Vegetarian Lifestyle

About & method

vegetarianlifestyle.org is a small, independent reference site with one tool: a calculator that shows how much of the key nutrients a vegetarian or vegan adult needs per day, where to get them from food, and when a supplement is the reliable route.

No accounts, no ads, no affiliate links, no product recommendations. The site does not sell anything.

What the calculator does

  1. You choose diet (lacto-ovo, lacto, ovo or vegan), sex, age group, body weight, and a reference system (US DRI or NNR 2023). Women aged 18–50 can add pregnancy (with trimester) or breastfeeding.
  2. It looks up the official adult reference value for each nutrient for that group. Nothing is estimated from your weight except protein (and, in NNR mode, the ALA gram figure, which uses the NNR reference energy intake).
  3. It applies a small set of fixed rules (below) for vegetarian adjustments, risk level and supplement advice.

Reference values

  • US DRI (default): Recommended Dietary Allowances (RDA) or Adequate Intakes (AI) from the National Academies (Institute of Medicine) Dietary Reference Intakes, as tabulated in the NIH Office of Dietary Supplements fact sheets.
  • NNR 2023: Recommended Intakes (RI) or Adequate Intakes (AI) from the Nordic Nutrition Recommendations 2023, Tables 11–15 and 21.

The exact figures used are listed on the sources page. The age group 70+ uses the US “>70 years” and NNR “>70 y” rows.

Vegetarian adjustments

  • Iron, US mode: RDA × 1.8. The NIH ODS iron fact sheet states that the iron requirement is 1.8 times higher for people who follow vegetarian diets, because non-heme iron from plants is less bioavailable.
  • Zinc, US mode: RDA × 1.5. The IOM zinc chapter (2001) states that the requirement for dietary zinc may be as much as 50% greater for vegetarians, especially where grains and legumes are staples.
  • NNR mode: the official figure is shown without any multiplier, together with a warning that plant iron and zinc are absorbed less well. NNR’s zinc values assume about 600 mg phytate per day; NNR notes that EFSA’s values for higher phytate intakes can be used for diets rich in whole grains and legumes.
  • Protein: 0.8 g/kg (US RDA) or 0.83 g/kg (NNR RI). From age 70 the calculator uses 1.2 g/kg in both modes — the NNR 2023 planning target for older adults (about 18 E%, “about 1.2 g protein per kg body weight per day”). The official US RDA for 70+ remains 0.8 g/kg and is shown next to it. Pregnancy: US 1.1 g/kg in the second half of pregnancy, lactation 1.3 g/kg; NNR adds 1 / 9 / 28 g per day by trimester and 19 g per day in the first 6 months of breastfeeding. For vegans the target is the same, with a note to aim a little higher and mix legumes and grains.
  • Omega-3: US mode shows the ALA adequate intake. NNR sets ALA at ≥0.5% of energy; the gram figure is calculated at the NNR reference energy intake for your group (Table 8, average activity) using 37 kJ per gram of fat. There is no official RDA for EPA + DHA.

Risk levels

“Risk of a gap” is a simple, fixed rating of how often this nutrient is hard to cover with the chosen diet. It is not a measure of your own status.

  • Protein: low; medium for vegans.
  • Vitamin B12: high for vegan and ovo; medium for lacto and lacto-ovo (high from age 51, when food-bound B12 is absorbed less well).
  • Iron: high for women 18–50 and in pregnancy; medium otherwise.
  • Zinc: medium for vegans; low otherwise.
  • Calcium: high for vegan and ovo (no dairy); low for lacto and lacto-ovo.
  • Vitamin D: medium for everyone (little sun at northern latitudes in winter).
  • Iodine: high for vegan and ovo; medium for lacto and lacto-ovo.
  • Omega-3: medium for vegans and in pregnancy/breastfeeding; low otherwise.
  • Selenium: medium for everyone.

Supplement advice

  • Yes — food alone is not a reliable route: B12 for vegans (supplement or fortified foods every day); iodine for vegan and ovo (iodized salt or a modest supplement).
  • Consider — depends on what you actually eat or on your situation: B12 for ovo, age 51+, pregnancy/breastfeeding or low dairy/egg intake; iron for women 18–50 and in pregnancy (preferably after a ferritin test / via maternity care); calcium for vegan and ovo without fortified foods or calcium-set tofu; vitamin D in winter; iodine in pregnancy/breastfeeding; algae oil if you want EPA/DHA.
  • No — food normally covers it; supplement only if a test shows a deficiency: protein, zinc, selenium, and the remaining cases.

Limitations

  • Adults only (18+). Not for children, teenagers, or people with medical conditions, malabsorption, bariatric surgery or on medication that affects nutrients.
  • Reference values are designed to cover nearly all healthy people in a group. Your own need may be lower or higher; only a clinician with a blood test can tell you your status.
  • The calculator does not know what you eat. It does not count calories or track meals.
  • US 70+ values use the “>70 years” rows; the NNR vitamin D value of 20 µg applies from age 75.

Found an error? Email info@vegetarianlifestyle.org. Last reviewed: September 2026.