Food & nutrition

Nuts and seeds

10 sources · Latest source check 2026-10-20 UTC

On this page

Nuts and seeds are edible plant foods supplying fats, protein, fibre and micronutrients. Familiar nuts include almonds, walnuts, cashews and pistachios; peanuts are legumes but are commonly grouped with nuts in food discussions. Seeds include pumpkin, sunflower, sesame, chia and flaxseed.[1]

Common groups and preparations

Common groups and preparations
Group	Examples or distinction
Tree nuts	Almonds, walnuts, cashews, pistachios, hazelnuts, pecans, macadamias and Brazil nuts.[1]
Peanuts	A legume used like a nut; a separate allergen category in UK labelling.[7]
Seeds	Pumpkin, sunflower, sesame, chia and flaxseed; the ingredients are not interchangeable.[1]
Whole, chopped or butter	The same almond can have different physical structure and measured energy availability.[4]

High fat does not answer the weight-gain question by itself

A 2021 systematic review included six prospective cohort studies and 86 randomized trials. In the trials, nuts did not produce an adverse average effect on body weight compared with the study controls. The cohort association with a lower incidence of overweight or obesity is a different kind of evidence. Neither finding makes portions irrelevant or promises weight loss for an individual. It addresses the concern that nuts’ energy density necessarily translates into weight gain under the conditions studied.[3]

The result concerns average differences between intervention and control groups. It does not mean that nuts contain no usable energy, or that adding an unrestricted quantity to any unchanged diet has been tested. The comparison food, background diet and individual circumstances remain part of the question.[3]

Whole nuts and nut butter have different food structures

An 18-person randomized crossover feeding experiment compared whole natural almonds, whole roasted almonds, chopped almonds, almond butter and a no-almond control. Researchers measured usable energy from the controlled diets and collected urine and faeces. Whole and chopped almonds supplied less metabolizable energy than standard prediction factors suggested; almond butter was closer to the predicted value. Roasting and grinding changed the physical structure. This experiment explains why form can matter, without proving that almond butter is an inferior food or establishing long-term weight effects.[4]

Whole flaxseed, milled flaxseed and oil answer different questions

A 2008 study compared three forms of flaxseed over one month. Plasma alpha-linolenic acid, a plant omega-3 fatty acid, increased significantly in the flaxseed-oil and milled-seed groups. The result concerns availability of a particular fatty acid, not proof of reduced disease events. A seed, a milled ingredient and an extracted oil are therefore distinct preparations when reading research. Evidence for one preparation should not be transferred to another merely because both packages say flax.[5]

NCCIH’s separate overview concerns flaxseed and flaxseed-oil supplements. It distinguishes mucilage powder, lignan extract and oil: limited findings for one formulation do not establish the same weight or glucose effects for all of them. It describes research of varying quality and unresolved questions for several uses. This is also why a general claim about “seeds” is broader than the research on a named flaxseed preparation and outcome.[6]

A concentrated supplement needs its own assessment

NCCIH reports possible digestive symptoms with higher amounts of flaxseed or oil supplements, potential medicine interactions and uncertainty during pregnancy or breastfeeding. Those supplement questions do not establish a personalized culinary dose. The product formulation and purpose matter: using an ingredient in a meal is a different question from taking a concentrated extract for a claimed treatment effect.[6]

Seeds are not an automatic substitute for someone with nut allergy

Food Standards Scotland lists peanuts, tree nuts and sesame as separate key allergens. Sesame can appear in hummus, tahini, bread and sesame oil; nuts can appear in spreads, sauces and desserts. A product’s familiar name does not reveal all those ingredients. The UK requires information about the specified allergens, but people can also be allergic to foods outside that list. Substituting a seed product therefore does not, by itself, establish that it suits a particular person’s allergy.[7]

Evidence & uncertainty

Evidence is specific to the food and outcome studied. A tree-nut trial review found improvements in several blood-lipid markers, not a universal effect on every marker. That does not establish identical benefits for every seed, extracted oil or sweetened nut product.[2]

Selected-source overview · Independent review pending

Published questions

Are peanuts nuts or beans?

Selected-source overview · Independent review pending. Read the evidence context.

Peanuts are legumes, but are commonly grouped with nuts for food discussions. That culinary grouping does not erase differences between peanuts, tree nuts and seeds.[1]

Evidence behind this answer

Nuts and seeds
agency condition or prevention explanation · 2026
Selected relevant original official page passages inspected · Food examples, peanuts as legumes, micronutrient variation and raw/unsalted-roasted options; reviewed 28 January 2026