A pair of recent studies linking poor diets to an increased risk of death and other alarming consequences like blindness underscore the critical importance of quality nutrition education in health care.
The news that soda and sausages are not exactly fountains of youth won't surprise readers of Holistic Primary Care. But these new studies are important for their sheer size, and for the astonishing scope of morbidity that they describe.
Soft Drinks Raise Mortality Risk
In the largest study of its kind to date, researchers from several European medical centers examined soft drink consumption and related mortality outcomes in an international cohort of more than 450,000 people. They found that individuals who regularly consume soft drinks––including both sugar- and artificially-sweetened varieties––had a higher risk of all-cause mortality than non-drinkers.
Investigators analyzed data from ten countries (Denmark, France, Germany, Greece, Italy, the Netherlands, Norway, Spain, Sweden, and the UK), as part of the ongoing European Prospective Investigation into Cancer and Nutrition (EPIC) trial. Their findings, published in September 2019 in JAMA Internal Medicine, reflect those of previous smaller studies showing strong associations between sugary beverages and heightened disease risk (Mullee, A. et al. JAMA Intern Med. 2019).
The EPIC database included 451,743 individuals recruited from January 1992 through December 2000. Participants, who averaged 50.8 years of age, recorded the number of glasses of soft drinks they consumed per month, per week, or per day, with one glass equalling approximately 250 mL. Those with reported histories of cancer, heart disease, stroke, or diabetes at enrollment were excluded.
Researchers assessed participants’ dietary intake data and looked at health outcomes associated with total soft drink consumption. Most countries participating in EPIC ask subjects to report on the specific types of beverages they drink; in those cases, investigators subdivided overall intake into sugar-sweetened versus artificially sweetened soft drink consumption.
During a mean follow up period of 16.4 years (ranging from 11.1 years in Greece to 19.2 in France), there were 41,693 deaths among the EPIC participants. Investigators identified higher all-cause mortality in individuals who consumed two or more glasses of soft drinks daily, as compared to those drinking less than one glass per month (HR, 1.17; 95% CI, 1.11-1.22; P < .001).
Mortality risk was also elevated in participants who drank two glasses or more per day of sugar-sweetened soft drinks specifically (HR, 1.08; 95% CI, 1.01-1.16; P = .004) and artificially sweetened soft drinks only (HR, 1.26; 95% CI, 1.16-1.35; P < .001).
Small Glasses, Big Risks
Drinking even a small amount of soda each day appeared to have negative health consequences. All cause mortality begins to increase at consumption levels over 125 mL per day for artificially sweetened soft drinks, and over 225 mL per day of sugar-sweetened soft drinks––that’s just half a cup and a bit less than one cup daily, respectively. For reference, a single 12-ounce can of soda contains about 355 mL.
The JAMA paper also documented cause-specific mortality from a host of different health conditions. There were strong correlations between total and artificially sweetened soft drink consumption––but not sugar-sweetened soft drinks––and risk of death from ccerebrovascular disease and ischemic heart disease.
Circulatory disease mortality risk was highest in participants consuming two or more glasses per day (vs. <1 glass per month) of total soft drinks (HR, 1.27; 95% CI, 1.14-1.40; P < .001) and artificially sweetened soft drinks (HR, 1.52; 95% CI, 1.30-1.78; P < .001).
The authors speculate that artificial sweeteners induce glucose intolerance, which in turn increases CVD risk. They call for additional research into the possible adverse effects of long-term consumption of aspartame, acesulfame potassium, and other artificial sweeteners.
While sugar-sweetened drinks alone did not seem to raise heart disease risk, they were implicated digestive disease mortality. People who drank one or more glasses of sugar-sweetened drinks per day had a 59% greater risk of dying from a digestive disease than those who dran less than one glass per month (HR, 1.59; 95% CI, 1.24-2.05; P < .001).
“Hyperglycemia resulting from consumption of sugar-sweetened soft drinks may alter gut-barrier function and increase the risk of enteric infection,” the authors suggest, adding that fructose--a sugar used to sweeten many soft drinks and countless other foods-- “promotes liver lipogenesis, which can lead to nonalcoholic fatty liver disease and lower insulin sensitivity.”
Lastly, the investigators looked at cancer and neurodegenerative disease mortality. While there was no connection between soft drink consumption and overall cancer mortality, there was a clear association between soft drink intake and colorectal cancer death (≥1 glass per day vs <1 glass per month; HR, 1.25; 95% CI, 1.07-1.47; P = .004).
They also found that total soft drink consumption raised the risk of death from Parkinson’s disease (≥1 glass per day vs <1 glass per month; HR, 1.59; 95% CI, 1.07-2.36; P = .02). The magnitude of this correlation was similar for artificially sweetened versus sugar-sweetened beverages. Soft drinks were not associated with Alzheimer’s disease mortality in the EPIC data.
A Taxing Question
Previous large-scale studies conducted primarily in the US suggests that regular soda drinkers are prone to obesity, type 2 diabetes, and heart disease.
Earlier this year, a study published in the American Heart Association journal Circulation linked long-term sugar-sweetened beverage consumption with increased risk of cardiovascular disease death (Malik, V. et al. Circ. 2019; 139(18): 2113-2125).
The authors stress that sugar-sweetened beverages are the single largest source of added sugar in the US diet. "Our results provide further support for recommendations and policies to limit intake of [sugar-sweetened beverages] and to consume [artificially sweetened beverages] in moderation to improve overall health and longevity."
"Policies and recommendations should continue to call for reductions and limits on [sugar-sweetened beverage] intake" and "should also address alternative beverage options with an emphasis on water,” they urge.
People often look to replace sugar with low- or no-calorie artificial sweeteners, thinking that they are doing something "healthy." Food and beverage marketers push that message. But in recent years, the the long-term safety of artificial sweetener consumption has been called into question. The EPIC data make it clear that artificial sweeteners are no boon to health.
Many communities across the country are implementing public health measures to reduce soda consumption and raise awareness about the dangers of sugar. Several cities and states have implemented so-called soda taxes on beverages that contain added sugars, expecting higher prices to discourage consumers. Maine led the way in 1991 with a 5.5% state-wide soft drink sales tax. Ohio followed in 2003, with a similar 5% tarriff.
Studies of the impact of soda taxes are turning up conflicting results. A 2015 study of retail scanner data by University of Massachusetts researchers, indicates that these taxes have largely failed to deliver the desired deterrent effect. There were no statistically significant downturns in sales of major soda brands in either state, compared to surrounding states (Colantuoni F, Rojas C. Contemporary Economic Policy. 2015).
Another study looking at the net effect of Berkeley, California's 2015 city-wide soda tax claims that soft drink consumption decreased by 21% in Berkeley following enactment of the new law. However, soda consumption increased by 4% in the comparison cities of Oakland and San Francisco. The finding is based on oral interviews with 990 participants, not actual cash register data, so the veracity of the conclusions is questionable.
We expect that a consistent junk food diet will lead to diabetes, obesity, and heart disease. But blindness? That comes as a surprise.
Researchers at the University of Bristol, UK, published a case study detailing the health history of a 14-year old boy who reportedly developed blindness as a result of his “fussy eating.”
From a young age, the teen’s diet consisted almost entirely of nutrient-poor foods with textures he found palatable, including French fries, potato chips, white bread, processed ham slices, and sausage. He complained of general tiredness and was initially diagnosed with macrocytic anemia and low vitamin B12, but was otherwise healthy and took no medications.
At first, his physician offered dietary advice and treated the boy with vitamin B12 injections. A year later, on a repeat visit, the boy described worrisome vision problems and hearing loss. His vision continued to worsen progressively until he developed permanent visual impairment by age 17.
He was ultimately diagnosed with nutritional optic neuropathy, a condition marked by optic nerve dysfunction typically resulting from malnutrition. It’s reversible when identified early, but can cause lasting damage and blindness if untreated.
“I think the issue was that the link between the patient's B12 deficiency and diet had not been fully appreciated in the past when he initially presented to his GP with tiredness and anemia,” the study's lead author Denize Atan, PhD, told Holistic Primary Care.
Atan is a senior lecturer in ophthalmology at Bristol Medical School and clinical lead for Neuro-ophthalmology at Bristol Eye Hospital.
The patient “did not have a malabsorption syndrome, so his B12 deficiency was entirely dietary,” she explained. “Earlier intervention at that time to improve his diet could have prevented his later problems.”
Collecting Dietary Histories
Atan and her colleagues hope that their case report will “alert clinicians of the visual complications of a diet restricted to junk food.” They urge health practitioners to consider the possibility of nutritional optic neuropathy in any patients with unexplained vision symptoms and poor diet, regardless of other typical markers of nutritional status (Harrison, R. et al. Ann Intern Med. 2019; Epub ahead of print. doi: 10.7326/L19-0361).
“A dietary history is relatively easy and should be part of taking [a patient’s] clinical history,” Atan recommended. “A nutritional cause should be considered in the differential diagnosis of anyone with progressive optic neuropathy, irrespective of BMI,” she added.
Her team’s report underscores the importance of nutrition education in medicine. Clinicians are uniquely poised to teach their patients about the risks of a diet high in processed food products and low in nutrient-dense fresh, whole foods.
“In my opinion, the argument is much like counseling patients about their smoking and alcohol consumption,” Atan suggested. “Most doctors ask about smoking and alcohol history when they are taking a patient's clinical history, even if smoking or alcohol intake are not necessarily related to the problem the patient is complaining of. If someone then says they are smoking or drinking outside recommended guidelines, then you have an opportunity to advise them to change their lifestyle.”
By extension, she proposed that the same could be true of asking about a patient's diet. "If the diet is poor, there is the opportunity to counsel the patient even if diet may not be causing the problem they are seeing you for, as in future, they will run into problems.”
She cautioned that while a breadth of diet and health information is publicly available online, “not all of it is very informed or evidence-based and is more reflective of the opinion of the writer of the article.” Health care practitioners can help identify and direct patients towards reputable resources and nutrition professionals.