Aside from chia seeds (a “superfood” seed), other seed varieties don’t get as much airtime, yet are becoming more and more popular with restrictions being placed on nut consumption due to the rising prevalence of allergies. Do they have the same health properties?
Let’s look at three seeds that are increasing in popularity.
Flaxseeds (also known as linseeds) have long been revered for health properties including their omega 3 content, fibre and the presence of a plant constituent known as lignans. Flaxseed is made up of around 40 per cent fat, and is one of the richest sources of alpha linolenic acid, a plant-based omega 3 fat.
It is a shorter-chained polyunsaturated fat that is converted to the longer chained polyunsaturated fats eicosapentonoic acid (EPA) and docohexanoic acid (DHA), which have potent health benefits. Though the conversion rate is quite low, there is evidence to suggest people following a vegetarian or vegan diet may have a higher conversion rate.
Omega 3 fats make up the most abundant fat type in our brain, reduce inflammation and overall risk of cardiovascular disease.
Flaxseeds are also a substantial source of fibre, boasting 28g of fibre per 100g of flaxseed. This has been found to be a mix of soluble and insoluble fibre, both of which have their own unique health properties. The soluble fibre is comprised of mucilage gums which turn viscous when mixed with water — in our gut this helps lower the overall blood glucose response to a meal, allowing for more glycaemic control and helping keep us fuller for longer.
The insoluble fibre in flaxseed can also assist in bowel health by preventing constipation, by increasing faecal bulk and reducing bowel transit time. Flaxseeds contain up to 800 times more lignans than other plant foods.
Lignans act as both antioxidants and phytoestrogens. They are found in the cells of plant walls and have been known to reduced waist circumference and risk of thrombosis in type 2 diabetes patients. Buy flaxseeds whole, store them in the fridge and grind them when you need them (in a spice grinder or food processor) to add to smoothies, with fruit and yoghurt or with your rolled oats.
Sesame seeds are approximately 55 per cent fats witha further 28 per cent protein and 8 per cent fibre — the little seed carries quite a nutritional punch. Though the fats in sesame are predominantly polyunsaturated (being generally unstable at higher temperatures and leaving them open to oxidation and rancidity), the presence of natural antioxidants protect the oils from oxidative damage.
A 30g serve contains up to a quarter of daily requirements for calcium, magnesium and iron, however these minerals are not as bioavailable in plant-based forms due to the oxalic acid present in the outer layer of the seed. They are a source of lignans that have garnered scientific interest due to their antioxidant, heart health and phytoestrogen activity.
Laboratory studies have found the lignans in sesame seeds provide a buffer against the effects of endotoxins produced in the brain due to excess build up of nitric oxide, and have the ability to reduce brain injury that occurs after a stroke.
In human trials, sesame seeds have reduced inflammation, blood pressure and the risk of blood clot formation (a risk factor for heart attacks and strokes), and in postmenopausal women enhanced the production of sex hormone binding globulin, responsible for transporting hormones testosterone and oestrodial around the body.
Black sesame seeds contain a greater amount of lignans compared to their white counterparts, but both can be good choices to include in the diet. Toasting seeds over low heat to throw into a salad, or adding oil to a hot dish before serving as a flavour enhancer is the best way to enjoy sesame. Or add to smoothies.
Although being part of traditional cultural fare in North African and Eastern Mediterranean countries, watermelon seeds (yes, the ones that we used to spit out as kids when eating wedges of the fruit) are not commonplace here. There, they are roasted and salted, eaten as a common snack, and the ground seeds are used to thicken soups and stews, and are sometimes soaked, fermented, boiled, and wrapped in leaves to form seasoning for dishes.
The seeds are also used as a meat substitute and roasted and ground into a spread to be had with other vegetables. Here in New Zealand, I have seen a watermelon seed spread from the company Vigour & Vitality, who offer a beautiful range of nut and seed spreads (this is not sponsored, but my opinion).
Like most seeds, those of watermelon are rich in fat at around 50 per cent, predominantly linoleic fatty acid, an omega 6 fat. They are also a substantial source of plant protein, at 36 per cent. They contain calcium, magnesium, zinc and manganese in substantial proportions, though the high presence of phytic acid reduces their bioavailability, therefore watermelon seeds would not be a good source of these nutrients.
However if you were to soak and sprout these seeds before roasting, effectively “activating” the seed, much of the phytic acid would be removed. These seeds may not be the nutritional powerhouse the other two are, but the watermelon seed spread would make a good alternative to nut spreads or to make into a milk alternative.