Guide to seeds
Seeds are a great addition to muesli, trail mixes or salads. HFG senior nutritionist Rose Carr investigates the nutritional benefits seeds offer.
Seeds and health
Full of flavour and nutrients, seeds are a great addition to the diet. Seeds are rich in healthy polyunsaturated and monounsaturated fats, fibre and phytonutrients and frequent consumption of seeds is associated with lower risk for cardiovascular disease and type 2 diabetes. With up to 50 per cent fat, seeds are also very high in energy, so adding them to meals and snacks is a useful way for people wanting to gain weight to boost their energy intake. For those watching their weight, seeds are best used in moderate amounts.
We need omega-3 and omega-6 polyunsaturated fats but our bodies cannot make these fats so we must get them from our diets.
Most of the poly-unsaturated fats we consume are omega-6 fats, and seeds are a rich source of these.
Flaxseeds and chia seeds are also rich sources of ALA, the plant-based short-chain omega-3.
Fatty fish is the best source of the long-chain omega-3s we need but some of the ALA we consume converts to the long-chain forms in our bodies. While a number of studies have found this conversion rate to be quite low, it has more recently been found that higher amounts of ALA do result in higher blood levels of long-chain omega-3s for people who don’t eat fish. So flaxseeds and chia seeds are a good way to boost omega-3.
Handling and storing
The high oil content of seeds means they need to be handled and stored with care. The oils can absorb odours from other foods and are prone to oxidation, which means the seeds become rancid and can smell off or stale. Bruising, light, heat and moisture will all promote rancid seeds. Ideally, seeds should be stored in an opaque, airtight container at a cool temperature. Seeds will keep for longer in the fridge, and can also be frozen.
When buying seeds, look for signs of appropriate handling and storage. For example, are the seeds exposed to direct light where they are displayed in store? Are they in see-through packaging? If you’re not sure about a particular store or brand, we suggest first buying a small amount of seeds to try. You can taste the difference between ‘fresh’ dried seeds and ones that have started to go off from poor handling.
Ways to use seeds
- Seeds such as sunflower seeds or pumpkin kernels can be eaten as a snack by themselves, either raw or dry-fried.
- Dry-fry seeds in a pan to bring out their flavour. Take them off the heat once they start to colour as they will continue cooking for a little while. When you dry-fry seeds, the heat will affect the oils, so it is advisable to heat only the amount you are going to use straight away. If kept, dry-fried seeds will quickly go rancid.
- Use seeds as a garnish or mixed through salads to add texture and flavour.
- Add seeds to muesli or other cereals.
- Seeds can be used in breads and baking, either whole or ground.
- Ground flaxseeds (also called linseeds) or chia seeds can be added to smoothies to add fibre, texture and flavour.
- Around 190kJ per tablespoon
Also known as pepitas, pumpkin seeds or kernels are found in the centre of the pumpkin. The shell or husk is removed from the kernel which is then dried.
- Around 160kJ per tablespoon
Native to Central and South America, chia seeds look a little like tiny sesame seeds and are black or white. Chia seeds are around one-third fat, which is lower than other seeds, and around one-third fibre, which is remarkably high. Just one tablespoon of chia seeds provides around 2.8g of fibre (10 per cent of daily fibre needs for women). Chia seeds are also rich in ALA, second only to flaxseeds, with 1.4g in one tablespoon.
- Around 190kJ per tablespoon
Poppy seeds are from a west Asian plant, Papaver somniferum, the same plant from which opium is extracted. Poppy seeds are very tiny. There are about 3300 seeds in one gram. The seed pigment is brown but due to a layer of cells containing calcium oxalate crystals, which act like tiny prisms, the seeds can appear blue. Poppy seeds are particularly high in calcium, with 120mg in one tablespoon, although it should be noted this is not comparable to 120mg from dairy products – the calcium from poppy seeds is not well absorbed.
Flaxseeds (also known as linseeds)
- Around 220kJ per tablespoon (whole seeds) and 160kJ per tablespoon (ground seeds)
Flaxseeds, from the Linum plant, have been used for over 7000 years to produce both food and linen fibre. Flaxseeds are small reddish-brown seeds with a glossy appearance. Of all plants, this seed is the richest source of ALA, the plant-derived omega-3, with around 1.6g in one tablespoon of ground flaxseeds. Flaxseeds are also a great fibre boost: one tablespoon of flaxseeds provides 2.8g fibre, or 1.9g in one tablespoon of ground flaxseeds.
- Around 220kJ per tablespoon
Sunflower seeds are from the flower of Helianthus annuus, a north American native plant from the daisy family. Known for their large yellow flower heads, the sunflower can grow up to 3.5m tall, and a flower head as large as 75cm has been recorded. With a mild nutty flavour, these seeds are particularly rich in vitamin E, containing even more than almonds. Just one tablespoon of sunflower seeds provides 3mg of vitamin E, which is 20 per cent of the suggested dietary target each day for women and 16 per cent for men.
- Around 180kJ per tablespoon
Sesame seeds are from the Sesamum indicum plant native to Africa, an upright herb growing about 2m tall. The small pear-shaped seeds with a rich, nutty, earthy flavour in white, brown or black are released from pods about 3cm long. One tablespoon of sesame seeds contains around 75mg calcium and 1mg iron, although these are less bioavailable than calcium from dairy products and iron from meat.
Did you know?
- If you continue grinding seeds past the ‘meal’ phase, you end up with a paste similar to a nut butter. Tahini, an essential ingredient in hummus, is made in this way from ground sesame seeds.
- The pods of early strains of the sesame plant had a tendency to suddenly split open when ripened, scattering the seeds. It’s thought this may account for the term ‘open sesame’.