The annual meeting of the American Society for Nutrition—called NUTRITION 2023—is known for its breakthrough research on ways to boost diet for better health. Here are some recent findings you can put into action with minimal effort for big benefits…

Omega-3s lower risk for hearing loss. Many research studies associate higher blood levels of omega-3 fatty acids, namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), with reduced risk for cardiovascular incidents and with maintaining the health of our brains and eyes. A new study from University of Guelph and Friedman School of Nutrition Science and Policy at Tufts University suggests that DHA also helps maintain hearing function and reduces risk for age-related hearing loss.

Background: The three major omega-3 fatty acids are alpha-linolenic acid (ALA), EPA and DHA. ALA is considered essential because it must be obtained from diet. Our bodies can convert ALA to EPA and then DHA but not very efficiently. Moreover, the enzymes involved in this conversion also are involved in the omega-6 conversion pathway. When we get proportionately more omega-6, usually linoleic acid (LA), than omega-3 in our diet, the imbalance adversely affects our bodies’ ability to convert ALA to EPA and DHA. The way to overcome this is to increase EPA and DHA intake.

Study findings: Previous cross-­sectional studies have suggested that higher omega-3 fatty acid or fatty fish consumption is linked to lower risk for hearing loss. Using available data from the UK Biobank Cohort, researchers looked at the relationship between self-reported hearing loss and blood levels of DHA in more than 100,000 people between the ages of 40 and 69.

Results: People whose blood DHA levels were the highest were 16% less likely to answer yes to the question “Do you have difficulty hearing?” versus those whose DHA levels were the lowest. Similarly, people with the highest DHA levels were 11% less likely to answer yes to the question “Do you have difficulty following conversations when there is background noise?” versus people whose DHA levels were the lowest.

What this means: There is a significant association between DHA levels and self-reported hearing loss, but this one cross-sectional population study does not provide enough evidence to definitively say that increasing DHA levels will maintain hearing or that inadequate DHA levels contribute to hearing loss. The findings add to a mounting body of evidence about the importance of omega-3 fatty acids, in particular DHA, to maintain health and help protect against aging-related declines in a variety of body functions.

What to do: You can increase your EPA/DHA levels by regularly eating fatty fish and foods enriched with added EPA+DHA, such as some brands of yogurt, milk, juice and soy drinks, or by taking supplements. When comparing supplements, read the Supplement Facts panel for EPA+DHA content on the labels. Products with 600 mg EPA and 300 mg DHA per softgel can be found at most grocery stores. If you’re a vegetarian or vegan, look for omega-3 supplements made from marine algae—these vegan oils are rich in EPA and/or DHA. Vegetarians/vegans are likely to have lower blood levels of EPA and DHA.

Michael I. McBurney, PhD, senior scientist with the Fatty Acid Research Institute, adjunct professor in the Department of Human Health and Nutritional Sciences at University of Guelph and Friedman School of Nutrition Science and Policy at Tufts University, and coauthor of the research “Association of Plasma Omega-3 Blood Levels and Prevalent Hearing Loss in the UK Biobank.”

Minerals beyond calcium that protect bone density. As estrogen declines after menopause, women become more vulnerable to osteoporosis. The focus usually is on major minerals, mostly calcium, to protect bone health. Trace minerals receive less attention, but a study from Florida State University found that certain trace minerals actually are vital for bone health.

Background: The major minerals are calcium, chloride, magnesium, phosphorus, potassium, sodium and sulfur. Trace minerals that are important for good health but are needed in much smaller amounts: Chromium, copper, fluoride, iodine, iron, manganese, molybdenum, selenium and zinc.

Study findings: This cross-­sectional study included 132 healthy postmenopausal women who had osteopenia (when the body does not make new bone as quickly as it absorbs old bone) but were otherwise healthy and were not on hormone therapy or any medication aimed at improving bone strength. DEXA scans were used to assess bone-mineral density (BMD) as well as blood tests to measure bone turnover…and exercise levels and a seven-day food-frequency questionnaire were analyzed and evaluated.

Results: There is a link between some trace minerals and better BMD in key bones—L3, the third lumbar spine ­vertebra, was positively and significantly linked with iron, copper, zinc, fluorine and manganese as well as phosphorus…L4, the fourth lumbar spine vertebra, was positively and significantly linked with copper, zinc, fluorine, manganese and phosphorus…copper on its own was significantly linked with better BMD of the ultra-distal radius (part of the forearm, a good place to assess bone loss) and of the total body…zinc and copper were positively and significantly associated with better BMD in the upper and lower neck.

What this means: Increasing intake of certain minerals may be beneficial for bone health after menopause. While these trace minerals are vital, too much can be toxic so it is best to get them through food rather than relying on supplements. Food provides a balance of many diverse nutrients, including micronutrients that may be lacking in supplements.

What to do: Focus on eating a well-rounded diet of whole foods, including nuts, seeds, fruits and vegetables as well as meat, fish, dairy and grains to provide what you need for bone health. Of special note are dried fruits because they have concentrated minerals in a single serving—prunes, which protect bone in the absence of estrogen, are at the top of the ­leaderboard. They not only help prevent bone loss but also have the potential to erase a loss after it has occurred.

Bahram H. Arjmandi, PhD, RDN, professor and director of the Center for Advanced Exercise and Nutrition Research on Aging, Department of Health, Nutrition, and Food Sciences at the College of Health and Human Sciences of Florida State University and coauthor of the study “Associations Between Major and Trace Minerals Intake and Bone Health in Postmenopausal Women with Osteopenia.”

Top prebiotic-rich foods for gut health. Prebiotics—specific types of fiber that promote good bacteria in your gut—are like fuel for a healthy microbiome. Prebiotics occur naturally in many foods, but until now, there was no database ranking the richest sources. Researchers at San José State University set out to determine the prebiotic content of the 8,690 foods listed in the 2015–2016 Food and Nutrient Database for Dietary Studies and identify those highest in total prebiotics. Also calculated was the ounce portion size that would deliver five grams of ­prebiotics—the daily minimum needed to confer a health benefit, according to the nonprofit International Scientific Association for Probiotics and Prebiotics. It turns out that getting prebiotics in your diet is easier than you might imagine.

Background: Prebiotics include galactooligosaccharides (GOS), inulin-type fructans (inulin, fructooligosaccharides or FOS, and oligofructose) and lactulose. Studies have linked higher prebiotic intake not only to improved digestive function but also steadier blood sugar and better mineral absorption.

Study findings: Here are the whole foods that have the highest prebiotic content in milligrams (mg) per gram (g) and the portion size needed to get the recommended five grams of prebiotics…

Whole FoodsPrebiotic ContentPortion Size
Dandelion greens155 mg/g to 243 mg/g0.7 to 1.1 ounces
Jerusalem artichokes210 mg/g0.8 ounce
Garlic191 mg/g to 193 mg/g0.9 ounce
Leeks123 mg/g to 128 mg/g1.4 ounces
Onions79 mg/g to 106 mg/g1.7 to 2.2 ounces
Peas and onions545 mg/g to 559 mg/g3.2 ounces
Cowpeas50 mg/g3.5 ounces
Asparagus50 mg/g3.5 ounces

What this means: Rich sources of prebiotics—onions, leeks, garlic and others in the allium group—are used in so many cuisines that it is easy to get prebiotics through diet. It’s not yet known to what extent cooking these or any foods affects their prebiotic content, but it’s reasonable to figure that you’ll need to eat a somewhat larger portion to get those five grams of prebiotics. According to this analysis, a 3.1-ounce portion of onion rings and 3.5 ounces of creamed onions were the equivalent of two ounces of raw onions.

What about prebiotic supplements? They appear to be as beneficial as food-based prebiotics, but you need to do serious label reading to be sure the supplement you choose contains the recognized prebiotics listed above. Still, it’s important to point out that foods high in prebiotics, like onions, are easy to shop for and less expensive than supplements—they’re also tastier.

Cassandra Boyd, BS, MS, candidate and researcher in the Department of Nutrition, Food Science and Packaging at San José State University and coauthor of “Determination of the Prebiotic Content of Foods in the 2015-2016 Food and Nutrient Database for Dietary Studies.”

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