Whenever you eat food containing starches or sugar, the effect will be to raise your blood glucose level causing a blood glucose ‘spike’. If you regularly eat foods containing starches and sugars throughout the day you will have frequent blood glucose spikes. Is this harmful to health? Can you do anything to reduce these spikes? The answer to these questions is yes and yes. Read on to find out more…
How do blood glucose spikes harm your health?
Studies have shown that repeated glucose spikes are harmful to cardiovascular health, leading to arterial stiffness (1) and thickening of the lining of blood vessels (2). Though these problems are worse for the person who is diabetic or has metabolic syndrome, the arterial stiffness is seen in healthy people too (1). Over time, repeated glucose spikes can contribute to an increased risk of cardiovascular disease.
Glucose spikes are followed by insulin spikes as the pancreas releases insulin to push glucose into cells. Insulin spikes have been shown to increase the urinary excretion of calcium (3) and the urinary retention of sodium (4). It has been suggested that the excretion of calcium caused by insulin and glucose spikes may lead to development of osteoporosis (5) and the retention of sodium is a risk factor for developing hypertension (6)
Spiking your blood sugars frequently also contributes to oxidative stress in cells leading them to malfunction (7) and also to chronic inflammation (8) which can lead to diseases such as obesity, diabetes, auto-immune diseases, arthritis and some forms of cancer.
Prevention is better than cure!
The only sure way of minimising glucose spikes is to not cause them in the first place! Since glucose spikes are caused by consuming meals and snacks rich in starches and sugars it makes sense that reducing your consumption of these foods is a good starting point for regularising your blood sugar levels.
A low-carb diet is a sure way of minimising glucose spikes. In this way of eating sugars and starches are kept to a minimum whilst protein and fat intake is increased. This rebalancing of these energy providing nutrients results in suppression of both glucose and insulin spikes, resulting in greater insulin sensitivity and control of appetite, whilst still providing plenty of fuel for your cells from the metabolism of fats rather than sugars.
What if I still want to eat some carbs?
However, even with the best will in the world many people following low carb diets will find themselves in situations where avoiding carbs is difficult and they may feel the need to eat something starchy or sweet. Most cafes are ‘carb city centrals’ and finding something low-carb to eat may feel like an impossible task. Likewise, eating out at restaurants may present problems, or being served starchy or sweet food at a friend’s dinner party may be unavoidable if you want to stay friends!
So, what can you do to mitigate the effects of eating some starch or sugar?
Fortunately, there are a few ‘hacks’ that have been shown through research to flatten glucose spikes even when starchy or sugary foods have been eaten. Here’s three of them that you could try if you need to flatten your glucose spikes.
Three tips for reducing blood glucose spikes when you eat carbs
1. Eating foods in the right order
Who’d have thought that just eating the food on your plate in a certain order would have any effect on how big a glucose spike you will get over the next two hours? Yet study after study has shown this to be true.
The studies generally go like this: You provide a group of test subjects with a meal containing carbs, e.g. rice, potatoes or pasta, some protein e.g. meat or fish, and some vegetables. Then on 3 consecutive days, after an overnight fast, you ask them to eat the same meal but in a different order: vegetables, protein then carbs, or carbs, vegetables then protein, or protein, carbs then vegetables. You then measure their blood glucose levels over the next 2 hours. What you consistently find is that when the vegetables are eaten first and the carbs eaten last you get the smallest glucose spike. This is true for diabetics (9), pre-diabetics (10) and healthy people (11, 12).
Why does this work?
1. Phytonutrients in plants inhibit the enzyme alpha-amylase which breaks down starches and sugars to glucose (13) . Phytonutrients are chemicals found in a range of plants and wholegrains that protect the plant from predators and disease. By inhibiting alpha-amylase the digestion and release of glucose is slowed down, lessening the height of the glucose spike.
2. Eating the veggies first slows down the rate of gastric emptying (14). This is because food has to be broken down into very tiny pieces in the stomach before it can be passed into the small intestine and fibre is very hard to breakdown, so it takes longer. This has the effect of delivering partly digested starches and sugars to the small intestine at a slower rate and thus absorption of glucose is also slowed down.
3. When the digesting food is delivered to the small intestine and it includes lots of fibrous vegetables, its consistency is more viscous, making it more difficult for starches and sugars to be in contact with digestive enzymes and slowing down their digestion and absorption further (14)
One helpful trick is to have a small green salad before any meal that contains carbohydrates, or eat the side salad on your plate first. For even better effects combine this tip with hack 2. Also, if you want to eat fruit, then eat it as a dessert rather than a snack, that way you will still get the benefit of the previously eaten vegetables helping to control your blood glucose absorption.
2. Add vinegar to your salads and starches.
Consuming a drink of a tablespoon of vinegar in a glass of water before you eat your meal can significantly reduce glucose spikes after eating a meal containing carbohydrates (15). This is true for healthy people (16) diabetic and obese people where it also produces significant improvements in weight loss and blood lipid levels (17). Citric acid from lemon juice can have a similar effect on blood glucose levels (18).
The active ingredient in vinegar is acetic-acid and it appears to have two ways of modulating glucose metabolism: It inhibits the alpha-amylase enzyme, slowing down the absorption of glucose in the intestine and it increases glucose uptake by muscle cells, thus removing glucose from the blood more quickly, particularly if the muscles are being exercised (19)
Which vinegar works best?
Well, it doesn’t really matter. The most researched vinegar is apple cider vinegar (ACV), which probably tastes better than other vinegars, but any type of vinegar will have the same effect – wine vinegar, sherry vinegar, malt vinegar, rice vinegar, balsamic vinegar – just be sure it is an edible vinegar and not designed for domestic cleaning purposes!
If you don’t fancy drinking vinegary water, then add a vinegar dressing to your salad or stir in a tablespoon of rice vinegar to your rice (very Japanese). Make sure your vinegar dressing is homemade as shop bought ones often contain a lot of sugar. Just a simple dressing of olive oil and vinegar will help control your blood sugar if you are eating carbs.
Just a few tips about consuming vinegar: drink vinegary water through a straw to protect your teeth from regular acid attacks which can erode teeth enamel; don’t consume more than 3-4 tablespoons of vinegar per day as over-consumption may begin to have negative health consequences, and don’t use this hack if you have a very sensitive stomach. You may want to begin with just 1 teaspoon of vinegar in a glass of water to begin with and gradually increase it to 1 tablespoon as you get used to the taste.
3. Exercise after you have eaten.
Many studies have shown that doing some exercise within an hour of eating a meal containing carbohydrates can increase glucose uptake from the blood into the muscles, where it is metabolised to make energy in the form of ATP (20,21, 22). Increasing glucose uptake reduces the height of the glucose spike as glucose can removed from the blood as soon as it enters from the digestive system.
Both high and medium intensity exercise has the same effect, so just a 20 minute walk after a meal can be sufficient to control glucose spikes. During this post-prandial (after a meal) exercise glucose uptake by the muscles is not dependent on insulin and thus is not affected by insulin resistance. This means that people with pre-diabetes and diabetes can benefit from post-prandial exercise just as much as healthy people (20)
For exercise to be effective at flattening glucose spikes after a meal containing carbohydrates, it should be started within 1 hour of eating, preferably within 20-30 minutes. Once you are past the post-prandial period (about 4 hours after eating) then the glucose spike will have come and gone and the opportunity to flatten it will have passed.
Any kind of exercise will help flatten the spike including walking, climbing stairs, running, cycling, playing ball games and gardening or housework. If you have to sit after a meal because you are in a restaurant or at a friend’s house then do some calf raises under the table – even that will help!
For best effect combine all three hacks together
1. Have a glass of vinegar water before you eat or put a vinegar dressing onto a pre-meal salad
2. Pay attention to food order: eat your veggies first, then your meat/fish and leave your carbs until last. If you want to eat fruit, have it as a dessert.
3. Go for a walk or do some other exercise within an hour of eating
REMEMBER!
You can’t out-hack a bad diet!
If you really want to reduce those glucose spikes, then reducing your total consumption of starches and sugars in your diet is the best way (prevention is better than cure). If you are doing that then you have no need for these hacks, so save these tips for those days when you can’t avoid the carbs!