Here is a nutritionist guide to nuts and seeds, including the why, the what and how much you need to benefit from the nutrition that nuts and seeds provide.
What are nuts and seeds?
They’re actually the embryos of trees, bushes and other plants. That’s what makes them so nutritious. If you think about what’s needed to create plants and help them grow, nuts and seeds are absolute powerhouses of nutrients.
Nuts and seeds are good sources of:
- Protein
- Good Fats
- Plant Sterols
- Minerals – potassium, calcium, iron, magnesium and zinc in particular
- Vitamins – E, B’s (including folate and niacin in particular)
A source of protein
Nuts and seeds provide protein in varying amounts. Hemp seeds and pumpkin seeds top the protein charts with 31.6g and 28.8g of protein per 100g of seeds, sunflower seeds and almonds also rank high with 23.4g of protein per 100g and 21.1g of protein per 100g respectively. Pecans and pine nuts are at the lower end of the protein scale with 9.5g, and 11.6g of protein per 100g respectively. However, often those lower in protein tend to offer more in terms of health-giving fats.
A source of good fats
Like many other plant foods, nuts and seeds provide a range of nutrients, including large quantities of healthy monounsaturated and polyunsaturated fats (49–74% total fat) except chestnuts which are naturally very low in fat. Health-promoting monounsaturated and polyunsaturated fats help regulate blood cholesterol. They also provide satiety i.e. eating nuts and seeds can have a positive effect on your appetite thanks to their naturally high fat content.
A source of fibre
Nuts and seeds are also a good source of dietary fibre. With most nuts a 50g serving provides about 4-5g of fibre. Fibre and plant sterols have been shown to reduce cholesterol re-absorption from the gut. This is particularly useful for those with high cholesterol in their families. Fibre is also filling and so again consumption of nuts and seeds can have a positive outcome where appetite is concerned.
Health giving properties of nuts and seeds
According to this research carried out in 2015 nuts may help you to lose weight. This research revealed that nuts may actually suppress both the appetite and the brain's desire for food, which can lead people to overeat even when they're full.
Another review (see here) of 31 trials, found that those whose diets included extra nuts or nuts substituted for other foods lost about 1.4 extra pounds and half an inch from their waists when compared to those who did not.
Nuts and seeds may also reduce your likelihood of developing insulin resistance and type 2 diabetes. In fact a large study (see here) found that women who ate about 30g of nuts per day on five or more days of the week had approximately 30% less risk of developing type 2 diabetes compared with those who ate few or no nuts.
When nuts and seeds are added to meals rich in carbohydrate they appear to slow the passage of the meal through the gut and reduce blood glucose levels following the meal. The mechanisms for slowing down carbohydrate metabolism are thought to be related to the protein, fat and fibre content of nuts and seeds as well as the phytochemicals found in their skins. A Harvard meta-analysis, which groups together many studies, (see here) found a 13% reduced risk of type 2 diabetes when four 30g (approx) serves of nuts are eaten each week.
Nuts and seeds provide antioxidant vitamins and minerals, e.g. vitamin E, copper, manganese, selenium and zinc, and other antioxidant compounds such as flavonoids and resveratrol that have been shown to reduce oxidation and inflammation. Nuts and seeds are naturally low in sodium and high in potassium. This is a combination which helps to maintain a healthy blood pressure.
Types of nuts and seeds and advantages
- Almonds: protein, calcium and vitamin E for bone and skin health
- Brazil nuts: fibre and selenium: just two brazil nuts a day provides 100% RDI for selenium for an adult
- Cashews: non haem (plant based) iron and a low GI rating
- Chestnuts: fibre, low GI rating and a good source of B Vitamins
- Chia Seeds: especially high in fibre and are also recognised for their ability to provide sustainable energy. The word ‘chia’ is derived from the ancient Mayan word for ‘strength’
- Flax Seeds: High in omega 3 fats, which play a role in maintaining normal cholesterol levels
- Hazelnuts: fibre, potassium, folate which may help keep homocysteine in check
- Macadamias: highest in monounsaturated fats, thiamin and manganese
- Pecans: fibre, antioxidants and plant sterols linked to lower cholesterol levels
- Pine nuts: vitamin E and the arginine amino acid
- Pistachios: protein, potassium, plant sterols and the antioxidant resveratrol
- Walnuts: alpha linoleic acid: plant omega 3 – an essential fat, and antioxidants
- Pumpkin Seeds: zinc, magnesium, phosphorous, plant sterols so help to reduce fatigue and contribute to healthy hair, skin, teeth and bones
- Sunflower Seeds - vitamin E, B vitamins, selenium, magnesium, plant sterols so will help protect cells from oxidative stress, and help maintain a healthy metabolism
- Sesame seeds – best eaten as tahini which is simply sesame seed paste, a fantastic source of calcium
What's a portion?
A 30g portion of nuts or seeds could be made up of:
20 almonds
15 cashews
20 hazelnuts
15 macadamias
15 pecans
2 tablespoons of pine nuts
30 pistachio kernels
9 walnut kernels
a small handful of mixed nuts
a small handful of seeds
Sources:
www.theepochtimes.com/lose-weight-eat-nuts_1738708.html
ajcn.nutrition.org/content/early/2013/04/17/ajcn.111.031484
www.ncbi.nlm.nih.gov/pubmed/12444862
