Ketogenic Diet in PDD, Autism, and Other Neurological Conditions

“I’ve been on a gluten-free and casein-free diet, but I don’t see any progress.”
“My son has been on the diet for years, he’s taking supplements, but he’s still irritable and shows stereotyped behaviors.”
“I tried the ketogenic diet with my son, but I didn’t see any results.”
“The ketogenic diet caused constipation.”

Ketogenic Diet in Patients with ASD

The ketogenic diet is characterized by a very high intake of fats, controlled protein consumption, and low carbohydrate intake.
For years, it has been applied as an effective and well-tolerated treatment in children with refractory childhood epilepsy. It has also been recommended to improve brain function in children with PDD (Pervasive Developmental Disorders).

In patients with Autism or PDD, the ketogenic diet is advisable in cases of pronounced stereotypies, or when the patient has plateaued on a gluten-free, casein-free, and allergen-restricted diet. This approach focuses on the redistribution of macronutrients (carbohydrates, proteins, and fats), meaning the fat intake can be increased at the expense of carbohydrates—always under the supervision of a nutritionist specialized in autism.

It has been commonly observed that patients with these diagnoses often have issues related to excessive carbohydrate intake, which tends to promote intestinal infections and brain inflammation, as well as deficiencies in neurotransmitter production, presence of epilepsy, poor muscle tone, attention and connection problems, among others.

Scientific sources, reported clinical cases, and our experience with patients reveal many positive changes after applying this type of diet, which is why we put it into practice.

Objective of the Ketogenic Diet in ASD Patients

According to García-Peñas (2016), the main objectives of the ketogenic diet are:

1. Energy Production:
   When fats are broken down, substances called ketones are produced. These feed the brain with energy, and they are much more efficient than glucose. Additionally, ketone metabolism produces less oxidative damage.
2. Anti-inflammatory Effect:
   Neurological conditions are inherently inflammatory. A high-fat diet promotes brain de-inflammation due to the quantity and quality of fatty acids consumed, combined with the low intake of carbohydrates.
3. Neuroprotection and “Neuronal Regeneration”:
   Neurons have a protective fatty layer. When neuronal damage occurs, there is a lack of this nutrient in the brain. Consuming healthy fats reduces the risk of neuronal injury and death.
4. Changes in the Microbiota:
   The microbiota produces short-chain fatty acids, which nourish beneficial gut bacteria. There is a feedback relationship between fat intake and microbiota, which enhances communication.
5. Signal Transmission:
   The ketogenic diet improves communication between neurons, as it affects sodium, calcium, potassium, and chloride channels—key for neurotransmitter release (often imbalanced in children with ASD)—as well as muscle contraction and even gene expression.
6. Improving Mitochondrial Respiration:
   It has positive effects on mitochondrial oxidative metabolism, serving as an alternative energy source.
7. Homeostatic Balance:
   It helps maintain equilibrium between the inside of cells and the bloodstream (homeostasis). For example, if nerve impulses are excessive, the diet helps reduce them; if they are insufficient, it helps increase them.
8. Genetic Modulation:
   Fats have the ability to inhibit the expression of certain genes and regulate protein expression. Patients with ASD often have SNPs (small genetic variations) that can be mitigated through a rigorous ketogenic diet.

When to Start This Diet

It’s essential to begin this diet only after:

• Implementing a 100% gluten-free, grain-free, casein-free, sugar-free, soy-free, additive-free, dye-free, and pesticide-free diet,
  since these are the main foods that trigger intestinal and brain inflammation.
• Achieving a less inflamed gut, good fat digestion, and proper lab results—especially pancreatic and liver enzyme levels.

Have You Tried the Keto Diet and Seen No Results?

If you’ve already tried this way of eating and haven’t seen results, we recommend re-evaluating and extending the trial period (at least 30 days) to achieve the ketosis necessary for benefits to appear.
It’s crucial to understand that this treatment must be personalized, supervised, and recommended by a specialist experienced in its application—not everyone is qualified to manage it.

Common mistakes when following a ketogenic diet include consuming too much protein or not properly tracking carbohydrate intake. It’s also important to choose the most suitable variant of the ketogenic diet for each patient’s condition. These include:

• Classic Ketogenic Diet (70–80% fats)
• Modified Ketogenic Diet
• MCT Oil Diet
• Low Glycemic Index Treatment
• Modified Atkins Diet

Other Considerations

This type of diet may cause constipation, dehydration, acidosis, or kidney stones if not properly managed. Therefore, continuous monitoring is essential. Alongside dietary adjustments, supplementation, hydration, and daily activity planning are highly recommended.

The 3 Key R’s of the Ketogenic Diet

1. Remove:
   All types of carbohydrates—especially those from grains, fruits, tubers (potato, cassava, sweet potato, etc.), and pseudocereals (quinoa, amaranth, buckwheat, etc.).
   Also, remove ultra-processed and grain-based oils (corn, soy, etc.).
2. Replace:
   Large amounts of healthy fats—virgin, cold-pressed oils such as coconut, olive, avocado, butter, and ghee (preferably from grass-fed cows), along with plenty of water and electrolytes.
3. Recalculate:
   The amount of daily protein intake. Consuming too much protein can prevent the positive effects of the ketogenic diet.

We recommend considering this diet at some stage of life—you’ll see there’s nothing to lose and everything to gain.

References:

1.    GARCÍA-PEÑAS JJ, Trastornos del espectro autista y epilepsia: el papel de la dieta cetogénica [XVIII Curso Internacional de Actualización en Neuropediatría y Neu, ropsicología Infantil] Revista de Neurología 2016;62(Supl.1): 73-S78, dirección web: https://www.neurologia.com/articulo/2015525

2.    Koppel SJ, Swerdlow RH., Neuroketotherapeutics: A modern review of a century-old therapy, 2018 Jul, https://www.ncbi.nlm.nih.gov/pubmed/28579059

3. R ALBERO, A SANZ, J PLAYÁN Servicio de Endocrinología y Nutrición. Hospital Universitario Miguel Servet. Zaragoza. España

4. José Guevara-Campos, Lucía González-Guevara, Autismo asociado a una deficiencia del Complejo III y IV de la cadena respiratoria mitocondrial, http://go.galegroup.com/ps/anonymous?id=GALE%7CA344827163&sid=googleScholar&v=2.1&it=r&linkaccess=abs&issn=05355133&p=AONE&sw=w