Super superfoods – by Dr Alex Ryan
I tend to veer from anything labelled a ‘superfood’ as it’s very subjective, and there are no specific criteria for the definition. However, the American Diabetes Association has published a list of diabetes superfoods. At first appearance it seems to be a sensible list of fruits, vegetables and other good things, but if you look a little deeper you can see the benefits of these foods, especially to those with diabetes. All of them contain low glycaemic index; a measure of how much a food affects the blood sugar levels. A low index means that the food does not increase blood sugar levels by very much. Below I have explored several of the superfoods in a bit more detail, and explained how they can benefit you.
Sweet potatoes are great. As well as providing several vitamins and minerals, they are a good source of fibre and complex carbohydrates. Compounds derived from the sweet potatoes have been shown to lower blood sugar levels in mice, after only three weeks, and there are no studies suggesting that hypoglycaemia occurs. This is important as it suggests that sweet potatoes may be able to help control blood sugar levels, without dangerously lowering it too much. It also improves insulin resistance, a key factor in the development of Type 2 diabetes, and lowers HbA1c, suggesting that those at risk of Type 2 diabetes would also benefit from sweet potatoes.
Berries and Dark Green Leafy Vegetables
Berries and leafy vegetables such as spinach and kale are often lauded for their anti-oxidant capabilities. Anti-oxidants are a superfood staple, but are they all they’ve cracked up to be? Recently, a major review found that anti-oxidants offered no benefits to people in the general population. Oxidative stress is common in the body, and actually plays a key role in healthy insulin signalling. However, problems can arise from increased oxidative stress, and this is a common feature of Type 2 diabetes. However, unlike some the anti-oxidants in this list, I couldn’t find much evidence for either of these supplying specific benefits for Type 2 diabetes.
Citrus fruits contain compounds called flavonoids, which have been linked to improved metabolic function. These flavonoids are anti-oxidants and anti-inflammatory; two conditions which are increased in Type 2 diabetes. Two recent papers have shown that treatment with citrus fruit extracts can improve insulin resistance and obesity.
A Mediterranean diet has been shown to have several health benefits. Improved glycaemic control, insulin sensitivity and cardiovascular disease risk factors all correlate with a Mediterranean diet. High levels of tomatoes, legumes, nuts, whole grains and fish are all consumed in a Mediterranean diet, and feature in the list of super foods.
Lycopene is an anti-oxidant compound found in tomatoes, which may be able to lower the risk of long-term complications associated with diabetes. Tomatoes also contain a PPAR agonist, which has been shown to decrease levels of fatty acids in the blood. If you recognise the term “PPAR agonist” that’s because thiazolidinediones (or glitazones) are a family of drugs used to treat Type 2 diabetes, which work by activating PPAR.
Regardless of kidney, pinto or black, legumes are high in protein and fibre, as well as many vitamins and minerals. Beans have a very low glycaemic, and insulin, index, meaning that they do not cause elevated blood glucose or insulin levels after eating. They also improve cardiovascular risk factors, meaning they could be beneficial in preventing the complications seen with Type 2 diabetes. It’s a good idea to avoid baked beans though, as they contain a surprisingly large amount of sugar.
Fat-free Milk and Yoghurt
Dairy products contain high levels of vitamin D and calcium; which have been shown to improve insulin sensitivity and obesity. Furthermore, increased milk intake has been linked with lower rates of insulin resistance and Type 2 diabetes. Specific fats found in diary have also been shown to improve the fat profile of those with Type 2 diabetes, as well as decreasing fasting insulin levels.
Fish High in Omega-3 Oils
Omega-3 has long been regarded as a healthy fat, and its roles in treating hyperlipidaemia are well documented. Eating fish is prevalent in a Mediterranean diet, and high levels of omega-3 are linked to decreased rates of Type 2 diabetes. It has also been shown to have beneficial effects on those with Type 2 diabetes, by improving circulating levels of damaging fats. These can exacerbate insulin resistance and Type 2 diabetes, as well as play an active role in the onset of several long-term complications.
If anyone has any questions, feel free to leave a comment below. Or if you have a personal superfood that you want me to investigate, then write it below, and I’ll give it a go.