How to fine-tune plant-based diets for longevity

Highlights

• Plant-based diets have to be adjusted for potential nutrient deficiencies in vitamin B12, omega-3 fatty acids, iron, calcium, zinc, iodine, and vitamin D, among the most common
• Plant-based protein is an excellent choice for longevity, and the overall protein quantity should be increased with age
• Adding a time constrain to plant-based diets can help further increase their ability to lower the risk of disease

Introduction

Plant-based diets such as vegetarian and vegan can be an excellent choice to increase a healthy lifespan. They are associated with lowering the risk of a variety of chronic diseases including obesity, type 2 diabetes, and cardiovascular disease. Plus, the amino acid composition of plant-based protein can be beneficial in aging. To take full advantage of these benefits, it is important to compensate for the nutritional weak points of plant-based diets. The right food choices, supplements, or strategic inclusion of animal-based foods can make plant-based diets sustainable over the long term. And with an added layer of food timing, plant-based diets can become a powerful tool for longevity.

Risks of deficiencies on plant-based diets

It is well established that the quality of the plant-based diet matters. Choosing whole and minimally processed foods as well as minimizing junk food is crucially important. But even with that in mind, reduction or absence of animal foods can lead to insufficiency or deficiency of several essential nutrients. Nutrient deficiencies can cause a variety of health problems that, when left unaddressed, would take away all the benefits of a well-formulated plant-based diet. The most common nutrients of concern are vitamin B12, omega-3 fatty acids, iron, calcium, zinc, iodine, and vitamin D.

Vitamin B12

Research shows that vegetarians and vegans are at a higher risk of deficiency in vitamin B12 than people who include meat in their diet (1). The only way to get this vitamin naturally from food is through animal products. Vegans who are unable to reach the recommended dietary allowance (RDA) for vitamin B12 using fortified foods (foods with added vitamins and minerals) should include a daily supplement providing 25–100 µg of cyanocobalamin or a weekly dosage of 2,000 µg. Vegetarians can source B12 from eggs and dairy, but should have its levels tested. The ability to absorb vitamin B12 also decreases with age. It is advised that everyone over the age of 51, regardless of diet, should consider fortified foods or a vitamin B12 supplement.

Omega-3 fatty acids

Studies consistently show that vegetarians and vegans have up to 50% lower blood and tissue concentrations of long-chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), than people who eat meat (2). This is likely because plants only contain short-chain omega-3 fatty acid, alpha-linolenic acid (ALA), that needs to be converted in the body to the beneficial long-chain forms. Research estimates that the conversion of ALA to EPA may be as low as 5%, while its conversion to DHA may be as low as 2% (3). The best plant sources of ALA include flax seeds, chia seeds, and walnuts while the best sources of EPA and DHA are fatty fish and fish oil. Vegans should consider supplementing with algae oil which is a source of EPA and DHA that does not involve animals.

Iron

Iron deficiency anemia is more prevalent among vegetarians compared to nonvegetarians, especially for premenopausal vegetarian women, as research suggests (4). Heme iron, a form of iron available in animal foods, is more easily absorbed than non-heme iron found in plants. For this reason, vegans should aim for 1,8 times the normal RDA of iron. Iron-rich plants include mainly cruciferous vegetables, beans, peas, dried fruit, nuts, and seeds. Iron-fortified foods can help as well. When it comes to supplements, it is important to note that excessive supplementation with iron can do more harm than good by damaging cells and blocking the absorption of other minerals. Practitioners should check hemoglobin and ferritin levels of clients before recommending supplements.

Calcium

Research suggests that vegans have higher fracture risk because of their considerably lower mean calcium intake. Fracture risk of meat eaters and vegetarians is similar probably due to inclusion of dairy, which is an excellent source of calcium (5). Good plant sources of calcium include kale, mustard greens, turnip greens, broccoli, chickpeas, and calcium-fortified foods. Vegans should consume at least 525 mg of calcium per day. Supplements should be recommended if this cannot be achieved through diet.

Zinc

A review study showed that vegetarians and vegans have lower zinc intakes and slightly lower blood levels of zinc than those who include meat (6). The issue is that not many plant foods are rich in zinc and its absorption from plant foods is lower. The best plant-based sources of zinc include legumes, nuts, seeds, and whole grains. Vegetarians and vegans should aim for 1,5 times the normal RDA of zinc. If they cannot hit this amount through their diet a daily zinc gluconate or zinc citrate supplement that provides 50–100% of the RDA should be used.

Iodine

Studies report that vegans have up to 50% lower blood iodine levels than vegetarians which puts them at a higher risk of deficiency (7). The only foods with consistently high iodine levels are dairy products, seafood, and seaweed. Some plants grown in soil near the ocean can have higher iodine levels but that is typically not reliable enough. Iodized salt is another way to increase iodine intake, only a half teaspoon per day is enough to meet daily demands. Vegans that do not eat seaweed several times per week and do not want to consume iodized salt should be recommended an iodine supplement.

Vitamin D

Vitamin D deficiency is not exclusive to plant-based diets. Research shows that it affects almost 50% of the population worldwide. An estimated 1 billion people across all ethnicities and age groups have a vitamin D deficiency (8). Fatty fish such as salmon, sardines, herring and mackerel, egg yolks, red meat, and fortified foods are the only foods that contain appreciable amounts of vitamin D. Unfortunately, even regular intake of these foods is not considered sufficient to cover daily vitamin D needs. The best way to prevent vitamin D deficiency is spending 15 minutes every day in the midday sun with exposed skin and without sunscreen. However, the following groups of people might not be able to produce enough vitamin D this way.

• the elderly
• people with darker skin
• people who live in colder climates and northern latitudes
• people who spend little or no time outdoors in the sun

People in these cohorts should be tested for vitamin D levels and supplement accordingly.

Protein intake optimization

Plant-based protein is lower in several amino acids such as lysine, tryptophan, leucine, or methionine. Consuming this type of protein influences several pathways and signaling proteins involved in regulating the aging and death of cells and their resistance to stress. We currently only have cellular and model organism research supporting these benefits. But if long-term studies confirm these effects in humans, then plant-based protein would be the perfect choice for longevity thanks to its amino acid composition.

The overall quantity of protein is also an important consideration. Research suggests that a low-protein diet in middle age is useful for preventing cancer and reducing mortality. However, this benefit is outweighed in older people by a risk of increased frailty and unwanted weight loss (9). Guidelines typically recommend a minimum of 0,8 g of protein per 1 kg of body weight for the general population. Studies suggest that for people over the age of 65 these guidelines should be increased to 1–1,2 g of protein per kilogram (10) to improve weight and muscle retention.

Time-constrained eating

Adding a time constraint to plant-based eating patterns can help further increase their ability to lower risk of disease. There are three types of approaches that introduce an element of fasting and by extension temporary calorie restriction. Research shows that all of these intermittent fasting patterns can counteract disease processes of age-related disorders (11) and promote healthy aging as a result. Applying time-constrained eating patterns should always be consulted with a physician.

• Time-restricted eating - Eating is limited to a number of hours each day. For example, this approach could include a 16-hour overnight fast followed by an 8-hour eating window between 8:00 and 16:00.
• Alternate day fasting - This approach would include a whole day of fasting or reduced energy intake is followed by a day of normal or increased energy intake.
• Periodic fasting - The fasting period with this approach lasts multiple days. A popular schedule includes 2 days of fasting followed by 5 days of normal eating.

Conclusion

Plant-based diets bring many benefits by reducing meat consumption and focusing on whole, minimally processed plant food. They can also pose a risk as people following plant-based diets are at an increased risk of deficiency in vitamin B12, omega-3 fatty acids, iron, calcium, zinc, and iodine. It is essential to prevent these to make plant-based diets sustainable over the long term. That combined with sufficient protein intake and time-constrained eating, make plant-based diets an excellent choice for everyone interested in healthy aging and longevity.

References

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2.       Angela V Saunders, Brenda C Davis, Manohar L Garg. Omega-3 polyunsaturated fatty acids and vegetarian diets. Med J Aust. 2013 Aug 19;199(S4):S22-6. doi: 10.5694/mja11.11507.

3.       Brenda C Davis, Penny M Kris-Etherton. Achieving optimal essential fatty acid status in vegetarians: current knowledge and practical implications. Am J Clin Nutr. 2003 Sep;78(3 Suppl):640S-646S. doi: 10.1093/ajcn/78.3.640S.

4.       Roman Pawlak, Julia Berger, Ian Hines. Iron Status of Vegetarian Adults: A Review of Literature. Am J Lifestyle Med. 2018 Nov-Dec; 12(6): 486–498. Published online 2016 Dec 16. doi:10.1177/1559827616682933

5.       P Appleby, A Roddam, N Allen, T Key. Comparative fracture risk in vegetarians and nonvegetarians in EPIC-Oxford. Eur J Clin Nutr. 2007 Dec;61(12):1400-6. doi: 10.1038/sj.ejcn.1602659. Epub 2007 Feb 7.

6.       Meika Foster, Anna Chu, Peter Petocz, Samir Samman. Effect of vegetarian diets on zinc status: a systematic review and meta-analysis of studies in humans. J Sci Food Agric. 2013 Aug 15;93(10):2362-71. doi: 10.1002/jsfa.6179.

7.       Angela M Leung, Andrew Lamar, Xuemei He, Lewis E Braverman, Elizabeth N Pearce. Iodine status and thyroid function of Boston-area vegetarians and vegans. J Clin Endocrinol Metab. 2011 Aug;96(8):E1303-7. doi: 10.1210/jc.2011-0256. Epub 2011 May 25.

8.       Rathish Nair, Arun Maseeh. Vitamin D: The “sunshine” vitamin. J Pharmacol Pharmacother. 2012 Apr-Jun; 3(2): 118–126. doi: 10.4103/0976-500X.95506

9.       Morgan E Levine, Jorge A Suarez, Sebastian Brandhorst, Priya Balasubramanian, Chia-Wei Cheng, Federica Madia et al. Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population. Cell Metab. 2014 Mar 4;19(3):407-17. doi: 10.1016/j.cmet.2014.02.006.

10.   Jürgen Bauer, Gianni Biolo, Tommy Cederholm, Matteo Cesari, Alfonso J Cruz-Jentoft, John E Morley et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc. 2013 Aug;14(8):542-59. doi: 10.1016/j.jamda.2013.05.021. Epub 2013 Jul 16.

11.   Mattson MP, Longo VD, Harvie M. Impact of intermittent fasting on health and disease processes. Ageing Res Rev. 2017 Oct;39:46-58. doi: 10.1016/j.arr.2016.10.005. Epub 2016 Oct 31.