Could that healthy green smoothie actually be doing you more harm than good? Nutritionist Lucy Stewart breaks down how to get the most nutrients for your smoothie buck.
Smoothies and smoothie bowls are often portrayed as the ultimate shortcut to a healthy diet, but could they be doing us more harm than good? While they can be a convenient source of valuable nutrients within a balanced diet, many contain too much sugar and are consumed far too quickly and too frequently. But before you swear off the green stuff, there are solutions to the problems many smoothies raise.
The red flag: Smoothies have the potential to wreak havoc on your blood sugar
Most smoothies contain far too much sugar. Sure, these sugars may come from natural sources like fruit, but it’s still a lot more fruit than you would be able to consume in one sitting. Whole fruit contains fibre, which forms a barrier in your gut to provide a slow release of energy from sugar. When you blitz fruit in a smoothie, you destroy the structure of the fibre and increase the release of energy (blood sugar spike). Most store-bought smoothies also contain added sweeteners like fruit juice and frozen yoghurt. Blood sugar spikes can leave you feeling irritable and hungry just a few hours later.
To reduce the amount of sugar in your smoothie, choose low-sugar fruits like lemons, pears and berries and only add a small amount.
Red flag: There is a chance of weight gain
In a misguided effort to be healthy and “lean”, many smoothies have removed all of the nutritious fat and protein and are purely fruit based. But fat and protein are what sustain your energy and satiety - without these, you’ll be left feeling hungry only a few hours later and subsequently consuming more calories. Need more proof? Research shows that if you take exactly the same energy as a liquid instead of a solid, you'll consume more calories later because the liquefied energy doesn’t satisfy your appetite as well as the solid food.
Most of us will be drinking a smoothie on-the-go, but when you sit down and eat your food slowly, your body secretes the hormone leptin, which helps to increase how full you feel. If you drink a smoothie quickly, you can easily consume too much of it before your body has a chance to signal that you've had enough, or leave you feeling unsatisfied and hungry afterwards.
Slow down, sit down and take your time when you have your smoothie.
The red flag: Cold smoothies can slow down your metabolism
When you consume cold foods or drinks, your body has to work extra hard to warm it up so it can be digested. Smoothies made up of frozen fruits or ice can cause your digestive system to go into shock, slowing blood flow and weakening its ability to transform and transport nutrients.
So that your smoothie doesn’t slow down your metabolism, allow it to come to room temperature before drinking.
Red flag: Drinking our food impairs digestion and nutrient absorption
Drinking your food skips an important part of the digestive process, chewing. Chewing serves as the first step to proper digestion and stimulates the release of saliva, which starts to break down food so their nutrients can be absorbed. Blended food also moves through your digestive system faster and you may end up absorbing fewer nutrients, which over time, can lead to nutrient deficiencies.
Chew your mouthfuls of smoothies instead of gulping them down, or try eating it with a spoon.
The red flag: Green smoothies contain anti-nutrients
Yes, we should all be eating more greens that are full of wonderful antioxidants and phytochemicals, but drinking large amounts of raw greens has taken things a step too far. Leafy greens contain anti-nutrients called oxalates, which bind to calcium and iron in the body and prevent absorption of these important minerals. Excess oxalates can also deplete the body of its master antioxidant, glutathione. Cruciferous greens (kale, broccoli, watercress) contain goitrogens, which suppress thyroid function and inhibit the uptake of iodine.
Cooking reduces both oxalates and goitrogens, so lightly steam your greens first before adding them to your smoothie.
Lucy's perfect green smoothie recipe
Simply combine and blitz the following. Serves one.
• 1 cup GREENS. Consisting of lightly steamed leafy greens, celery, cucumber, or fresh herbs
• 1-2 Tbsp FIBRE. Try oats, chia seeds, ground flax seeds, hemp seeds or sunflower seeds
• 1-2 Tbsp FAT: Take your pick of avocado, cold pressed coconut oil, MCT oil, organic unsweetened full cream yoghurt, coconut yoghurt, nuts or nut butter
• 1 serving PROTEIN (approx. 20g): Such as bone broth, collagen, hemp seeds, sprouted pea or hemp protein. Serving sizes may vary depending on your selected protein, read the directions and add one serving.
• ¼ cup FRUIT - OPTIONAL: The best bets are blueberries, raspberries, strawberries, lemon, lime, pear or acai
• 1 cup LIQUID: Your choice of filtered water, coconut milk, coconut water, organic full cream milk, unsweetened nut or seed milk
• OPTIONAL EXTRAS: Feel free to add cacao powder, cinnamon, turmeric, bee pollen or cacao nibs