A study that examined the scepticism about the nutritional quality of low-carb diets found that they can meet and sometimes even exceed one's nutrient needs.
It is commonly advised for people with diabetes to use low-carb diets to regulate their blood sugar levels. These diets limit the consumption of foods that are high in carbohydrates or added sugars, such as sweets, starches, and refined grains.
While low-carb diets have been proven to offer health benefits like weight loss, some researchers say there is still doubt about the nutritional value of low-carb diets.
Some argue that reducing carb intake can lead to excessive consumption of protein or fat and insufficient intake of essential nutrients. The group of researchers, which includes experts from the University of Vermont in the US, made this claim.
In a study published in the journal Frontiers in Nutrition, they evaluated the nutritional adequacy of three different seven-day low-carb meal plans. Two of these were ketogenic diets - one with an average of around 20 grams of net carbs per day, and the other with an average of about 40 grams of net carbs per day. The third meal plan was more lenient, containing an average of around 100 grams of net carbs per day.
"All three low-carbohydrate meal plans exceeded recommendations (US) for vitamins A, C, D, E, K, thiamin, riboflavin, niacin, B6, folate and B12 in males and females in the age group of 31-70 years and exceeded calcium recommendations for adults in the age group of 31-50 years," the authors wrote.
"Our findings suggest that, in addition to their well-established ability to support weight management, low-carb eating patterns can actually help promote better diet quality and close critical nutrient gaps," co-author Beth Bradley, from the University of Vermont, said.
The researchers said that for certain sub-sections of the population—such as younger women requiring higher amounts of iron or older people needing more calcium—the low-carb meal plans fall slightly short in a few nutrients.
Further, they found that two of the three meal plans in the study—those containing 40 grams and 100 grams of net carbohydrates, respectively—also provided more than enough fibre for women aged 31-70.
While some low-carb diets are also known to be low on fibre, the researchers said the results do not support this idea.
"The idea that a low-carb diet must also be low in fibre is simply not supported by the data. High-fibre foods are actually an important part of a low-carb lifestyle, in part because fibre-rich food choices can help lower net carbohydrate intake," Bradley explained.
"Non-starchy vegetables, nuts and seeds, and, in moderation, even higher-carb fruits, starchy vegetables and whole grains can contribute fibre to the diet while keeping overall net carb intake in check, especially in the more liberal low-carb approach," the co-author said.
The researchers added that the low-carb meal plans provided more protein than needed to prevent deficiency without delivering an excessive amount that could be unsafe.