Optimal Nutrition for Health and Wellbeing

What is the optimal diet to provide us with the maximal long term health benefits, wellbeing and, ultimately, longevity? Scientists have been looking to answer this in an effort to address the global disease burden and to meet the basic aspiration of humanity to live long and healthy lives. The question we set out to ask is whether there is scientific consensus around an optimal human diet – at least for those seeking a long healthy life as a core aspiration.

OUR ANCESTRAL GENOME AND MODERN NUTRITION

Our physiological needs as a species, and associated genetics have predominantly been molded by the environmental pressures during the many millennia we spent living as hunter-gatherers; before we became farmers and food processors. Here we were sustained on a diet rich in plant-derived foods including berries, nuts, seeds, with additional protein from wild fish, birds, and game. The relative proportions would have varied by our geographical area and abundance of food [Cordain et al., 2005].

Agriculture and farming, beginning around 12,000 years ago and industrial food processing from the last few hundred years are comparatively recent additions on our evolutionary scale. Fatty meats, cereals, high levels of dairy, refined sugars, refined fats, alcohol, and salt would have been completely absent from our ancestors diet. And yet these food categories are now thought to make up over >70% of a modern US diet [Cordain et al 2005]. Moreover, many of these dietary components are consumed in a processed or highly processed form – meaning they are changed considerably from when they were harvested or reared – leaving ‘foods’ that are energy dense but micronutrient deficient.

The mismatch between modern day dietary preferences and our ancestral genome has been postulated by many as a, if not the, major cause in the global rises in non-communicable diseases  (NCDs) including many cancers, cardiovascular diseases (CVD), Type 2 diabetes and other obesity-related diseases, accounting, per the WHO, for 71% of all deaths globally.

So what are the physiological requirements of a human diet? There is broad scientific consensus as to the recommended quantities and ratios of macronutrients, micronutrients, vitamins, and minerals and calorie intake required to avoid deficiencies; see for example, the recommendations of the UK National Health Service (link) and the World Health Organization (link). However, such  guidelines by themselves describe nutritional building blocks rather than the practical aspects of preparing meals, which is ultimately how the quest for an ‘optimal diet’ is usually framed.

With that in mind, what does the scientific evidence base tell us about the optimal diet in practice? Here we examine scientific studies of several diets popularly touted as offering health and longevity benefits.

THE MEDITERRANEAN DIET

The Mediterranean Diet is predominantly plant-based from vegetables, fruits, lentils, pulses, tree nuts, seeds, whole grains, plus fish and other seafood, small amounts of dairy products and olive oil as a primary source of fat. Red and processed meat is limited and alcohol consumption moderate.

The diet is supported by numerous research studies as being optimal for reducing the incidence of several diseases, including conditions that lead to premature death [Dinu M et al 2018; Martinez-Gonzalez, MA et al., 2019; Schwingshackl L, Hoffmann G, 2020]. A comprehensive review of 13 observational studies and 17 meta-analyses of randomized clinical trials (RCTs), covering 12.8 million individuals showed a reduced risk of overall mortality, cardiovascular disease and heart attacks, stroke, cancer and neurodegenerative disease (particularly Alzheimer’s and Dementia) [Dinu M et al 2018]. Fish and seafood feature prominently in the diet contributing omega-3 fatty acids, which reduce the incidence of Type 2 diabetes, hypertension, atherosclerosis, depression, some cancers and cognitive decline [Horrocks, L. A. & Yeo, Y. K.1999; Kris-Etherton, P et al., 2002; Swanson, D et al., 2012].

JAPANESE DIETS

Japanese diets are commonly associated with longevity. As with Mediterranean diets, a traditional Japanese diet has low levels of red meat, dairy products, and sugars. It also incorporates relatively high levels of fish and seafood. In addition, rice, soybeans, and tea (mostly green) figure prominently. Overall calorie intake in Japan is lower per individual than with other developed nations, with a corresponding reduction in obesity levels [Tsugane, S. 2020].

The Okinawa Islands are of particular interest given the highest numbers of centenarians and the lowest rates of NCDs in the world amongst the generation currently aged 65+. Their staple food, by contrast with the polished rice consumed in mainland Japan, is sweet potato as part of a high vegetable intake, accounting for over half of their daily calories. Research shows that this generation of Okinawans also experienced low caloric intake until middle age, mimicking a calorie restricted diet, with a negative energy balance [Wilson et al 2007; Chan et al., 1997].

One limitation often noted is the high sodium content of Japanese diets, which can correlate to elevated rates of hypertension, cardiovascular diseases [Miura et al., 2010; Nagata et al., 2004; Umesawa et al., 2008; Tsugane and Sasazuki, 2007]. Although this is much less pronounced in Okinawa [Willcox et al., 2007].

THE DASH DIET

The ‘Dietary Approaches to Stop Hypertension’ (DASH) diet was developed and trialed by researchers at John Hopkins University, for cardiovascular health [Appel et al.,1997]. It is based on fruit, vegetables, whole grains and lean meats, including fish and poultry, with a limited daily intake of dairy and a weekly quota of beans, nuts and seeds. It contains less sodium, sugar, fats, and red meat than the usual Western diet. [National Heart Lung and Blood Institute, US DASH eating plan]. Combining the diet with a reduction in sodium-intake (maximum 2300 mg/day) can further amplify its positive effects [Sacks et al., 2001]. Long-term studies have associated the diet with lower risk for diabetes, and several types of cancer, among other chronic age associated diseases [Shirani et al., 2013; Soltani 2020; Chiavaroli et al., 2019].

PALAEOLITHIC DIET

The Palaeolithic, or ‘Paleo’ diet requires individuals to consume food groups that mimic our hunter-gather ancestors. This usually includes fish, lean meats, eggs, vegetables, fruits, and nuts, and excludes cereals, whole grains, legumes, pulses, dairy products, alcohol, processed foods and sugar.

A small number of RCTs with short-term time scales (weeks or a few months), and limited subjects have shown some benefits of this style of diet for weight loss, inflammatory bowel disease and Type 2 diabetes with improved glucose control, compared to other conventional healthy diets [Masharani et al., 2015; Jönsson et al., 2009]. Yet, a review of four studies with a total of 98 subjects concluded that whilst beneficial, the Paleo diet did not materially differ from other types of diets commonly perceived as healthy (eg the Mediterranean diet), especially with regard to effects on glucose and insulin homeostasis [Jamka et al., 2020]. Commonly noted limitations with the Paleo diet are potential deficiencies in iron, calcium and vitamin D, which have been observed in some clinical trials due to the exclusion of many food groups [Konijeti et al., 2017 reported this finding in their clinical trial for IBD management]. In addition, Paleo diets exclude wholegrains, which, as a primary source of fiber, have been shown to reduce rates of chronic diseases and all-cause premature mortality [Aune D et al., 2016].

KETOGENIC DIET

‘Keto’ diets (of which the ‘Atkins’ is a well-known example) hijack the natural inclination of the body to go into a metabolic state called ‘physiological ketosis’ when it has insufficient carbohydrates to use for energy, ultimately resulting in weight loss.

The standard keto diet includes high levels of fat (~70%), medium amounts of protein (~20%) and very limited quantities of carbohydrate intake (around 10% equating to <50 g a day on an average 2000 calorie a day diet). There are also high protein variants with 35% protein and only 5% carbohydrates.

A US clinical trial of 132 morbidly obese individuals comparing the keto diet with a traditional low fat diet for weight loss showed more than double the weight loss over 6 months from the former (8.6 kg versus 4.2 kg) [Samaha et al., 2003]. There are also short-term studies (over weeks) showing a reduction of certain cardiovascular risk factors [Reviewed in Paoli et al., 2013] and longer term interventions (> 1 year) showing marked improvements for disease markers for individuals with Type 2 diabetes, including a halving of fasting circulating glucose and improved insulin sensitivity [Reviewed in Paoli et al., 2013]. Keto diets have been used with success in the management of epilepsy by changing neuronal metabolism and excitability to reduce the seizure frequency [D’Andrea Meira et al., 2019].

Whilst there is no current consensus in the scientific community regarding the safety and efficacy of the diet long term, some research has highlighted potential health concerns with versions of the keto diet. [See for example, Hariharan et al 2015]. Animal-based protein keto diets may be high red and processed meats and low in fruits, vegetables, and whole grains. This approach has been widely shown to increase the risk of chronic diseases [Fung et al., 2010].

VEGETARIAN AND VEGAN DIETS

Vegetarian diets involve excluding all types of meat, fish and seafood. They usually include dairy intake. Vegan diets, on the other hand are plant-based and exclude all animal-derived products.

There is ample evidence for the health benefits of these diets. A meta-analysis of 96 individual studies in Europe (UK, Germany) and the US looking at vegetarian and vegan diets showed a significant reduced risk of incidence and/or mortality from ischemic heart disease and occurrence of total cancer, ( -25% and -8% amongst vegetarians compared to omnivores), but not of total cardiovascular and cerebrovascular diseases, all-cause mortality and mortality from cancer. The vegan diet showed a significant further reduction in total cancer rates (-15%) [Reviewed in Dinu et al., 2017]. Vegetarians and vegans are shown to have lower BMI’s, less likely to be obese, have lower fasting blood glucose, total cholesterol, LDL-cholesterol and triglycerides levels than omnivores, all protective effects against the development of chronic disease [Dinu et al., 2017].

A well-known study commonly known as ‘the Cornell China Study’ (or just ‘The China Study’) compared the diets and mortality data for >50 diseases, including 7 different cancers, from 65 counties and 130 villages in rural mainland China versus the US. Chinese subjects consumed low levels of animal protein (10% of typical US intake) or no meat and all had a high vegetable intake, particularly of green leafy vegetables. They had dramatically lower incidences of mortality from NCDs. Notably, coronary artery disease mortality was 17-fold lower for men and 6-fold lower for women than their American counterparts. Limitations of the study include the fact that differences in lifestyle factors were not taken into consideration.

Care must be taken, in vegan diets in particular, that sufficient levels of micronutrients commonly found in animal sources like B12, iron and vitamin D are taken through the diet. More fundamentally, it is possible to have an unhealthy vegetarian diet. There is a higher prevalence of Type 2 diabetes and chronic diseases in the Indian vegetarian population compared to elsewhere. Evaluation of the Indian vegetarian diet by researchers attributes this to higher intakes of dairy, fried foods and desserts with refined sugars [Jaacks et al., 2016].

INTERMITTENT FASTING AND CALORIC RESTRICTION

Dietary restriction (DR) is where calorie intake is significantly reduced – for example, a reduction of 25% of energy expenditure is seen as moderate DR and 55% severe DR. In a DR program, care is taken that malnutrition is avoided and at least 100% of the recommended daily intake for each essential vitamin and mineral is consumed. Alternative versions include fasting or eating in a restricted time window.

In human cohort studies and clinical trials with moderate and severe DR, protection has been shown against muscle-loss, inflammatory pathways that contribute to aging, cardiovascular disease, brain atrophy, obesity, Type 2 diabetes and cancer amongst others risk factors, including a decrease in the measures of biological ageing [Heilbronn et al., 2006; Cava & Fontana. 2013; Fontana and Partridge 2015, Belsky et al., 2017]. One of the limitations of severe DR, and even moderate DR, is that it is hard to maintain over any long period; requiring close dietary monitoring and supplementation, so that malnutrition and deficiencies do not result.

A NOTE ON RED MEAT AND PROCESSED MEATS

One area of important study has been of potential links between the consumption of red meat and processed meats and although the detail is beyond the scope of this article, we can state that a plethora of peer-reviewed research studies have shown the adverse effects of high levels of red meat, particularly those in a processed form as being a causative factor for cancer, specifically colon cancer, through multiple pathways [Bastide et al., 2011; Cross et al., 2004; Fiorito et al., 2020; Santarelli et al., 2008].

GUT MICROBIOME: A VECTOR OR DASHBOARD FOR HEALTH AND LONGEVITY

A huge number and diversity of microbes live in the linings of our gut, including bacteria, viruses, yeasts and fungi, comprising our ‘gut microbiome.’ A balanced and diverse gut microbiome has been proven by numerous research studies to have a significant role in optimal health and an imbalance is implicated in several disease categories including neurodegenerative disease, obesity, type 2 diabetes and several cancers. The gut microbiome also forms a critical concentration point of our immune cells, which research suggests has far reaching implications for our health in totality.

An in depth analysis of the function of the gut microbiome and its impact on health and longevity can be found in our recent article (link). Suffice to say here that studies show that our nutrition is a significant influence on the composition of our microbiota. Dietary interventions, like consuming whole grains, fiber-rich foods including fruit and vegetables, low levels of animal fats, plant-derived proteins, polyphenol-rich food and drinks, pro- and prebiotics have all been shown to enrich beneficial microbiota that are associated with optimal health and longevity. Unsurprisingly, these foods have significant overlap with the composition of the healthiest global dietary approaches we’ve discussed.

CONCLUSIONS

Cumulative scientific studies indicate that the Mediterranean, Japanese, DASH, vegan, vegetarian and pesco-vegetarian diets (with low dairy, saturated fats and refined sugars) promote a longer, healthier life. The keto approach may be good for weight loss in the short-term, but a high animal fat and protein approach could lead to higher levels of chronic disease long term. Paleo diets lack long term studies, and nutrient deficiencies can arise. Intermittent fasting or dietary restriction to limit calorie intake, or increased activity, for a minor negative energy balance (-11%), whilst ensuring micronutrient needs are covered, has also been shown to be strongly advantageous for health and longevity.

To summarize the findings further, the commonalities between all of the optimal diets are high plant-based intake, a whole food approach (i.e. taking the food in its naturally occurring state rather than processed), low levels or absence of red meat, moderate to regular fish intake (particularly fatty fish rich in omega-3), limited consumption of saturated fats, inclusion of monounsaturated fats from olive oil and nuts, nutrient variance, limited refined sugars, moderate sodium and low alcohol levels. Managing calorific equilibrium and eating during time restricted windows are also of benefit.

© SX2 VENTURES (2021)

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REFERENCES

Appel LJ, Moore TJ, Obarzanek E, Vollmer WM, Svetkey LP, Sacks FM, Bray GA, Vogt TM, Cutler JA, Windhauser MM, Lin PH, Karanja N. A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N Engl J Med. 1997 Apr 17;336(16):1117-24. doi: 10.1056/NEJM199704173361601

Aune D, Keum N, Giovannucci E, Fadnes LT, Boffetta P, Greenwood DC, Tonstad S, Vatten LJ, Riboli E, Norat T. Whole grain consumption and risk of cardiovascular disease, cancer, and all cause and cause specific mortality: systematic review and dose-response meta-analysis of prospective studies. BMJ. 2016 Jun 14;353:i2716. doi: 10.1136/bmj.i2716.

Belsky DW, Huffman KM, Pieper CF, Shalev I, Kraus WE. Change in the Rate of Biological Aging in Response to Caloric Restriction: CALERIE Biobank Analysis. J Gerontol A Biol Sci Med Sci. 2017 Dec 12;73(1):4-10. doi: 10.1093/gerona/glx096.

Campbell TC, Parpia B, Chen J. Diet, lifestyle, and the etiology of coronary artery disease: the Cornell China study. Am J Cardiol. 1998 Nov 26;82(10B):18T-21T. doi: 10.1016/s0002-9149(98)00718-8. PMID: 9860369.

Cava E, Fontana L. Will calorie restriction work in humans? Aging (Albany NY). 2013 Jul;5(7):507-14. doi: 10.18632/aging.100581. PMID: 23924667; PMCID: PMC3765579.

Chan YC, Suzuki M, Yamamoto S. Dietary, anthropometric, hematological and biochemical assessment of the nutritional status of centenarians and elderly people in Okinawa, Japan. J Am Coll Nutr. 1997 Jun;16(3):229-35. doi: 10.1080/07315724.1997.10718679. PMID: 9176829.

Chiavaroli L, Viguiliouk E, Nishi SK, Blanco Mejia S, Rahelić D, Kahleová H, Salas-Salvadó J, Kendall CW, Sievenpiper JL. DASH Dietary Pattern and Cardiometabolic Outcomes: An Umbrella Review of Systematic Reviews and Meta-Analyses. Nutrients. 2019 Feb 5;11(2):338. doi: 10.3390/nu11020338.

Cordain L, Eaton SB, Sebastian A, Mann N, Lindeberg S, Watkins BA, O’Keefe JH, Brand-Miller J. Origins and evolution of the Western diet: health implications for the 21st century. Am J Clin Nutr. 2005 Feb;81(2):341-54. doi: 10.1093/ajcn.81.2.341

D’Andrea Meira I, Romão TT, Pires do Prado HJ, Krüger LT, Pires MEP, da Conceição PO. Ketogenic Diet and Epilepsy: What We Know So Far. Front Neurosci. 2019;13:5. Published 2019 Jan 29. doi:10.3389/fnins.2019.00005

Dinu M, Abbate R, Gensini GF, Casini A, Sofi F. Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies. Crit Rev Food Sci Nutr. 2017 Nov 22;57(17):3640-3649. doi: 10.1080/10408398.2016.1138447. PMID: 26853923.

Dinu M, Pagliai G, Casini A, Sofi F. Mediterranean diet and multiple health outcomes: an umbrella review of meta-analyses of observational studies and randomized trials. Eur J Clin Nutr. 2018 Jan;72(1):30-43. doi: 10.1038/ejcn.2017.58.

Fontana L, Partridge L. Promoting health and longevity through diet: from model organisms to humans. Cell. 2015 Mar 26;161(1):106-118. doi: 10.1016/j.cell.2015.02.020. PMID: 25815989; PMCID: PMC4547605.

Fung TT, van Dam RM, Hankinson SE, Stampfer M, Willett WC, Hu FB. Low-carbohydrate diets and all-cause and cause-specific mortality: two cohort studies. Ann Intern Med. 2010 Sep 7;153(5):289-98. doi: 10.7326/0003-4819-153-5-201009070-00003

Hariharan D, Vellanki K, Kramer H. The Western Diet and Chronic Kidney Disease. Curr Hypertens Rep. 2015 Mar;17(3):16. doi: 10.1007/s11906-014-0529-6. PMID: 25754321.

Heilbronn LK, de Jonge L, Frisard MI, DeLany JP, Larson-Meyer DE, Rood J, Nguyen T, Martin CK, Volaufova J, Most MM, Greenway FL, Smith SR, Deutsch WA, Williamson DA, Ravussin E; Pennington CALERIE Team. Effect of 6-month calorie restriction on biomarkers of longevity, metabolic adaptation, and oxidative stress in overweight individuals: a randomized controlled trial. JAMA. 2006 Apr 5;295(13):1539-48. doi: 10.1001/jama.295.13.1539

Jaacks LM, Kapoor D, Singh K, Narayan KM, Ali MK, Kadir MM, Mohan V, Tandon N, Prabhakaran D. Vegetarianism and cardiometabolic disease risk factors: Differences between South Asian and US adults. Nutrition. 2016 Sep;32(9):975-84. doi: 10.1016/j.nut.2016.02.011

Jamka M, Kulczyński B, Juruć A, Gramza-Michałowska A, Stokes CS, Walkowiak J. The Effect of the Paleolithic Diet vs. Healthy Diets on Glucose and Insulin Homeostasis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Clin Med. 2020 Jan 21;9(2):296. doi: 10.3390/jcm9020296

Jönsson T, Granfeldt Y, Ahrén B, Branell UC, Pålsson G, Hansson A, Söderström M, Lindeberg S. Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study. Cardiovasc Diabetol. 2009 Jul 16;8:35. doi: 10.1186/1475-2840-8-35

Konijeti GG, Kim N, Lewis JD, et al. Efficacy of the Autoimmune Protocol Diet for Inflammatory Bowel Disease. Inflamm Bowel Dis. 2017;23(11):2054-2060. doi:10.1097/MIB.0000000000001221

Masharani U, Sherchan P, Schloetter M, Stratford S, Xiao A, Sebastian A, Nolte Kennedy M, Frassetto L. Metabolic and physiologic effects from consuming a hunter-gatherer (Paleolithic)-type diet in type 2 diabetes. Eur J Clin Nutr. 2015 Aug;69(8):944-8. doi: 10.1038/ejcn.2015.39

Miura K, Okuda N, Turin TC, Takashima N, Nakagawa H, Nakamura K, Yoshita K, Okayama A, Ueshima H; NIPPON DATA80/90 Research Group. Dietary salt intake and blood pressure in a representative Japanese population: baseline analyses of NIPPON DATA80. J Epidemiol. 2010;20 Suppl 3(Suppl 3):S524-30. doi: 10.2188/jea.je20090220.

Nagata C, Takatsuka N, Shimizu N, Shimizu H. Sodium intake and risk of death from stroke in Japanese men and women. Stroke. 2004 Jul;35(7):1543-7. doi: 10.1161/01.STR.0000130425.50441.b0. Epub 2004 May 13

National Heart Lung and Blood Institute, US DASH eating plan

https://www.nhlbi.nih.gov/health-topics/dash-eating-plan

NHS fact sheet; Live well Eat well https://www.nhs.uk/live-well/eat-well/what-are-reference-intakes-on-food-labels/

Paoli A, Rubini A, Volek JS, Grimaldi KA. Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets [published correction appears in Eur J Clin Nutr. 2014 May;68(5):641]. Eur J Clin Nutr. 2013;67(8):789-796. doi:10.1038/ejcn.2013.116

Samaha FF, Iqbal N, Seshadri P, Chicano KL, Daily DA, McGrory J, Williams T, Williams M, Gracely EJ, Stern L. A low-carbohydrate as compared with a low-fat diet in severe obesity. N Engl J Med. 2003 May 22;348(21):2074-81. doi: 10.1056/NEJMoa022637. PMID: 12761364.

Shirani F, Salehi-Abargouei A, Azadbakht L. Effects of Dietary Approaches to Stop Hypertension (DASH) diet on some risk for developing type 2 diabetes: a systematic review and meta-analysis on controlled clinical trials. Nutrition. 2013 Jul-Aug;29(7-8):939-47. doi: 10.1016/j.nut.2012.12.021

Soltani S, Arablou T, Jayedi A, Salehi-Abargouei A. Adherence to the dietary approaches to stop hypertension (DASH) diet in relation to all-cause and cause-specific mortality: a systematic review and dose-response meta-analysis of prospective cohort studies. Nutr J. 2020 Apr 22;19(1):37. doi: 10.1186/s12937-020-00554-8

Tsugane S, Sasazuki S. Diet and the risk of gastric cancer: review of epidemiological evidence. Gastric Cancer. 2007;10(2):75-83. doi: 10.1007/s10120-007-0420-0. Epub 2007 Jun 25. PMID: 17577615.

Tsugane S. Why has Japan become the world’s most long-lived country: insights from a food and nutrition perspective. Eur J Clin Nutr. 2020 Jul 13. doi: 10.1038/s41430-020-0677-5. Epub ahead of print. PMID: 32661353.

Umesawa M, Iso H, Date C, Yamamoto A, Toyoshima H, Watanabe Y, Kikuchi S, Koizumi A, Kondo T, Inaba Y, Tanabe N, Tamakoshi A; JACC Study Group. Relations between dietary sodium and potassium intakes and mortality from cardiovascular disease: the Japan Collaborative Cohort Study for Evaluation of Cancer Risks. Am J Clin Nutr. 2008 Jul;88(1):195-202. doi: 10.1093/ajcn/88.1.195

WHO: Statistics on non-communicable diseases https://www.who.int/news-room/fact-sheets/detail/noncommunicable-diseases

Willcox BJ, Willcox DC, Todoriki H, Fujiyoshi A, Yano K, He Q, Curb JD, Suzuki M. Caloric restriction, the traditional Okinawan diet, and healthy aging: the diet of the world’s longest-lived people and its potential impact on morbidity and life span. Ann N Y Acad Sci. 2007 Oct;1114:434-55. doi: 10.1196/annals.1396.037