• Salmon contains unique compounds that are associated with improved cardiometabolic health indicators, such as lower cholesterol, a new nutrimetabolomic study shows.
  • The study explored the health benefits of salmon in the context of a Mediterranean diet, known for focusing on healthy oils and fats.
  • As part of the study, participants ate two servings of salmon a week, for two five-week periods.
  • Nutrimetabolomics is a cutting-edge means of investigating food nutrients, however, not everyone is sold on it.

Salmon has long been considered a healthy food, especially when eaten in diets that forgo excessive salts, processed foods, and unhealthy oils. Now, a new study examines salmon from a metabolomic perspective, and describes, on a molecular level, the health benefits of salmon.

The study found that salmon contains 508 food-specific compounds, or FSCs, including 237 metabolites that are unique to salmon.

When it is eaten as part of a Mediterranean diet, salmon delivers to the body at least 48 of these compounds, along with 30 metabolites — substances produced during digestion or other body chemical processes. Four of these metabolites are associated with significant improvements in cardiometabolic health indicators, or CHI.

A Mediterranean diet has an emphasis on healthy oils for fat, such as olive oil. It favors plant-based sources of nutrition, including vegetables, fruits, and whole grains. Protein is supplied by sources such as poultry, fish, and vegetable proteins such as beans, as well as yogurt and cheese.

Compared to the standard Western diet, the Mediterranean diet largely avoids red meats, sugars, excessive salt, and unhealthy fats.

For the new study, researchers performed a secondary analysis of an existing random controlled feeding trial involving 41 participants who ate a Mediterranean diet for two five-week periods, with a four-week break in between. Individuals ate two servings of salmon per week during the diet intervention periods.

Participants were recruited in the Greater Lafayette, IN area, and none were already eating a Mediterranean diet. Their ages ranged from 30 to 69. They had obesity or overweight, although none had any active metabolic conditions — such as type 2 diabetes — or acute illnesses.

The researchers recorded their CHIs, and collected the participants’ blood plasma samples before and after the study.

The researchers used chromatography-mass spectrometry-based metabolomics to analyze participants’ plasma, as well as salmon and 99 other foods consumed on a Mediterranean diet. If the researchers found a compound in all instances of salmon but not in other diet foods, they characterized it as a salmon FSC.

They then identified metabolites associated with the salmon FSCs via machine learning.

The researchers found increases in two annotated salmon FSCs and two metabolites were associated with greater cardiometabolic health, evident by CHIs in the participants’ blood plasma at the end of the trial. These cardiometabolic benefits included reductions in total cholesterol, low-density lipoprotein cholesterol, triglycerides, and apolipoprotein B, which is an indicator of heart disease.

The study is published in The Journal of Nutrition.

Michelle Routhenstein, cardiology dietician and preventive cardiology nutritionist at EntirelyNourished.com, who was not involved in the study, said the study and its “findings suggest that this approach could help find important compounds in foods that might be helpful for health. But more research is needed to confirm this.”

“Metabolomic studies have highlighted the diverse array of bioactive compounds present in olive oil, such as phenolic compounds and oleic acid, which are associated with anti-inflammatory, antioxidant, and cardiovascular health benefits,” she explained.

The same sort of research, said Routhenstein, has found barley, quinoa, and bulgur to be rich sources of phytochemicals. These include phenolic acids, flavonoids, lignans, and phytosterols, compounds possessing antioxidant properties that help to combat oxidative stress and inflammation in the body.

Conner Middelmann, a nutritionist specializing in the Mediterranean diet who was likewise not involved in the study, expressed some doubts, however, saying, “research that reduces food to infinitesimally tiny molecules that may or may not have some sort of effect on health isn’t highly relevant to my work.”

For her patients, Middelmann continued: “I’m just wondering: will the metabolites of a particular food have the same effect on a wide range of people with different biochemistries and histories? If not, how relevant is this sort of research to people’s day-to-day lives?”

Middelmann cited, among other things, variations in people’s individual biochemistry, genetics, age, sex, medical conditions, and treatments, as well as psycho-socioeconomic and environmental factors that affect biochemistry.

“If anything, I try to help my clients move away from this hyper-granular approach to food as medicine where they obsess about getting compound ‘X’ from one food and avoiding compound ‘Y’ from another,” she said.

“[H]ealth is about so much more than food, and the idea that if we eat ‘perfectly, we’ll be perfectly healthy’ is an illusion,” said Middelmann.

Middelmann noted that several of her clients are now recovering from hyper-focusing on ‘good’ versus ‘bad’ foods.

The investigation of salmon in a Mediterranean diet demonstrates the flexibility of the diet, since salmon are native to the coasts of the North Atlantic and Pacific Oceans, far from the Mediterranean Sea. They are, however, grown in aquaculture in other locations.

Routhenstein suggested the reason that the non-Mediterranean fish nonetheless qualified as a sensible candidate for the study.

“The diet includes a variety of other fish that have a similar nutritional profile and are associated with numerous health benefits. For instance, sardines and trout are rich in omega-3 fatty acids, particularly EPA and DHA, which are beneficial for heart health. They are also a good source of protein, vitamin D, and calcium,” she noted.

To Middelmann, who specializes in the Mediterranean diet, it “is about joyfully eating lots of different types of fish and seafood, but also a wide variety of everything else — veggies, legumes, whole grains, fruits, nuts, seeds, olives, eggs, yogurt, cheese, etc. — because it tastes good, makes you feel good, and is nutritious.”

“I know that doesn’t sound very scientific, but it seems to work pretty well for the folks living in the Mediterranean region,” she added.

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