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Optimum Nutrition Summer 2018 PREVIEW

FOOD FACT FILE

FOOD FACT FILE ResvEratrol A glass of wine is commonly thought to be good for our health. Valerio Esposito finds out why For centuries, humans have fantasised about the so-called elixir of life. As it turns out, a simple trip to the grocery store may quench your thirst for youth: and could red wine be the answer? According to David Sinclair, a professor in genetics and co-director of the Paul F Glenn Center for the Biology of Aging at Harvard Medical School in the US, it’s a possibility. “A glass of wine a day provides polyphenols that appear to be beneficial to health,” he says. “There is a cocktail of molecules, including resveratrol, that have shown antiageing effects in lab studies.” Since the early 2000s, Dr Sinclair has been studying the anti-ageing effects of resveratrol, a special type of polyphenol antioxidant much-touted for its purported benefits to health. It is found in pine trees, peanuts, berries, and especially the skin and seeds of grapes, which determines its significant content in red wine. The presence of resveratrol in wine has often been used to explain the so-called ‘French Paradox’, which describes the low incidence of coronary diseases in France, despite high consumption of saturated fats and red wine. 1 But Dr Randolph Arroo, head of research at Leicester School of Pharmacy, believes that cause and effect is unclear. “There are many theories on resveratrol,” he says. “It is true that in France and Mediterranean countries, people regularly drink red wine and have a lower chance of heart attack. But it’s very hard to say if that’s a consequence of their wine intake.” Yet the apparent miracle properties of resveratrol have attracted the attention of the medical community, becoming the subject of numerous studies published in respected scientific journals. Some animal-based studies, in fact, have shown resveratrol to be associated with lower incidence of conditions associated with ageing2 and an increase in the lifespan of some organisms.3 It is argued that resveratrol may protect cells and promote their replication, 4 while reducing the inflammation associated with premature ageing. 5 This is partially owing to the “Resveratrol is very poorly absorbed in the human body. It doesn’t get into your blood in high concentration...” stimulating effect that resveratrol has on the production of SIRT1, an enzyme involved in DNA repair, inflammation pathways, insulin production and mitochondria production. 2 It has also been suggested that resveratrol may have positive effects against cancer, diabetes, neurological diseases and skin problems. However, whilst a recent study has shown that resveratrol has promising effects in halting the proliferation of cancer in some tumour models, 6 its application is yet to be determined. An earlier study published in 2013 in the Annals of the New York Academy for Sciences concluded that the antioxidant “lacks potency, high efficacy, and target specificity” to make it a good candidate for a drug. 7 Similarly, resveratrol has shown potential in preventing cardiovascular diseases 8 and managing congestive heart failure. But clinical trials on humans are still limited. It could be suggested that one of the best ways to benefit from resveratrol is to eat foods that contain a lot of it. Yet an Italian study on ageing, published in 2014, concluded that the amount of resveratrol one can get from food alone has no measurable impact on human health, nor does it reduce the risk of mortality. 9 The solution might be to take resveratrol supplements or use a topical cream. But supplements are not sufficient, says Arroo. “Resveratrol is very poorly absorbed in the human body. It doesn’t get into your blood in high concentration,” he says. “It goes to your intestine and it leaves your body at the other end and only a small portion is absorbed into the body and even that is quickly rejected by the kidneys.” Dosages contained in commercial supplements are also usually lower than those that have been shown to produce beneficial effects and, in addition to this, it is not clear how much one should take. It is also virtually impossible to determine the purity of commercial products. With the exception of its possible 8 OPTIMUM NUTRITION | SUMMER 2018

FOOD FACT FILE role as an enhancer of certain kinds of breast carcinoma, 10 however, resveratrol supplements appear to be safe, but their effectiveness is still questionable. Most of the scepticism towards the miraculous effect of resveratrol lies in the fact that to this day, much of the research has been conducted in the laboratory and mostly on animals such as mice, fruit flies and other small organisms. While these studies show a potential use in human health, only a few human trials have been conducted. “If a drug is made on the structure of resveratrol, then normally it takes 10-15 years before it’s accepted,” says Arroo. “The first test is whether it’s safe. And that seems quite clear now. But does it really help? That will take much longer to prove.” Sinclair, however, seems hopeful about the results of existing trials. “Synthetic molecules have been made that are a thousand times more potent than resveratrol. These are in clinical trials and have worked to treat psoriasis, for example,” he says. According to Arroo, however, the idea that drinking red wine may help us live longer thanks to its high resveratrol content is little more than a dream. “It could be beneficial as part of your diet,” he says. “But, to put it crudely, if you have cancer I would not advise to drink lots of red wine because that’s clearly not going to help.” References: 1. Zhang LB et al (2007). New enlightenment of French paradox: Resveratrol’s potential for cancer chemoprevention and anti-cancer therapy. Cancer Biol & Ther, 6(12), 1833-1836. 2. Hubbard B et al (2013). Evidence for a common mechanism of SIRT1 regulation by allosteric activators. Sci, 339(6124), 1216-1219. 3. Howitz K et al (2003). Small molecule activators of sirtuins extend Saccharomyces cerevisiae lifespan. Nat, 425(6954), 191-196. 4. Safaeinejad Z et al (2017). Resveratrol promotes human embryonic stem cells self-renewal by targeting SIRT1-ERK signaling pathway. Eur J Of Cell Biol, 96(7), 665-672. 5. Csiszar A (2011). Anti-inflammatory effects of resveratrol: possible role in prevention of agerelated cardiovascular disease. Annals Of The New York Acad Of Sci, 1215(1), 117-122. 6. Jiang Z et al (2017). Resveratrol and cancer treatment: updates. Annals Of The New York Acad Of Sci, 1403(1), 59-69. 7. Ogas T et al (2013). Resveratrol analogs: promising chemopreventive agents. Annals Of The New York Acad Of Sci, 1290(1), 21-29. 8. Yeung P (2017). Therapeutic potential of resveratrol for cardiovascular protection. Cardio Pharma: Open Access, 06(02). 9. Semba R et al (2014). Resveratrol levels and all-cause mortality in older community-dwelling adults. JAMA Internal Med, 174(7), 1077. 10. Andreani C et al (2017). Resveratrol fuels HER2 and ERα-positive breast cancer behaving as proteasome inhibitor. Aging (Albany NY), 9(2), 508. Nightshades Lisa Patient looks at why some shun these common foods White potatoes, tomatoes, chillies, peppers, aubergines, goji berries, okra and paprika are all members of the plant species known as nightshades — a food group that is often excluded from the diet as part of a strategy to help relieve symptoms of joint conditions such as osteoarthritis and rheumatoid arthritis, or from atopic conditions such as eczema and asthma. However, although eliminating nightshades from the diet has been widely adopted by complementary and alternative healthcare practitioners, any scientific evidence to support the practice is patchy. Jonathan Prousky, a professor of naturopathy, who advocates cutting out nightshades to relieve joint pain, offers an insight into his reasons in an article published in 2015. “It is doubtful that rigorous controlled trials will be ever conducted on these interventions (nightshades),” he writes. But the practice, he adds, is harmless and inexpensive. “Given the safety, putative efficacy, and low-cost of these interventions, they should be offered to patients that want complementary and/or alternative options for osteoarthritis.” 1 Prousky, like other similar advocates, bases this opinion on observation and the work of the late Dr Norman Childers, a botanist who published a paper in 1993 describing a complete turnaround in his symptoms of diverticular disease and joint pain when he stopped eating nightshades. 2 Childers put forward several theories as to why nightshades might be harmful for health; one being that chemicals in the plants might cause the body to deposit too much calcium in joints and soft tissue (known as calcinosis). He cited studies from the 1950s, in which an association was established between sudden attacks of crippling arthritis and joint pain in cattle and sheep that grazed on pastures rich in nightshade plants 3 — although there does not appear to be any evidence that eating nightshade foods causes calcinosis in humans. The chemicals in nightshades thought to cause problems are called glycoalkaloids, particularly solanine (the Latin name for these plants begin with solanum; for example aubergine is Solanum melongena. They may also be collectively referred to as solanines). The plant produces glycoalkaloids to protect them against pests and fungi, which in high doses can cause vomiting, diarrhoea, headache and fever. 4 Potatoes, for example, are known to produce a higher amount of solanine when they are green and at the stage where they are more vulnerable to pests and disease. This is why we generally don’t eat green potatoes. However, a 2002 study on mice that had been genetically modified to have inflammatory bowel disease found that high doses of glycoalkaloids from potatoes caused damage to their guts. Using sections of mouse intestine, researchers were able to show that glycoalkaloids caused lesions to appear in the epithelial layer of the skin lining the intestine in a manner similar to the way gluten affects people with coeliac disease. 5 However, although glycoalkaloids should be avoided in excess, they may also have some positive health benefits. Studies on glycoalkaloids in aubergines, potatoes and tomatoes have shown that they prevent the growth of cancer cells, both in the laboratory and in human clinical trials. 6 They also have an anti-fungal effect, and there is research underway to determine whether or not there may be a medical application for these chemicals as antifungal treatments in the future. 7 However, the lack of research into any connection between nightshade foods and joint pain or skin conditions makes it difficult for sufferers or health practitioners to reach an evidence-based conclusion on whether these foods should be eliminated or not. But if other interventions aren’t helping, based on anecdotal evidence it may be worth a shot. Nightshade foods • Tomatoes (products containing tomatoes such as ketchup or baked beans) • Aubergines (aubergine-based processed foods such as brinjal pickle) • Potatoes • Goji berries • Peppers (bell peppers, chillies, paprika, pimentos, cayenne, etc.) • Seasonings such as curry powder, jerk seasoning etc. which contain chillies SUMMER 2018 | OPTIMUM NUTRITION 9