out red meat for fear of ingesting cholesterol, could actually be at the detriment of several important nutrients.

Hence, it can be seen that a combination of factors can impact on cholesterol levels.  This is important to bear in mind when interpreting findings from studies looking at trends between foods such as red meat and cholesterol levels, as these factors often act as confounders, skewing results.

Thursday, October 23, 2014

Red meat and fertility


Professor Robert Pickard discusses fertility and nutrition.

Reproduction is so important to the species that we have evolved a body chemistry that will usually sacrifice the wellbeing of the individual for the benefit of the reproductive system. Thus, even malnourished individuals can be highly fertile at the expense of their own survival.

A high nutritional status protects the individual from this effect and maximises fertility potential, provided that the damaging effects of alcohol, smoking and obesity are avoided.

 In women, only a relatively small number of cell replication cycles are needed to produce ova and fertility problems are often associated with hormonal imbalance and the chemistry of the membranes that line the reproductive tracts.

 In men, millions of cell replication cycles are needed to produce normal quantities of sperm. Therefore, oxidative damage to replicating DNA and poor protein metabolism particularly reduce fertility in men.

 In addition, a spermatozoon requires an elegant protein motor that can only function with an extremely efficient battery, considering the very small cell volume that is available to it compared with a single ovum.

 Since cows, sheep and pigs share 80% of their genes with humans, red meat with liver and kidney is the most nutrient-dense food that we consume in our balanced diet.

 Red-meat animals need most of the molecules that we need and not all of them have yet been identified. In particular, lean red meat is an ideal source of the amino-acid range that is required for the protein chemistry used in gametogenesis.

 All the vitamins are needed for a high nutritional status but fertility is likely to be enhanced in older men with additional intakes of vitamins B6, B12, C, D, E and folic acid.

 We cannot construct DNA without the B vitamins and B12 is not found in any of the conventional table vegetables.

 Unsaturated fatty acids, well represented in grass-fed animals, are also beneficial to the reproductive process.

 Iron, magnesium, selenium and zinc are often identified, experimentally, as promotive of fertility.

 Since most biochemical pathways require the presence of several vitamins and minerals, it is na├»ve to think of any one micronutrient as a critical key to the deliverance of fertility.

 A lean, red-meat meal with green plant material and low-starch seed germ, to supply additional vitamin C and phytonutrients, is an ideal basis for the promotion of fertility in both men and women.

Thursday, October 2, 2014

Nutritional cost of 'health' campaigns

Dr Carrie Ruxton

There continues to be an increasing number of so-called ‘awareness’ weeks and months encouraging us to turn to a vegetarian or vegan diet or eat less red meat due to the risk of over consumption. Often these campaigns vilify meat, and more often than not incorrectly identify red meat as a cause of chronic health conditions. 

As detailed in the National Diet and Nutrition Survey, vegetarian diets are currently followed by just 2 - 4% of the population and, in many cases, include eggs, cheese and fish. While avoidance of meat can work for the committed vegetarian who is prepared to source a variety of protein-rich alternatives, this is not the case for others and research shows that meat-free diets are low in zinc, calcium, iron, manganese, selenium, and copper[1].
 
Vegan and vegetarian diets restrict opportunities for vitamin D intake[2],[3] and following these types of diets greatly reduces intakes of long-chain omega-3 fatty acids which are found in both oily fish and certain meats[4]. Another key nutrient, vitamin B12, is a major issue for vegans as it is only present in foods of animal or microbiological origin[5].

While iron is found in small amounts in some non-meat foods, such as beans, pulses and fortified foods, it is of the ‘non-haem’ variety which is poorly absorbed. Indeed, only 10% of non-haem iron is absorbed compared with up to 30% of haem iron from red meat[6]. Interestingly, the presence of haem iron in foods increases the absorption of non-haem iron.

A final point is that humans are naturally omnivorous which means that we evolved to include meat in the diet. Evidence from fossilised bones, gut physiology and the diets of contemporary hunter-gatherer societies suggests that two thirds of calories in the diet of ancient man came from animal products[7].

Therefore lean red meat is second to none as a source of bioavailable nutrients.

 



[1] Freeland-Grave-J (1988) Mineral adequacy of vegetarian diets. The American Journal of Clinical Nutrition  48:859-62
[2] Calvo Ms, Whiting SJ, Barton CN (2005) Vitamin D intake: a global perspective of current status. Journal of Nutrition 135 310-6
[3] Laskowska-Kilta T, Chelchowska M, Ambroszkiewicz J, Gajewska J, Klemarczyk W (2011) The effect of vegetarian diet on selected essential nutrients in children 15:318-25
[4] Welch AA, Shakya-Shrestha S, Lentjes MA, Wareham NJ, Khaw KT (2010) Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the product-precursor ratio [corrected] of a-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. The American Journal of Clinical Nutrition 92:1040-51
[5]Ambroszkiewicz J, Klemarczyk W, Chelchowska M, Gajewska J, Laskowska-Klita T (2006) Serum homocysteine, folate, vitamin B12 and total antioxidant status in vegetarian children.Advances in medical science 51:265-8
[6] SACN (2010). Iron and health. London: The Stationery Office. Available at: www.sacn.gov.uk/pdfs/sacn_iron_and_health_report_web.pdf
[7] Cordain L et al. (2002) The paradoxical nature of hunter-gatherer diets: meat-based, yet non-atherogenic. Eur J Clin Nutr 56: S42-52.

Friday, August 1, 2014

BBQing up a storm ?

by Dr Emma Derbyshire
The summer is here.  And as soon as that ray of sunshine comes out we gather friends and family and light the BBQ to enjoy some tasty food together. But when summer comes round, so does the discussion around Heterocyclic amines (HCAs) and carcinogenics – often citing research about the health risks of eating charred meat, fish and poultry.

On that note, I was interested to read about the Cancer Research UK’s new campaign – BBQ to beat cancer – encouraging people to invite friends round for a BBQ to raise funds for this much admired charity.  Now this campaign caught my attention because it’s a cancer charity encouraging people to have BBQ’s – where typically there’s a lot of red meat consumed and the potential to consume charred food.  Lean red meat plays an important role our diets, providing us with many of the vitamins and minerals we need to function, but it is often, wrongly, vilified as a cause of cancer – so it’s great to see a cancer charity encourage people to enjoy eating red meat.

Anyway, back to the charred meat topic. Carcinogenics. Preventing burning of meat is one of several measures which are recommended to minimise any potential health risk of HCAs, but the British Dietetic Association (BDA) has examined this area and states that there is no need to exclude barbecued meat from diets but recommends some preparation and serving suggestions which can reduce the potential risk from HCAs, identified when grilling meat, poultry and fish, by 95%,
BDA recommendations contained in their Food Facts information entitled ‘Beef up on Healthy Barbecues’ include:

  • Marinate meats before cooking to reduce HCS levels by over 95%.  It seems that ingredients in marinades are rich in cancer-fighting anti-oxidants such as citrus juices, herbs, spices and olive oil.
  • Remove badly burnt bits before eating!
  • Serve barbecue meats with a yoghurt dip – yoghurt bacteria bind these chemicals and protect the digestive tract.
Hope you all have a great summer, and get the BBQs smouldering gently.

For some meaty recipes visit www.meatmatters.com 

Thursday, April 17, 2014

Mind the knowledge gap…………..


Professor Robert Pickard, Emeritus Professor of Neurobiology at the University of Cardiff , takes a look at the nation’s understanding of red meat.


We recently conducted some research  with 2000 members of the public  to ascertain people’s views of red meat and to identify if people are aware of and understand its nutrient make-up. The results were quite surprising and revealed a few misconceptions. Misconceptions that could ultimately leave Britons at risk of health problems.

Perhaps one of the main things the report highlighted was the confusion about nutrients and which foods provide which nutrients. For example, nearly half of those asked thought that spinach was a better source of iron than red meat, which isn’t true. Red meat actually has three times as much iron as spinach and the iron in red meat comes in a far more readily absorbed form than that found in plants.

One in five also thought that green leafy vegetables provide vitamin D and one in ten thought  that citrus fruits provide vitamin D, when in fact they contain none. It was encouraging that one in 10 did identify that red meat is a useful source of vitamin D, but this again highlights a lack of overall awareness about where nutrients can be found.
Confirming people’s lack of understanding of red meat is the response that one in five admitted that they felt that they did not know enough about meat to buy at a butcher’s shop. Surprisingly,  less than half named pork as a type of red meat and one in five didn’t realise that lamb is also classed as a red meat.
However, it is heartening  to see that when it comes to our meat-eating habits, two out of three believe red meat is an important part of a healthy diet and almost half reported that they tuck into a red meat meal between one and four times a week.

Everyone wants a balanced, healthy diet and as the report showed, many people know that red meat has an important role to play in this. However, there are still some basic knowledge gaps that need to be addressed so that people have more opportunity to make the most of a healthy diet and enjoy their food.
If you want to learn more about red meat and its nutrients, take a look around our website to find out about its role in our diet

 

Wednesday, April 2, 2014

Vegetarianism


Professor Robert Pickard

Emeritus Professor of Neurobiology at the University of Cardiff

 
The ancestor of all the primates was a carnivorous tree shrew and human primates have progressively added plant material to their diet over a 7-million-year period. Currently, humans are classified as omnivores and one-third of their balanced diet is normally derived from foods of animal origin and two-thirds are normally derived from foods of plant origin. Humans thrive when they eat a little bit of everything and not too much of any one thing.

 The hallmarks of the omnivore can be seen in the dentition; the simple gut structure; the gut ecosystem; the adaptability and range of the digestive enzymes; and the requirement for essential nutrients that are usually provided by both animal and plant products. Unlike dedicated herbivores, we have no mechanism for the degradation of cellulose, the key molecule that differentiates plants from animals. Animal products, such as red meat with liver, provide humans with the full range of amino acids, fats, minerals and vitamins; all in forms so chemically suited to human digestion and absorption that there is usually little or no faecal waste. This is not surprising, since cows, sheep and pigs share 80% of their genes with humans.

 As we age beyond 60 years, our ability to make certain molecules diminishes, as does our absorption efficiency. Animal products, with their high nutrient densities, are particularly helpful at this time: a biological insurance. If we can’t make it, there’s a very good chance that a cow can. Plant products, such as broccoli with peas, nuts and yeast, provide humans with non-digestible fibre, most of the required amino acids, most of the required fats, most of the minerals and vitamins, notably vitamin C. In addition, plant foods provide carbohydrates, which are largely absorbed as sugars, and pharmacologically active phytonutrients, such as glucosinolates and salicylates.

 Sugars are vilified, unjustifiably, in the popular press because overconsumption is allowed to obscure their true nutritional significance. Sugars are the best source of energy for humans. Glucose is the major source of energy for the brain. DNA, required in most human cells, is constructed from a molecular variant of the sugar, ribose.

 Most vegetarians construct a healthy, balanced diet by supplementing plant foods with eggs, fish, dairy produce and a source of iron. Even extreme vegetarians, vegans, can still construct a healthy, balanced diet by supplementing plant foods with iron and vitamin B12  sources but this is more difficult and requires more awareness on the part of the eater. There is no biological justification for choosing to restrict one’s diet only to foods of plant origin but a vegetarian may have many other reasons for taking this course of action.

Friday, February 28, 2014

Why go meat-free when you can enjoy lean red meat in a healthy balanced diet?

Dr Carrie Ruxton, registered Dietitian and member of the Meat Advisory Panel

There’s an increasing number of so-called ‘awareness’ weeks and months encouraging us to turn to a vegetarian or vegan diet. Often these campaigns vilify meat, and more often than not incorrectly link red meat as a cause for health conditions.  Should we all be jumping on the bandwagon and turning vegetarian, or is it a better option to follow a healthy balanced diet made up of a number of food sources?

 Vegetarian diets are currently followed by 2 - 4% of the population, but if we take a moment to look at ourselves; we are omnivores – historically and physically. We are not designed to digest cellulose like naturally vegan animals, such as cows, rabbits and sheep.  

 In terms of health, choosing to follow a vegetarian, or vegan, diet is a lifestyle choice, it is not vital for health as some may suggest.  In fact, any choice that restricts eating habits, such as a meat-free diet, brings with it a risk of inadequate intake of nutrients.

 Studies have shown that vegetarian diets can be low in zinc, calcium, iron, manganese, selenium, and copper[1]. Vegan and vegetarian diets can restrict vitamin D intake[2],[3] and following these types of diets greatly reduce intakes of long-chain omega-3 fatty acids[4]. Another key nutrient, vitamin B12 is a major issue in vegans as this nutrient is only present in foods of animal or microbiological origin[5].

 While iron is present in some vegetables, beans and pulses, and fortified foods, it is of the non-haem variety which is poorly absorbed - only 10% of non-haem iron is absorbed compared with 30% of haem iron from red meat[6]. In addition, the presence of haem iron in foods increases the absorption of non-haem iron. Therefore, red meat is irreplaceable as a source of bioavailable iron in the diet.

With reference to red meat and health conditions, the evidence is inconsistent and research usually depends on observational studies which do not allow conclusions about ‘cause and effect’[7]. In many cases, studies combine fatty meat pies and pastries with lean red meat, and most do not account for differences in fibre intakes. Indeed, other studies have not found associations between red meat and cancer[8], and rates of bowel cancer are similar in meat eaters and vegetarians[9].

 Including red meat in the diet offers an array of nutritional benefits and helps us, as omnivores, achieve our recommended intakes of vitamins and minerals. We should be aiming to eat up to 70g of cooked lean red meat per day and up to 500g per week[10]which is beneficial for our overall health.



[1] Freeland-Grave-J (1988) Mineral adequacy of vegetarian diets. The American Journal of Clinical Nutrition  48:859-62
[2] Calvo Ms, Whiting SJ, Barton CN (2005) Vitamin D intake: a global perspective of current status. Journal of Nutrition 135 310-6
[3] Laskowska-Kilta T, Chelchowska M, Ambroszkiewicz J, Gajewska J, Klemarczyk W (2011) The effect of vegetarian diet on selected essential nutrients in children 15:318-25
[4] Welch AA, Shakya-Shrestha S, Lentjes MA, Wareham NJ, Khaw KT (2010) Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the product-precursor ratio [corrected] of a-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. The American Journal of Clinical Nutrition 92:1040-51
[5]Ambroszkiewicz J, Klemarczyk W, Chelchowska M, Gajewska J, Laskowska-Klita T (2006) Serum homocysteine, folate, vitamin B12 and total antioxidant status in vegetarian children.Advances in medical science 51:265-8
[6] SACN (2010). Iron and health. London: The Stationery Office. Available at: www.sacn.gov.uk/pdfs/sacn_iron_and_health_report_web.pdf
[7] Wyness L et al. (2011) Red meat in the diet: An update. Nutrition Bulletin 36: 34-77.
[8] Alexander DD et al. (2011) Meta-analysis of prospective studies of red meat consumption and colorectal cancer. European Journal of Cancer Prevention 20: 293-307.
[9] Key TJ et al. (2009) Cancer incidence in vegetarians: results from the European prospective investigation into cancer and nutrition (EPIC-Oxford). American Journal of Clinical Nutrition 89: 1620S–6S.
[10] SACN (2010). Iron and health. London: The Stationery Office. Available at: www.sacn.gov.uk/pdfs/sacn_iron_and_health_report_web.pdf


 

Thursday, February 6, 2014

Why does fat get a bad name ?

Dr Carrie Ruxton, registered dietitian and member of the Meat Advisory Panel

Since the 1970s, dietary fats have been a major target of Government nutrition policy, with advice to lower fat intake making a regular appearance in dietary initiatives. Yet current science seems to indicate that not all fats are equal, suggesting that our rather negative view of dietary fats needs to be updated.

Fats can be grouped into two different ‘families’ called saturated and unsaturated fats. Within these, there are several categories of fatty acids, as shown below:
  • Saturated fats: mainly from animal foods, such as dairy products, chocolate and meat products (pies and pasties), but also from some plant foods, such as coconut
  • Omega-3 polyunsaturated fats: mainly from oily fish, eggs, red meat, nuts, seeds and marine oil supplements
  • Omega-6 polyunsaturated fats: mainly from vegetable oils, such as sunflower oil and rapeseed oil, poultry, eggs, avocado and nuts
  • Omega-9 polyunsaturated fats: mainly from olive oil, rapeseed oil and nut oils.
Traditionally, saturated fats were viewed as ‘bad’ while unsaturated fats were viewed as ‘good’. This was informed by people -based studies which suggested associations between high intakes of saturated fat and an increased risk of heart disease. However, this opinion has been challenged in recent years due to evidence that certain saturated fatty acids, such as myristic and palmitic acids, have a negative impact on blood cholesterol levels while others, such as stearic acid present in red meat, does not appear to affect cholesterol1 . This suggests that saturated fats behave differently in the body.

There is also debate from some nutrition commentators on whether saturated fat should be targeted at all in dietary recommendations due to the weak association between saturated fat consumption and mortality from cardiovascular disease. However, this view has not been accepted by Government experts and more evidence is needed.

In the meantime, it is wise to continue choosing lower fat, nutrient-rich foods which provide a variety of types of fatty acids in the diet. Lean red meat is a good choice as it is now lower in fat and calories thanks to changes in farming practices over the past few decades. In fact many people don’t realise that red meat, on average, contains more unsaturated than saturated fats. It also contains a range of fatty acids, including those from the beneficial omega-3 and omega-6 groups.

[1] Hunter JE, Zhang J, Kris-Etherton PM. Cardiovascular disease risk of dietary stearic acid compared with trans, other saturated, and unsaturated fatty acids: a systematic review. Am J Clin Nutr. 2010;91:46–63.



Tuesday, January 14, 2014

Medical writing; the limitations on reporting on medical trials and research

Dr Gill Jenkins BM, DRCOG, DFFP, BA

As a media medic I’m aware of the power of science and how it is reported. Front page stories often carry new information on what is supposedly good, or bad, for us. But by the nature of the limited space in most media for the full report, much of this information is incomplete, or not taken in context and can be confusing. Often unproven associations are made by people who don’t understand the science or the detail of the study. For people with health or body concerns, some stories could unnecessarily increase anxiety.

Looking briefly at a health story we can go through what has been said, or not said, by the science. For example,  I use the study ‘Increased Iron Levels and Decreased Tissue Integrity in Hippocampus of Alzheimer’s Disease Detected in vivo with Magnetic Resonance Imaging’, from the Journal of Alzheimer’s Disease, 2013.

This used radiographic imaging to measure iron levels in people with and without Alzheimer’s in a section of the brain called the Hippocampus, which supports memory function and can be damaged in the early stages of Alzheimer’s. It showed that people with Alzheimer’s had a higher presence of iron in the Hippocampus. A couple of resulting headlines ran ‘Alzheimer’s’ link to red meat’ and ‘Too much red meat may raise Alzheimer’s risk, scientists warn’.

From the headlines you might think there must be a link between red meat and Alzheimer’s but in the study the diet of participants was not considered and so the source of this iron was not identified, nor why people with Alzheimer’s have more iron in their Hippocampus. The study was not designed to do that, but was designed to simply find out how much iron is present. The study doesn’t explore what role red meat plays in Alzheimer’s. Some of the participants with Alzheimer’s may be vegetarian or have a diet low in red meat - Broccoli, lentils, sardines and pumpkin seeds are also rich sources of iron that could be a cause for the increased iron presence.

The connection to red meat by the media is poorly thought out guess work, with questionable logic. We do not know whether the patients smoked, drank excessively or exercised, for example, or whether there were other factors such as genetic reasons for the high iron deposits. When studies suggest behaviours could create the element of risk in developing an illness it accepts that it can make no significant claim. This makes the information a very small piece of a very big puzzle. I believe that incremental innovation is essential but we need to resist the temptation to reach a dubious conclusion on the information before the science proves that there is definitely a conclusion to reach.