Can Nuts Heal the Body?

Eating nuts is a great way to fuel your body with essential nutrients because they are often packed with vitamins and minerals the body needs. However, no two nuts are alike, so choosing which one to eat and why is a great way to incorporate nuts into your life while tailoring them to what your body needs.

What “healing” actually means

People have long hailed nuts as healthy superfoods that can make serious changes in the body. And while nuts are a healthy option to include in a whole food diet, anyone who tells you they can ‘heal’ you is sadly mistaken.

Nutrients in nuts provide the framework for an overall healthy body and mind, but they cannot heal anything, from gut imbalances to chronic disease. They are simply nutritional tools that can support overall health.

For example, many nuts contain healthy fats that can help lower cholesterol and reduce the risk of cardiovascular disease. However, they cannot treat heart disease or cholesterol. They are merely a dietary tool you can use on the road to good heart health alongside other means, such as exercise.

Walnuts

Walnuts are often highlighted for their benefits to cognitive function and gut and heart health, but research on heart health is most prominent. A narrative review of epidemiologic studies pooled data from 173,295 participants found that eating 42.5-85 g of walnuts five times a week was associated with a 40% lower risk of coronary heart disease, LDL cholesterol 9 to 16% lower, and lower diastolic blood pressure. Those are observational findings, so they show an association rather than proof that the walnuts caused the difference.

The research showed that the compounds found in walnuts, including polyunsaturated fats such as alpha-linolenic (ALA) and linoleic (LA) acids, work together to promote a healthier heart.

Another narrative review examined several studies and found that people who eat walnuts daily over the long term may also see reductions in inflammatory biomarkers, such as C-reactive protein. Almonds also saw a modest reduction, but not as significant as walnuts.

Neither review flags a medical reason to avoid walnuts. The randomized, controlled study used a 2-ounce daily dose and excluded people with conditions like diabetes, sleep apnea and established cardiovascular disease from enrolling, which is a rule about who the researchers studied rather than a warning about who can eat walnuts.

If anything the opposite holds: the American Diabetes Association lists walnuts among the foods it recommends for people with diabetes. The real limits are a tree nut allergy and the calories, since walnuts run about 185 per ounce.

Almonds

Almonds are another option for people looking to reduce their risk of cardiovascular disease because they can lower bad cholesterol levels and improve endothelial function, or blood flow, in the body.

In a comprehensive review of several clinical studies, from randomized trials to meta-analyses, researchers found that daily consumption of almonds at a dose of 28 to 84 g reduces bad cholesterol levels by 3 to 10%, with those eating higher amounts seeing the greatest benefits, due to their monounsaturated and polyunsaturated fat content. The dietary fiber and plant compounds in almonds also help by blocking the intestine’s ability to absorb dietary cholesterol.

The antioxidant content has also been shown to reduce oxidation of LDL cholesterol, which researchers track because oxidized LDL is involved in how plaque forms. That is a biomarker result rather than evidence that almonds prevent plaque, which no trial has tested.

While almonds can be beneficial, they may not be for everyone. A small study of seven participants found that eating 150g of almonds increases oxalates in the urine, which could increase the risk of kidney stone development.

Pistachios

Pistachios are a great option if you’re looking to improve cardiometabolic health, which is the health of your metabolic system as well as your cardiovascular system. One systematic review and meta-analysis of randomized controlled clinical trials examined the effects of eating pistachios in 506 adults and found that eating 1.5 to 3 ounces of pistachios per day can improve overall cardiometabolic markers.

The pooled changes were modest in absolute terms: fasting blood sugar down 3.73 mg/dL, fasting insulin down 2.43 µIU/mL, and systolic blood pressure down 3.10 mmHg. The researchers attribute these effects to pistachios’ nutritional profile, with essential amino acids and dietary fiber affecting blood sugar and insulin, and potassium, magnesium, and healthy fats helping lower blood pressure and cholesterol.

While the literature doesn’t mention any caveats, other research suggests that processing pistachios could make these benefits less pronounced. For example, roasted pistachios high in salt can increase salt intake, which some people should monitor, and reduce the antioxidants found in these nuts.

Peanuts

Peanuts are popular, and when it comes to health, they can benefit blood sugar management, especially insulin resistance. Insulin resistance occurs when the body’s cells don’t respond to insulin as well as they should and can be a risk factor for developing diabetes.

One systematic review and meta-analysis of 40 randomized controlled trials with 2,832 participants found that consuming between 28 and 84 g per day, depending on the study, reduced fasting insulin and improved insulin sensitivity.

Two things are worth knowing about that analysis. It pooled tree nuts and peanuts together, with only four of the forty trials testing peanuts, and the effects were small, with fasting insulin down 0.40 µIU/mL and no significant change in fasting blood sugar or HbA1c. The usual explanations — that the fats improve how insulin receptors work, or that the fiber slows how quickly food leaves the stomach — are plausible mechanisms rather than things these trials measured.

Blood sugar management also improved because of a high concentration of antioxidants and the mineral magnesium, which improved the function of cellular insulin signaling that acts as a doorway to the cells, telling them to open up to let sugar in to be used for energy.

Hazelnuts

Research on hazelnuts has found several benefits to eating them, including a reduced risk of major cardiovascular events, which include heart attack and stroke. One multi-center, parallel-group randomized controlled trial of 7,447 participants looked at mixed nuts, including hazelnuts, and found that a Mediterranean diet supplemented with mixed nuts — 7.5 g of hazelnuts alongside 15 g of walnuts and 7.5 g of almonds daily — carried a 28% lower risk of a major cardiovascular event than low-fat dietary advice. For stroke, that reduction was 46%. The comparison was between two whole diets rather than between nuts and no nuts, and the absolute event rates were 3.4% against 4.4%.

The results showed that monounsaturated fatty acids, antioxidants such as vitamin E, dietary fiber, and the amino acid L-arginine are behind the health benefits. It is important to note, however, that this study looked at the combined consumption of hazelnuts with other nuts, so those benefits are associated with more than one nut, not hazelnuts alone, and research is more limited when looking at these nuts on their own.

That said, a smaller, single-group, double-control study looked at 21 people with high cholesterol and examined how hazelnuts, specifically, support cardiovascular health. It found that blood flow improved by 56.6%, and cholesterol decreased by 6.17% to 7.8%. Both high cholesterol and impaired blood flow can be risk factors for major cardiovascular events.

People with nut allergies should avoid all the nuts on this list, but those with birch pollen allergies should be especially wary of hazelnuts because a specific hazelnut protein can be mistaken for birch pollen and trigger an allergic reaction.

Brazil nuts

While Brazil nuts are healthy, they are exceptionally high in selenium, a mineral the body uses to help manage thyroid hormones and build antioxidants and DNA.

That said, the body can only take so much selenium in before it becomes a problem. Selenium toxicity can occur when people eat more than 400 mcg per day and lead to symptoms such as muscle and joint pains, headache, foul breath, fatigue and weakness, and hair loss. While 400 mcg is the tolerable upper limit, the recommended daily intake for adults is 55 mcg a day, rising to 60 mcg in pregnancy and 70 while breastfeeding.

One Brazil nut can contain as much as 91 mcg of selenium, which is above the daily recommendation but well under the 400 mcg upper limit. Passing the recommendation now and then is not the problem. Selenium toxicity comes from staying above the upper limit over time, which is why a daily handful is the thing to avoid rather than the occasional nut.

That said, a randomized clinical study of 10 healthy participants tested a single serving of 0, 5, 20 or 50 g of Brazil nuts and found LDL cholesterol lower nine hours after the 20 g and 50 g servings. It did not test eating four nuts every day, and 20 to 50 g daily would push selenium toward the limit described above. Since many other nuts can lower cholesterol, relying on Brazil nuts may not be the best option unless you’re sure you won’t exceed the daily selenium limit.

Pecans

In a pooled analysis of 10 randomized trials, pecan intake reduced total cholesterol by a mean 8.49 mg/dL. In 7 studies, pecan consumption reduced LDL cholesterol by 7.42 mg/dL (regardless of dose and duration), triglycerides by 14.06 mg/dL (the triglyceride drop only in studies running longer than 4 weeks), and showed little sign of any effect on HDL cholesterol. There was little sign of an effect on fasting blood sugar, insulin, insulin resistance, waist size, body weight or blood pressure.

The largest of these trials ran 12 weeks and put 138 people with at least one marker of metabolic syndrome on 57 grams of pecans a day in place of their usual snacks. What it was built to measure was the flexibility of their blood vessels. The people eating pecans saw bigger reductions than those who carried on as before: total cholesterol down 8.1 mg/dL, LDL down 7.2 mg/dL, non-HDL cholesterol down 9.5 mg/dL and triglycerides down 16.4 mg/dL, with diet quality up 9.4 points.

On that measure it found nothing. Artery stiffness and blood pressure did not move either. And weight edged up in the pecan group by about 0.7 kg.

Macadamias

One trial fed macadamias to 35 adults carrying excess weight around the middle. For 8 weeks the adults consumed about 15 percent of their calories from macadamias. For another 8 weeks they ate their usual diet with no nuts. BMI, waist circumference, body fat percentage and body weight didn’t budge during the study. Macadamias are the fattiest nut on this list, and eating them daily for two months did not make anyone gain weight or body fat.

The problem is that the study showed no difference in insulin sensitivity in the group during the eight weeks they ate macadamia nuts. And nothing changed in their blood sugar, either. (It didn’t go down, but it didn’t go up.) Their total cholesterol did drop, but only 2.1%, which won’t make much difference in the long run. Their LDL did decrease 4%, which is a bit better, but still not much. When it comes down to it, neither the total cholesterol or LDL drops were big enough to be labeled as “statistically reliable.” 

Cashews

Two well-run trials on cashews reached opposite conclusions, and the disagreement is the useful part. In the first, 51 men and women with high LDL cholesterol consumed 28 to 64 grams of cashews per day for 28 days and their cardiometabolic risk factors were compared to a calorie matched control who consumed potato chips. Total cholesterol decreased 3.9%, LDL cholesterol decreased 4.8%, non-HDL cholesterol decreased 5.3%. There was no change in HDL cholesterol and triglycerides.

A second, equally well-run trial had 42 adults eat 42 grams of cashews daily for four weeks on a calorie-matched diet, and found no change in cholesterol, blood pressure, blood sugar, clotting, or inflammation and no change in body weight. The one exception being PCSK9 decreased significantly even though LDL didn’t change. What separates the two is the swap, not the cashews. In the first trial every meal was provided, and trading potato chips for cashews moved the numbers. The second looked at what happens when people whose diet and weight were already steady simply added cashews, and nothing changed.

Three you’ll see on every list that the research hasn’t caught up to yet

Pine nuts

The appetite claim comes from Korean pine nut oil, not from pine nuts. Given two grams of it thirty minutes before an all-you-can-eat buffet lunch, 42 overweight women ate 9% less than those given olive oil. A commercial oil preparation taken before a test meal is not a bag of pine nuts from the store. Also, Korean pine nut oil comes in two types, free fatty acids (FFA) and triglycerides (TG), and it’s the FFA type that works (while the TG type did nothing at 2, 4 or 6 grams).

Bags of pine nuts contain fats in the form of TGs. Even on the form that worked, the women did not report feeling less hungry, and the mix of carbohydrate, fat and protein they chose did not change. The effect is real. It is an effect of an oil.

Chestnuts

Chestnuts are very different from most nuts. They are the only one on this list made up mostly of carbohydrate, 44.2 grams per 100 grams against a macadamia’s 13.8, which puts them closer to a starchy vegetable than to a nut. It is also why they are the one on this list people roast and eat hot. Chestnuts also have far fewer calories than other nuts, 196 per 100 grams, a little over a quarter of the calories in a macadamia (718 per 100 grams).

The fat is the starker gap. Chestnuts carry 1.25 g per 100 grams, about one sixtieth of a macadamia’s 75.8 g. Almonds come in at 49.9 g of fat and 579 calories, pecans at 72 g and 691 calories. Recent lab-based research suggests the fiber in chestnuts, as well as certain extracts, may have prebiotic activity, an effect yet to be studied in humans.

Tiger nuts

Tiger nuts are not nuts. They are tubers, which grow underground like potatoes. What holds up about them is the fiber they contain. They are marketed hard for digestive health, and there are no published studies in people testing whether they do it. The studies behind the prebiotic claim fed the fiber to bacteria in a dish, or simply measured how much fiber was there. No trial in people does not mean they do nothing. It means nobody has checked.

What a portion looks like

Portions of nuts tend to range from one to three ounces. Since nut sizes vary, the amount of nuts could range significantly. For almonds, one to three ounces could be anywhere between 23 and 69 nuts, whereas peanuts would be anywhere from 28 to 84 nuts. Nuts are also calorie-dense, with a one-ounce serving coming in at about 160 to 200 calories.

On heart disease the FDA allows only qualified wording, and it is worth repeating here: scientific evidence suggests, but does not prove, that eating 1.5 ounces a day of most nuts as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease. The cholesterol and metabolic effects measured in trials are real but small. That said, they are not healing in the sense that if you have a condition or are ill, they turn into magical pills as soon as you put them on your plate.

They are also high in calories, which can affect weight management if eaten in excess, and Brazil nuts, specifically, come with their own risk of selenium toxicity.

If you want to add nuts to your diet for a specific health reason, they’re great additions, but don’t expect miracles.

The numbers, at a glance

• Eating 42.5- 85 g of walnuts five times a week can reduce the risk of coronary heart disease by 40%, lower cholesterol by 9 to 16%, and reduce diastolic blood pressure.
• Eating 28 to 84 g of almonds daily can reduce bad cholesterol levels by 3 to 10%, with those eating higher amounts seeing the greatest benefits
• 1.5 to 3 ounces of pistachios per day lowered fasting blood sugar by 3.73 mg/dL, fasting insulin by 2.43 µIU/mL, and systolic blood pressure by 3.10 mmHg.
• A Mediterranean diet supplemented with mixed nuts, 7.5 g of hazelnuts alongside 15 g of walnuts and 7.5 g of almonds daily, carried a 28% lower risk of a major cardiovascular event and 46% lower stroke risk than low-fat dietary advice, or 3.4% against 4.4% in absolute terms.
• In a single-group study of 21 people with high cholesterol eating 49 to 86 g of hazelnuts a day, a measure of blood vessel function improved 56.6% and cholesterol fell 6.17% to 7.8%. There was no control group.

Angelica Bottaro

Angelica Bottaro is a medical writer and researcher with a background in psychology and journalism.

Stephanie Wright, RN, BSN

Stephanie Wright, RN, BSN, is a Registered Nurse with more than 15 years of experience in critical care, mental health, managed care, and clinical leadership. She is currently pursuing her MSN in Public Health and is passionate about translating medical research into clear, practical information readers can trust. Drawing on both her clinical background and health writing experience, Stephanie brings an evidence-based yet approachable perspective to topics related to sleep, wellness, and preventive health. She is passionate about helping people better understand their health and feel more confident making informed decisions about their care. LinkedIn