Medical Compass: Diet quality and its impact on life expectancy

Medical Compass: Diet quality and its impact on life expectancy

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Diet may also affect quality of life as we age

By David Dunaief, M.D.

Dr. David Dunaief

Here’s a stunning statistic: 60 percent of American adults have a chronic disease, with 40 percent of adults having more than one (1). This is likely a factor in the slowing pace of life expectancy increases in the U.S., which have plateaued in the past decade at around 78.8 years old (2).

Most chronic diseases, including common killers, such as heart disease, stroke, diabetes and some cancers, can potentially be prevented, modified and even reversed with a focus on nutrients, according to the Centers for Disease Control and Prevention (CDC). 

The truth is that many Americans are malnourished. How could that be, when so many are overweight or obese? We are not a developing country, where access to healthy food is more challenging. Still, malnourishment is common at all levels of socioeconomic class. The definition of malnourished is insufficient nutrition, which in the U.S. results from low levels of much-needed nutrients.

I regularly test patients’ carotenoid levels. Carotenoids are nutrients that are incredibly important for tissue and organ health. They are measurable and give the practitioner a sense of whether the patient may lack potentially disease-fighting nutrients. Testing is often covered if the patient is diagnosed with moderate malnutrition. Because the standard American diet is very low in nutrients, classifying a patient with moderate malnutrition can be appropriate. A high nutrient intake approach can rectify the situation and increase, among others, carotenoid levels.

High nutrient intake

A high nutrient intake is an approach that focuses on micronutrients, which literally means small nutrients, including antioxidants and phytochemicals -— plant nutrients. Micronutrients are bioactive compounds found mostly in foods and some supplements. While fiber is not considered a micronutrient, it also has significant disease modifying effects. Micronutrients interact with each other in synergistic ways, meaning the sum is greater than the parts. Diets that are plant-rich raise the levels of micronutrients considerably in patients.

In a 2017 study that included 73,700 men and women who were participants in the Nurses’ Health Study and the Health Professionals Follow-up Study, participants’ diets were rated over a 12-year period using three established dietary scores: the Alternate Healthy Eating Index–2010 score, the Alternate Mediterranean Diet score, and the Dietary Approaches to Stop Hypertension (DASH) diet score (3).

A 20 percent increase in diet scores (indicating an improved quality of diet) was significantly associated with a reduction in total mortality of 8 to 17 percent, depending on whether two or three scoring methods were used. Participants who maintained a high-quality diet over a 12-year period reduced their risk of death by 9 to 14 percent than participants with consistently low diet scores over time. By contrast, worsening diet quality over 12 years was associated with an increase in mortality of 6 to 12 percent. Not surprisingly, longer periods of healthy eating had a greater effect than shorter periods.

This study reinforces the findings of the Greek EPIC trial, a large prospective (forward-looking) cohort study, where the Mediterranean-type diet decreased mortality significantly – the better the compliance, the greater the effect (4). The most powerful dietary components were the fruits, vegetables, nuts, olive oil, legumes and moderate alcohol intake. Low consumption of meat also contributed to the beneficial effects. Dairy and cereals had a neutral or minimal effect.

Quality of life

Quality of life is also important, though. Let’s examine some studies that examine the impact of diet on diseases that may reduce our quality of life as we age.

A study showed olive oil reduces the risk of stroke by 41 percent (5). The authors attribute this effect at least partially to oleic acid, a bioactive compound found in olive oil. While olive oil is important, I recommend limiting olive oil to one tablespoon a day. There are 120 calories per tablespoon of olive oil, all of them fat. If you eat too much, even of good fat, it defeats the purpose. The authors commented that the Mediterranean-type diet had only recently been used in trials with neurologic diseases and results suggest benefits in several disorders, such as Alzheimer’s. 

In a case-control (compare those with and without disease) study, high intake of antioxidants from food is associated with a significant decrease in the risk of early Age-related Macular Degeneration (AMD), even when participants had a genetic predisposition for the disease (6). AMD is the leading cause of blindness in those 55 years or older. There were 2,167 people enrolled in the study with several different genetic variations that made them high risk for AMD. Those with a highest nutrient intake, including B-carotene, zinc, lutein, zeaxanthin, EPA and DHA- substances found in fish, had an inverse relationship with risk of early AMD. Nutrients, thus, may play a role in modifying gene expression. 

Though many Americans are malnourished, nutrients that are effective and available can alter this predicament. Hopefully, with a focus on a high nutrient intake, we can re-ignite the pace of increased life expectancy and, on an individual level, improve our quality of life.

References:

(1) cdc.gov. (2) macrotrends.net. (3) N Engl J Med 2017; 377:143-153. (4) BMJ. 2009;338:b2337. (5) Neurology June 15, 2011. (6) Arch Ophthalmol. 2011;129(6):758-766.

Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, visit www.medicalcompassmd.com.       

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