I think I’ll be doing a FAQ tag on the blog so I can answer some of the questions many of my friends ask me in relation to nutrition.
A friend asked me which nut is healthiest? Or the unhealthiest?
To answer the question, let’s take a look at what nuts are.
a fruit consisting of a hard or tough shell around an edible kernel (Oxford Dictionary, 2011).
Let’s not get finicky in botanical classification, so basically it’s just a seed. Peanuts are actually legumes, not nuts, but they are very similar in characteristics of other nuts. (the difference between nuts and legumes are also best left to the botanists. Both nuts and legumes are encased on a shell, but nuts contain one (or at most, two) seeds, while legumes contain multiple seeds, among other differences nicely summarised here).
Nuts have long been known to be healthy and a nutritional powerhouse, packed full of protein, healthy fats, vitamins, minerals and dietary fibre. Many people think that nuts are unhealthy as they are high in fat; while the latter is true, they are the mono- and polyunsaturated kind (good for your heart) and nuts are actually very healthy. Although they are high in fat, studies have shown that a moderate intake of nuts can actually lower the risk of weight gain and obesity. This is because nuts are very satisfying; just a handful, and all the fibre, protein and fat can help make you feel fuller. Research has also shown that about 10-15% of the energy in nuts are not absorbed in the gut, passing straight out of your body as stool (cell walls are resistant to the enzymatic breakdown in the GIT, so some cells don’t rupture and thus don’t release their fats; this is also why nut butters have greater bioavailability than whole nuts). I learned that yesterday when my supervisor (for a summer research project I’m involved in) was teaching a patient about weight management. But it’s really interesting. There are more mechanisms as to why nuts can help with weight management, which you can read further in the reference above.
Regular nut consumption can also lower your risk of other chronic diseases like cardiovascular (heart) disease, type 2 diabetes and some cancers. So, having a small handful of nuts everyday as a snack can be beneficial to your health. They’re also great as snacks because they’re small and handy to carry around, great to ward off the vending machine temptations!
Now to answer the question you’ve all been waiting for! Each different nut has their own unique nutritional profile that have different benefits to offer. Generally, unsalted, unroasted nuts of any kind are healthier. Salt can raise blood pressure (acting like a sponge in the kidney, so the more salt in your body, the more water is reabsorbed), whilst roasting nuts reduces their antioxidant content and alters the lipid profile, potentially raising the content of harmful chemicals (however, the effect is probably not enough to warrant complete exclusion of roasted nuts in your diet, especially if you enjoy roasted more, although it is best to have most of your nuts raw!). Roasted and salted nuts also make them tastier and harder not to overeat!.
Despite these answers, I wasn’t actually too certain of the specific answer. So I searched it up on Google (hehe..) and found that a study claimed that walnuts are the healthiest of the nuts (sorry about the newspaper link, I tried searching for the original article for 30 mins and couldn’t find it! Oh wait I finally found it!). The scientists found that walnuts contain twice the antioxidant content as other nuts (nine nuts were tested).
You can watch this video for a little more info on the study:
Antioxidants are the new buzz word going around in nutrition news, and rightly so. They are substances found in food that can help mop up free radicals in our bodies to prevent oxidative damage. Free radicals are molecules that have one or more unpaired electrons in their outer shell, making them unstable and highly reactive, formed when oxygen reacts with body compounds during metabolism. These free radicals will oxidise substances in the body, stealing their electrons to gain stability. The attacked molecule (that lost the electron/s) becomes a free radical itself, starting a chain reaction of electron-snatching, that produces more free radicals. This can cause oxidative damage of tissues, such as in phospholipids of cell membranes (disrupting the transport of substances across cells), DNA (creating mutations), and proteins (altering their functions).
Antioxidants are substances in foods that inhibits this chain reaction of oxidative damage, protecting substances in the body from being oxidised by free radicals. Antioxidants neutralise free radicals by oxidising themselves (acting as a reducing agent): donating electrons to the free radical to stabilise their outer shell, whilst they don’t become free radicals themselves as they can receive electrons again to become reactivated. Examples of antioxidants include the vitamins A C E, as well as polyphenols.
Because that is a whole heap of science that I copy and pasted from revision I did for my exam last year (!), I shall sum it up using layman’s terms! An easy analogy of an ‘oxidative reaction’ is the rusting of iron (or the browning of apples, that’s how quickly oxidative reactions occur!). The iron naturally rusts, and if you do something to protect the iron from rusting, then the rusting won’t happen. Now imagine that’s what happens in our body, with oxidative reactions, which ultimately lead to damage to tissue. This can lead to diseases like cancer, heart disease, and accelerating the ageing of the eyes and brain. So if we can protect those oxidative reactions from occurring using antioxidants which mop up free radicals, we can protect the tissue from damage and help us stay healthier for longer.
Back to Vinson et al’s study, it found that walnuts contained 69.3 units of polyphenol/g walnut (and polyphenols are up to 15x the potency of vitamin E). Another suggestion was that walnuts are usually eaten raw, hence there is a higher chance that more antioxidants are eaten (vs. other nuts that are often roasted). Here is a graph of the total polyphenol content of different nuts, courtesy of TIME.
Brazil nuts come a close second, and hazelnuts third (it is also evident that raw nuts are generally higher in antioxidants than roasted counterparts). Of course, antioxidants aren’t the only factor in health, and it isn’t the only reason walnuts deserve the title of ‘healthiest nut’ (and this title is certainly not entirely true, since different nuts have different benefits!). Walnuts can also protect the elasticity of the arteries, which can reduce the risk of atherosclerosis (plaque forming on the arteries that blocks blood flow), and are rich in omega-3 fatty acids (alpha-linolenic acid; the only nut that contains this), those very hard-to-find fats, which can help with many functions in the body such as reducing inflammation and cholesterol, and promoting heart health).
However, the key is balance and variety. Even though walnuts are ‘healthiest’, each nut possesses a plethora of unique merits. By ensuring a varied intake, you can reap the benefits of other nuts too.
- Almonds help stabilise blood sugar and are a great source of calcium.
- Brazil nuts are excellent sources of selenium (a mineral that helps vitamin E (antioxidant!) operate). They also have more methionine than other nuts, making them of slightly higher protein quality (although still not excellent).
- Cashews are high in magnesium which can help build strong bones. Cashews have a greater carbohydrate and lower fat content than most other nuts. And they taste so good. :)
- Hazelnuts are a good source of vitamin E and beta-sitosterol which contributes to cardioprotection and chemoprevention.
- Macadamia nuts are high in monounsaturated fat and thiamin (vit B1).
- Peanuts are often victimised into being labelled the ‘bad/unhealthy nut’, but such a label is clearly unfair and untrue. Peanuts are healthy and high in monounsaturated fat, folate, and resveratrol (the phenolic antioxidant more famously known in red wine) which can help protect the heart. When buying peanut butter (which, in moderation, is perfectly fine), avoid any varieties that list “hydrogenated fat/oil” in the ingredients list. Buying the pure/organic type with nothing but pure peanuts (no sugar, oil, or salt) is the healthiest, but often a lot more expensive, and arguably unnecessary if you are on a budget and not consuming excessive amounts.
- Pecans are high in vitamin E and regular consumption may help decrease LDL (bad) cholesterol in the blood.
- Pistachios are rich sources of calcium, magnesium, vitamin A, and iron.
Just like how eating a variety of fruits and vegetables are recommended, to take advantage of all the different nutrients in different types, so too are nuts. Having a variety of nuts also confers benefits of factors that have not been studied or are less black-and-white (which is also true for fruit and vegetables). For example, some research shows that pine nuts can help suppress appetite, thus helping with weight management. So the answer to the question is, conventionally, walnuts are probably ‘best’, but the healthiest nut a mixture of nuts! So, while some nuts contain more cardioprotective nutrients than others, the type of nut you eat isn’t very important, and what’s important is that you do include a small amount of nuts in your regular diet (whatever nuts you choose). Nevertheless, most people don’t eat much walnut, preferring peanuts instead (I admit to being one of them!). So if you’d like to make the most out of the nuts you eat, consider trying a mix of walnuts and other tree nuts instead of just peanuts!
There is no nut that is the most ‘unhealthy’ or the ‘worst nut’. However, if you are watching your weight, macadamias and pecans are the most energy-dense, and although coconut is formally classified as a drupe, if classified as a nut, it is the least healthy due to its high saturated fat content .
I’ve been extolling the virtues of nuts throughout this whole post, but of course this doesn’t mean that you should eat a few cups a day! As with everything, you can overdo a good thing, and it’s all about moderation. Nuts are very energy-dense and too much can lead to weight gain, so the general rule is to have around a small handful each day (~1/3 cup is equivalent to a Meat & Alternative serve of the Australian Guide to Healthy Eating [AGHE]). And raw, unsalted nuts are best. Try them au naturel as snacks, sprinkled on pasta/stir-fries/cereal/yoghurt/ice-cream, baked into cakes, or blended to make butter or vegan cream (I have a yummy recipe for cashew cream for cakes, which I’ll post later!).