by Discover how strategic low-carb meal plans not only meet your daily nutritional needs but also improve heart health by optimizing critical fatty acid and sodium-potassium balances, challenging conventional nutritional wisdom.
Study: Nutritional analysis of three low-carbohydrate diets differing in carbohydrate content. Image Credit: Chinnapong / Shutterstock
Article published in Limits in Nutrition provides a detailed overview of nutritional adequacy through a low-carbohydrate diet with variations carbohydrate content.
Background
The popularity of low-carbohydrate diets is increasing worldwide, especially among middle-aged women. Low-carbohydrate diets contain less than 130 grams of carbohydrates per day, or 10-25% of energy from carbohydrates. Similarly, very low-carbohydrate diets contain 20-50 grams of carbohydrate or less than 10% of carbohydrate-derived energy per day.
A large number of studies have found that low-carbohydrate diets are clinically effective in treating a variety of chronic metabolic diseases, including type 2 diabetes, metabolic syndrome, obesity, and polycystic ovarian syndrome.
A difference in the prevalence of cardiometabolic diseases has been observed among people belonging to historically marginalized racial, ethnic, socio-economic and cultural backgrounds. As noted in the study, well-planned low-carbohydrate diet plans can serve as an effective intervention to address such health disparities.
The Recommended Dietary Allowance (RDA) for total carbohydrates is 130 grams per day, based on the average amount of glucose used by the brain daily. This standard has been a significant barrier to the inclusion of low-carbohydrate diets in current nutritional guidelines despite clinical evidence supporting their benefits.
In this study, scientists have estimated the macro and micronutrient content of three 7-day low-carbohydrate diet plans to explore the nutritional adequacy of different types of carbohydrate restriction.
Study design
The study analyzed the nutrient content of two very low-carbohydrate diets and a low-carbohydrate diet, which provided 20, 40, and 100 grams of net carbohydrates per day, respectively. Net carbohydrate refers to the total non-fibrous saccharides that are digestible in humans.
The nutrients of public health concern identified in the 2020 Dietary Guidelines for Americans were considered when selecting food items for diet plans. Specifically, these diet plans were designed based on dietary patterns used in studies of ketogenic and low-carbohydrate diets as well as commercial low-carbohydrate diets.
Diet plan nutrient content was analyzed using the US Department of Agriculture Food Data Central, which includes five separate data types that provide information on food and nutrient profiles.
Important comments
The energy and nutrient analysis of three diet plans showed that two very low-carbohydrate diets with 20 grams and 40 grams of carbohydrates (VLCD20 and VLCD40) and the low-carbohydrate diet with 100 grams of carbohydrates (LCD100) provide 91 %, 94%. , and 100% of the RDA for energy, respectively, among females aged 31 – 70 years.
For older females aged 51 – 70 years, VLCD20 and VLCD40 met the RDA for energy; however, LCD100 provided 12% more energy than the RDA. In males, none of the diet plans could meet the RDA for energy across all age groups.
Among males and females aged 31 – 70 years, VLCD20, VLCD40, and LCD100 provided 37, 55, and 98% of the RDA for dietary carbohydrates, respectively. Among women aged 31 – 70 years, VLCD40 and LCD100 provided 9% and 16% more dietary fiber than the RDA, respectively. However, VLCD20 could not meet the RDA for dietary fiber in this age group.
For older females aged 51 – 70 years, VLCD20 provided adequate dietary fiber, while VLCD40 and LCD100 exceeded the RDA by more than 20%. In males aged 31 – 70 years, none of the diet plans could meet the RDA for dietary fiber; however, VLCD40 and LCD100 met the requirement for older men aged 51 – 70 years.
All three diet plans provided higher amounts of protein than the RDA in males and females aged 31 – 70 years. However, the amounts were within the Acceptable Macronutrient Distribution Range of 10-35% of energy.
For saturated fat and sodium, all diet plans slightly exceeded the RDA. However, the study shows that despite this, the ratio of omega-6 to omega-3 fatty acids was much lower than the average American diet, which may offer protective benefits against chronic diseases. The sodium-to-potassium ratio in all three diets was also favorable, still well below one, which is considered beneficial for cardiovascular health. This is particularly noteworthy since most American diets exceed recommended sodium intake and fall short of potassium, a pattern associated with increased cardiovascular risk.
Essential Micronutrients
All three diet plans exceeded the RDA for vitamins A, C, D, E, and K, thiamin, riboflavin, niacin, B6, folate, and B12 in adults aged 31 – 70 years and the RDA for calcium in adults aged 31-50 years. However, all values remained below the Upper Tolerable Intake Level.
For females aged 31 – 50 years, all three diet plans met or exceeded the Estimated Average Requirement for protein and essential micronutrients.
Study importance
The study shows that low-carbohydrate diets intentionally designed to provide lower amounts of carbohydrates than the RDA can deliver adequate amounts of fiber and micronutrients to Americans’ diets.
In addition, the results indicate that these well-constructed diet plans not only meet the dietary requirements for essential micronutrients in specific populations, especially females between 31-50 years of age, who are most likely to these diets would continue but may exceed those requirements. This challenges the common perception that low-carbohydrate diets are nutritionally inadequate and highlights the importance of considering dietary quality, not just carbohydrate quantity, in dietary guidelines.
The study also highlights the importance of the ratio of omega-6 to omega-3 fatty acids and sodium to potassium provided by the diets, especially for individuals who already have metabolic health problems. These ratios may play a critical role in reducing the risk of chronic diseases, such as cardiovascular disease, in populations following low-carbohydrate diets.
