Category: Diet and Nutrition

Categories : Diet and NutritionTags :

World Food Day (16/10) Highlights SU Study on Meat Alternatives for Africa

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Photo by Nico Smit on Unsplash

It’s estimated that the majority of the expected 73% increase in the global demand for meat by 2050 will come from sub-Saharan Africa (SSA). Since human and environmental health concerns are likely to become more prominent with this increased consumption, plant-based meat alternatives have been touted as a possible alternative. But it may take some time before consumers in the region substitute their juicy steak of chicken wings for a vegan burger.

A review on plant-based meat alternatives in SSA published recently in Scientific African shows that before there can be any large-scale adoption of plant-based meat products in the region, we will first have to determine the social implications of eating less meat, the barriers to eating plant-based meat analogues, consumers’ acceptance of these products, and strategies that could get people to supplement their meat intake with plant-based alternatives. Plant-based meat analogues are foods designed to mimic the appearance, flavour, and texture of meat products. These can include, among others, burgers, sausages, nuggets, mince and meatballs.

The review was conducted by Omamuyovwi Gbejewoh and Dr Jeannine Marais from the Department of Food Science at Stellenbosch University and Dr Sara Erasmus from the Food Quality & Design Group at Wageningen University & Research in The Netherlands. They examined the available literature on the production and consumption of plant-based meat alternatives by searching the Web of Science and Scopus databases for academic papers and Google for news or popular articles.

Ahead of World Food Day on 16 October, the researchers say their review has shown that there are certain barriers to consumers’ acceptance of plant-based meat analogues even though worldwide, plant-based meat product sales accounted for $12.1 billion in 2019 and are likely to increase by 15% to reach $27.9 billion by 2025 and $149 billion by 2029. They do point out, however, that different versions of plant-based meat products have been available in South Africa and the rest of SSA over the past 25 years.

Barriers

“Consumers’ preference for meat is the most significant barrier to eating plant-based meat products or following a plant-based diet. In addition, meat has important socio-cultural connotations such as status, power, hierarchy, and subjugation of others.

“For example, studies in Zambia revealed that eating and sharing of meat, and even the type of meat that is served connote economic prosperity, power and respect. Chicken was more popular for regular consumption and entertaining guests because it is more readily accessible and relatively cheaper. On the other hand, beef is reserved for important visitors and landmark celebrations as it usually implies wealth because it is more expensive and usually eaten by well-to-do households.

“Other studies found that different ethnic groups in South Africa have various meat cuisines made from different types of domesticated and free-roaming wild animals.”

The researchers add that price is another significant barrier to the adoption of plant-based meat.

“In South Africa, for example, plant-based meat alternatives are considered expensive niche products associated with status and class.”

When it comes to the environmental and health risks associated with eating meat from domesticated animals regularly, the researchers point out that while consumers will acknowledge these risks, they are still unlikely to eat less meat. This phenomenon is known as the “meat paradox”.

‘Halo effect’

“Our review has shown that the ‘halo effect’ (consumers’ perception that plant products are more environmentally friendly) afforded to plant-based meat is not completely warranted because researchers are (un)knowingly discounting the processed nature of meat alternatives in any environmental or health risk assessment.”

“While the reduced environmental impacts of meat alternatives are apparent, a ‘cradle to grave’ environmental assessment needs to be carried out to ensure that the environmental burden is not shifted to other stages of the production cycle.”

The researchers say the review also found that plant-based meat products are similar in nutrient composition to meat, although differences in essential nutrients warrants caution.

“In terms of nutritional composition between traditional meat and meat alternatives, there is inconclusive evidence on which is healthier.”

According to them, the available literature is replete with strategies to reduce traditional meat consumption and to try plant-based meat alternatives. These include, among others, meatless days, partially substituting traditional meat with plant-based ingredients (e.g., “hybrid burgers”), cultural and lifestyle changes, food labelling, consumer education, and taxes on traditional meat or subsidies on plant-based meat.

“However, some of these strategies are not without drawbacks. For instance, food labels on the health and environmental benefits of plant-based meat may contain too much information that could confuse the consumer.

“If consumers in SSA are to be convinced to eat less meat and/or substitute it for plant-based alternatives, the latter should not be marketed as a replacement for traditional meat products but as a complement. Marketing strategies should be tailored to different sections of consumers because such a contextual approach is bound to provide more favourable and long-term results than a ‘one- size-fit-all strategy.”

The researchers emphasise the need for a comprehensive environmental and health impact assessment of meat alternatives in the region.

Categories : Ageing Diet and NutritionTags :

A Mediterranean Diet Doesn’t Keep Dementia at Bay

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It has been suggested in a number of studies that eating a healthy diet may reduce a person’s risk of dementia. A new study published in the journal Neurology has found, however, that both the conventionally recommended diet and the Mediterranean diet are not linked to a reduced risk of dementia.

The Mediterranean diet features a high intake of vegetables, legumes, fruits, fish and healthy fats such as olive oil, and a low intake of dairy products, meats and saturated fatty acids. “Previous studies on the effects of diet on dementia risk have had mixed results,” said study author Isabelle Glans, MD, of Lund University. “While our study does not rule out a possible association between diet and dementia, we did not find a link in our study, which had a long follow-up period, included younger participants than some other studies and did not require people to remember what foods they had eaten regularly years before.”

For the study, researchers identified 28 000 people from Sweden. Participants had an average age of 58 and did not have dementia at the start of the study. They were followed over a 20-year period. During the study, participants filled out a seven-day food diary, a detailed food frequency questionnaire and completed an interview. By the end of the study, 1943 people, or 6.9%, were diagnosed with dementia, including Alzheimer’s disease and vascular dementia.

Researchers examined how closely participants’ diets aligned with conventional dietary recommendations and the Mediterranean diet. After adjusting for age, gender, and education, researchers did not find a link between following either a conventional diet or the Mediterranean diet and a reduced risk of dementia. Dr Glans noted that further research is needed to confirm the findings.

Nils Peters, MD, of the University of Basel in Switzerland, who wrote an editorial accompanying the study, said, “Diet on its own may not have a strong enough effect on memory and thinking, but is likely one factor among others that influence the course of cognitive function. Dietary strategies will still potentially be needed along with other measures to control risk factors.” A limitation of the study was the risk of participants misreporting their own dietary and lifestyle habits.

Source: American Academy of Neurology

Categories : Diet and NutritionTags :

Guar Gum Limits Inflammation and Delays MS-like Symptoms

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Guar gum is a common additive in foods such as gummy sweets, but a healthier alternative should be found for its inflammation-limiting benefits. Photo by Amit Lahav on Unsplash

Guar gum is derived from guar beans, and is a common food additive and dietary fibre. Surprisingly, limited inflammation and delayed the onset of multiple sclerosis (MS) symptoms in mice, according to new research published in Cell Reports.

“The rapid increase of autoimmune and inflammatory disorders in industrialised countries in the last few decades indicates dietary choices are one environmental factor contributing to incidence,” said Dr Lisa Osborne, senior study researcher on the study.

“Dietary fibres are potent modulators of immune responses and can control inflammation in multiple diseases, but they’re a very biochemically diverse family. Our study gives us a clearer window into the potential of several sources of fibre in maintaining immune health.”

Dr Osborne and colleagues exposed groups of mice to a variety of diets: a control diet with 5% cellulose fibre, a no-fibre diet, or diets enriched (30%) with fibre in either resistant starch, inulin, pectin, or guar gum. Guar gum was the only fibre type that significantly limited the MS-like symptoms. 

Guar gum (guaran) is extracted from guar beans, and is often used as an additive to thicken and stabilise food and animal feed, and in industrial applications.

“Guar beans aren’t that common in western diets, and the gum isn’t used at these high levels as an additive in the west,” says Naomi Fettig, first author on the study and a PhD student with the Department of Microbiology and Immunology at UBC.

“Experts have consistently been saying fibre is good for you – and a variety of fibre sources is important to immune health – but there hasn’t been very much critical work into identifying how the body responds to different fibre types. It’s fascinating that this particular source has such an impact.”

In the US and Canada, the average daily intake of fibre is 15g – current recommendations are 30g, with no regard to specific fibre type. “Incorporating guar beans might be challenging to achieve at the doses we gave to mice,” says Dr Osborne. “But a guar gum derivative, partially hydrolysed guar gum, is commercially available as a prebiotic.”

After the gum is broken down by the gut microbiota of mice, the resulting molecules appeared to reduce the activity and proliferation of a type of CD4+ T cells, Th1 cells, which have a key role in triggering the autoimmune response, which can lead to MS-like symptoms in mice. The effects of fibre on Th1 cells remained largely unknown prior to this study, and these findings suggest that the biochemical differences in fibre structures can influence diverse immune pathways.  

Dr Osborne and her lab now want to explore the potential benefits in humans – including developing a more detailed understanding of the molecular picture, which might help design therapeutics that offer the benefits of such high guar gum diets in a more practical form.

Source: University of British Columbia

Categories : Cardiovascular Disease Diet and NutritionTags :

Milk Risky for CVD Patients – but Perhaps not Cheese

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For people with established cardiovascular disease (CVD), consuming more dairy products was linked to worse health outcomes, according to a study in the European Journal of Preventive Cardiology. However, the type of dairy product appeared to make a difference, with the outcomes for cheese remaining unclear.

In patients with stable angina, significant associations with stroke, cardiovascular mortality, and all-cause mortality were seen with increasing daily intakes of total dairy and milk over follow-up of 5 to 14 years.

While acute myocardial infarction (MI) had no clear linear relationship with total dairy intake or milk consumption, a risk increase was seen for butter consumption of more than 2g per 1000kcal of daily intake.

Data were also inconclusive when it came to cheese consumption and CVD risk, with no significant associations between greater cheese consumption with acute MI, stroke, CVD mortality, or all-cause mortality.

Thus, the study draws a more complicated picture of dairy’s risks that supports other observational data suggesting that different dairy products may have different effects. “We can speculate that at least part of the differential associations seen for milk, butter, and cheese may be because cheese contains intact MFGM [milk fat globule membrane], while milk and butter does [sic] not,” the researchers wrote.

Dairy is “probably harmful” overall, the verdict on cheese is unclear, and some of the fermented dairy products may be less dangerous if dairy is to be consumed at all, commented Andrew Freeman, MD, a cardiologist at National Jewish Health in Denver, who was not involved with the study.

Even without a randomised trial, Dr Freeman said in an interview, “there’s enough signal in the noise to draw the conclusion that higher-fat dairy products, the number one source of saturated fat in our diet, are probably not going to be helpful to human health, and heart health in particular.”

He nevertheless cautioned that there may be worldwide variation in the effects of dairy products, which may be different between countries that place more restrictions on raising cattle with chemicals such as growth hormones.

Nevertheless, the global PURE study of people around the world consistently found the best outcomes from eating a balanced diet including lots of fruits and vegetables and a modest amount of dairy, unprocessed red meat, and nuts and legumes. The PURE investigators had also reported that at least two servings of dairy per day was linked with less CVD and mortality, compared with no dairy.

“Dairy is a heterogenous food group with divergent health effects and dairy products should therefore be investigated individually,” the researchers maintained.

Their data was drawn from 1929 patients with stable angina (80% men, mean age 62 years) from the Western Norway B Vitamin Intervention Trial.

All had undergone coronary angiography due to suspected coronary artery disease or aortic stenosis in 1999–2004. Use of preventive medications was high and included aspirin (90%), statins (90%), and beta-blockers (77%).

Participants self-reported dietary habits on a food frequency questionnaire. Average dairy intake was 169g/1000 kcal; mostly milk (133g/1000 kcal).

Bias and confounding were possible due to the observational nature of the study: people who ate more dairy already tended to eat less meat, vegetables, fruit and berries, fish, and potatoes. These individuals also got more calories from protein and less from fats (except saturated fats).

Further limitations include the lack of additional dietary evaluations over years of follow-up and the potential for participants to mischaracterize their diets on a survey.

Source: MedPage Today

Categories : Diet and Nutrition TransplantsTags :

Is Protein Restriction the Best Option after Kidney Transplant?

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Anatomic model of a kidney
Photo by Robina Weermeijer on Unsplash

Scientists at Osaka Metropolitan University have challenged the conventional wisdom that low protein intake is essential for kidney disease patients with their recent study on the relationship between protein intake and skeletal muscle mass in kidney transplant recipients. Their findings were published in Clinical Nutrition.

Chronic kidney disease patients are known to have induced sarcopenia due to chronic inflammation, hypercatabolism, decreased nutrient intake, and decreased physical activity associated with impaired kidney function. A successful kidney transplantation is able to correct or improve many of those physiological and metabolic abnormalities, with the transplant recipients increasing skeletal muscle mass after receiving their new kidney. Since excessive protein intake worsens kidney function, it is commonly believed that patients with chronic kidney disease, including kidney transplant recipients, should limit protein intake to protect their kidneys. On the other hand, it has been suggested that severe protein restriction may worsen sarcopenia and adversely affect prognosis.

Since nutrition and exercise therapy are recommended to improve sarcopenia, protein intake is suspected to relate to recovery of skeletal muscle mass after kidney transplantation. However, few studies have examined the relationship between skeletal muscle mass and protein intake in kidney transplant recipients.

In order to fill this knowledge gap, a research group led by Drs Akihiro Kosoku and Tomoaki Iwai, and Professor Junji Uchida at Osaka Metropolitan University followed 64 kidney transplant recipients for 12 months after their procedure. They investigated the relationship between changes in skeletal muscle mass, as measured by bioelectrical impedance analysis, and protein intake from urine sample. The results showed that changes in skeletal muscle mass during this period were positively correlated with protein intake, and that insufficient protein intake resulted in decreased muscle mass.

Drs Iwai and Kosoku commented, “To improve the life expectancy of kidney transplant recipients, further research is needed to clarify the optimal protein intake to prevent either deterioration in kidney function or sarcopenia. We hope that nutritional guidance, including protein intake, will lead to improved life expectancy and prognosis.”

Source: Osaka Metropolitan University

Categories : Diet and Nutrition Injury & TraumaTags :

Increased Risk of Hip Fractures for Women on Vegetarian Diets

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Middle-aged women on vegetarian diets have a significantly higher risk of hip fractures than those on diets that include fish or meat, according to a long-term study publish in BMC Central. This risk remained even after accounting for the differences in available nutrient intake and body mass index.

Hip fractures greatly impact quality of life and and health outcomes, and carry a significant financial burden, with an average of $44 000 estimated to spent in the 12 months following a hip fracture. The growing trends of meat-free diets have prompted concern over their impact on hip fracture rates.

While increased intake of vegetable proteins has been associated with lower hip fracture risk, vegetarian diets have also been characterised by lower dietary intakes of nutrients that boost bone mineral density (BMD) and which are more abundant in animal products. Examples include total protein, calcium, vitamin D, vitamin B12, and ω-3 fatty acids, though the relationship with BMD is complex.

The researchers drew on data from the United Kingdom Women’s Cohort Study (UKWCS), and included 26 318 participants aged 35–69 who were classed into regular meat-eaters (> 5 servings/week), occasional meat-eaters (< 5 servings/week), pescatarians (eating fish but no meat) and vegetarians.

On average, vegetarians and pescetarians had a lower BMI (23.3 for both) than regular meat-eaters (25.2). At recruitment, regular meat-eaters had the highest prevalence of CVD, cancer, or diabetes (10.2%), and vegetarians the lowest (5.8%). A higher proportion of vegetarians reported never drinking alcohol. Regular meat-eaters reported the highest absolute dietary intakes of protein, vitamin D, and vitamin B12, whilst vegetarians reported the lowest. Calcium intakes were similar across the diet groups.

Before adjustments, compared with regular meat-eaters, vegetarians (hazard ratio 1.40) but not occasional meat-eaters (1.03) or pescatarians (1.04) had a greater hip fracture risk. Adjustment for confounders slightly attenuated these associations in the adjusted model, but the higher risk in vegetarians remained and was statistically significant: vegetarians 1.33; occasional meat-eaters 1.00; pescatarians 0.97.

However, even after adjustment for factors such as reported differences in nutrient intake and lower BMI, which is a known risk factor in hip fractures, the relative risk difference remained. This suggests that other, as yet unknown, factors related to the diets may be involved.

Categories : Diet and Nutrition GastrointestinalTags :

Non-nutritive Sweeteners Impact Human Glycaemic Responses

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Photo by Amit Lahav on Unsplash

Since the late 1800s, non-nutritive sweeteners have been used to provide sweetness without sugar. Long been believed to have no effect on the human body, researchers reporting in the journal Cell now challenge this notion by finding that these sugar substitutes are not inert, and, in fact, some can alter human consumers’ microbiomes and thereby their glycaemic responses – albeit in a highly individualised fashion.

Previous research has already found found that non-nutritive sweeteners affected the microbiomes of mice in ways that could impact their glycaemic responses, something which the same researchers now investigated in humans.

To address this important question, the research team carefully screened over 1300 individuals for those who strictly avoid non-nutritive sweeteners in their day-to-day lives, and identified a cohort of 120 individuals. These participants were broken into six groups: two controls and four who ingested well below the FDA daily allowances of either aspartame, saccharin, stevia, or sucralose.

“In subjects consuming the non-nutritive sweeteners, we could identify very distinct changes in the composition and function of gut microbes, and the molecules they secret into peripheral blood. This seemed to suggest that gut microbes in the human body are rather responsive to each of these sweeteners,” said senior author Eran Elinav, an immunologist and microbiome researcher. “When we looked at consumers of non-nutritive sweeteners as groups, we found that two of the non-nutritive sweeteners, saccharin and sucralose, significantly impacted glucose tolerance in healthy adults. Interestingly, changes in the microbes were highly correlated with the alterations noted in people’s glycaemic responses.”

To prove the microbiomes were responsible, the researchers transferred microbial samples from the study subjects to mice that have been raised in completely sterile conditions, with no microbiome of their own.

“The results were quite striking,” explained Elinav. “In all of the non-nutritive sweetener groups, but in none of the controls, when we transferred into these sterile mice the microbiome of the top responder individuals collected at a time point in which they were consuming the respective non-nutritive sweeteners, the recipient mice developed glycaemic alterations that very significantly mirrored those of the donor individuals. In contrast, the bottom responders’ microbiomes were mostly unable to elicit such glycaemic responses,” he added. “These results suggest that the microbiome changes in response to human consumption of non-nutritive sweetener may, at times, induce glycaemic changes in consumers in a highly personalised manner.”

Elinav says that he expects the effects of the sweeteners will vary across individuals because of how unique our microbiomes are. “We need to raise awareness of the fact that non-nutritive sweeteners are not inert to the human body as we originally believed. With that said, the clinical health implications of the changes they may elicit in humans remain unknown and merit future long-term studies.”

“In the meantime, we need to continue searching for solutions to our sweet tooth craving, while avoiding sugar, which is clearly most harmful to our metabolic health,” says Elinav. “In my personal view, drinking only water seems to be the best solution.”

Source: Science Daily

Categories : Diet and Nutrition ExerciseTags :

IV Nutrition is a Growing and Potentially Dangerous Trend among Athletes

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Intravenous IV drip
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Once a last resort solution, intravenous (IV) nutrition is threatening to become the norm for competitive athletes, despite no scientific evidence that it works or that it is safe, warn experts in an editorial in the British Journal of Sports Medicine.

To halt this trend, the experts urge that ‘food first’ and ‘no needle’ messages need to be amplified among all athletes and their support teams.

The authors, who interact with professional team players in European and American leagues and their support teams on a regular basis, have become increasingly aware of the practice.

While it is not known how common it is, anecdotally, some players are hooked up to IV nutrition drips as often as every week as part of a pre- or post-game routine, they say. 

So-called ‘drip bars’ and concierge IV nutrition services claim to boost health and performance, restore hydration and speed up recovery. These services offer a menu of B vitamins, amino acids, glutathione, vitamin C and electrolytes, which could potentially boost levels beyond any therapeutic range.

These services seemed to have slipped under the regulatory radar despite being quite visible, and there is no guidance on their use for players or practitioners, the authors pointed out.

The principle of reducing needle use in sport and a ‘food first’ approach is taught in sports nutrition courses around the world, and a ban on needle use by athletes at the Olympic Games, except for appropriate medical use, and where a therapeutic use exemption (TUE) is obtained, has been in place for all recent Games, they highlight.

IV nutrition drips have traditionally been reserved for serious clinical conditions, such as anaemia, symptoms caused by nutrient deficiencies, or to correct severe dehydration caused by marathon running in a desert, for example. But they are now being used for tiredness, fatigue, or recovery, say the authors.

“But the evidence is sparse and not supportive. We are aware of just two studies assessing vitamin injections in otherwise healthy participants, neither of which yielded an effect for the injection group,” note the authors.

They add that these drips are risk-free, potentially interfering with the liver and gut microbes with implications for detoxification and immunity.

“Bypassing these mechanisms appears foolhardy unless there is a significant clinical rationale,” they write, adding that IV drips also carry risks of infection at the needle site and of blood clots.

Excessive vitamin B6 is associated with peripheral neuropathy, while athletes regularly receiving IV iron risk liver disease, they point out.

“Given that the long-term effects of supratherapeutic doses of B vitamins and other nutrients are unknown in athletes, it does not appear to be worth the risk, especially given the lack of evidence-based benefits,” they write. 

“More than this is the reputational risk to sport if it is normalised for athletes to regularly partake in self-directed IV [nutrition] use with a worrying shift away from what ‘works’ (according to scientific standards), to that which is unproven. 

“Furthermore, some athletes risk an anti-doping violation by participating in self-directed IV [nutrition] use.”

Figures on the prevalence of IV nutrition need to be gathered in tandem with governing bodies and players’ associations in the professional leagues providing guidance on the potential risks of IV nutrition use, say the authors.

“The ‘food first’ and ‘no needle’ messages need to be amplified among all athletes and multidisciplinary support teams to avoid what was previously a ‘last resort’ treatment becoming normal without scientific evidence of benefit,” they warn.

Source: EurekAlert!

Categories : Cancer Diet and NutritionTags :

Can a Banana per Day Keep the Oncologist Away?

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Banana
Photo by Mike Dorner on Unsplash

A trial in people with hereditary colon cancer has shown that daily supplements of resistant starch, equivalent to a slightly green banana per day, had a major preventative effect against many cancers. Published in Cancer Prevention Research, the findings showed that, while bowel cancers were unaffected, the supplement reduced cancers in other parts of the body by more than half.

This effect was particularly pronounced for upper gastrointestinal cancers including oesophageal, gastric, biliary tract, pancreatic and duodenum cancers. What is even more remarkable is that the effects lasted for 10 years after the participants stopped taking the supplements.

The CAPP2 trial involved almost 1000 patients with Lynch syndrome from around the world and revealed that a regular dose of resistant starch, also known as fermentable fibre, taken for an average of two years, cut their risk for many cancers.

The present study is a planned double blind 10 year follow-up, supplemented with comprehensive national cancer registry data for up to 20 years in 369 of the participants.

A previous study as part of the same trial and published in The Lancet revealed that aspirin reduced cancer of the large bowel by 50%.

“We found that resistant starch reduces a range of cancers by over 60%. The effect was most obvious in the upper part of the gut,” explained Professor John Mathers at Newcastle University. “This is important as cancers of the upper GI tract are difficult to diagnose and often are not caught early on.

“Resistant starch can be taken as a powder supplement and is found naturally in peas, beans, oats and other starchy foods. The dose used in the trial is equivalent to eating a daily banana; before they become too ripe and soft, the starch in bananas resists breakdown and reaches the bowel where it can change the type of bacteria that live there.

“Resistant starch is a type of carbohydrate that isn’t digested in your small intestine, instead it ferments in your large intestine, feeding beneficial gut bacteria – it acts in effect, like dietary fibre in your digestive system. This type of starch has several health benefits and fewer calories than regular starch. We think that resistant starch may reduce cancer development by changing the bacterial metabolism of bile acids and to reduce those types of bile acids that can damage our DNA and eventually cause cancer. However, this needs further research.”

Professor Sir John Burn, from Newcastle University and Newcastle Hospitals NHS Foundation Trust who ran the trial with Prof Mathers, said: “When we started the studies over 20 years ago, we thought that people with a genetic predisposition to colon cancer could help us to test whether we could reduce the risk of cancer with either aspirin or resistant starch.

“Patients with Lynch syndrome are high risk as they are more likely to develop cancers so finding that aspirin can reduce the risk of large bowel cancers and resistant starch other cancers by half is vitally important.

“Based on our trial, NICE now recommend Aspirin for people at high genetic risk of cancer, the benefits are clear – aspirin and resistant starch work.”

Between 1999 and 2005, nearly 1000 participants began either taking resistant starch in a powder form every day for two years or aspirin or a placebo.

At the end of the treatment stage, there was no overall difference between those who had taken resistant starch or aspirin and those who had not. However, the research team anticipated a longer-term effect and designed the study for further follow-up.

During follow-up, only five new cases of upper GI cancers were diagnosed among the 463 participants who had taken the resistant starch compared with 21 among the 455 who were on the placebo.

The team are now leading the international trial, CaPP3, involving more than 1800 participants with Lynch syndrome to look at whether smaller, safer doses of aspirin can be used to help reduce the cancer risk.

Source: Newcastle University

Categories : Diet and Nutrition General InterestTags :

Evolution of Lactose Tolerance Driven by Starvation and Disease

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The ability to digest lactose is thought to have evolved in concert with milk entering the diet where dairy farming was commonplace, but a new study published in Nature paints a much grimmer picture: starvation and disease appeared to drive its spread through European populations.

Five thousand years ago virtually all humans were (like all other mammals) lactose intolerant, losing the ability to produce lactase to digest milk after weaning and suffering bloating, gas and diarrhoea as adults when they they drank milk.

Professor George Davey Smith, Director of the MRC Integrative Epidemiology Unit at the University of Bristol and a co-author of the study, said: “However, a genetic trait called lactase persistence has evolved multiple times over the last 10 000 years and spread in various milk-drinking populations in Europe, central and southern Asia, the Middle East and Africa. Today, around one third of adults in the world are lactase persistent.”

Using archaeological data, genetic samples and computer modelling, the team demonstrated that lactase persistence genetic trait was not common until around 1000 BCE, nearly 4000 years after it was first detected around 4700–4600 BCE.

“The lactase persistence genetic variant was pushed to high frequency by some sort of turbocharged natural selection. The problem is, such strong natural selection is hard to explain,” added Professor Mark Thomas, study co-author from University College London.

In order to establish how lactose persistence evolved, Professor Richard Evershed, the study’s leader, assembled a database of over 7000 animal fat residues from 13 181 pottery fragments. His findings showed that milk was used extensively in European prehistory, dating from the earliest farming nearly 9000 years ago, but its use waxed and waned in different areas and times.

To understand how this relates to the evolution of lactase persistence, the research team, led by Prof Thomas, tracked the presence of the lactase persistence gene using ancient DNA sequences from more than 1700 prehistoric European and Asian individuals. The first instance seen was after around 5000 years ago, and 2000 years later it was at appreciable frequencies and today is very common. Next, his team developed a new statistical approach to examine how well changes in milk use through time explain the natural selection for lactase persistence. Surprisingly, no association was found, challenging the long-held view the extent of milk use drove lactase persistence evolution.

Professor George Davey Smith’s team had been probing the UK Biobank data, comprising genetic and medical data for more than 300 000 living individuals, found only minimal differences in milk drinking behaviour between genetically lactase persistent and non-persistent people. Critically, the large majority of people who were genetically lactase non-persistent experienced no short or long-term negative health effects when they consume milk.

Professor Davey Smith added: “Our findings show milk use was widespread in Europe for at least 9000 years, and healthy humans, even those who are not lactase persistent, could happily consume milk without getting ill. However, drinking milk in lactase non-persistent individuals does lead to a high concentration of lactose in the intestine, which can draw fluid into the colon, and dehydration can result when this is combined with diarrhoeal disease.”

This can have implications for individuals who are unwell, according to Prof Smith. “If you are healthy and lactase non-persistent, and you drink lots of milk, you may experience some discomfort, but you not going to die of it. However, if you are severely malnourished and have diarrhoea, then you’ve got life-threatening problems. When their crops failed, prehistoric people would have been more likely to consume unfermented high-lactose milk – exactly when they shouldn’t.”

To test these ideas, Prof Thomas’s team applied indicators of past famine and pathogen exposure into their statistical models. Their results clearly supported both explanations – the lactase persistence gene variant was under stronger natural selection when there were indications of more famine and more pathogens.

The authors concluded: “Our study demonstrates how, in later prehistory, as populations and settlement sizes grew, human health would have been increasingly impacted by poor sanitation and increasing diarrheal diseases, especially those of animal origin. Under these conditions consuming milk would have resulted in increasing death rates, with individuals lacking lactase persistence being especially vulnerable. This situation would have been further exacerbated under famine conditions, when disease and malnutrition rates are increased. This would lead to individuals who did not carry a copy of the lactase persistence gene variant being more likely to die before or during their reproductive years, which would push the population prevalence of lactase persistence up.

“It seems the same factors that influence human mortality today drove the evolution of this amazing gene through prehistory.”

Source: University of Bristol