Low-carbohydrate diets, which provide less than 130 grams of carbohydrates per day, have been criticized for potentially lacking essential nutrients. However, a recent study published in Frontiers in Nutrition suggests that well-planned low- and very-low-carbohydrate diet plans may meet the nutrient needs of specific populations, particularly middle-aged women. While these diets can offer benefits, they may not be suitable for everyone, as they may lack some key nutrients while exceeding recommendations for others. Therefore, health professionals generally recommend a moderate to high consumption of carbohydrates from nutrient-dense, plant-based foods for optimal health.
The study, funded by Simply Good Foods USA, Inc., assessed the calorie and nutrient content of three well-planned 7-day low-carb diet plans. These plans were formulated to provide 20, 40, or 100 grams of net carbohydrates daily, along with varying amounts of other nutrients and calories. The researchers found that while the plans generally met or exceeded calorie requirements for middle-aged women, they fell short for older women and all men across both age groups. The meal plans, which replaced carbohydrates with fats, contained higher fat levels and lower carbohydrate levels than typically recommended.
Although the meal plans provided sufficient amounts of certain essential vitamins and minerals, such as vitamins A, C, D, E, K, and more, they failed to meet the calcium needs of older adults and iron needs of middle-aged women. The plans also contained saturated fats, exceeding recommended limits, but had a favorable omega-6 to omega-3 fatty acid ratio. Moreover, fiber intake varied among the different meal plans, with some groups exceeding recommended levels while others fell short. Adequate fiber intake is crucial for maintaining a healthy digestive system and controlling cholesterol levels.
According to Dr. Thomas M. Holland, a physician-scientist, animal-heavy low-carb diets may offer benefits, particularly when including high-quality protein sources like fatty fish rich in omega-3s. However, the saturated fats from full-fat dairy and red meats in the meal plans could increase LDL cholesterol levels and cardiovascular disease risks. Therefore, while animal proteins have their benefits, the overall dietary composition, particularly emphasizing plant-based foods, is generally superior for cardiovascular health.
Registered dietitian Alyssa Simpson emphasized that while low-carb diets can be nutritionally adequate for certain groups when carefully planned, the challenge lies in real-world implementation. Many low-carb diets rely on ultra-processed products, which may lack the health benefits of whole, nutrient-dense foods. Simpson stressed the importance of choosing high-quality, minimally processed foods to ensure that low-carb diets are both nutritionally complete and promote optimal health outcomes. Ultimately, while low-carb diets may offer benefits, their long-term sustainability and adherence can be challenging, highlighting the importance of considering practical factors when following such restrictive dietary patterns.
