Vegetables For Diabetics – What To Eat And Avoid

Assorted vegetablesVegetables are a vital component of a healthy diet and this is particularly true for diabetics. Most fruits and vegetables are high in fiber and nutrient dense but low in calories making them ideal for diabetics who often need to watch their calorie intake. The general rule of thumb for diabetics is that root vegetables should be eaten in moderation (no more than 1 serving a day), while green and red vegetables are great choices and should be consumed in high amounts, preferably 3-5 servings a day. There are exceptions to this rule that we will discuss in more detail below.

Root Vegetables & Tubers

Root vegetables and tubers are relatively concentrated sources of sugars and starches and tend to contain only small amounts of fiber. This can be problematic for diabetics because they can produce a large glycemic response in situations when they are not combined with high fiber foods. The glycemic index of root vegetables and tubers range from moderate (40-60) to very high (80+). The lowest GI vegetables are yams, carrots and sweet potatoes with GI values of 38, 47 and 55 respectively. High GI root vegetables include potatoes (GI of 60-90), parsnip (97), rutabaga (71), and beets (65). If you like these vegetables, try and limit your intake to one serving (approx. 200g) a day.

Cooking method also has a significant impact on the GI value of the vegetable. In general, boiling rather than baking or mashing a root vegetable will result in a lower GI. Boiled potatoes for example have a GI of around 70 compared to 80-90 for mashing or baking.

Cooking root vegetables converts some of the starch into simple sugars which are more readily absorbed by the body, increasing their GI values. A raw carrot for example has a GI of just 15, while over-cooking a carrot until it turns to mush can result in a GI as high as 75. The best method of cooking carrots is to lightly steam them as most of the nutritional value will be retained and they will not have a significant impact on your blood sugar levels.

Green And Red Vegetables

Green leafy vegetables such as lettuce, chard, spinach, and the brassicas: broccoli, brussel sprouts, cabbage, cauliflower, bok choy, and kale, are all excellent choices for diabetics and can be consumed in any amounts. These vegetables tend to consist largely of water and fiber and contain very little of the starches and sugars that affect blood sugar levels. 100g of raw cabbage for example contains 92g of water, 2.5g of fiber, and just 3g of sugars.

Red vegetables are also helpful for diabetics because they contain lycopene, a red coloured carotenoid that has been linked to lower rates of prostate cancer and improved cardiovascular health. A 1999 study, published in the American Journal of Epidemiology, found that in both diabetics and individuals with impaired glucose tolerance, lycopene levels were significantly lower than in the general population. The authors also found a negative correlation between fasting insulin levels and levels of lycopene in the blood. High fasting insulin levels are an indicator of insulin resistance suggesting a potential link between high lycopene levels and improved insulin sensitivity.

Lycopene is found in high amounts in red vegetables such as tomatoes, red peppers, and red cabbage. Although not a red vegetable, asparagus also contains a significant amount of lycopene. Cooking tomatoes greatly increases the bioavailability of lycopene, as does consuming the food with a small amount of oil.

Magnesium Rich Vegetables

A high intake of magnesium has been linked to a lower risk of developing type-2 diabetes as well as increased insulin sensitivity. Magnesium deficiency has also been linked to a faster decline of renal function in type-2 diabetics. Diabetics are at a higher risk of magnesium deficiency than the general population because they lose more magnesium through their urine. It has been estimated that as many as 60% of type-2 diabetics are deficient in magnesium.

Magnesium rich vegetables include black beans, spinach, okra, broccoli, artichokes, peas, and Swiss chard.

Other Vegetables

In general, most other vegetables have low to moderate GI values and will not cause diabetics significant problems with glycemic control. In-fact most studies find that a diet high in vegetables reduces an individuals risk of developing diabetes.

Although not vegetables, legumes (peas, beans, and lentils) have GI values ranging from 25-50 and can therefore be eaten safely by diabetics. Legumes are relatively high in amylose, which along with amylopectin, are the two components of starch. Amylose is more slowly digested than amylopectin and thus is less likely to spike blood sugar and insulin levels.