The health benefits of nuts and seeds

By Isabelle Sadler, PBHP UK Research Assistant and MSc Nutrition Student

Nuts and seeds are a fundamental part of a plant-based diet, providing a rich source of protein, unsaturated fats and several micronutrients. They’re also a great way to increase fibre intake, which is associated with a decreased incidence in mortality from several common chronic diseases.

There is growing evidence for the beneficial and protective effects of consuming nuts and seeds regularly, especially for cardiovascular health. Studies have demonstrated that eating a handful of nuts at least 5 days a week can increase lifespan by around 2 years. However, there is a global underconsumption of nuts, and this food group represents one of the largest gaps between recommended intake and current consumption levels. Not eating enough nuts and seeds is also one of the leading dietary risk factors for disease burden globally.

Nuts and seeds in healthy dietary patterns

Various dietary patterns have been developed to promote good health, such as the Planetary Health, Mediterranean, Portfolio, Dietary Approaches to Stop Hypertension (DASH), and Whole-Food Plant-Based (WFPB) dietary patterns. These diets share several core, healthy components, one of these being nuts and seeds!

The Portfolio diet is a plant-based eating pattern that is designed to lower cholesterol. It includes nuts and seeds as one of several cholesterol lowering foods, alongside plant protein, viscous fibre sources, phytosterols, and plant unsaturated fat sources. A higher plant-based Portfolio Diet Score has been associated with a 14% lower risk of cardiovascular disease, coronary heart disease, and stroke in 3 prospective cohort studies, as well as a more favourable blood lipid and inflammatory profile.

Similarly, regular nut consumption is a key component of the Mediterranean-style dietary pattern. In a randomised trial in people with raised cardiovascular disease risk, a Mediterranean diet with added nuts, compared to control diet, reduced the risk of cardiovascular disease, type 2 diabetes, cognitive decline, and other adverse health outcomes.

The EAT-Lancet Commission Planetary Health Diet also recommends consuming 50g of nuts per day (tree nuts and peanuts). In a systematic review and meta analysis including a total of over 2.21 million participants, this dietary pattern was associated with a significantly reduced odds of diabetes, CVD, cancer and mortality.

Cardiovascular health

Some of the strongest evidence for the health benefits of nuts and seeds is related to a reduced risk of cardiovascular disease and its risk factors.

In a systematic review and meta-analysis, consuming the high versus lowest quantity of nuts and seeds was associated with a reduced risk of cardiovascular disease, cardiovascular mortality, coronary heart disease, and coronary heart disease mortality. A smaller, but still relevant, risk reduction was also seen for stroke.

The reduction in risk of cardiovascular disease could, in part, be due to the impact that consuming nuts and seeds can have on blood lipids. In the same meta-analysis as above, intake of nuts (median ~50 g/day) lowered total cholesterol by 0.15 mmol/L and LDL-cholesterol by 0.13 mmol/L. These findings are supported by a comprehensive review of the literature, which studied 19 systematic reviews and meta-analyses of randomised controlled trials. Across the trials, there was a consistent beneficial effect of total nuts and tree nuts, including walnuts, almonds, cashews, peanuts, and pistachios, for decreasing total cholesterol by 0.09 to 0.28 mmol/L, LDL-cholesterol by 0.09 to 0.26 mmol/L, and triglycerides by 0.05 to 0.17 mmol/L. One of the included reviews also examined the effect of nuts on apolipoproteins and found a significant reduction in apolipoprotein B of 0.042 g/L, across 13 trials.

Nuts and seeds can also lower the risk of high blood pressure, a leading driver of cardiovascular disease. Flaxseeds are particularly notable for their blood pressure lowering effect, with an effect size worthy of use in people with hypertension.

Why are nuts and seeds so good for us?

Nuts and seeds are a rich source of monounsaturated and polyunsaturated fats, as well as plant protein, dietary fibre, phytosterols and polyphenols. Individually, these nutrients are beneficial for health and may, for example, have modest cholesterol-lowering effects. However, when they are combined within the natural matrix of a nut or seed, their effects appear to be even greater, contributing to the reductions in LDL-cholesterol observed in studies of regular nut consumption.

We know that the favourable fatty acid profile of nuts contributes to improvements in blood lipids, particularly when nuts replace foods high in saturated fat. Evidence has also demonstrated that phytosterols contribute to the cholesterol-lowering effects of nuts and seeds. Phytosterols interfere with cholesterol absorption in the intestinal lumen, helping to lower blood cholesterol levels. The phytosterol content of nuts varies, with pistachios, almonds, and walnuts containing some of the highest amounts.

Nuts and seeds also provide important micronutrients, including magnesium, zinc, iron, calcium, copper, phosphorus, potassium, selenium, vitamin E, and B vitamins. Together, these nutrients support several aspects of health, including cardiovascular function, immune health, bone health, and protection against oxidative stress. Nuts also contain a relatively high amount of L-arginine, which has cardiovascular health benefits.

The array of healthy nutrients in nuts together with the fact that they are likely to be replacing less healthy foods in the diet results in reduced mortality from all causes and from cardiovascular diseases, cancer, respiratory diseases and infectious diseases.

Are nuts associated with weight gain?

Despite the mounting evidence for the health benefits of nuts, concerns persist that they may contribute to weight gain due to their high energy density. Nuts are known to have a high fat content, making up at least 40% of their total energy content, ranging from around 44% in pistachios and cashews to 76% in macadamia nuts.

This may be a barrier for increasing the consumption levels of nuts in line with healthy eating recommendations, as they are seen as more energy dense and more likely to contribute to weight gain compared to other healthy foods.

Despite this concern, robust evidence from a systematic review and meta-analysis suggests that the opposite might even be true. Across six cohort studies, nuts were associated with lower incidence of overweight/obesity and across 86 randomised controlled trials, researchers found no adverse effect of nuts on body weight.

There are a number of reasons why nuts are not associated with weight gain. The high protein and fibre content and the need for prolonged chewing may contribute to an increased feeling of fullness. Not all of the fat in nuts is absorbed and unsaturated fats may result in a greater thermogenic effect (the increase in the metabolic rate that occurs after eating a meal/food) than saturated fats.

Best nuts and seeds to include in a plant-based diet

All nuts and seeds can contribute to a healthy dietary pattern and provide a wide range of beneficial nutrients. Including a variety is likely to provide the greatest nutritional benefit, as different nuts and seeds contain different combinations of unsaturated fats, fibre, vitamins, minerals, and phytochemicals.

For individuals following a plant-based diet, flaxseeds, chia seeds, hemp seeds, and walnuts are particularly valuable additions due to their content of alpha-linolenic acid (ALA), an essential omega-3 fatty acid. ALA is essential because we must obtain it from our diet. Daily requirements of ALA can be met by eating a tablespoon of chia seeds or ground flaxseeds (linseeds), two tablespoons of hemp seeds or six walnut halves.

Sesame seeds and tahini provide a useful source of calcium and zinc, while pumpkin seeds are rich in iron and zinc. Brazil nuts are notable for their selenium content, with just two nuts often providing enough selenium to meet daily requirements, though content can vary depending on where they’re grown. Almonds and hazelnuts are rich in vitamin E, and pistachios and walnuts provide particularly high levels of phytosterols, which may contribute to cholesterol lowering.

Nut and sesame allergy

Tree nut and peanut allergies are among the most common food allergies and can range from mild to severe. Individuals with a diagnosed allergy should continue to avoid the foods they are allergic to and seek guidance from their healthcare professionals regarding safe food choices.

For information on introducing peanuts safely to infants and children, please refer to the factsheet on our website.

Allergy to sesame is also increasing and is one of the 14 allergens that are mandated to be listed on food products when present.

Top tips for incorporating nuts and seeds into the diet

• Enjoy a handful of your favourite nuts as a quick and delicious snack, choosing mostly unsalted and minimally processed nuts and seeds is recommended where possible.
• Making your own homemade trail mix using unsalted nuts, seeds, and dried fruit can be a simple way to have a ready-to-go snack
• Sprinkle nuts and seeds on top of soups, salads, stir-fries, oatmeal and cereal. For example, sesame seeds on stir fries and curries, pumpkin seeds on salads.
• Blend seeds such as flax, chia, or hemp into smoothies
• Use nut butters to top off a snack, such as peanut butter with apple slices, almond butter on whole grain toast, or a tahini sauce drizzled over roasted vegetables
• Incorporate nuts into savoury meals. For example, walnuts can be added to lentil bolognese, cashews can create creamy sauces, and mixed nuts can be used in nut roasts or veggie burgers.
• Use nuts and seeds such as pistachios and pine nuts to make homemade pestos, dips, and salad dressings
• Add nuts and seeds to home baking, such as breads, muffins, flapjacks, and granola, or experiment with nut flours in baking recipes