Iron Deficiency: Let’s talk about why you might be tired…

February 15, 2021

Keto vs Vegan what does the research say?

Hey everyone!

I wanted to share with you a recent review of the literature. This is by no means an exhaustive or systematic review, but it does consider very recent peer reviewed, scholarly meta-analysis, on two specific diet trends and offers unbiased information about the potential strengths, weaknesses and nutrient deficiencies of each.

A Comparative Review: Ketogenic Diet and Plant-Based Diet

A diet refers to food types people eat (“diet”, 2021). There are numerous diet methods, some contain rigorous guidelines for specific results, ethical or religious beliefs, while others attempt to treat medical conditions. A current literature review was utilized to compare the major differences and health-based outcomes of two diet regimes: ketogenic diet (KD) and plant-base/vegan diet (PBD).

Review Method

The review completed is not exhaustive, however recent (>2017) search of University of Porthmouth library and associated databases for meta-analysis, systematic reviews of human-based control trials. The parameters for KD or very low carbohydrate are < 30grams/day (carbohydrate) and for PBD no consumption of animal meat or no animal products. Utilizing 9 PBD and 9 KD articles provided a range of comparative literature to appraise (table below).

Plant-Based diet

The majority of PDB nutrients are derived from vegetables, fruits, pulses, nuts and seeds. This carbohydrate heavy diet consists of no animal products and relies on plants sources for all nutrients.

Benefits Plant-based Diet

PBD can have considerable positive health outcomes for anyone, but especially overweight clients or those suffering from preventable health conditions. PBD increases soluble, insoluble fibre and phytonutrient components due to the high consumption of fibrous vegetables, fruits and other antioxidant containing food, resulting in a disease preventing effects (Yeung et al., 2019). Specifically, PBD is associated with reduction in body weight (McMacken & Shah, 2017), decreased risk of cardio-cerebrovascular diseases and reductions in cancer (Dinu et al., 2017). This could be related to diverse plant-based fibre intake, and the production of butyrate, a short chain fatty acid (SCFA) which facilitates cell repair, tumour growth suppression and combats intestinal permeability (Carlson & Slavin, 2016). Human control trials suggest PBD’s are the most effective for weight loss and significantly reduce cholesterol without limiting intake or imposing exercise routines (Wright et al., 2017; Dinu et al, 2017). Additionally, the removal of animal meat components like histidine and leucine are correlated fat mass reductions and improved insulin resistance in a human study (Kahleova et al., 2018).

Young females who doubled their intake of plant-based proteins had more fibre, folate, vitamin E and iron in their diet (Demmer et al., 2017). 
Longitudinally, adolescents eating PBD had high levels of calcium, magnesium, zinc, vitamins A, E, K, C, iron, potassium and fibre overtime and generally healthy dietary intake (Michels, 2020).
Mariotti and Gardener suggest there is little evidence for protein deficiency in PBD’s especially if taking plant-proteins (e.g., legumes) (2019).

The PBD has the ability to change our moral future, with animal welfare and planet sustainability at the forefront. The motivation to adopt a PBD is of increased interest for ethical and climate change reasons (Miki et al., 2020). Adolescent females appear to adopt a PBD based on social norms, ethical beliefs, taste and appearance (Ensaff et al., 2015). Eating a variety of plants can have a tremendous positive effect for our bodies as well as our environment, but the removal of animal products has potential limitations.

Deficits Plant-based Diet

PBD limitations are related to the complete removal of animal products often without adequate replacement. PBD has been linked to reductions of B vitamins especially B2, B3, B12 (Selinger et al., 2019), as well as iodine, vitamin D, calcium, potassium, zinc, selenium (Bakaloudi et al., 2020) and heme iron (McMacken & Shah, 2017). Eating ‘double’ PBD may still not adequately replace vitamins D, Mg, Zn, Ca, K, however, the use of diary can provide sufficiently replace these nutrients (Demmer at al., 2017). After 10 years on a PBD, deficiencies in vitamin B12 and D still remain (Michels, 2020). Young people may have a very limited education of the impacts and nutritional effects of a PBD (Ensaff et al., 2015) and vegan foods can be mis-marketed to assume health, causing misinformation and influencing choice.

Consistently, PBD's are associated with micronutrient deficiency of zinc, vitamin B12, vitamin D and calcium (Bakaloudi et al., 2020; Michels, 2020; Selinger et al. 2019).

Although supplement of vegan protein is favourable for weight gain (Campmans-Kuijpers et al., 2015), it may not be favourable for some nutrient deficiencies. Education about how to adequately supplement for deficiencies with this diet is vital as vitamin B12 and calcium are necessary for creation of things like growth of bones, muscle function, development of DNA, red blood cells and other vital roles.

Ketogenic diet

In contrast, ketogenic diet (KD) derives nutrients mainly from animal sources, comprised of high fat, moderate proteins and low to no carbohydrates (Masood, Annamaraju & Uppaluri, 2020). KD was discovered to treat epilepsy in 1921 by Russel Wilder (Masood et al., 2020) and this treatment is still utilized today to treat pediatric epilepsy. In KD, carbohydrate intake is less than 30g/day, which causes a decrease in insulin secretion and the body enters a catabolic state. Eventually, after glucose stores are used, ketogenesis begins to occur and the body uses ketone bodies as the primary source of fuel and this sustained state is referred to as “nutritional ketosis” (Masood et al., 2020, p. 2).

Benefits Ketogenic

The use of KD in neurological disorders is an established medical treatment for many years, involving strict dietary guidelines. The mechanisms of KD involves the transfer of ketone bodies for use in the brain, and it is thought, the fatty acids resulting from KD may be the main therapeutic component that aids in neurological illness (Arora & Mehta, 2020). There are changes in the gut microbiome with a KD (Paoli et al., 2019) and although it is unclear if the changes are positive or negative, they appear necessary to facilitate the therapeutic effects for epilepsy treatment (Olson et al., 2018). Although following a KD does not appear to make a difference in lifestyle or physical activity, it may benefit those suffering from breast cancer by reducing inflammatory and cancer markers (Khodabakhshi et al., 2020).

A reason for choosing this diet is that ketogenesis facilitates fatty acid oxidation which leads to weight loss.

Clinically, KD can also reduce hepatic fat content (Lundgaard et al., 2019; Watanabe et al., 2020) and overall body fat (including visceral) without sacrificing lean muscle mass (Vargas et al., 2018). Compared to general low-fat diets, KD appears to have a greater effect on weight loss (Bueno et al., 2013). KD has the potential to mimic fasting, thus supporting metabolic regulation, reducing inflammation, oxidative stress (Rusek et al., 2020) and obesity in women (Lichtash et al., 2020). The KD has clinical implications for serious illness and potential preventative outcomes, however, is not without deficits.

Deficits Ketogenic

KD shows great potential for reducing obesity and the associated diseases; however, this does not come without side effects and unwanted variables.

A meta-analysis reveals KD can increase both HDL and LDL cholesterol (Mansoor et al., 2016; Bueno et al., 2013) and has also been associated with hypoglycemia and dyslipidemia in type 1 diabetes (Leow et al., 2018).

Diets low in fruits and vegetables, high in animal fat have been linked to kidney disease, reduced glomerular filtration rate and renal blood flow (Hariharan, Vellanki & Kramer, 2016).

Pre and probiotics are significantly reduced in the KD (Tagliabue et al., 2017), potentially resulting in dysbiosis due to low phytonutrient and fiber intake (Rinniella et al., 2019). Side effects from the KD are mainly gastrointestinal, including constipation relating to the lack of fibre as well as nausea and vomiting (Arora & Mehta, 2020). Pediatric growth is of concern due to the limiting of proteins and other nutrients. A 6-month study of children with epilepsy following this diet demonstrates that linear growth can be affected due to the disproportionate ratio of protein intake (Nation et al., 2014).

Lack of longitudinal studies and long-term compliance are issues with KD.

Limited foresight about the potential long-term effects of any nutritional program is of concern, due to the length of time necessary to observe nutritional deficiencies. Although short term positive cellular effects have been seen for Alzheimer’s and other neurodegenerative diseases in the elderly, Wlodarek (2019) found that reducing any food group in this population is too risky due to malnutrition and nutrient deficiencies overtime. Neurogenerative disease is a multidimensional illness with numerous factors including appetite suppression, changes in taste and smell (Wlodarek, 2019), adequate intake of calories must be of priority to prevent malnutrition.

What does this all mean?

From the research, KD is centered around disease treatment (e.g., obesity/ epilepsy), whereas PBD appears more a lifestyle choice. Both have side effects as omitting either animal products or fibrous carbohydrates has implications.

PBD is linked to reductions in weight, insulin resistance, cholesterol and prevention of cardiovascular illness, but has a greater potential for nutrient deficiencies mainly vitamin B12, zinc and calcium.

Monitoring nutrient levels and potentially supplementing these deficiencies in a PBD would be necessary, as they can result in significant symptoms like osteoporosis, fatigue and immune dysfunction. The PBD trend in young adults demonstrates the need for lifestyle and culinary education to prevent nutritional deficits in this still-growing population. There is also potential for protein and essential fatty acid deficiencies within uneducated populations, therefore supplementation and increasing daily intake of plant-based proteins, omega 3’s (e.g., tofu and ground flaxseed) and potentially adding dairy could prevent symptoms associated.

KD has clinical effectiveness for neurogenerative disease and epilepsy, however; there are several unknowns due to lack of long-term human trials and malnutrition risks for the elderly and pediatrics may outweigh the benefits.

Less nutrient deficiencies are reported with KD possibly because animal products facilitate the bio-availability of nutrients (Leroy & Barnard, 2020), 
but such an extreme limiting fibre and possible intake of low-quality animal fat could be detrimental to health.

If KD is necessitated due to illness, it would be vital to seek out nutritional support to prevent common issues like dyslipidemia and ensure that you are eating adequate fibre. Suggestions for KD followers, ensure adequate intake of low-carb antioxidants, phytonutrients and fibre, like blueberries (100 grams = 9.2 mmol of antioxidants) (Wolf et al., 2008) and chia seeds. Also ensuring high quality grass fed organic products, as these contain a higher level of bioactive compounds (Ribas‐Agustí et al., 2019). Choosing one of these pathways without significant erudition regarding the potential long-term consequences is major health concern, therefore, education and nutritional guidance would be the primary suggested intervention for either diet.

Limitations

The data search was limited in capacity and in time. This review was completed with a comparative approach, without systematic guidelines. The majority of clinical trials reviewed indicate association not causation.

In conclusion, this comparative review demonstrated that both KD and PBD have positives and negatives in regard to nutrients, lifestyle and health. Depending on specific goals e.g., weight loss or neurological treatment, either diet could be utilized. Understanding the potential implications of any specific diet is fundamental. Deciphering the differences in these two opposing diets, provided critical knowledge when recommending individualized dietary programs and what the potential deficiencies may be.

My advice: if you are going to change your diet or if you currently follow one of these diets – be sure you educate yourself or seek out assistance to ensure you are adequately getting the nutrient intake your specific body needs (we are all different). Nutrient deficiencies are root causes to significant health concerns and numerous chronic health issues!

Well I hope you enjoyed the review!

Warmest wishes,

Kaley Johnson

MN BN RN

Nutritional Suggestions related to main deficiencies for each diet

Diet

Main Deficiency and Symptoms

Potential Food recommendations

Plant-Based Diet

Vitamin B12

(Ataxia, fatigue, weight loss, muscle weakness, breathlessness, irritability, etc.)

Calcium

(Osteoporosis, heart palpitations, brittle nails, aching joints, anxiety, etc.)

Zinc

(Recurrent infections, weakness, delayed growth, wound healing etc.)

Essential Fatty Acids

(Mental health disorders, Skin disordered, thirst and frequent urination, etc.)

Proteins

(Fatigue, hormonal issues, immune system issues, brain fog, etc.)

Vitamin B12

· Nutritional yeast

· Fortified plant-milk

· Tempeh

· Mushrooms

Calcium

· Green leafy vegetables

· Pulses

· Soy milk fortified

· Sesame seeds

Zinc

· Benas

· Chickpeas

· Lentils

· Chia seeds

· Tofu

Essential Fatty Acids

· Walnuts

· Ground flax seed

· Hempseeds

· Soy

· Seaweed

Proteins

· Quinoa

· Nut butters

· Tofu

· Chia seeds

· Oats

Ketogenic Diet

Fibre

(Constipation, GI issues, high cholesterol, dysbiosis)

Phytonutrient

(Dysbiosis and associated symptoms, kidney disease, renal blood flow impairment)

Fibre & Phytonutrient (low carbs)

· Lettuce

· Celery

· Cucumber

· Leafy greens

· Cauliflower

· Cabbage

· Blueberries

· Flax

· Chia seeds

· Pistachios

· Avocado

References

Arora, N., & Mehta, T. R. (2020). Role of the ketogenic diet in acute neurological diseases. Clinical neurology and neurosurgery, 192, 105727. https://doi.org/10.1016/j.clineuro.2020.105727

Bakaloudi, D. R., Halloran, A., Rippin, H. L., Oikonomidou, A. C., Dardavesis, T. I., Williams, J., … & Chourdakis, M. (2020). Intake and adequacy of the vegan diet. A systematic review of the evidence. Clinical Nutrition. https://doi.org/10.1016/j.clnu.2020.11.035

Campmans-Kuijpers, M. J., Sluijs, I., Nöthlings, U., Freisling, H., Overvad, K., Weiderpass, E., … & Beulens, J. W. (2015). Isocaloric substitution of carbohydrates with protein: the association with weight change and mortality among patients with type 2 diabetes. Cardiovascular diabetology, 14(1), 1-10. https://doi.org/10.1186/s12933-014-0162-3

Carlso, J., & Slavin, J. (2016). Health benefits of fibre, prebiotics and probiotics: A review of intestinal health and related health claims. Quality Assurance and Safety of Crops & Foods, 8(4), 539-554. https://doi.org/10.3920/QAS2015.0791

Demmer, E., Cifelli, C. J., Houchins, J. A., & Fulgoni, V. L. (2017). The impact of doubling dairy or plant-based foods on consumption of nutrients of concern and proper bone health for adolescent females. Public health nutrition, 20(5), 824-831. From https://pubmed.ncbi.nlm.nih.gov/27829485/

diet. (2021). Retrieved 8 April 2021, from https://dictionary.cambridge.org/dictionary/english/diet

Dinu, M., Abbate, R., Gensini, G. F., Casini, A., & Sofi, F. (2017). Vegetarian, vegan diets and multiple health outcomes: a systematic review with meta-analysis of observational studies. Critical reviews in food science and nutrition, 57(17), 3640-3649. https://doi.org/10.1080/10408398.2016.1138447

Ensaff, H., Coan, S., Sahota, P., Braybrook, D., Akter, H., & McLeod, H. (2015). Adolescents’ Food Choice and the Place of Plant-Based Foods. Nutrients, 7(6), 4619–4637. https://doi.org/10.3390/nu7064619

Hariharan, D., Vellanki, K., & Kramer, H. (2015). The Western diet and chronic kidney disease. Current hypertension reports, 17(3), 16. https://doi.org/10.1007/s11906-014-0529-6

Kahleova, H., Fleeman, R., Hlozkova, A., Holubkov, R., & Barnard, N. D. (2018). A plant-based diet in overweight individuals in a 16-week randomized clinical trial: metabolic benefits of plant protein. Nutrition & diabetes, 8(1), 1-10. https://doi.org/10.1038/s41387-018-0067-4

Khodabakhshi, A., Seyfried, T. N., Kalamian, M., Beheshti, M., & Davoodi, S. H. (2020). Does a ketogenic diet have beneficial effects on quality of life, physical activity or biomarkers in patients with breast cancer: a randomized controlled clinical trial. Nutrition journal, 19(1), 1-10. https://doi.org/10.1186/s12937-020-00596-y

Leow, Z. Z. X., Guelfi, K. J., Davis, E. A., Jones, T. W., & Fournier, P. A. (2018). The glycaemic benefits of a very‐low‐carbohydrate ketogenic diet in adults with Type 1 diabetes mellitus may be opposed by increased hypoglycaemia risk and dyslipidaemia. https://doi.org/10.1111/dme.13663

Leroy, F., & Barnard, N. D. (2020). Children and adults should avoid consuming animal products to reduce risk for chronic disease: NO. The American Journal of Clinical Nutrition, 112(4), 931-936. https://doi.org/10.1093/ajcn/nqaa236

Lichtash, C., Fung, J., Ostoich, K. C., & Ramos, M. (2020). Therapeutic use of intermittent fasting and ketogenic diet as an alternative treatment for type 2 diabetes in a normal weight woman: a 14-month case study. BMJ Case Reports CP, 13(7), e234223. http://dx.doi.org/10.1136/bcr-2019-234223

Lundsgaard, A. M., Holm, J. B., Sjøberg, K. A., Bojsen-Møller, K. N., Myrmel, L. S., Fjære, E., … & Kiens, B. (2019). Mechanisms preserving insulin action during high dietary fat intake. Cell metabolism, 29(1), 50-63. https://doi.org/10.1016/j.cmet.2018.08.022

Mansoor, N., Vinknes, K., Veierød, M., & Retterstøl, K. (2016). Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: A meta-analysis of randomised controlled trials. British Journal of Nutrition, 115(3), 466-479. http://doi:10.1017/S0007114515004699

Mariotti, F., & Gardner, C. D. (2019). Dietary protein and amino acids in vegetarian diets—A review. Nutrients, 11(11), 2661. https://doi.org/10.3390/nu11112661

Masood, W., Annamaraju, P., & Uppaluri, K. R. (2020). Ketogenic diet. StatPearls [Internet]. From https://www.ncbi.nlm.nih.gov/books/NBK499830/

McMacken, M., & Shah, S. (2017). A plant-based diet for the prevention and treatment of type 2 diabetes. Journal of geriatric cardiology : JGC, 14(5), 342–354. https://doi.org/10.11909/j.issn.1671-5411.2017.05.009

Miki, A. J., Livingston, K. A., Karlsen, M. C., Folta, S. C., & McKeown, N. M. (2020). Using evidence mapping to examine motivations for following plant-based diets. Current developments in nutrition, 4(3), nzaa013. From https://academic.oup.com/cdn/article/4/3/nzaa013/5727296

Nation, J., Humphrey, M., MacKay, M., & Boneh, A. (2014). Linear growth of children on a ketogenic diet: does the protein-to-energy ratio matter?. Journal of child neurology, 29(11), 1496-1501. https://doi.org/10.1177/0883073813508222

Olson, C. A., Vuong, H. E., Yano, J. M., Liang, Q. Y., Nusbaum, D. J., & Hsiao, E. Y. (2018). The Gut Microbiota Mediates the Anti-Seizure Effects of the Ketogenic Diet. Cell, 174(2), 497. https://doi.org/10.1016/j.cell.2018.06.051

Paoli, A., Mancin, L., Bianco, A., Thomas, E., Mota, J. F., & Piccini, F. (2019). Ketogenic Diet and Microbiota: Friends or Enemies?. Genes, 10(7), 534. https://doi.org/10.3390/genes10070534

Ribas‐Agustí, A., Díaz, I., Sárraga, C., García‐Regueiro, J. A., & Castellari, M. (2019). Nutritional properties of organic and conventional beef meat at retail. Journal of the Science of Food and Agriculture, 99(9), 4218-4225. https://doi.org/10.1002/jsfa.9652

Rinninella, E., Cintoni, M., Raoul, P., Lopetuso, L. R., Scaldaferri, F., Pulcini, G., … & Mele, M. C. (2019). Food components and dietary habits: Keys for a healthy gut microbiota composition. Nutrients, 11(10), 2393. https://doi.org/10.3390/nu11102393

Rusek, M., Pluta, R., Ułamek-Kozioł, M., & Czuczwar, S. J. (2019). Ketogenic Diet in Alzheimer’s Disease. International journal of molecular sciences, 20(16), 3892. https://doi.org/10.3390/ijms20163892

Schüpbach, R., Wegmüller, R., Berguerand, C., Bui, M., & Herter-Aeberli, I. (2017). Micronutrient status and intake in omnivores, vegetarians and vegans in Switzerland. European journal of nutrition, 56(1), 283-293. From http://search.ebscohost.com/login.aspx?direct=true&db=s3h&AN=121083255&site=ehost-live

Selinger, E., Kühn, T., Procházková, M., Anděl, M., & Gojda, J. (2019). Vitamin B12 Deficiency Is Prevalent Among Czech Vegans Who Do Not Use Vitamin B12 Supplements. Nutrients, 11(12), 3019. https://doi.org/10.3390/nu11123019

Tagliabue, A., Ferraris, C., Uggeri, F., Trentani, C., Bertoli, S., de Giorgis, V., … & Elli, M. (2017). Short-term impact of a classical ketogenic diet on gut microbiota in GLUT1 Deficiency Syndrome: A 3-month prospective observational study. Clinical nutrition ESPEN, 17, 33-37. https://doi.org/10.1016/j.clnesp.2016.11.003

Vargas, S., Romance, R., Petro, J. L., Bonilla, D. A., Galancho, I., Espinar, S., … & Benítez-Porres, J. (2018). Efficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trial. Journal of the International Society of Sports Nutrition, 15(1), 1-9. https://doi.org/10.1186/s12970-018-0236-9

Watanabe, M., Tozzi, R., Risi, R., Tuccinardi, D., Mariani, S., Basciani, S., … & Gnessi, L. (2020). Beneficial effects of the ketogenic diet on nonalcoholic fatty liver disease: A comprehensive review of the literature. Obesity Reviews, 21(8), e13024. https://doi.org/10.1111/obr.13024

Waterall, J. (2015, October 12). High cholesterol: Beating the build-up during CHOLESTEROL MONTH. Retrieved March 26, 2021, from https://publichealthmatters.blog.gov.uk/2015/10/12/high-cholesterol-beating-the-build-up-during-cholesterol-month/

Włodarek D. (2019). Role of Ketogenic Diets in Neurodegenerative Diseases (Alzheimer’s Disease and Parkinson’s Disease). Nutrients, 11(1), 169. https://doi.org/10.3390/nu11010169

Wolfe, K. L., Kang, X., He, X., Dong, M., Zhang, Q., & Liu, R. H. (2008). Cellular antioxidant activity of common fruits. Journal of Agricultural Food Chemistry, 56(18), 8418-8426. https://doi.org/10.1021/jf801381y

Wright N., Wilson, L., Smith, M., Duncan, B., & McHugh, P. (2017). The BROAD study: A randomised controlled trial using a whole food plant-based diet in the community for obesity, ischaemic heart disease or diabetes. Nutrition & diabetes, 7(3), e256-e256. https://doi.org/10.1038/nutd.2017.3

Yeung, A. W. K., Tzvetkov, N. T., El-Tawil, O. S., Bungǎu, S. G., Abdel-Daim, M. M., & Atanasov, A. G. (2019). Antioxidants: scientific literature landscape analysis. Oxidative medicine and cellular longevity, 2019. https://doi.org/10.1155/2019/8278454

Summary of studies compared

Study

Type and description of study

Key findings/Results

Limitations

Plant-based Diet

16 week Randomized control trial.

Overweight participants n=75 or control n=37

The plant-based vegan diet proved to be superior to the control diet in improving body weight, fat mass, and insulin resistance markers.

Food diaries taken by subjects themselves. X

Wright, N., Wilson, L., Smith, M., Duncan, B., & McHugh, P. (2017). The BROAD study: A randomised controlled trial using a whole food plant-based diet in the community for obesity, ischaemic heart disease or diabetes. Nutrition & diabetes, 7(3), e256-e256. Retrieved from https://www.nature.com/articles/nutd20173?report=reader

12 Week Randomized control trial.

Diagnosed with Obesity or overweight subjects n=65 (control (normal care): 32 and intervention WFPB: 33)

Weight reduction was greater on a plant-based diet.

Reduction in mean cholesterol greater in intervention group.

Increased testing for normal subjects may have led to greater focused on treatment.

Self-reporting and recall. X

McMacken, M., & Shah, S. (2017). A plant-based diet for the prevention and treatment of type 2 diabetes. Journal of geriatric cardiology: JGC, 14(5), 342. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5466941/

Narrative Summary of current evidence. Including cohort, observation, interventional studies.

Multiple potential mechanisms underlie the benefits of a plant-based diet in ameliorating insulin resistance, including promotion of a healthy body weight, increases in fiber and phytonutrients, food-microbiome interactions, and decreases in saturated fat, advanced glycation end products, nitrosamines, and heme iron.

Non mentioned

Female adolescents (n1594) aged 9–18 years

Increase current intakes by 100 % of the following: (i) plant-based foods; (ii) protein-rich plant-based foods; and (iii) milk, cheese and yoghurt. The first two scenarios had commensurate reductions in animal products.

Doubling plant-based foods lowered intakes of total fat and saturated fat while increasing the intakes of dietary fibre, folate and vitamin E, but also resulted in lowered intakes for protein, Ca and vitamin D.

None mentioned

Ensaff, H., Coan, S., Sahota, P., Braybrook, D., Akter, H., & McLeod, H. (2015). Adolescents’ food choice and the place of plant-based foods. Nutrients, 7(6), 4619-4637. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4488805/

This study sought to explore adolescents’ attitudes and perceptions towards plant-based foods. Semi-structured focus group interviews were conducted with adolescents (age 14–15 years) (n = 29) attending an inner-city school in Yorkshire, UK

In the emergent grounded theory, a clear disconnect between plant-based foods and the parameters that adolescents use to make food choices, is highlighted. Further, key barriers to adolescents adopting a plant-based diet are differentiated and considered with respect to practice and policy.

The selection bias (self-selection and then by the school).

Miki, A. J., Livingston, K. A., Karlsen, M. C., Folta, S. C., & McKeown, N. M. (2020). Using evidence mapping to examine motivations for following plant-based diets. Current developments in nutrition, 4(3), nzaa013. Retrieved from https://academic.oup.com/cdn/article/4/3/nzaa013/5727296

Using evidence mapping to identify methods that capture motivations to follow plant-based diets and summarize. 56 publications that described 90 samples of plant-based diet followers and their dietary motivations. We categorized the samples by type of plant-based diet: vegan (19%), vegetarian (33%), semi-vegetarian (24%), and other, unspecified plant-based diet followers (23%). Of 90 studies examined, 31% administered multiple-choice questions to capture motivations, followed by rate items (23%), Food Choice Questionnaire (17%), free response (9%), and rank choices (10%).

Based on this framework, we saw that vegans and vegetarians tended to endorse ethical motivations, whereas semi vegetarians tended to endorse health motivations.

Non noted

Michels, N. (2020). A healthy plant-based diet from adolescence towards young adulthood: psychosocial determinants and nutrient intake/status correlates. The Proceedings of the Nutrition Society, 79(OCE2). Retrieved from https://www.cambridge.org/core/journals/proceedings-of-the-nutrition-society/article/healthy-plantbased-diet-from-adolescence-towards-young-adulthood-psychosocial-determinants-and-nutrient-intakestatus-correlates/31DAD82D6DE46A71E33806A03FB6BF86

10 year recall study. 69 healthy plant-based diets (hPDI) were remeasured in 2016 as young adults. The psychosocial determinants nutritional knowledge, advantages, awareness, social support, social norm, self-efficacy, barriers, availability and intention were tested by multiple linear regression. Nutrient status was determined by 16 markers in fasting blood.

In adolescents, hPDI was associated with lower energy intake, especially less overall fat, cholesterol, saturated fatty acids, mono-unsaturated fatty acids, proteins and mono/di-saccharides but more fibre. In micronutrients, higher intake of calcium, iron, magnesium, potassium, zinc, copper, vitamin A, C, E, K but less vitamin B12 and D were detected. Concerning nutrient status, hPDI was related to higher low-density cholesterol, vitamin D, vitamin C and beta-carotene levels.

Systematic review of clinical trials?

Energy intake were lower but not below RNI.

Regarding macronutrients, vegan diets are lower in protein intake compared with all other diet types. Veganism is also associated with low intake of vitamins B₂, Niacin (B₃), B₁₂, D, iodine, zinc, calcium, potassium, selenium. Vitamin B₁₂ intake among vegans is significantly lower (0.24–0.49 μg, recommendations are 2.4 μg) and calcium intake in the majority of vegans was below recommendations (750 mg/d). No significant differences in fat intake were observed. Vegan diets are not related to deficiencies in vitamins A, B₁, Β₆, C, E, iron, phosphorus, magnesium, copper and folate and have a low glycemic load.

Overall good quality of studies and number. Some self-reported/diary based can reduce validity.

Eighty-six cross-sectional and 10 cohort prospective studies were included. The overall analysis among cross-sectional studies reported significant reduced levels of body mass index, total cholesterol, LDL-cholesterol, and glucose levels in vegetarians and vegans versus omnivores.

This comprehensive meta-analysis reports a significant protective effect of a vegetarian diet versus the incidence and/or mortality from ischemic heart disease (−25%) and incidence from total cancer (−8%). Vegan diet conferred a significant reduced risk (−15%) of incidence from total cancer.

-Small sample size, accuracy of consumption and adherence of the diet.

Ketogenic Diet

12 Week control trial of 80 patients with locally or advanced breast cancer.

Results: No significant differences were seen in quality of life or physical activity scores between the two groups after 12 weeks; however, the KD group showed higher global quality of life and physical activity scores compared to the control group at 6 weeks (P = 0.02 P = 0.01). Decreases seen in levels of lactate and ALP in the KD group suggest that a KD may benefit patients with breast cancer.

Heterogeneous nature of the sample in regards to cancer stage.

A secondary limitation was the small sample size.

Randomized control trials of 24 healthy men in an 8-week program.

Results suggest that a KD might be an alternative dietary approach to decrease fat mass and visceral adipose tissue without decreasing lean body mass; however, it might not be useful to increase muscle mass during positive energy balance in men undergoing RT for 8 weeks.

No blood analysis, small subject group,

Arora, N., & Mehta, T. R. (2020). Role of the ketogenic diet in acute neurological diseases. Clinical neurology and neurosurgery, 192, 105727. Retrieved from https://doi.org/10.1016/j.clineuro.2020.105727

An overview of the scientific literature- both clinical and pre-clinical studies is presented along with the proposed mechanism of ketogenic diet.

This systematic review summarizes the mechanism by which the KD works and literature to support the use of KD in traumatic brain injury, status epilepticus, aggressive brain tumor and ischemic stroke.

Limited human studies, less randomized control trials, small sample size in the studies and most of these studies being case reports or retrospective studies.

Bueno, N. B., de Melo, I. S. V., de Oliveira, S. L., & da Rocha Ataide, T. (2013). Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. British Journal of Nutrition, 110(7), 1178-1187. Retrieved from https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/verylowcarbohydrate-ketogenic-diet-v-lowfat-diet-for-longterm-weight-loss-a-metaanalysis-of-randomised-controlled-trials/6FD9F975BAFF1D46F84C8BA9CE860783

randomized

controlled trials that assigned adults to a VLCKD or a LFD, with 12 months or more of follow-up. The secondary outcomes were TAG, HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), systolic and diastolic blood pressure,

glucose, insulin, HbA1c and C-reactive protein levels.

Individuals assigned to a VLCKD achieve a greater weight loss than those assigned to a LFD in the long

term; hence, a VLCKD may be an alternative tool against obesity. However, increased levels of HDL and LDL over a period of 12 months.

Dietary adherence and implementation measures are needed for quality control.

Rusek, M., Pluta, R., Ułamek-Kozioł, M., & Czuczwar, S. J. (2019). Ketogenic diet in Alzheimer’s disease. International journal of molecular sciences, 20(16), 3892. Retrieved from

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6720297/

Systematic review

Based on the limited animal studies and clinical trials, KD has beneficial effects for enhancing mitochondrial function and cellular metabolism

None-noted

Comprehensive review

Review of observational, cohort, clinical control, case-control studies which reported on ketogenic diet (and variation of) and non-alcoholic fatty liver disease (NAFLD) in relation to nutritional intervention

Non- noted

Leow, Z. Z. X., Guelfi, K. J., Davis, E. A., Jones, T. W., & Fournier, P. A. (2018). The glycaemic benefits of a very‐low‐carbohydrate ketogenic diet in adults with Type 1 diabetes mellitus may be opposed by increased hypoglycaemia risk and dyslipidaemia. Retrieved from https://onlinelibrary.wiley.com/doi/abs/10.1111/dme.13663

Observational study 11 adults underwent sampling and analysis of fasting blood, and were fitted with a blinded continuous glucose monitor for 7 days to measure glycaemic variability.

This study provides the first evidence that, ketogenic diets in adults with Type 1 diabetes are associated with excellent HbA_1c levels and little glycaemic variability, but may also be associated with dyslipidaemia and a high number of hypoglycaemic episodes.

None noted

Mansoor, N., Vinknes, K. J., Veierød, M. B., & Retterstøl, K. (2016). Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials. British Journal of Nutrition, 115(3), 466-479. Retrieved from https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/effects-oflowcarbohydrate-diets-v-lowfat-diets-on-body-weight-and-cardiovascular-risk-factors-ametaanalysis-of-randomised-controlledtrials/B8FBAC51C156D8CAB189CF0B14FB2A46

Meta-analysis of randomised controlled trials (RCT), assessing the effects of low-carbohydrate (LC) diets v. low-fat (LF) diets on weight loss and risk factors of CVD. Studies had to fulfil the following criteria: a RCT; the LC diet was defined in accordance with the Atkins diet, or carbohydrate intake of <20 % of total energy intake; twenty subjects or more per group; the subjects were previously healthy; and the dietary intervention had a duration of 6 months or longer

Compared with participants on LF diets, participants on LC diets experienced a greater reduction in body weight but increases in HDL and LDL.

Paoli, A., Mancin, L., Bianco, A., Thomas, E., Mota, J. F., & Piccini, F. (2019). Ketogenic diet and microbiota: friends or enemies?. Genes, 10(7), 534.

The aim of this systematic review is to dissect the complex interactions between ketogenic diet and gut microbiota and how this large network may influence human health.

The observations that a ketogenic diet can modulate and reshape gut microbiota represents a potential and promising future therapeutic approach.

None-noted