Almonds are a great source of fiber, healthy fats, protein, vitamins, and minerals. Because of these nutritional properties, the health benefits of almonds have been investigated in clinical trials around the world. This includes a clinical trial underway at the Linus Pauling Institute that explores the benefits of daily almond snacking in people with metabolic syndrome.
Metabolic syndrome is a cluster of risk factors, such as high blood pressure, elevated blood lipids, and insulin resistance, that signifies an increased risk for developing much more serious conditions, including type 2 diabetes and heart disease.
Evidence suggests that people with metabolic syndrome are three times as likely to suffer a heart attack or stroke and twice as likely to die from coronary heart disease compared to people without this condition.
Metabolic syndrome is more common than most people think. It is estimated that over 40 percent of American adults meet the diagnostic criteria set for metabolic syndrome (see page 5 for these criteria). Although it is more prevalent among older adults than younger adults, the incidence among young people is rising.
While poor diet and inactivity contribute to the development of metabolic syndrome, recent scientific advances suggest that gut health and chronic inflammation may also play a role.
What is Metabolic Syndrome?
Metabolic syndrome is a cluster of related conditions. It is diagnosed by a health care professional using diagnostic tests, a physical exam, and family history. According to the criteria set by the American Heart Association (AHA) and the National Heart, Blood, and Lung Institute (NHBLI), a person is considered to have metabolic syndrome if they have three or more of these clinical indicators:
- High fasting blood glucose 100 mg/dL or higher* or a diagnosis of type 2 diabetes
- High blood pressure 130/85 mm Hg or higher*
- Low HDL cholesterol Below 40 mg/dL for men* Below 50 mg/dL for women*
- High blood triglycerides 150 mg/dL or higher*
- Large waist circumference More than 40 inches for men More than 35 inches for women
*The use of medication to control high blood pressure, glucose, triglycerides, or cholesterol also qualifies as an indicator for metabolic syndrome according to the AHA/NHBLI
Why Almonds?
Put simply, nuts are part of a healthy diet. Many people avoid nuts due to their fat content and caloric density, thinking that eating them would contribute to weight gain. However, the research on beneficial compounds found in nuts, including unsaturated fats, protein, fiber, and other plant compounds, supports several roles in regulating body weight and maintaining health. Because almonds contain potent antioxidant and anti-inflammatory compounds, they may benefit people with metabolic syndrome. A team of investigators at the Linus Pauling Institute, including Drs. Laura Beaver, Emily Ho, and Maret Traber, wanted to know if snacking on two ounces of almonds every day for 12 weeks could help.
“There is good reason to believe that eating almonds would benefit people with metabolic syndrome,” explains Traber. “Almonds are an excellent source of vitamin E — a nutrient of concern in the United States because many people don’t even come close to meeting their dietary requirements.”
To test the hypothesis that the nutrients in almonds would benefit people with metabolic syndrome, the LPI research team designed a 12-week study for participants ages 35-60 who met the criteria for the condition.
Enrolled participants were randomly assigned to eat almonds or non-whole grain crackers as daily snacks. Crackers served as a control food that had equal caloric value (about 320 calories) but lacked many of the beneficial compounds contained in almonds. Participants were asked to provide blood, stool, and urine samples at the start of the study, then again after 4 and 12 weeks of eating the study snacks for comparison.
Vitamin E is also known as alpha-tocopherol. There is a family of related molecules (beta-, delta-, and gamma-tocopherols) found in foods we eat.
While these other tocopherols share some of the same properties as alpha-tocopherol, their health benefits are not equivalent to vitamin E nor are they essential for life.
For more information on vitamin E, visit the Micronutrient Information Center.
Demonstrable Benefits
To start their analysis, the research team assessed the impact of daily almond snacking on vitamin E status. Blood samples obtained from participants in the almond group showed a marked increase in vitamin E (alpha-tocopherol) concentrations at 4 and 12 weeks. This was significant compared to the samples taken before the study began and when compared to blood samples obtained from the cracker group.
Reflecting the increased vitamin E consumption, a vitamin E metabolite known as alpha-CEHC was higher in urine samples obtained from the almond group at four weeks compared to samples provided by the cracker group. Urinary alpha-CEHC has been used in previous clinical studies at the Institute and is thought to be a good indicator of an increase in vitamin E status.
While changes in vitamin E status were expected with the consumption of almonds, the study team also saw changes in other important health biomarkers. For example, daily almond consumption led to a decline in total cholesterol and LDL cholesterol (considered the “bad” cholesterol) after 12 weeks. These changes were modest — 10 mg/dL or less on average — yet statistically significant compared to the cracker group.
No changes to body weight have been observed in research participants who have completed the study so far. However, in the almond group, there was a decline in waist circumference, whereas participants eating crackers experienced no overall change in the size of their waist. These differences were small (3/4 of an inch) but statistically significant at the four-week check-in, with indications the differences persisted throughout the 12-week study period.
A Gut Health Helper?
There are many reasons to believe that almonds benefit gut health. Aside from vitamin E, almonds have polyunsaturated and monounsaturated fats, fiber, biotin, copper, potassium, and magnesium. They also contain plant compounds known as polyphenols that have antioxidant and anti-inflammatory properties.
While a full assessment of the nutritional impact of almonds is ongoing, the changes in cholesterol levels mentioned above suggest that a metabolic shift occurred in people who snacked on almonds daily. Although there are many possible explanations, recent research suggests that gut health plays a role in this type of metabolic change.
“Now we are turning our attention to assessing gut health,” explains Beaver. “And we started by looking for markers of inflammation in the intestinal wall as a measure of the anti-inflammatory properties of almonds.”
The preliminary analyses show that after four weeks, participants consuming almonds had lower levels of myeloperoxidase in their stool samples compared to the samples from the cracker group, indicating the almond consumers had a lower number of inflammatory cells in their intestinal tracts.
At the time of this writing, the study team is conducting a more detailed analysis of other gut health markers found in participants’ samples.
The Future of Almonds for Metabolic Syndrome
It is important to note that the data presented above are preliminary and based on the results from a subgroup of research participants who completed the study. The full report will provide a comprehensive view of all study participants, and we encourage you to stay tuned for more updates on this study in a future LPI Research Newsletter.
Thus far, the positive changes observed in blood lipids and gut inflammation are encouraging signs for people with metabolic syndrome. As more results emerge from the analysis of inflammatory markers, we may better understand how almonds promote these benefits.
Meanwhile, other studies have linked nut consumption with a decreased risk of developing metabolic syndrome in adults and teens. Unless there is concern about nut allergies, it is easy to recommend a handful or two of almonds as a healthy snack for people concerned about their metabolic disease risk.
References
Beaver et al. Curr Dev Nutr. 8 (2024) doi: 10.1016/j.cdnut.2024.102235
Julibert et al. J Nutr. 150 (2020) doi: 10.1093/jn/nxaa289
Jung et al. Eur J Nutr. 57 (2017) doi: 10.1007/s00394-017-1480-5
