Verifying Tabloid Advice on a Mediterranean Diet

Using PubMed to Check Tabloid Articles Touting a Diet of 
Olive Oil & Omega-3 Fatty Fish

http://www.nutritioulicious.com/2013/02/mediterranean-diet-good-for-your-heart/

Evelyn Smith

MS in Library Science, University of North Texas, 2012

Many readers disregard tabloid articles that give health advice because tabloids usually sensationalize information, and they ordinarily don’t provide enough substantiating detail to verify the facts they pass on to the reader.  Nevertheless, as this sampling shows, they bear investigating, even though the wise health consumer shouldn’t take them at face value without examining the original sources they may--or may not--mention.

On January 27, 2014,  for example, the following article appeared in the British tabloid The Daily Mail that this blog also summarizes:

Olive oil may keep your bones strong: Study finds people who consume more have higher levels of osteocalcin protein - a marker of strong bones. 2014, January 27).  Daily Mail.  Retrieved from http://www.dailymail.co.uk/health/article-2546943/Olive-oil-bones-strong-Study-finds-people-consume-higher-levels-osteocalcin-protein-marker-strong-bones.html

A study from the University of Madrid suggests “olive oil is good for the bones”, noting that two years of research found that diners who regularly consumed more olive oil had higher levels of osteocalcin (olive oil, 2014, January 27, para. 1). Osteocalcin is a protein secreted by bone-forming cells. It may prevent insulin resistance (olive oil, 2014, January 27, para. 2-3).

The article leaves out some information, even though it does emphasize that a protein found in olive oil might contribute to bone density: The study (summarized below) first appeared in a medical journal in October 2012, but the two-year trial specifically compared what happened when Spanish men between the ages of 55 and 80 followed a Mediterranean diet that either emphasized the consumption of nuts or olive oil paired with other ingredients in a Mediterranean diet.  True, olive oil is part of a Mediterranean diet, yet it’s not the only part of this low-fat, high in fresh vegetables and fish regime.   

A summary and a link to the October 2012 full-text online article that The January 2014 Daily Mail obliquely mentions are as follows:

Fernández-Real, José , Bulló, Mónica, & Salas-Salvadó Jordi.  (2012, October). A Mediterranean diet enriched with olive oil is associated with higher serum total osteocalcin levels in elderly men at high cardiovascular risk. The Journal of Clinical Endocrinology and Metabolism, 97(10), 3792-2798.  doi: 10.1210/jc.2012-2221 Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3462931/

The longitudinal study of older Spanish men compared the effects on of a low-fat control diet, a Mediterranean diet enriched with nuts, or a Mediterranean diet that is enhanced with virgin olive oil by grouping them in three randomly selected groups to determine whether or not following a particular diet plan enhances bone formation.  Blood tests that looked for the protein marker osteocalcin indicated that bone formation “increased robustly” in those men who followed a Mediterranean diet enriched with virgin olive oil, but not in those men who either followed the low-fat control diet or the Mediterranean plus nuts diet.  The researchers thus concluded that following a Mediterranean diet that includes virgin olive oil for two years will increase serum osteocalin, thus protecting the bones.

Using the key words “olive oil” AND “bones” also pulls up a Huffington Post article, summarized below,  that simplifies and summarizes the findings of the original study most probably by accessing published abstracts that appeared online in advance of the article’s actual publication.  Additionally, it gives more detailed and specific information than the Daily Mail article does:

Food for healthy bones: Olive oil and 8 other picks.  (2012, August 16).  Huffington Post.  Retrieved from http://www.huffingtonpost.com/2012/08/16/food-for-bones_n_1784377.html

Not only does olive oil protect against cardiovascular disease and breast cancer, improve cognitive function, and make for healthy hair, skin, and nails, but it also may strengthen the bones according to a study made by Spanish researchers of 127 men between the ages of 55 and 80 that showed that those who regularly followed a Mediterranean diet enriched with olive oil had markedly higher levels of osteocalcin in their blood—“a known marker of strong and healthy bones” (Food, 2012, August 16, para. 1-3).

While earlier studies showed that olive oil might protect against osteoporosis in experimental and in vitro models, this randomized, longitudinal study showed that olive oil preserves bone in humans.  The Huffington Post article also notes that bone disease is also less frequent in Mediterranean countries where olive oil is part of the diet (Food, 2012, August 16, para. 4), although correlation is not necessarily causation.  After all, people that live nearer the equator receive more Vitamin D from direct sunlight than those peoples who live in Northern climates.

To The Huffington Post's credit, the article also acknowledges that it’s also important not to replace calcium and vitamin D in the diet since all three of these components along with regular exercise contribute to healthy bones.  In addition to olive oil, milk, yogurt, and cheese, other foods also build and maintain healthy bones: Soy, omega-3 fatty fish, fortified cereal, almonds, leafy green vegetables, like spinach, potatoes, bananas, and fortified orange juice (Food, 2012, August 16, para. 4-5 & slideshow).

A little research using PubMed also pulls up the following articles that furnish necessary additional information that verifies or further explains the information that appears in the first part of the original Daily Mail article :  For example, experimenting with entering specific keywords into PubMed's search engine finds  a similar research study in rats that underlines the importance of including olive oil in a low-cholesterol, Mediterranean-style diet: http://www.ncbi.nlm.nih.gov/pubmed 

Saleh, N. K. & Saleh, H. A. (2011, February 4). Olive oil effectively mitigates ovariectomy-induced osteoporosis in rats.  BMC Complementary and Alternative Medicine,11(10). {Abstract only].  doi: 10.1186/1472-6882-11-10. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/21294895

In a study that compared a control group of female rats, a group of rats whose ovaries had been removed, and a group of rats whose ovaries had been removed and whose diet was supplemented with olive oil, olive oil effectively diminished the effects of ovariectomy-induced osteoporosis in rats, which makes it a promising alternative treatment for postmenopausal osteoporosis.

While another study gives readers an either/or option of either consuming fish or olive oil for keeping older bones strong:

Bullon, P., Battino, M., & Varela-Lopez, A. et al.  (2013, September 1).  Diets based on virgin olive oil or fish oil but not on sunflower oil prevent age-related alveolar bone resorption by mitochondrial-related mechanisms. PLoS One, 8(9), e74234. doi: 10.1371/journal.pone.0074234.  Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3774624/

A study in which rats were fed monounsaturated fatty acids, such as those found in virgin olive oil, the n-6 polyunsaturated fats, present in sunflower oil, or n-3PUFA, that is part of omega-3 fish oil, showed that either MUFA or n-3PUFA, but not in sunflower oil, might counteract age-related oxidative stress that results in alveolar bone loss that is a feature of periodontal disease associate with age.

The last part of the Daily Mail article also publicizes that an unidentified and undated study from the University of Athens has found that a diet “high in olive oil and low in red meat” correlates these variables with healthier bone density in women (olive oil, 2014, January 27, para. 4).

A PubMed search using the key words “olive oil” AND “meat” AND “bones” AND “University of Athens” matches a February 2009 article first published in Nutrition. Unfortunately, however, The Daily Mail article leaves out the consumption of omega-3 fatty fish. The original article, for which this blog has provided a synopsis can be accessed in full below:

Kontogianni, M. D., Melistas, L., & Yannakoulia, M., et al. (2009, February). Association between dietary patterns and indices of bone mass in a sample of Mediterranean women. Nutrition, 25(2), 165-71.  doi: 10.1016/j.nut.2008.07.019. Epub 2008 Oct 11.  Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/?term=Olive+Oil+AND+meat+AND++bone+density++AND+University+of+Athens

A study of 220 adult Greek women found that following a Mediterranean dietary pattern alone didn’t necessarily ensure bone health; however, a high consumption of both fish and olive oil coupled with limiting servings of red meat to only a few times a month “was positively related to bone mass”.

During the past week, Daily Mail readers have also found an article touting fish oil as a means to prevent Alzheimer’s:

Hope, Jenny.  (2014, January 22).  Fish oil could help prevent Alzheimer's and also give you a bigger brain. Daily Mail.  Retrieved from http://www.dailymail.co.uk/health/article-2544287/Fish-oil-help-prevent-Alzheimers-bigger-brain.html

According to the Daily Mail, this eight-year-long  study of 1.111 women between the ages of 70 and 78 equated higher levels of fish oil  in 70-year-old females with better cognitive functioning at age 78 while those women whose blood contained lower levels of omega-3 fatty acids at age 70 had smaller brain volumes at age 78 (Hope, 2014, January 22, para. 9-13).

The article’s first two paragraphs cite unnamed researchers who claim that eating fish can offer protection against Alzheimer’s and “give you a bigger brain”.  However, it isn’t until the reader comes to the third paragraph that the story identifies the type of fish responsible for this medical miracle as omega 3-fatty fish while the fourth paragraph notes that consuming high levels of fish  rich in omega 3 fatty acid may give individuals two extra years of brain health, according to a new study in Neurology (Hope, 2014, January 22, para. 1-4). 

The key words “Women’s Health Initiative Memory Study” AND “omega-3 fatty acid” from the Daily Mail article pull up a the Neurology article that the Daily Mail’s story is popularizing:

Pottala, J.V., Yaffe, K., & Robinson, J. G., et al. (2014, January 22).  Higher RBC EPA + DHA corresponds with larger total brain and hippocampal volumes: WHIMS-MRI Study.  Neurology. Abstract only. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/24453077

The WHIMS-MRI study indeed correlates with a larger brain volume in postmenopausal women with a higher omega-3 index while those women with a lower omega-3 index increase their risk of hippocampal atrophy.

Since the Daily Mail article also jives with the old wives’ tale that fish is brain food, it bears further investigating, so the researcher  enters  the key words found in it--“Omega-3 fatty acids” AND “Alzheimer’s”–to pull up additional articles.  Similar studies  to the Neurology article thus produce similar findings—a diet high in omega-3 fatty acids combined with other food selections from what in recent years is popularly called a Mediterranean diet and a healthy lifestyle reduces the risk of dementia.

Demarin, V., Lisak, M.,  & Morović, S.  (2011, March).  Mediterranean diet in healthy lifestyle and prevention of stroke. Acta Clinica Croatia, 50(1), 67-77.  Abstract only. Retrieved from

http://www.ncbi.nlm.nih.gov/pubmed/22034786

Regular consumption of fish lessens the changes of ischemic stroke, but it doesn’t decrease the risk of hemorrhagic stroke because of the potential antiplatelet aggregation property of LCn3PUFAs.  Moreover, eating fish only once weekly significantly reduces the risk of stroke while including fish in the diet five days per week lowers the risk of stroke 31 percent. Even though omega-3 fatty acids don’t reduce plague, including regular servings of fatty, non-fried fish in the diet reduces the thickness of plaque within the walls of carotid arteries.  Research therefore not only associates a Mediterranean-style diet with reduced rates of cardiovascular disease and stroke, but studies also link it with lower cancer mortality rates and a decreased incidence of Parkinson’s, Alzheimer’s and Mild Cognitive Impairment.

http://kopiaste.org/2008/07/psari-magioneza-fish-with-mayonnaise-and-fish-soup/

Gu, Y., Schupf, N., & Cosentino, S. A. et al. (2012, June 5).  Nutrient intake and plasma β-amyloid. Neurology, 78(23), 1832-1840.  doi:  10.1212/WNL.0b013e318258f7c2

Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3369517/

Obtaining plasma Aβ40 and Aβ42 from 1,219 cognitively healthy individuals over age 65, researchers evaluated the association between nutrient intake and plasma Aβ levels and found that test subjects with a higher dietary intake of omega-3 PUFA had lower plasma levels of  Aβ42, which correlates with a reduced risk of Alzheimer’s and a slower rate of cognitive decline.  

Otaegui-Arrazola, A., Amiano, P., & Elbusto, A., et al.  (2014, February).  Diet, cognition, and Alzheimer's disease: food for thought.  European Journal of Nutrition, 53(1), 1-23. Abstract only. doi: 10.1007/s00394-013-0561-3.  Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/23892520

Researchers conducted a search on Medline and Web of Knowledge for epidemiological and clinical studies using the keywords “Alzheimer's disease”, “mild cognitive impairment”, “cognitive function”, “dietary factors”, “omega-3”, “antioxidants”, “B vitamins”, “dietary patterns”, and “Mediterranean diet” and found that observational studies verified that nutrients like omega-3 fatty acids, antioxidants or B vitamins and a Mediterranean diet protected cognitive function.  However, randomized controlled trials didn’t show consistent results. Although these nutrients may safeguard those who consume them from dementia, researchers don’t yet know how they influence brain vascular health.

Shinto, L., Quinn, J., & Montine, T., et al.  A randomized placebo-controlled pilot trial of omega-3 fatty acids and alpha lipoic acid in Alzheimer's disease. Journal of Alzheimer’s Disease: JAD, 38(1),111-20. doi: 10.3233/JAD-130722.  Abstract only.  Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/24077434

When comparing the effect of supplements contain omega-3 fatty acids alone and omega-3 plus alpha lipoic acid, and a placebo over a year’s time, research found no significant different between the groups that took a fish oil supplement only containing omega-3 fatty acids or omega-3 plus alpha lipoic acid when neurologists tested 39 individuals placed in three randomized groups using the Mini-Mental State Examination (MMSE), Activities of Daily Living/ Instrumental Activities of Daily Living (ADL/IADL), and Alzheimer Disease Assessment Scale-cognitive subscale (ADAS-cog). Compared to the placebo, the omega 3 plus alpha lipoic acid showed less decline on the MMSE and the IADL. Thus, taking a supplement that contains omega 3 plus alpha lipoic acid slows cognitive decline.

Tan, Z. S., Harris, W. S., Beiser, A. S., et al. (2012, February).  Red blood cell ω-3 fatty acid levels and markers of accelerated brain aging.  Neurology, 78(9), 658-64.  doi: 10.1212/WNL.0b013e318249f6a9. Abstract only.  Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/22371413

Researchers related red blood cell fatty acid levels and higher dietary intake and circulating levels of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) to a reduced risk of dementia in a study of 859 women aged 67 to 76.  Conversely, they found that those women with lower brain volumes also had lower RBC, DHA+EPA levels (or DHA and Omega-3 index). These women exhibited a “vascular” pair of “cognitive impairment” even when they were “free of clinical dementia”.  Bottom Line:  Fatty fish, like salmon, sardines, anchovies, and tuna, may indeed be brain food.

Conclusion:

Following health advice garnered from the tabloid press gives the reader some helpful information, but since these new sources often don't provide a source for the research they mention or give the findings in context, they often leave a few important puzzle pieces missing. All of which begs the question, “Why don't tabloid articles provide links to PubMed since it provides abstracts to the actual studies?”  However, the inquisitive reader in the meantime can quickly fill-in this information by entering a few well-chosen key words into PubMed's advance search engine,  pulling up the actual research as well as sometimes finding articles that simplify medical terms. Conversely, since a large percentage of the United States population reads at about the 8th- or 9th-grade level, librarians and family doctors might also search for simplified articles that explain complicated information found in medical journals if at the same time they check to see if they have left out advice by pulling up the PubMed source. 

Accordingly, using the summaries and links provided on this Web page, the reader should reason that a diet that includes several weekly servings of fish high in omega-3 fatty acids provides some protection against Alzheimer’s and cardiovascular disease when combined with the consumption of other ingredients in a Mediterranean diet, including dark green and leafy vegetables and fresh fruit.  Additionally, including virgin olive oil as well as omega-3 fish in the diet can keep bones healthy and strong.